Second harmonic generation in anisotropic stratified media: a generalization of the Berreman method and its application to photonic materials

We have developed a numerical method for calculating the second-harmonic generation (SHG) generated by an anisotropic material whose optical properties present an arbitrary modulation in one dimension. The method is based on the Berreman 4 × 4 matrix formalism, which is generalized to include nonlinear optical phenomena. It can be used under oblique incidences of the input beam, and is valid even when the SHG frequency is close to photonic bands, where the usual slowly-varying-amplitude approximation breaks down. As an example of application, we have studied the SHG performance of ferroelectric and helielectric fluids. The obtained results indicate that the present procedure may contribute to improving the structural design and enlarging the variety of nonlinear optical materials for application in optical devices.

Intestinal perforation after pediatric liver transplantation: risk factors and management

BACKGROUND

Intestinal perforation (IP) after pediatric liver transplant (PLT) is an uncommon complication with high mortality reported. The aim of this study is to identify the risk factors and management of this complication.

MATERIALS AND METHODS

Retrospective study of IP after PLT from January 2014 to October 2020.

RESULTS

Four intestinal perforations were indentificated in 102 PLT (3,9%). Three patients with BA and one neonate with hemochromatosis (HC) presented this complication. The mean weight of patients with IP was 6.3± 2.5kg (3.1-9) and 19.9 ± 15.4kg for the rest (p< 0.05). All IP with BA had a previous laparotomy. Two living donors and two left lateral reduced liver were implanted. The diagnosis of intestinal perforation was done on day 11 ± 3.3 (8-15 days). Diagnosis was suspected with clinical and biological signs of perforation, CT scan confirmed the diagnosis in patiens with BA and by direct visualization through the mesh for temporary closure in the patient with hemocromatosis. Urgent laparotomy was performed. We identified three colonic perforations, all of them in BA patients and all repaired with direct suture. The patient with HC presented multiple perforations secondary to necrotizing enterocolitis requiring an ileostomy and finally died due to multiorgan failure.

CONCLUSION

Intestinal perforation after PLT is an infrequent complication. Age, weight, previous laparotomy and BA could be risk factors for IP in PLT. Urgent laparotomy after diagnosis should be performed in order to reduce mortality. Isolated IP with adequate treatment might not affect long term outcomes after pediatric liver transplantation.

Cohort profile: the ESC EURObservational Research Programme Non-ST-segment elevation myocardial infraction (NSTEMI) Registry

AIMS

The European Society of Cardiology (ESC) EURObservational Research Programme (EORP) Non-ST-segment elevation myocardial infarction (NSTEMI) Registry aims to identify international patterns in NSTEMI management in clinical practice and outcomes against the 2015 ESC Guidelines for the management of acute coronary syndromes in patients presenting without ST-segment-elevation.

METHODS AND RESULTS

Consecutively hospitalised adult NSTEMI patients (n = 3620) were enrolled between 11 March 2019 and 6 March 2021, and individual patient data prospectively collected at 287 centres in 59 participating countries during a two-week enrolment period per centre. The registry collected data relating to baseline characteristics, major outcomes (in-hospital death, acute heart failure, cardiogenic shock, bleeding, stroke/transient ischaemic attack, and 30-day mortality) and guideline-recommended NSTEMI care interventions: electrocardiogram pre- or in-hospital, pre-hospitalization receipt of aspirin, echocardiography, coronary angiography, referral to cardiac rehabilitation, smoking cessation advice, dietary advice, and prescription on discharge of aspirin, P2Y12 inhibition, angiotensin converting enzyme inhibitor (ACEi)/angiotensin receptor blocker (ARB), beta-blocker, and statin.

CONCLUSION

The EORP NSTEMI Registry is an international, prospective registry of care and outcomes of patients treated for NSTEMI, which will provide unique insights into the contemporary management of hospitalised NSTEMI patients, compliance with ESC 2015 NSTEMI Guidelines, and identify potential barriers to optimal management of this common clinical presentation associated with significant morbidity and mortality.

The influence of anastomotic techniques on postoperative anastomotic complications: Results of the Oesophago-Gastric Anastomosis Audit

BACKGROUND

The optimal anastomotic techniques in esophagectomy to minimize rates of anastomotic leakage and conduit necrosis are not known. The aim of this study was to assess whether the anastomotic technique was associated with anastomotic failure after esophagectomy in the international Oesophago-Gastric Anastomosis Audit cohort.

METHODS

This prospective observational multicenter cohort study included patients undergoing esophagectomy for esophageal cancer over 9 months during 2018. The primary exposure was the anastomotic technique, classified as handsewn, linear stapled, or circular stapled. The primary outcome was anastomotic failure, namely a composite of anastomotic leakage and conduit necrosis, as defined by the Esophageal Complications Consensus Group. Multivariable logistic regression modeling was used to identify the association between anastomotic techniques and anastomotic failure, after adjustment for confounders.

RESULTS

Of the 2238 esophagectomies, the anastomosis was handsewn in 27.1%, linear stapled in 21.0%, and circular stapled in 51.9%. Anastomotic techniques differed significantly by the anastomosis sites (P < .001), with the majority of neck anastomoses being handsewn (69.9%), whereas most chest anastomoses were stapled (66.3% circular stapled and 19.3% linear stapled). Rates of anastomotic failure differed significantly among the anastomotic techniques (P < .001), from 19.3% in handsewn anastomoses, to 14.0% in linear stapled anastomoses, and 12.1% in circular stapled anastomoses. This effect remained significant after adjustment for confounding factors on multivariable analysis, with an odds ratio of 0.63 (95% CI, 0.46-0.86; P = .004) for circular stapled versus handsewn anastomosis. However, subgroup analysis by anastomosis site suggested that this effect was predominantly present in neck anastomoses, with anastomotic failure rates of 23.2% versus 14.6% versus 5.9% for handsewn versus linear stapled anastomoses versus circular stapled neck anastomoses, compared with 13.7% versus 13.8% versus 12.2% for chest anastomoses.

CONCLUSIONS

Handsewn anastomoses appear to be independently associated with higher rates of anastomotic failure compared with stapled anastomoses. However, this effect seems to be largely confined to neck anastomoses, with minimal differences between techniques observed for chest anastomoses. Further research into standardization of anastomotic approach and techniques may further improve outcomes.

Antithrombotic Treatment after Carotid Stenting in Patients with Concomitant Atrial Fibrillation

BACKGROUND AND PURPOSE

Antithrombotic therapy following carotid artery stent placement with concomitant atrial fibrillation is not well-established. Our aim was to assess the safety and efficacy of the combination of direct oral anticoagulants and a P2Y12 inhibitor at 30 days after carotid artery stent placement in patients with atrial fibrillation.

