Testing Hadronic Interactions at Ultrahigh Energies with Air Showers Measured by the Pierre Auger Observatory

Ultrahigh energy cosmic ray air showers probe particle physics at energies beyond the reach of accelerators. Here we introduce a new method to test hadronic interaction models without relying on the absolute energy calibration, and apply it to events with primary energy 6-16 EeV (E_{CM}=110-170  TeV), whose longitudinal development and lateral distribution were simultaneously measured by the Pierre Auger Observatory. The average hadronic shower is 1.33±0.16 (1.61±0.21) times larger than predicted using the leading LHC-tuned models EPOS-LHC (QGSJetII-04), with a corresponding excess of muons.

Medical undergraduates' contributions to publication output of world's top universities in 2013

BACKGROUND

Medical undergraduates' (UGs) involvement in research activities is thought to be mutually beneficial to students, their mentors and the scholarly productivity of their universities. However, most evidence in favor of such assumption relies on subjective measures such as the self-reported gains in skills or knowledge rather than robust objective estimates for assessing impact.

AIM

We aimed to objectively track and describe publications with UG co-authors-their proportion to the total publication output of world's top universities, their characteristics and their potential impact on biomedical literature.

METHODS

We contacted the corresponding authors of the 2013's Medline-indexed publications affiliated to world's top 10 universities to investigate if any of their co-authors was an UG. Articles with UG co-authors were further assessed to determine, along with other variables: the type of study design, field of the article, publishing journal and its impact factor (IF), and number of received citations.

RESULTS

Out of 25 152 publications, 2537 articles (10.1%) contained at least one UG co-author who was the first author in 635 papers (25%). Articles with UG co-authors were published in 1114 journals with a median IF of 3.661. Most UGs' co-authored publications (82.7%, n = 2098) were cited at least once within 1 year, for a median of three citations per article.

CONCLUSION

UGs contributed to one in every 10 publications affiliated to top universities. Their papers were published in journals with good IFs and received a fair number of citations, which would reflect the relatively good quality and impact of these articles.

Early postoperative tissue harmonic sonography of the thyroid gland

Purpose: Fundamental gray-scale imaging (FGI) is known to be unuseful for thyroid imaging in the early postoperative setting. Thus, we evaluated the feasability of tissue harmonic imaging (THI) early after thyroid resection.

Material and Methods: FGI and THI of the neck were perfomed in 48 consecutive patients 4 days after surgery. The examiner was blinded to patient diagnoses and types of surgery. FGI and THI examinations were stored on videotape and reviewed offline by two different readers who rated the quality of delineation of the organ borders and presence or absence of focal lesions. The results were compared to neck US performed 12 weeks after surgery.

Results: Delineation of the thyroid remnants in THI/FGI was rated to be excellent in 22/2, good in 11/9, poor in 3/16 and not visible at all in 4/13 patients. The correlation between THI-volumetry and control-volumetry was very high (r=0.81; p<0.0001). THI but not FGI depicted presence or absence of solid thyroid nodules with 100% accuracy.

Conclusion: THI is a feasible method for thyroid US in the early postoperative setting. It permits volumetry of the residual thyroid tissue and accurately depicts nodules within the thyroid remnant.

Measurement of the Radiation Energy in the Radio Signal of Extensive Air Showers as a Universal Estimator of Cosmic-Ray Energy

We measure the energy emitted by extensive air showers in the form of radio emission in the frequency range from 30 to 80 MHz. Exploiting the accurate energy scale of the Pierre Auger Observatory, we obtain a radiation energy of 15.8±0.7(stat)±6.7(syst)  MeV for cosmic rays with an energy of 1 EeV arriving perpendicularly to a geomagnetic field of 0.24 G, scaling quadratically with the cosmic-ray energy. A comparison with predictions from state-of-the-art first-principles calculations shows agreement with our measurement. The radiation energy provides direct access to the calorimetric energy in the electromagnetic cascade of extensive air showers. Comparison with our result thus allows the direct calibration of any cosmic-ray radio detector against the well-established energy scale of the Pierre Auger Observatory.

