Modeling thin-film piezoelectric polymer ultrasonic sensors

This paper presents a model suitable to design and characterize broadband thin film sensors based on piezoelectric polymers. The aim is to describe adequately the sensor behavior, with a reasonable number of parameters and based on well-known physical equations. The mechanical variables are described by an acoustic transmission line. The electrical behavior is described by the quasi-static approximation, given the large difference between the velocities of propagation of the electrical and mechanical disturbances. The line parameters include the effects of the elastic and electrical properties of the material. The model was validated with measurements of a poly(vinylidene flouride) sensor designed for short-pulse detection. The model variables were calculated from the properties of the polymer at frequencies between 100 Hz and 30 MHz and at temperatures between 283 K and 313 K, a relevant range for applications in biology and medicine. The simulations agree very well with the experimental data, predicting satisfactorily the influence of temperature and the dielectric properties of the polymer on the behavior of the sensor. Conversely, the model allowed the calculation of the material dielectric properties from the measured response of the sensor, with good agreement with the published values.

Oral-facial-digital syndrome type I: surgical approach and a case report

PURPOSE

Oral-facial-digital (OFD) syndromes constitute a heterogeneous group of embrionary development disorders. There are at least 11 different forms, with a broad spectrum of clinical features, causing an important problem with the diagnosis. There are only a few reports in the recent literature, and there is no surgical technique described for its correction.

MATERIALS AND METHODS

We present a newborn female referred to the Cleft Lip and Palate Division of our hospital with facial dysmorphology; her mother was affected by an incomplete form of this syndrome. Genetic investigation showed a mutation not reported before in the literature. We present the clinical features and a new surgical approach for its correction.

RESULTS

OFD syndrome type I (OFD I) is characterised by several clinical features, including incomplete central upper lip cleft, bifid tongue, intraoral hamartomas, upper lip frenula and soft palate cleft. With this technique, we get a good aesthetic result.

CONCLUSION

OFD I is extremely infrequent and it is important to differentiate it from other forms of OFD. We want to emphasise the importance of performing a correct differential diagnosis in patients affected by palate cleft who have intraoral masses or feeding problems, to rule out incomplete forms of this syndrome. Surgical correction of the malformations associated with this syndrome is a challenge for the paediatric surgeon, because none of the previously reported techniques approach the reparation of this central labial defect.

Stereodynamics of the photodissociation of nitromethane at 193 nm: unravelling the dissociation mechanism

The photodissociation of nitromethane at 193 nm is reviewed in terms of new stereodynamical information provided by the measurement of the first four Dixon's bipolar moments, β0(2)(20), β0(0)(22), β0(2)(02), and β0(2)(22), using slice imaging. The measured speed-dependent β0(2)(20) (directly related with the spatial anisotropy parameter β) indicates that after one-photon absorption to the S3(2 (1)A″) state by an allowed perpendicular transition, two reaction pathways can compete with similar probability, a direct dissociation process yielding ground-state CH3 and NO2(1 (2)A2) radicals and a indirect dissociation through conical intersections in which NO2 radicals are formed in lower-lying electronic states. A particularly important result from our measurements is that the low recoil energy part of the methyl fragment translational energy distribution presents a contribution with parallel character, irrespective of the experimental conditions employed, that we attribute to parent cluster dissociation. Moreover, the positive values found for the β0(0)(22) bipolar moment indicates some propensity for the fragment's recoil velocity and angular momentum vectors to be parallel.

[Transepithelial phototherapeutic keratectomy to treat chronic laser in situ keratomileusis-flap macrostriae. A case review]

OBJECTIVE

To describe the use of transepithelial phototherapeutic keratecomy for the long-term treatment of post-laser in situ keratomileusis (LASIK) flap macrostriae.

METHOD

We present the case of a 22 year old male with visual loss in the left eye due to chronic flap macrostriae that was treated with transepithelial PTK.

RESULTS

Striae and haze were no longer visible, with a significant improvement of best corrected visual acuity. Refraction in the third month was +9.75-4.00×170°. A phakic intraocular lens was implanted one year later with an uncorrected visual acuity of 0.8.

CONCLUSIONS

PTK can solve chronic flap striae, but refraction outcome is unpredictable.

Photodissociation of pyrrole-ammonia clusters below 218 nm: quenching of statistical decomposition pathways under clustering conditions

The excited state hydrogen transfer (ESHT) reaction in pyrrole-ammonia clusters (PyH·(NH(3))(n), n = 2-5) at excitation wavelengths below 218 nm down to 199 nm, has been studied using a combination of velocity map imaging and non-resonant detection of the NH(4)(NH(3))(n-1) products. Special care has been taken to avoid evaporation of solvent molecules from the excited clusters by controlling the intensity of both the excitation and probing lasers. The high resolution translational energy distributions obtained are analyzed on the base of an impulsive mechanism for the hydrogen transfer, which mimics the direct N-H bond dissociation of the bare pyrrole. In spite of the low dissociation wavelengths attained (~200 nm) no evidence of hydrogen-loss statistical dynamics has been observed. The effects of clustering of pyrrole with ammonia molecules on the possible statistical decomposition channels of the bare pyrrole are discussed.