MATERIALS AND METHODS

We designed an observational single-center study including patients who underwent carotid artery stent placement with concomitant atrial fibrillation. We studied 3 groups according to antithrombotic therapy: 1) the direct oral anticoagulants plus clopidogrel (DC) group: receiving direct oral anticoagulants plus a P2Y12 inhibitor; 2) the triple therapy group: anticoagulation and dual antiplatelet therapy; and 3) the dual antiplatelet therapy group: following dual antiplatelet therapy alone. The safety outcome was a major or clinically relevant non-major bleeding event at the first month. The efficacy outcomes were the thromboembolic events (myocardial infarction, stroke, systemic embolism, or stent thrombosis).

RESULTS

Of 959 patients with carotid artery stent placement, 91 met the inclusion criteria, including 24 patients in the DC group, 42 patients in the triple therapy group, and 25 in the dual antiplatelet therapy group. The mean age was 72.27 (SD, 8.1 ) years, with similar baseline characteristics. The median CHA₂DS₂-VASc score for each group was 6 (interquartile range  = 5-6), 5 (interquartile range = 4-6), and 5 (interquartile range = 4-6), respectively. The median HAS-BLED score was 4 in the 3 groups (P = .17). The primary safety end point was 23.8% in the triple therapy group compared with 4% in the dual antiplatelet therapy group (P = .032), with no bleeding events in the DC group (P = .007). There was 1 stent thrombosis in DC group and a cardioembolic stroke in the dual antiplatelet therapy group (P = .41).

CONCLUSIONS

Among patients with carotid artery stent placement with atrial fibrillation, triple therapy confers a high bleeding risk. A regimen of direct oral anticoagulants plus a P2Y12 inhibitor might confer a good safety profile with significantly lower rates of bleeding and optimal efficacy.

Textbook outcome following oesophagectomy for cancer: international cohort study

Background

Textbook outcome has been proposed as a tool for the assessment of oncological surgical care. However, an international assessment in patients undergoing oesophagectomy for oesophageal cancer has not been reported. This study aimed to assess textbook outcome in an international setting.

Methods

Patients undergoing curative resection for oesophageal cancer were identified from the international Oesophagogastric Anastomosis Audit (OGAA) from April 2018 to December 2018. Textbook outcome was defined as the percentage of patients who underwent a complete tumour resection with at least 15 lymph nodes in the resected specimen and an uneventful postoperative course, without hospital readmission. A multivariable binary logistic regression model was used to identify factors independently associated with textbook outcome, and results are presented as odds ratio (OR) and 95 per cent confidence intervals (95 per cent c.i.).

Results

Of 2159 patients with oesophageal cancer, 39.7 per cent achieved a textbook outcome. The outcome parameter ‘no major postoperative complication’ had the greatest negative impact on a textbook outcome for patients with oesophageal cancer, compared to other textbook outcome parameters. Multivariable analysis identified male gender and increasing Charlson comorbidity index with a significantly lower likelihood of textbook outcome. Presence of 24-hour on-call rota for oesophageal surgeons (OR 2.05, 95 per cent c.i. 1.30 to 3.22; P = 0.002) and radiology (OR 1.54, 95 per cent c.i. 1.05 to 2.24; P = 0.027), total minimally invasive oesophagectomies (OR 1.63, 95 per cent c.i. 1.27 to 2.08; P &lt; 0.001), and chest anastomosis above azygous (OR 2.17, 95 per cent c.i. 1.58 to 2.98; P &lt; 0.001) were independently associated with a significantly increased likelihood of textbook outcome.

Conclusion

Textbook outcome is achieved in less than 40 per cent of patients having oesophagectomy for cancer. Improvements in centralization, hospital resources, access to minimal access surgery, and adoption of newer techniques for improving lymph node yield could improve textbook outcome.

Textbook outcome following oesophagectomy for cancer: international cohort study

BACKGROUND

Textbook outcome has been proposed as a tool for the assessment of oncological surgical care. However, an international assessment in patients undergoing oesophagectomy for oesophageal cancer has not been reported. This study aimed to assess textbook outcome in an international setting.

METHODS

Patients undergoing curative resection for oesophageal cancer were identified from the international Oesophagogastric Anastomosis Audit (OGAA) from April 2018 to December 2018. Textbook outcome was defined as the percentage of patients who underwent a complete tumour resection with at least 15 lymph nodes in the resected specimen and an uneventful postoperative course, without hospital readmission. A multivariable binary logistic regression model was used to identify factors independently associated with textbook outcome, and results are presented as odds ratio (OR) and 95 per cent confidence intervals (95 per cent c.i.).

RESULTS

Of 2159 patients with oesophageal cancer, 39.7 per cent achieved a textbook outcome. The outcome parameter 'no major postoperative complication' had the greatest negative impact on a textbook outcome for patients with oesophageal cancer, compared to other textbook outcome parameters. Multivariable analysis identified male gender and increasing Charlson comorbidity index with a significantly lower likelihood of textbook outcome. Presence of 24-hour on-call rota for oesophageal surgeons (OR 2.05, 95 per cent c.i. 1.30 to 3.22; P = 0.002) and radiology (OR 1.54, 95 per cent c.i. 1.05 to 2.24; P = 0.027), total minimally invasive oesophagectomies (OR 1.63, 95 per cent c.i. 1.27 to 2.08; P < 0.001), and chest anastomosis above azygous (OR 2.17, 95 per cent c.i. 1.58 to 2.98; P < 0.001) were independently associated with a significantly increased likelihood of textbook outcome.

CONCLUSION

Textbook outcome is achieved in less than 40 per cent of patients having oesophagectomy for cancer. Improvements in centralization, hospital resources, access to minimal access surgery, and adoption of newer techniques for improving lymph node yield could improve textbook outcome.

Effect of the topical administration of corticosteroids and tuberculin pre-sensitisation on the diagnosis of tuberculosis in goats

Background

Caprine tuberculosis (TB) is a zoonosis caused by members of the Mycobacterium tuberculosis complex (MTBC). Caprine TB control and eradication programmes have traditionally been based on intradermal tuberculin tests and slaughterhouse surveillance. However, this strategy has limitations in terms of sensitivity and specificity. Different factors may affect the performance of the TB diagnostic tests used in goats and, subsequently, the detection of TB-infected animals. In the present study, the effect of two of the factors that may affect the performance of the techniques used to diagnose TB in goats, the topical administration of corticosteroids and a recent pre-sensitisation with tuberculin, was analysed.

Methods

The animals (n = 151) were distributed into three groups: (1) a group topically treated with corticosteroids 48 h after intradermal tuberculin tests (n = 53); (2) a group pre-sensitised with bovine and avian purified protein derivatives (PPDs) 3 days before the intradermal tuberculin test used for TB diagnosis (n = 48); and (3) a control group (n = 50). All the animals were tested using single and comparative intradermal tuberculin (SIT and CIT, respectively) tests, an interferon-gamma release assay (IGRA) and a P22 ELISA.

Results

The number of SIT test reactors was significantly lower in the group treated with corticosteroids when compared to the pre-sensitised (p < 0.001) and control (p = 0.036) groups. In contrast, pre-sensitisation with bovine and avian PPDs did not cause a significant reduction in the number of SIT and CIT test reactors compared with the control group. In fact, a higher number of reactors was observed after the prior tuberculin injection in the pre-sensitised group (p > 0.05). No significant effect was observed on IGRA and P22 ELISA due to corticosteroids administration. Nevertheless, a previous PPD injection affected the IGRA performance in some groups.