Outcome after pancreaticoduodenectomy for T3 adenocarcinoma: A multivariable analysis from the UK Vascular Resection for Pancreatic Cancer Study Group

BACKGROUND

Most resectable pancreatic cancers are classified as T3, including those involving the porto-mesenteric vein. Survival and perioperative morbidity for venous resection have been found to be comparable to standard resection. We investigate factors associated with short and long term outcomes in pancreaticoduodenectomy with (PDVR) and without (PD) venous resection exclusively for T3 adenocarcinoma of the head of the pancreas.

METHODS

This is a UK multicenter retrospective cohort study assessing outcomes in patients undergoing PD and PDVR. All consecutive patients with T3 only adenocarcinoma of the head of the pancreas undergoing surgery between December 1998 and June 2011 were included. Multivariable logistic and proportional hazards regression analyses were performed to determine the association between the surgical groups and in-hospital mortality (IHM) and overall survival (OS).

RESULTS

1070 patients were included of whom 840 (78.5%) had PD and 230 (21.5%) had PDVR. Factors independently associated with IHM were a high creatinine (aHR 1.14, p = 0.02), post-operative bleeding (aHR 2.86, p = 0.04) and a re-laparotomy (aHR 8.42, p = 0.0001). For OS, multivariable analyses identified R1 resection margin status (aHR 1.22, p = 0.01), N1 nodal status (aHR 1.92, p = 0.0001), perineural invasion (aHR 1.37, p = 0.002), tumour size >20mm (aHR 0.63, p = 0.0001) and a relaparotomy (aHR 1.84, p = 0.0001) to be independently associated with overall mortality.

CONCLUSION

This study on T3 adenocarcinoma of the head of the pancreas suggests that IHM is strongly associated with perioperative complications whilst OS is affected by histological parameters. Detailed pre-operative disease evaluation and advances in oncological treatment have the potential to improve OS.

Audit of preoperative localisation of tumor with tattoo for patients undergoing laparoscopic colorectal surgery

BACKGROUND

Preoperative localisation of tumour is an essential requirement in laparoscopic colorectal surgery. Since the introduction of laparoscopic colorectal resections in NGH in February 2010, the difficulties of tumour localisation at the time of surgery without tattoo have been highlighted. Furthermore, endoscopic documentation of site of tattoo with respect to the tumour can be inconsistent and at times misleading or difficult to interpret. Tattooing guidelines should be simple to follow and consistent for all lesions irrespective of the location of the tumour. The recommendations were to place at least three spots of tattoo one mucosal fold distal to the lesion and clearly document site of tattoo with respect to tumour in the endoscopy report.

METHOD

We identified 100 patients undergoing elective laparoscopic colorectal cancer resections over a two-year period. Data were collected regarding presence of tattoo preoperatively as documented in the colonoscopy report and subsequently the visibility of the tattoo at time of laparoscopy and its accuracy in relation to the tumour. Abdominoperineal resections and emergency colorectal operations were excluded.

RESULTS

Only 59% of the patients had a visible and accurate tattoo. In 17% of the patients, the tattoo was not visible at all, although it was documented in the endoscopy report that it had been administered. In 4% of patients, it was visible but inaccurately placed. In 20% of the patients, there were no tattoos at all, necessitating on table endoscopy and intraoperative specimen analysis to confirm that the tumour/lesion was within the resection specimen.

DISCUSSION

Preoperative tumour localisation is extremely important to correctly identify the site of tumour or lesion at laparoscopy. A standardised departmental protocol should be implemented by all endoscopists to place three spots of tattoo one mucosal fold distal to any significant lesions found. Failure to tattoo lesions/cancers preoperatively can lead to intraoperative delays and potential harm to patients from on-table endoscopy.

Is estimated intra-operative blood loss a reliable predictor of surgical outcomes in laparoscopic colorectal cancer surgery?

BACKGROUND

Studies have shown that laparoscopic surgery for colorectal cancer is often associated with significantly reduced intra-operative blood loss compared to the corresponding open procedures. Increased intra-operative blood loss can be associated with increased risk of post-operative morbidity and mortality. We sought to determine whether estimated intra-operative blood loss was a reliable predictor of post-operative surgical outcomes.