[Is experimental surgery necessary or essential in the training program of a pediatric surgeon?]

Many surgical procedures performed in pediatric surgery have a slow learning curve, the volume of patients and the existence of complex diseases that require extensive training and surgical skill, have taken our service to create a global training program of experimental surgery. This program based on the simulation and training invasive procedures in real anatomical models, aims to educate our residents in a global and efficiently way in order to obtain an improvement of technical training, and increased patient safety result of experience and expertise wined in the experimental animal. This paper presents the main features, objectives and results obtained with this training program and seeks to promote the incorporation of simulation programs in live animal as an essential part of the training of pediatric surgery resident.

Slice imaging and wave packet study of the photodissociation of CH3I in the blue edge of the A-band: evidence of reverse 3Q0 ← 1Q1 non-adiabatic dynamics

The photodissociation of CH(3)I in the blue edge (217-230 nm) of the A-band has been studied using a combination of slice imaging and resonance enhanced multiphoton ionization (REMPI) detection of the CH(3) fragment in the vibrational ground state (ν = 0). The profiles of the CH(3) (ν = 0) kinetic energy distributions and the photofragment anisotropies are interpreted in terms of the contribution of the excited surfaces involved in the photodissociation process, as well as the probability of non-adiabatic curve crossing between the (3)Q(0) and (1)Q(1) states. In the studied region, unlike in the central part of the A-band where absorption to the (3)Q(0) state dominates, the I((2)P(J)), with J = 1/2, 3/2, in correlation with CH(3) (ν = 0) kinetic energy distributions show clearly two contributions of different anisotropy, signature of the competing adiabatic and non-adiabatic dynamics, whose ratio strongly depends on the photolysis wavelength. The experimental results are compared with multisurface wave packet calculations carried out using the available ab initio potential energy surfaces, transition moments, and non-adiabatic couplings, employing a reduced dimensionality model. A good qualitative agreement is found between experiment and theory and both show evidence of reverse (3)Q(0)←(1)Q(1) non-adiabatic dynamics at the bluest excitation wavelengths both in the fragment kinetic energy and angular distributions.

Background subtraction in pulsed photoacoustics through neural-network processing

We report on the application of neural-network processing to pulsed photoacoustics for improving the detection limit by subtracting the window-heating-associated background. This technique was applied to the measurement of ethylene traces excited by a TEA (transverse electrical discharge in gas at atmospheric pressure) CO(2) laser. The signal contains a term that shows absorption saturation, characteristic of the absorbing gas, and another, generated by window heating, linearly dependent on laser energy. At low concentrations, normalization to laser energy is not possible owing to the different absorption mechanisms. To overcome this problem we relied on a neural-network filter, trained with experimentally obtained patterns, that subtracts the background and returns the sample concentration. This way, we reduced the detection limit to 20% of the previous limit obtained by reading the main resonance peak amplitude.

Evaluation of the quality of the water in El Hondo natural park located in the east of Spain

The purpose of the present work was to evaluate the quality of the water in El Hondo Park, an important wetland located in the east of Spain (province of Alicante) and included on the Ramsar List. The influence of the input of pollutants was assessed over a 14-month period in order to propose remedial action. Three different sources of waters were studied: irrigation water, brackish water and reservoir water. The irrigation water was found to have a high value of conductivity with high concentrations of Cl-, SO(4)2-, Na+ and K+ due to the influence of the brackish water. The concentration of organic matter given as CODT (total chemical oxygen demand) was found to be in the range of 70-600 mg/L of CODT, which was comparable to low-middle strength wastewater. A high concentration of Chlorophyll (a) was found in samples of reservoir water and the eutrophication of this water was thus observed. A high linear relationship was found among CODT, CODF (filtered COD) and BOD5; among electrical conductivity (E.C.), Cl-, SO4(-2), Na+, K+, Ca2+ and Mg2+ and among pH, CO3H- and CO(3)2- in all the samples evaluated. Taking this fact into consideration, a simplified water quality index (WQI) was calculated. Using this parameter, the quality of the water from different sources and its variation during the period evaluated was determined to be at a maximum during the months of December to February, which coincided with the period of high precipitations and low temperature. The highest values of this parameter were found in the samples corresponding to the reservoir water while the lowest values were found in the samples of the brackish water. By determination of the WQI, the influence of the brackish water on the quality of water for irrigation and reservoir waters was confirmed.