Conclusions

The application of topical corticosteroid 24 h before reading the SIT and CIT tests can reduce the increase in skin fold thickness and subsequently significantly decrease the number of positive reactors. Corticosteroids used can be detected in hair samples. A previous pre-sensitisation with bovine and avian PPDs does not lead to a significant reduction in the number of intradermal tests reactors. These results are valuable in order to improve diagnosis of caprine TB and detect fraudulent activities in the context of eradication programs.

Postoperative outcomes in oesophagectomy with trainee involvement

BACKGROUND

The complexity of oesophageal surgery and the significant risk of morbidity necessitates that oesophagectomy is predominantly performed by a consultant surgeon, or a senior trainee under their supervision. The aim of this study was to determine the impact of trainee involvement in oesophagectomy on postoperative outcomes in an international multicentre setting.

METHODS

Data from the multicentre Oesophago-Gastric Anastomosis Study Group (OGAA) cohort study were analysed, which comprised prospectively collected data from patients undergoing oesophagectomy for oesophageal cancer between April 2018 and December 2018. Procedures were grouped by the level of trainee involvement, and univariable and multivariable analyses were performed to compare patient outcomes across groups.

RESULTS

Of 2232 oesophagectomies from 137 centres in 41 countries, trainees were involved in 29.1 per cent of them (n = 650), performing only the abdominal phase in 230, only the chest and/or neck phases in 130, and all phases in 315 procedures. For procedures with a chest anastomosis, those with trainee involvement had similar 90-day mortality, complication and reoperation rates to consultant-performed oesophagectomies (P = 0.451, P = 0.318, and P = 0.382, respectively), while anastomotic leak rates were significantly lower in the trainee groups (P = 0.030). Procedures with a neck anastomosis had equivalent complication, anastomotic leak, and reoperation rates (P = 0.150, P = 0.430, and P = 0.632, respectively) in trainee-involved versus consultant-performed oesophagectomies, with significantly lower 90-day mortality in the trainee groups (P = 0.005).

CONCLUSION

Trainee involvement was not found to be associated with significantly inferior postoperative outcomes for selected patients undergoing oesophagectomy. The results support continued supervised trainee involvement in oesophageal cancer surgery.

Multicenter Retrospective Registry of Anterior Communicating Artery Aneurysms with Endovascular Therapy (MACAARET): safety and efficacy study according to morphological considerations and spatial orientations

AIM

To analyse the safety and efficacy parameters of endovascular treatment of anterior communicating artery (ACoA) aneurysms, according to their morphological considerations and three-dimensional orientation in a multicentric registry.

MATERIALS AND METHODS

A retrospective analysis was undertaken of a prospective database of consecutive patients that underwent endovascular embolisation for ACoA aneurysm in four high-volume neuroradiology interventional departments. The study has been registered in ClinicalTrial.gov. Data were collected regarding the clinico-demographic variables of the patients, anatomical variations of the circle of Willis, morphological considerations and spatial orientation of ACoA aneurysms were recorded. Safety and efficacy variables were also recorded. Associations between anatomical variations of the circle of Willis, morphological considerations, and spatial orientation of the ACoA aneurysms and safety and efficacy variables were assessed.

RESULTS

Data from 122 consecutive patients were collected in the MACAARET study (mean age (±SD) was 55 (±14) and 50.8% (62/122) were male). One hundred and five patients (86.1%) presented with subarachnoid haemorrhage (SAH). ACoA aneurysms with a neck size of >4 mm had less chance of having successful endovascular treatment than those of ≤4 mm (19.8% versus 46.7%; p=0.002) and were also more likely to recanalise during follow-up (61.5% versus 19.5%; p=0.003). Moreover, ACoA aneurysms with an aspect ratio of >1.7 had more chance of having immediate therapeutic success than those with a ratio of ≤1.7 (70.7% versus 44.8%; p=0.012). There were no other associations between the anatomical variables of the ACoA aneurysms and the safety-efficacy variables.

CONCLUSION

ACoA aneurysms are suitable for both endovascular and microsurgical approaches, but more data are required to determine which is the best approach regarding the morphological and spatial orientation of the aneurysm and the anatomical variations of the circle of Willis.

Mortality from esophagectomy for esophageal cancer across low, middle, and high-income countries: An international cohort study

BACKGROUND

No evidence currently exists characterising global outcomes following major cancer surgery, including esophageal cancer. Therefore, this study aimed to characterise impact of high income countries (HIC) versus low and middle income countries (LMIC) on the outcomes following esophagectomy for esophageal cancer.

METHOD

This international multi-center prospective study across 137 hospitals in 41 countries included patients who underwent an esophagectomy for esophageal cancer, with 90-day follow-up. The main explanatory variable was country income, defined according to the World Bank Data classification. The primary outcome was 90-day postoperative mortality, and secondary outcomes were composite leaks (anastomotic leak or conduit necrosis) and major complications (Clavien-Dindo Grade III - V). Multivariable generalized estimating equation models were used to produce adjusted odds ratios (ORs) and 95% confidence intervals (CI95%).

RESULTS

Between April 2018 to December 2018, 2247 patients were included. Patients from HIC were more significantly older, with higher ASA grade, and more advanced tumors. Patients from LMIC had almost three-fold increase in 90-day mortality, compared to HIC (9.4% vs 3.7%, p < 0.001). On adjusted analysis, LMIC were independently associated with higher 90-day mortality (OR: 2.31, CI95%: 1.17-4.55, p = 0.015). However, LMIC were not independently associated with higher rates of anastomotic leaks (OR: 1.06, CI95%: 0.57-1.99, p = 0.9) or major complications (OR: 0.85, CI95%: 0.54-1.32, p = 0.5), compared to HIC.

CONCLUSION

Resections in LMIC were independently associated with higher 90-day postoperative mortality, likely reflecting a failure to rescue of these patients following esophagectomy, despite similar composite anastomotic leaks and major complication rates to HIC. These findings warrant further research, to identify potential issues and solutions to improve global outcomes following esophagectomy for cancer.

POS0821 THE DIFFERENT SUBTYPES OF GIANT CELL ARTERITIS BY ULTRASOUND: RESULTS FROM A FAST-TRACK CLINIC

Background:

Giant cell arteritis (GCA) is a vasculitis that affects the medium and large vessels (LV). Although cranial artery involvement is better known, awareness of the importance of LV involvement is increasing. Imaging techniques currently constitute the basis for the diagnosis of LV-GCA and have improved its diagnosis and prevalence. In recent years, differences in clinical patterns and different inflammatory and etiopathogenic mechanisms of the disease have been suggested. Therefore, improving sensitivity to diagnosis is essential to improve the knowledge and care of our population.