METHOD

Prospective data were collected for patients undergoing elective laparoscopic colorectal cancer resections from July 2011 to November 2013. Weighing swabs and measuring blood volume in suction devices calculated the estimated intra-operative blood loss. The operative outcome data including post-operative 30 day morbidity and mortality, length of hospital stay, re-admission and re-operation within 30 days were collected. The operative blood loss was grouped into Group 1 (less than 50 ml, Group 2 (50-150 ml) and Group 3 (over 150 ml). Patients who underwent open operations and laparoscopic conversions were excluded.

RESULTS

The median age, length of hospital stay, male to female ratio and body mass index were similar in the three groups. There was no 30-day mortality in any of the groups. The number of re-admissions within 30 days was similar in all groups. The re-operation rates within 30 days were higher in Groups 2 and 3 at 11% and 8.6%, respectively. The post-operative complications were 12.5%, 16.7%, and 26% in groups 1, 2 and 3, respectively. There were no anastomotic leaks requiring re-operation noted in Group 3.

DISCUSSION

This study has shown that intra-operative blood loss was not associated with increased median length of stay nor did it increase the 30 day re-admission rate. However, increased intra-operative blood loss was associated with increased incidence of post-operative morbidity and risk of reoperation within 30 days.

Search for patterns by combining cosmic-ray energy and arrival directions at the Pierre Auger Observatory

Energy-dependent patterns in the arrival directions of cosmic rays are searched for using data of the Pierre Auger Observatory. We investigate local regions around the highest-energy cosmic rays with [Formula: see text] eV by analyzing cosmic rays with energies above [Formula: see text] eV arriving within an angular separation of approximately 15[Formula: see text]. We characterize the energy distributions inside these regions by two independent methods, one searching for angular dependence of energy-energy correlations and one searching for collimation of energy along the local system of principal axes of the energy distribution. No significant patterns are found with this analysis. The comparison of these measurements with astrophysical scenarios can therefore be used to obtain constraints on related model parameters such as strength of cosmic-ray deflection and density of point sources.

Normal values for transbulbar sonography and magnetic resonance imaging of the optic nerve sheath diameter (ONSD) in children and adolescents

PURPOSE

To establish normal values of the optic nerve sheath diameter (ONSD) in children and adolescents for transbulbar sonography and magnetic resonance imaging.

MATERIALS AND METHODS

In 99 children and adolescents (age: 5.6 - 18.6 years, mean: 12 years) without neurologic or ophthalmologic disease, measurements of the ONSD with transbulbar sonography were performed. For comparison 59 children and adolescents (age: 5.1 - 17.4 years, mean 12.3 years) with a normal MR examination of the brain had measurements of the ONSD on a T2-weighted thin section sequence of the orbit. Besides establishing modality-related normal values, age dependency, accuracy and reproducibility of measurements were assessed.

RESULTS

Overall the mean ONSD was 5.75 ± 0.52 mm for transbulbar sonography and 5.69 ± 0.31 mm for MRI. There was no statistical significance between the 95 % percentiles and age for both transbulbar sonography (p = 0.332) and MRI (p = 0.336). As a parameter for the reproducibility of measurements, the repeatability coefficient (RC) was between 0.34 mm and 0.46 mm. The concordance correlation coefficient (CCC) values revealed a high agreement between readers both for transbulbar sonography (0.868) and MRI (0.796).

CONCLUSION

Normal values for ONSD in children and adolescents found in this study are significantly higher than assumed. The values found for transbulbar sonography are confirmed by comparable results for MR measurements. A precise sonographic measurement technique and the consideration of normal values found hereby are essential for correct interpretation of ONSD measurements in children and adolescents.

Coumarin and salicylic acid activate resistance to Macrophomina phaseolina in Helianthus annuus

The induction of resistance to charcoal rot disease caused by Macrophomina phaseolina (Tassi) Goidanich in sunflower (Helianthus annuus L.) was studied after seed treatments with coumarin (COU) and salicylic acid (SA) at three different levels (0.3, 1.0 and 3.0 mM). The priming of sunflower seeds with 0.3 mM COU or 1.0 mM SA resulted in decreased disease severity and offered about 50% protection and more than 80% reduction in the length of stem lesions under greenhouse conditions. Both COU and SA treatments induced the accumulation of soluble sugars and phytoalexins, as well as stimulating the activity of β-1,3-glucanase and chitinase.