Estudio prospectivo sobre la utilidad de la ecografía de control tras la realización de pruebas invasivas hepáticas: biopsia hepática y punción aspiración con aguja fina (PAAF)

OBJECTIVE

To determine the need to perform ultrasound scans to all patients after liver biopsy or fine-needle aspiration (FNA) in order to detect complications with or without symptoms.

MATERIAL AND METHODS

After liver biopsy or FNA using a regular protocol the patient is observed for 24 hours at the hospital, and all patients undergo an abdominal sonography at that time even in the absence of evident complications.

RESULTS

298 liver biopsies and 98 FNAs were performed. There were complications in 37 patients (9.34%): 36 (9.09%) were minor complications such as pain, vasovagal episodes, or small bleeding, and 1 (0.25%) was a major complication with severe hemorrhage. Only 1 out of all 396 procedures had a complication detected by ultrasounds (intrahepatic hematoma) while the patient was asymptomatic.

CONCLUSIONS

The low incidence of complications occurring without symptoms, and their favorable course suggest that routine ultrasonography is not necessary after these techniques, and that it should be only performed when a complication is suspected.

[Nosocomial infection by multiresistant pathogens during one year in a secondary hospital: clinical an epidemiological analysis]

BACKGROUND

Currently growing medical and social significance of nosocomial infection by multiresistant pathogens (NIMP) prompted us to establish its incidence, nosology, presenting forms in admission areas, and mortality in a secondary hospital, Lleida (Spain).

METHOD

For that purpose, we analyzed the first year experience of a unit for the control of nosocomial infection (NI) created in our hospital. From January to December 2000, 79 patients with a NIMP admitted to the University Hospital Arnau de Vilanova entered in this prospective, descriptive study.

RESULTS

The overall annual incidence of NIMP was 4.0 per 103 patients admitted. Acinetobacter baumannii showed the highest individual rate of incidence, particularly, at the Intensive Care Unit (15.4 per 103 patients admitted; p < 0.001). By nosologies, infection prevailed over colonization (69.6% vs 30.4%; p < 0.001). Mean hospital stay length increased in colonized patients (38.9 days). Finally, overall mortality was high (29.1%); again, A. baumannii was the agent most frequently detected in death cases (66.6%; p < 0.001).

CONCLUSIONS

Surveillance and control measures are required for the prevention of NIMP. Incidence studies how this, can be useful to create a database to establish the distribution and occurrence of NI, including the detection of multiresistant pathogen outbreaks.

Prevention of de novo hepatitis B infection in liver allograft recipients with previous hepatitis B infection or hepatitis B vaccination

OBJECTIVES

To assess de novo hepatitis B virus (HBV) transmission from liver donors with HBV serum markers (HBM) to their recipients and the need for HBV vaccination before liver transplantation.

METHODS

A total of 108 orthotopic liver transplantations for nonviral disease and the risk of developing de novo hepatitis B based on HBMs before transplantation have been studied. Of the 108 patients, 94 met the study criteria and were divided into two groups: 27 who had HBMs before transplantation (from past infection or by previous vaccination) and 67 who had no HBM. Development of de novo hepatitis B was determined by analytical, serological, and histological parameters.

RESULTS

No case (0%) of de novo hepatitis B was detected in the pretransplantation HBM group, whereas there were 10 cases (14.5%) in the other group (p < 0.005).

CONCLUSIONS

The presence of pretransplantation HBM in liver transplant recipients protects these patients against the development of de novo hepatitis B. This is especially important considering that there is a high prevalence of donors with positive hepatitis B core antibody (especially in some countries), and that these donors transmit HBV infection to recipients without HBM in a significant number of cases. Thus, vaccination against HBV in patients who are candidates for liver transplantation is fundamental to avoid cases of de novo hepatitis B.

Myeloid mixed chimerism is associated with relapse in bcr-abl positive patients after unmanipulated allogeneic bone marrow transplantation for chronic myelogenous leukemia

BACKGROUND AND OBJECTIVE

Although bcr-abl polymerase chain reaction (PCR) positivity after bone marrow transplantation (BMT) for chronic myelogenous leukemia (CML) is significantly related to relapse, the predictive value of the assay is not very high and therefore most investigators consider that qualitative RT-PCR data alone are too imprecise to enable clinical decisions to be taken in individual cases. To define the clinical outcome of bcr-abl positive patients after unmanipulated BMT better, we sought the origin of hematopoiesis and traced its evolution over time.

DESIGN AND METHODS

Forty-nine patients received allogeneic BMT for CML (39 in chronic phase and 10 in accelerated phase/blast crisis). Median follow-up was 61 months (range 4-92). mRNA and DNA were used to assess bcr-abl and chimerism status respectively. Quantitative VNTR-PCR on total cells and lymphoid or myeloid population allowed us to assign and measure the origin of hematopoiesis.