Objectives:

The aim of this study was to know the prevalence of the different ultrasound patterns of GCA in our area.

Methods:

Retrospective records of available data were collected from all patients referred to our ACG fast track clinic in the past three years. The clinical and laboratory characteristics were evaluated at the time of referral. All patients underwent an ultrasound scan of cranial vessels (superficial temporal arteries (TA) and their frontal and parietal branches) and large vessels (axillary, subclavian and carotid arteries). The doctor confirmed the GCA diagnosis after at least six months of follow-up. The OMERACT definitions of halo sign with a hypoechoic wall thickness ≥ 0.34 mm were used for TA pathology for the ultrasound diagnosis of GCA and for axillary, subclavian and carotid arteries and homogeneous hypoechoic thicknesses ≥ 1 mm of the arterial wall were applied. Atherosclerosis lesions were evaluated to detect this disease as a possible false positive halo sign. An Esaote Mylab Twice with a 13 MHz probe in BT and 22 MHz for cranial vessels in 2017-2019 and an Esaote Mylab X8plus with a 15 MHz probe for BT and a 24 MHz probe for cranial arteries in 2019-2020 were used by two rheumatologist with long experience in ACG ultrasound.

Results:

A total of 261 patients (180 women / 81 men) with suspected GCA were evaluated in our fast track clinic. The mean age (± SD) was 76 ± 9.2 years and CRP at diagnosis was 75.7 ± 68.6 mg/L. The time elapsed since the first symptoms was less than 6, 6-12, 12-24 or >24 weeks in 37.5%, 19.9%, 12.3% and 15.7% respectively. Of the 261 cases explored, 160 had GCA, of which 102 were women and 58 men, and had a mean age of 77.21 ± 7.9 years. The ultrasound patterns of GCA were: 71 patients had exclusive involvement of the TA (cranial-GCA), 54 had a mixed pattern with involvement of both TA and LV (mixed-CGA), and 35 had isolated involvement of the LV (LV-GCA). That is, 125 patients had cranial involvement with or without LV involvement and 89 had LV-GCA associated or not with cranial involvement (Figure 1).

Figure 1.

Ultrasound patters of GCA

Conclusion:

Ultrasound is a useful tool for the screening of GCA and its different subtypes of vascular involvement. The isolated cranial subtype or associated with LV-GCA is the most common (78% of cases), but LV-GCA is also very common (55.6% of cases of GCA) and 21.9% presents as an isolated LV-GCA standard. The LV arteries should be included in the ultrasound examination for suspected GCA.

Disclosure of Interests:

Irene Monjo Speakers bureau: Roche, Novartis, UCB, Gedeon Richter, Consultant of: Roche, Elisa Fernández-Fernández: None declared, Javier Ortega: None declared, Eugenio de Miguel Speakers bureau: AbbVie, Novartis, Pfizer, MSD, BMS, UCB, Roche, Grunental, Janssen, Sanofi, Paid instructor for: Janssen, Novartis, Roche, Consultant of: AbbVie, Novartis, Pfizer, Galapagos, Grant/research support from: Abbvie, Novartis, Pfizer

AB0378 UTILITY AND ACCURACY OF SOUTHEND PRETEST PROBABILITY SCORE IN GCA FAST-TRACK CLINIC: ANALYSIS IN 261 CONSECUTIVE PATIENTS

Background:

Strategies for early diagnosis of Giant Cell Arteritis (GCA) have been implemented in the last decade in order to reduce the occurrence of blindness, ischemic events and other manifestations of the disease. The Southend pretest probability score (SPTPS) 1 seem to be useful in stratifying and select the referral patients sent to the GCA fast-track clinics.

Objectives:

The aim of this study was to test the validity and utility of this score in our patients.

Methods:

Retrospective available data records of all the patients referred to our GCA fast-track clinic in the last three years were collected. The clinical and laboratory features at referral were evaluated, and the SPTPS was generated. All patients had ultrasound of cranial and large vessel examination (axillary, subclavian and carotid arteries). GCA diagnosis was confirmed by the doctor after at least six months of follow-up. Quartile frequencies, ROC curves and accuracy of the SPTPS was calculated.

Results:

261 patients (180 females) with suspicions of GCA were evaluated in our fast-track clinic. Mean age (±SD) was 76±9.2 years, and C-reactive protein 75.7±68.6 mg/l. The time since the first symptoms was less of 6, 6-12, 12-24 or >24 weeks in 37.5%, 19.9, 12.3 and 15.7 respectively. Mean SPTPS was 11.4±4.4, with values of 9.1±3.2 and 12.9±4.4. The area under the ROC curve was 0.761 (95% confidence interval: 0.703-0.819). PTPS overall showed a 50th percentile score of 11 and a 75th percentile score of 14. We, therefore, classified “Low Risk” (LR) as SPTPS <11, “Intermediate Risk” (IR) 11–14 and “High Risk” (HR) >14. Of 261 referrals, 156 had GCA with cases categorised as LR (119), IR (91) and HR (51). HR score showed a specificity of 96.2% and in IR the specificity ranged between 86.7 and 94.3% (Table 1). Score below 7 appears in 29 cases with only 8 cases of GCA with a probability of GCA < 5%, more of these cases was associated a large vessel vasculitis: 3 cranial arteritis (CA), 4 large vessel vasculitis (LVV) and 1 mixed pattern (MP). LR score included 72 of the 105 (68.6%) non-GCA cases but 47 of 156 (30.1%) GCA patients (20 CA, 11 LVV and 16 MP). IR risk score included 26 (24.8%) of the non-GCA cases and 65 (41.7%) of GCA patients (31 CA, 13 LVV and 21 MP). Finally HR score had only 7 non-GCA cases and 44 (28.2%) patients with GCA (20 CA, 11 LVV and 13 MP). Mean score in cranial forms was 13.1±4.5 and in large vessel vasculitis 12.8±5.0 (p=0.807).

Table 1.

Sensitivity and Specificity of SPTPS at different cut-off points

Cut-off pointSensitivity1-Specificity21.0001.0003.50.9940.9714.50.9870.9435.50.9870.8766.50.949 0.7907.50.8970.6768.50.8460.4769.50.7500.36210.50.6790.24811.50.5380.13312.50.4490.08613.50.3530.05714.50.2180.03815.50.1470.01916.50.1280.01917.50.0770.010190.0380,00020.50.0320,00021.50.0190,00022.50.0130,000240.0000,000

Conclusion:

The SPTPS is helpful to stratified patients sent to the fast-track clinic. Scores below of 7 points has a very low probability to have GCA. The diagnostic probability increases directly with the score. There were minor differences without statistical significance between cranial or large vessel vasculitis patterns in the score.

References:

[1]Sebastian A, Tomelleri A, Kayani A, Prieto-Pena D, Ranasinghe C, Dasgupta B. Probability-based algorithm using ultrasound and additional tests for suspected GCA in a fast-track clinic. RMD Open. 2020 Sep;6(3):e001297. doi: 10.1136/rmdopen-2020-001297. PMID: 32994361; PMCID: PMC7547539.

Disclosure of Interests:

Javier Ortega: None declared, Irene Monjo Speakers bureau: Roche, Novartis, UCB, Gedeon Richter, Consultant of: Roche, Elisa Fernández-Fernández: None declared, Eugenio de Miguel Speakers bureau: AbbVie, Novartis, Pfizer, MSD, BMS, UCB, Roche, Grunental, Janssen, Sanofi., Paid instructor for: Janssen, Novartis, Roche, Consultant of: AbbVie, Novartis, Pfizer, Galapagos, Grant/research support from: Abbvie, Novartis, Pfizer

Comparison of short-term outcomes from the International Oesophago-Gastric Anastomosis Audit (OGAA), the Esophagectomy Complications Consensus Group (ECCG), and the Dutch Upper Gastrointestinal Cancer Audit (DUCA)

BACKGROUND

The Esophagectomy Complications Consensus Group (ECCG) and the Dutch Upper Gastrointestinal Cancer Audit (DUCA) have set standards in reporting outcomes after oesophagectomy. Reporting outcomes from selected high-volume centres or centralized national cancer programmes may not, however, be reflective of the true global prevalence of complications. This study aimed to compare complication rates after oesophagectomy from these existing sources with those of an unselected international cohort from the Oesophago-Gastric Anastomosis Audit (OGAA).

METHODS

The OGAA was a prospective multicentre cohort study coordinated by the West Midlands Research Collaborative, and included patients undergoing oesophagectomy for oesophageal cancer between April and December 2018, with 90 days of follow-up.

RESULTS

The OGAA study included 2247 oesophagectomies across 137 hospitals in 41 countries. Comparisons with the ECCG and DUCA found differences in baseline demographics between the three cohorts, including age, ASA grade, and rates of chronic pulmonary disease. The OGAA had the lowest rates of neoadjuvant treatment (OGAA 75.1 per cent, ECCG 78.9 per cent, DUCA 93.5 per cent; P < 0.001). DUCA exhibited the highest rates of minimally invasive surgery (OGAA 57.2 per cent, ECCG 47.9 per cent, DUCA 85.8 per cent; P < 0.001). Overall complication rates were similar in the three cohorts (OGAA 63.6 per cent, ECCG 59.0 per cent, DUCA 62.2 per cent), with no statistically significant difference in Clavien-Dindo grades (P = 0.752). However, a significant difference in 30-day mortality was observed, with DUCA reporting the lowest rate (OGAA 3.2 per cent, ECCG 2.4 per cent, DUCA 1.7 per cent; P = 0.013).

CONCLUSION

Despite differences in rates of co-morbidities, oncological treatment strategies, and access to minimal-access surgery, overall complication rates were similar in the three cohorts.

Tuberculosis caused by Mycobacterium caprae in a camel (Camelus dromedarius)

BACKGROUND

Animal tuberculosis (TB) is distributed worldwide and has a wide range of wild and domestic reservoirs. Few studies concerning TB in camelids have been published in the last decade, particularly as regards Old World Camelids (OWC), but the increase in reports of TB outbreaks in these species in recent years suggests a high susceptibility to the infection.

CASE PRESENTATION

We studied a dromedary camel (Camelus dromedarius) herd (n = 24) in which a Mycobacterium caprae infection was detected. The TB infection was confirmed in one animal at necropsy through the detection of TB lesions, mainly in the abdominal organs, and the subsequent isolation of M. caprae (SB0157 spoligotype). The whole herd was additionally tested using cellular and humoral based diagnostic techniques. The intradermal tuberculin test results were compared with those obtained using P22 ELISA for the detection of specific antibodies against the M. tuberculosis complex. The TB infected animal was a positive reactor to both the intradermal tuberculin tests and P22 ELISA, while the others were negative to all the diagnostic tests.

CONCLUSION

The present study found M. caprae infection in OWC. This is the first report of M. caprae infection in an OWC not living in a zoo. Since the animal was born in the herd and fed with goat's milk, this practice was suspected to be the potential source of TB infection, which was not confirmed in the other animals present in the herd. Moreover, our results highlight that the intradermal tuberculin test and the P22 ELISA could be valuable tools for the diagnosis of TB in OWC.

Reduction of the Carbapenemase Inactivation Method (CIM) assay time by real-time PCR

Carbapenemase Inactivation Method (CIM) is a test to detect presence of the carbapenemase in Gram-negative bacteria. Determination of the carbapenemase production by inactivation of meropenem requires that a zone of control E. coli inhibition be measured approximately 6-24 h after plating. We have modified the CIM test by developing a rapid method which instead measures the growth of E. coli indicator strain ATCC 25922 using real-time PCR, referred to as a nucleic acid testing CIM (natCIM). Our natCIM, therefore reduces the detecting time from 6 to 24 h to approximately 4 h.

Oral trichomonosis: Description and severity of lesions in birds in Spain

Avian trichomonosis is a parasitic disease caused by the flagellated protozoan Trichomonas gallinae. Columbiformes are the reservoir host of the parasite, with high levels of infection, but also other domestic and wild birds from a variety of orders are susceptible to the infection and development of gross lesions. In this paper we describe the type and severity of lesions in wild birds in four avian orders (Accipitriformes, Falconiformes, Strigiformes and Columbiformes). A total of 94 clinical cases diagnosed of trichomonosis were selected for the categorization of their lesions in the upper digestive tract. The affected birds were classified into three different categories (mild, moderate and severe) based on size (in relation to the tracheal opening), depth and location of the lesions. Mild cases are those with small and superficial lesions far from the oropharyngeal opening; moderate cases possess larger and deeper lesions, and severe cases very large and deep lesions that impede swallowing or affect the skull. Mild lesions were found in 10.6 % of cases; moderate lesions were observed in 18.1 % of the birds and severe lesions in 71.3 %. Treatment outcomes in birds with either mild or moderate lesions were favorable, while severe lesions were related to poor body score, leading to death or euthanasia in most cases. A relationship between severe lesions and avian order was found, with a higher percentage of birds with this type in Falconiformes, Columbiformes and Strigiformes. Multifocal lesions were more frequent in Columbiformes and Falconiformes. In Strigiformes, 93.3 % of birds showed lesions in the upper jaw. This study seeks to further understanding of avian trichomonosis and to provide information that will be useful to veterinarians and related professionals for assessment, prognosis and treatment choice for these birds.

Coupled Sublattice Melting and Charge-Order Transition in Two Dimensions

Two-dimensional melting is one of the most fascinating and poorly understood phase transitions in nature. Theoretical investigations often point to a two-step melting scenario involving unbinding of topological defects at two distinct temperatures. Here, we report on a novel melting transition of a charge-ordered K-Sn alloy monolayer on a silicon substrate. Melting starts with short-range positional fluctuations in the K sublattice while maintaining long-range order, followed by longer-range K diffusion over small domains, and ultimately resulting in a molten sublattice. Concomitantly, the charge order of the Sn host lattice collapses in a multistep process with both displacive and order-disorder transition characteristics. Our combined experimental and theoretical analysis provides a rare insight into the atomistic processes of a multistep melting transition of a two-dimensional materials system.

A robust approach to ab initio cryo-electron microscopy initial volume determination

Structural information from macromolecules provides key insights into the way complexes perform their biological functions. The reconstruction process leading to the final three-dimensional (3D) map is iterative and requires an initial volume to prime the refinement procedure. Particle images are aligned to this first reference and subsequently a new map is calculated from these particles. The accurate determination of an ab initio initial volume is still a challenging and open problem in cryo-electron microscopy (cryo-EM). Different algorithms are available to estimate an initial volume from the dataset. Some of these methods provide multiple candidate initial maps and users looking for robustness typically run different approaches. In this case, users arbitrarily evaluate the different obtained candidate maps, as we lack robust methods to objectively assess the accuracy of initial references. This workflow is subjective and error-prone preventing implementation of high-throughput data processing procedures. In this work, we present a robust method to determine the best initial map or maps from a set of ab initio initial volumes obtained from one or multiple different approaches. The method is based on evaluating multiple small subsets of candidate initial volumes and particle images through reference-based 3D classifications. Obtained 3D classes of accurate initial maps will result majoritarian and the respective attracted particles will be aligned with high angular accuracies. We have tested the proposed approach with structurally homogeneous and heterogeneous datasets providing satisfactory results with both type of data.

[Arthroscopic treatment of chronic lateral epicondylitis. Short-term results of 3 cases]

OBJECTIVE

To assess the outcome of arthroscopic release in three patients with chronical lateral epicondylitis.

MATERIAL AND METHODS

Arthroscopic release in three patients with lateral epicondylitis is performed. Mayo Clinic scale for evaluation of results is used. A review and discussion of the literature is made.

RESULTS

Three patients, two female and one male, the common activities was principal labors, not athletes. Patients had significant pain. It was the principal symptom that affect the score of the rating scale. These scores improved after surgery. It was achieved early return to normal daily activities. No neurological complications were reported.

DISCUSSION

Arthroscopic treatment was an alternative safe and effective for treating chronical lateral epicondilitis in this three cases. It allows simultaneous joint exploration for diagnostic purposes and to treat associated pathologies. Broader Series and studies are necessary in order to establish definitive protocols in our cases.

83 Effect of Synchronization Treatment and Estrus Expression on Conception Rates and Pregnancy Losses in Recipients Receiving In Vitro-Produced Embryos

The objective of this study was to evaluate the effect of synchronization treatment and oestrus expression on conception rates and pregnancy losses in recipients receiving in vitro-produced (IVP) embryos. Crossbred beef cows (n = 407) with a corpus luteum (CL) determined by ultrasonography and body condition between 2.5 and 4.5 (1 to 5 scale) received a progesterone-releasing device (DIB 0.5 g, Zoetis, Argentina) and 2 mg of oestradiol benzoate (EB, Gonadiol, Zoetis) on Day 0 and were randomly allocated to 1 of 2 treatments. Recipients in the Conventional group (n = 201) had their devices removed and received 500 µg of cloprostenol (PGF, Ciclase, Zoetis), 0.5 mg of oestradiol cypionate (ECP, Cipiosyn, Zoetis), and 400 IU of eCG (Novormón, Zoetis) on Day 8. Recipients in the J-Synch group (n = 206) had their devices removed and received PGF and eCG on Day 6. All recipients were tail-painted at device removal to determine the presence of oestrus on Day 10 (a.m.) in the Conventional group and on Day 9 (a.m.) in the J-Synch group. All recipients not in oestrus in both groups received 100 µg of gonadorelin (GnRH, Ovurelin, Bayer, New Zealand) at that time. In addition, the paint was observed again in the p.m. and it was recorded. Recipients were examined by ultrasonography 7 days after oestrus or GnRH treatment (Day 16 in the J-Synch group and Day 17 in the Conventional group) and those with a CL = 16 mm in diameter received an IVP fresh embryo non-surgically. Pregnancy was determined by ultrasonography 23 and 53 days after embryo transfer and calving rates were recorded. Data were analysed using generalized linear models for binary data and a logit link (InfoStat, https://www.infostat.com.ar/). The proportion of recipients transferred was higher (P < 0.05) in the Conventional group (90.0%, 180/201) than in the J-Synch group (83.5%, 172/206). However, conception rates and the percentage of recipients pregnant/treated did not differ between groups (Conventional: 36.6%; 66/180 and 32.8%; 66/201 v. J-Synch: 39.0%; 67/172 and 32.5%; 67/206). Although no interaction was detected between treatments and oestrus expression, the conception rate was higher (P < 0.05) in recipients showing oestrus (39.1%, 124/317) than in those not showing oestrus (25.7%, 9/35). Furthermore, embryo/fetal losses between 30 and 60 days were not affected by the synchronization treatment (P > 0.11), but they were lower (P < 0.01) in recipients showing oestrus (5.6%, 7/124) than in those not showing oestrus (66.7%, 6/9). Similarly, fetal losses between 60 days and calving tended to be lower (P < 0.06) in recipients showing oestrus (20.5%, 24/117) than in those not showing oestrus (66.7%; 2/3). Calving rates were higher in recipients showing oestrus (29.3%, 93/317) than in those not showing oestrus (2.9%, 1/35; P < 0.01). In conclusion, although both synchronization treatments performed similarly, recipients not showing oestrus after progesterone device removal had lower conception rates and higher pregnancy losses than those showing oestrus at the expected time after treatment.

Parasitic outbreak of the copepod Balaenophilus manatorum in neonate loggerhead sea turtles (Caretta caretta) from a head-starting program

BACKGROUND

Diseases associated to external parasitosis are scarcely reported in sea turtles. During the last decades several organism have been documented as a part of normal epibiont community connected to sea turtles. The copepod Balaenophilus manatorum has been cited as a part of epibiont fauna with some concern about its parasitic capacity. This study serves three purposes, i.e. (i) it sheds light on the type of life style that B. manatorum has developed with its hosts, particularly turtles; (ii) it makes a cautionary note of the potential health risks associated with B. manatorum in sea turtles under captivity conditions and in the wild, and (iii) it provides data on effective treatments against B. manatorum.

RESULTS

We report for the first time a massive infestation of the copepod B. manatorum and subsequent acute mortality in a group of loggerhead sea turtle hatchlings. Four-month-old turtles from a head-starting program started exhibiting excitatory and fin rubbing behavior preceding an acute onset of lethargy, skin ulceration and death in some animals. All the individuals (n = 57) were affected by severe copepod load and presented different degrees of external macroscopic skin lesions. The ventral area of front flippers, axillar and pericloacal skin were mostly affected, and were the main parasite distribution regions. Copepods were also detected on plastron and carapace sutures. The gut contents of B. manatorum reacted positively for cytokeratin, indicating consumption of turtle skin. Severe ulcerative necrotic dermatitis and large amount of bacteria presence were the major histopathological findings.

CONCLUSIONS

Individual fresh water immersion for 10 min and lufenuron administration (0.1 ppm) to the water system every 2 weeks proved effective for removing turtle parasites and to control re-infestation, respectively. The results from our study clearly indicated that B. manatorum individuals consume turtle skin. The pathological effects of this agent and the potential implications in sea turtle conservation and management are discussed.

7 INFLUENCE OF ESTRUS EXPRESSION AND TREATMENT WITH GnRH ON PREGNANCY RATES IN BEEF CATTLE SYNCHRONIZED WITH PROGESTERONE DEVICES AND ESTRADIOL AND INSEMINATED AT A FIXED-TIME

We have previously shown that expression of oestrus significantly influences the time of ovulation and pregnancy rates to timed-AI (P/TAI) in beef cattle synchronized with progesterone devices and oestradiol (Bó et al. 2016 Theriogenology 86, 388–396). Furthermore, delaying TAI from 48 h to 54–58 h after device removal improved P/TAI of those animals not showing oestrus by 48 h. The objective of the present study was to determine whether the administration of GnRH to those animals not showing oestrus by 48 h after device removal had an impact on P/TAI. Non-lactating and suckled beef cows and heifers (Bonsmara, Brangus, and Braford; n = 868), with a corpus luteum (CL) or a follicle ≥8 mm in diameter detected by ultrasonography (Mindray DP 30 Vet, 7.5 MHz, China) and body condition score 2 to 4 (1 to 5 scale) were synchronized in 3 replicates. On Day 0, animals received a progesterone device (DIB 0.5 g, Zoetis, Argentina) and 2 mg of oestradiol benzoate (Von Franken, Argentina). On Day 8, DIB were removed and cows received 0.150 mg of D+cloprostenol (Río de Janeiro, Argentina) plus 0.5 mg oestradiol cypionate (Cipiosyn, Zoetis). In addition, all cows were tail-painted on the sacrococcygeal area (CeloTest, Biotay, Argentina) at DIB removal and were observed to determine the expression of oestrus, according to the percentage of paint loss (PL) 48 h later. The animals that showed oestrus (PL > 30%) were recorded and TAI at that time while those with PL ≤ 30% (not in oestrus) were randomly allocated to receive 100 μg of gonadorelin (GnRH; Gonasyn, Zoetis) or no treatment and TAI between 54 to 58 h after DIB removal. Pregnancy was diagnosed by ultrasonography at 45 days after TAI, and data were analysed by logistic regression. There were no significant differences among replicates, inseminators, semen source or animal class (dry cows, suckled cows or heifers; P > 0.11). However, animals showing oestrus by 48 h after DIB removal had higher P/TAI (371/666; 55.7; P < 0.04) than those that did not show oestrus (96/202; 47.5%). Within animals not showing oestrus at 48 h, those that were in oestrus by the TAI at 54 to 58 h had higher P/TAI (71/124, 57.3%; P < 0.01) than those that did not show oestrus within that period (27/78; 34.6%). In addition, P/TAI was higher (P < 0.01) in animals that received GnRH (66/113; 58.4%) than in those that did not receive GnRH (30/89; 33.7%). In conclusion, the expression of oestrus significantly affected P/TAI in beef cattle synchronized with progesterone devices and oestradiol. Furthermore, treatment of animals not showing oestrus by 48 h after DIB removal with GnRH resulted in improved P/TAI performed 6 to 10 h later.

104 FACTORS AFFECTING PREGNANCY RATES AND EMBRYO/FETAL LOSSES IN RECIPIENTS RECEIVING IN VITRO-PRODUCED EMBRYOS BY FIXED-TIME EMBRYO TRANSFER

A retrospective analysis evaluated pregnancy rates and embryo losses with in vitro-produced embryos in a commercial embryo transfer program on 15 different beef farms. Recipients were beef cows and heifers (n = 1841) that were synchronized with 5 different protocols and transferred at a fixed-time (FTET). Recipients were examined by ultrasonography on Day 0, and those with a corpus luteum (CL) or a follicle ≥8 mm in diameter and with body condition score 2 to 4 (1 to 5 scale) were synchronized. The synchronization treatments were as follows. (T1) Recipients received an intravaginal device with 0.5 g of progesterone plus 2 mg of oestradiol benzoate on Day 0; device removal, plus 500 μg of cloprostenol (prostaglandin F2α), 400 IU of eCG, and 0.5 mg of oestradiol cypionate on Day 8; and FTET on Day 17. (T2) This treatment was similar to T1 but 1 mg of oestradiol cypionate was injected at device removal instead of 0.5 mg of oestradiol cypionate. (T3) This treatment was similar to T1 except that animals were tail-painted on Day 8 and observed on Day 10. Those with the tail-paint intact on Day 10 received 100 μg of gonadorelin (gonadotropin-releasing hormone) and all recipients were FTET on Day 17. (T4) Recipients received a progesterone device on Day 0; device removal, prostaglandin F2α, and eCG on Day 5; gonadotropin-releasing hormone on Day 8; and FTET on Day 15. (T5) Recipients received a progesterone device and 2 mg of oestradiol benzoate on Day 0; device removal, prostaglandin F2α, and eCG on Day 6; gonadotropin-releasing hormone on Day 9; and FTET on Day 16. On the day of FTET all recipients with CL ≥18 mm in diameter (G1), ≥16 and <18 mm in diameter (G2), and ≥14 mm and <16 mm in diameter (G3) received in vitro-produced fresh embryos. Pregnancy was diagnosed by ultrasonography at 30 and 60 days of gestation, and data were analysed by logistic regression. The overall proportion of recipients synchronized that were FTET was 80.8% (1487/1841), with a 30-day pregnancy rate to FTET (P/FTET) of 45.6% (678/1487) and the rate of 30- to 60-day embryo/fetal loses on the 528 recipients that were re-checked at 60 days was 12.8% (68/528). There were no significant differences in P/FTET among operators, animal category, time of the year, embryo stage, or body condition score; however, there was a significant effect of farm (P < 0.001) and CL diameter (P < 0.05), but no interaction between CL diameter and farm or treatment (P > 0.1). Recipients with G1 (443/953, 46%) and G2 (221/462, 47%) CL had higher pregnancy rates than those with G3 CL (23/71, 32%). There was a significant effect of synchronization treatment on the proportion of recipients transferred and on P/FTET (P < 0.01) that was highly influenced by farm (farm by treatment interaction P < 0.01). The proportions of recipients selected for embryo transfer were as follows: T1: 386/486, 79.4%; T2: 233/331, 70.3%; T3: 342/377, 90.7%; T4: 126/160, 78.7%; and T5: 400/487, 82.1%. The P/FTET were as follows: T1: 190/386, 49.2%; T2: 96/233, 41.2%; T3: 175/342, 51.1%; T4: 49/126, 38.8%; and T5: 168/400, 42.0%. Although 30- to 60-day embryo/fetal losses were not influenced by synchronization treatments, they were highly influenced by farm (P < 0.001) and ranged from 0 to 34.5%. In conclusion, P/FTET in a commercial program with beef in vitro-produced embryos was influenced by factors related to the recipient (CL diameter) and the environment (farm), whereas embryo/fetal losses were influenced by farm but not treatment or recipient factors.

Infection of Internal Umbilical Remnant in Foals by Clostridium sordellii

Omphalitis and the resulting septicemia contribute to perinatal mortality in several animal species. In foals, the most important causes of omphalitis are Escherichia coli and Streptococcus zooepidemicus. However to date, no information has been published about the role of Clostridium sordellii in these infections. In this paper, we describe 8 cases of perinatal mortality in foals associated with internal umbilical remnant infection by C. sordellii. The foals studied were between 12 and 21 days old at the time of death, and various breeds were represented in the group. Five of the foals were male and 3 were female. The diagnosis was established on the basis of the detection of C. sordellii by 3 methods (culture, fluorescent antibody test, and immunohistochemistry) and on gross and histopathologic findings. All foals had acute peritonitis, and the internal umbilical remnant was thickened by edema, hemorrhage, and fibrosis. A moderate amount of serosanguinous fluid with fibrin strands was present in the pericardial sac and pleural cavity. Histopathologically, the urachus and umbilical arterial walls were thickened by edema and exhibited hemorrhage, fibrin, and leukocytic infiltration. Gram-positive bacterial rods were observed in subepithelial areas of the urachus, the adventicia of umbilical arteries, and interstitium of the internal umbilical remnant. On the basis of these findings, we suggest that C. sordellii should be considered in the differential diagnosis for infections of the internal umbilical remnant in foals.

Kinetic behavior of light emission in cholesteric liquid crystal lasers: An experimental study

Some dynamical aspects of fluorescence and lasing have been studied in a dye-doped cholesteric liquid crystal by measuring the response of the material to nanosecond optical pumping. It has been found that as the pumping energy is increased the fluorescence pulse duration decreases, reaching a minimum at the lasing threshold. Above the threshold the temporal profiles are irregular and consist of a set of narrow pulses whose measured duration is limited by the detector risetime (1 ns). The results are interpreted in terms of a recently proposed model [JETP, 118, 822 (2014)] that makes use of rate equations to account for the laser generation in cholesteric liquid crystals. The prediction of such equations for an experimental configuration appropriate for fluorescence lifetime measurements is analyzed.

Ultrafast Atomic Diffusion Inducing a Reversible (2sqrt[3]×2sqrt[3])R30°↔(sqrt[3]×sqrt[3])R30° Transition on Sn/Si(111)∶B

Dynamical phase transitions are a challenge to identify experimentally and describe theoretically. Here, we study a new reconstruction of Sn on silicon and observe a reversible transition where the surface unit cell divides its area by a factor of 4 at 250 °C. This phase transition is explained by the 24-fold degeneracy of the ground state and a novel diffusive mechanism, where four Sn atoms arranged in a snakelike cluster wiggle at the surface exploring collectively the different quantum mechanical ground states.

Thermally induced light-scattering effects as responsible for the degradation of cholesteric liquid crystal lasers

We have studied the degradation process of the laser emission in a cholesteric liquid crystal laser. We have found that there exists a negative correlation between the laser efficiency and the amount of light scattered by the liquid-crystal sample in the illuminated area. The growth of scattering is attributed to the appearance of small imperfections generated in the sample as a result of certain thermal processes that involve the dye molecules. The scattering implies an increase of the coefficient of distributed losses, which is the main response of the rise of the laser threshold.

The role of charge transfer in the energy level alignment at the pentacene/C60 interface

Understanding the mechanism of energy level alignment at organic-organic interfaces is a crucial line of research to optimize applications in organic electronics. We address this problem for the C60-pentacene interface by performing local-orbital Density Functional Theory (DFT) calculations, including the effect of the charging energies on the energy gap of both organic materials. The results are analyzed within the induced density of interface states (IDIS) model. We find that the induced interface potential is in the range of 0.06-0.10 eV, in good agreement with the experimental evidence, and that such potential is mainly induced by the small, but non-negligible, charge transfer between the two compounds and the multipolar contribution associated with pentacene. We also suggest that an appropriate external intercompound potential could create an insulator-metal transition at the interface.

Spontaneous and field-induced mesomorphism of a silyl-terminated bent-core liquid crystal as determined from second-harmonic generation and resonant X-ray scattering

The polarity and structure of the phases of a liquid crystal constituted by thiophene-based bent-core molecules is investigated by means of optical second-harmonic generation (SHG), and resonant and conventional X-ray diffraction. The material studied is representative of a wide family of mesogens that contain silyl groups at the ends of the chains. These bulky terminal groups have been reported to give rise to smectic phases showing ferroelectric switching. However, the analysis of the SHG signal before and after application of electric fields has allowed us to establish unambiguously that the reported ferroelectricity is not intrinsic to the material but stabilized by the cell substrates once an electric field has been applied. In addition, the results obtained from resonant X-ray diffraction indicate that virgin samples have antiferroelectric undulated synclinic smectic structures.

On the organic energy gap problem

In conjugated organic molecules, the difference between the HOMO and LUMO Kohn-Sham eigenvalues is significantly smaller than the transport gap measured experimentally. We discuss here, within a local-orbital formulation of DFT, how this problem can be corrected using appropriate hybrid potentials, that add a fraction of Hartree-Fock exchange interaction in the DFT calculation. We illustrate this approach presenting calculations for two simple systems: H(2) and C(6)H(6); then, we discuss how to implement this hybrid approach in a general local-orbital calculation, adjusting the hybrid contribution to yield the correct experimental HOMO/LUMO energy gap for the molecule. We also consider the case of an organic molecule on a metal and analyze the effect of the molecule-metal interaction on the organic energy gap. In particular, we discuss how to introduce in this hybrid-potential scheme the effect of the image potential, and present results for the organic molecules PTCDA, TTF, benzene and pentacene on the metal surfaces Au(111), Ag(111) and Cu(111).

Brain lesions associated with clostridium perfringens type D epsilon toxin in a Holstein heifer calf

A 6-month-old dairy heifer calf with no premonitory signs was acutely down after the morning feeding and could not rise. On presentation, the heifer was in right lateral recumbency and moribund with opisthotonus and left hind limb paddling. Following euthanasia, gross examination of the brain revealed multifocal loss of gray-white matter distinction and extensive petechiae throughout the brainstem. On histopathological examination, there was striking white matter edema and marked perivascular proteinaceous edema surrounding many arterioles and venules (microangiopathy), mainly in the white matter of the internal capsule, thalamus, midbrain, cerebellum, and cerebellar peduncles. The perivascular neuropil was strongly positive for Alzheimer precursor protein A4. Clostridium perfringens epsilon toxin was detected in the intestinal contents. This is the first report of microangiopathy in postneonatal cattle associated with the detection of epsilon toxin in the intestinal contents.