RESULTS

Both bcr-abl positivity and the presence of mixed chimerism (MC) were significantly associated with relapse (p = 0.0009 and p < 0.0001 respectively). Relapse was observed in one of 39 patients with complete donor chimerism and in 6 of 9 patients with MC. These six cases showed increasing levels of host hemopoiesis and bcr-abl positivity in the CD15-positive population prior to relapse. The other three cases had decreasing or stable low-level MC which was restricted to the T-cells as well as bcr-abl negativity.

INTERPRETATION AND CONCLUSIONS

Whereas the simple detection of bcr-abl fails to identify patients who will relapse with certainty, the assessment of MC by VNTR-PCR does identify patients headed to relapse. Confirmation of myeloid involvement and increasing levels over time further elucidates the clinical outcome of bcr-abl positive patients after BMT.

Increasing mixed haematopoietic chimaerism after BMT with total depletion of CD4+ and partial depletion of CD8+ lymphocytes is associated with a higher incidence of relapse

In this study we analysed the incidence and clinical impact of the persistence of host haemopoiesis (mixed chimaerism, MC) after allogeneic BMT in 35 consecutive patients with haematologic malignancies using a total CD4+ cell-depleted graft with an adjusted dose of CD8+ cells (1x10(8)/kg). Chimaerism was assessed by PCR amplification of VNTRs in 30 evaluable patients: 19 non-CML and 11 CML cases which were also evaluated for the BCR-ABL transcript by RT-PCR. All but one had complete engraftment with a donor profile early post-BMT. At the end of the study period, 12 of 30 patients displayed MC (40%). The overall disease-free survival for MC patients was clearly unfavourable when compared to those who exhibited a donor profile (24.7% vs. 100%, P = 0.005). However, we found that only two of five patients with MC in the non-CML group relapsed, whereas a clear correlation could be made between MC and relapse in CML (seven showed MC, preceding cytogenetic or haematological relapse in six of them, which displayed a prior BCR-ABL mRNA positivity). In addition, a quantitative-PCR approach enabled us to demonstrate that increasing amounts of MC are invariably associated with subsequent relapse, whereas a low stable level of host or complete donor haemopoiesis is consistent with clinical complete remission. Although these results suggest that the clinical impact of MC may depend on the underlying disease, it is compatible with the concept that the graft-versus-leukaemia effect against CML is mainly exerted by donor CD4+ lymphocytes. Elimination of this cellular subset may be responsible for the inability of the graft to prevent a progressive increase in the tumor cell burden.

[Regression of left ventricular hypertrophy in hypertensive patients]

Left ventricular hypertrophy associated with systemic hypertension differs from left ventricular hypertrophy initiated by other pressure overload diseases. Its development depends not only of hemodynamics aspects but of biochemical factors. Many studies have demonstrated a close link between left ventricular hypertrophy and cardiovascular morbidity and mortality. For that reason the idea of reversal of left ventricular hypertrophy has been a goal of the antihypertensive treatment. From the literature review has been established that the most classes of antihypertensive medications reduce the left ventricular mass, though there is a variation in required duration of treatment. At this point the angiotensin converting enzyme inhibitors, probably because a double effect: hypotensive and blockers of the trophic stimulus of angiotensin II, seemed to be the most potent for reducing the left ventricular mass. Still we don't know if reversal of left ventricular hypertrophy, by the antihypertensive treatment, reduce independently the cardiovascular risk.

[Pharmacologic activity of the aqueous wood extract from Quassia amara (Simarubaceae) on albino rats and mice]

All the assays were done with an aqueous preparation of dry wood from Quassia amara (Simarubaceae). For the hippocratic assay, 12 female SDN rats were used, with an average weight of 144 g and separated in three groups of four individuals each. The dose used were 500 mg/kg and 1,000 mg/kg and the control group received 0.5 ml of distilled water. The extract administration and the observation of the animals were done daily during nine days. Acute toxicity of the preparation was studied with 25 male NGP mice with an average weight of 20.13 g, in groups of five individuals per dose. The oral administration was carry out with the following doses: 250, 500, 750 and 1,000 mg/kg, the control group received 0.5 ml of distilled water. No sign of acute toxicity was observed at any dose. For the toxicity analysis via intraperitoneal injection 15 male NGP mice were assigned to five groups (5 animals each) with doses of 500 and 1,000 mg/kg and a control group with 0.5 ml of distilled water. The group with the dose of 500 mg/kg, presented acute toxicity signs with a 24 hr recovery, and the 1,000 mg/kg dose was lethal to a 100% within 24 hr. The measuring of the peristaltic activity (movement of the intestinal content) were performed on 30 NGP male mice with an average weight of 22 g assigned to three groups of ten individuals each. One dose of 500 mg/kg and 1,000 mg/kg were orally administrated to each experimental group and 0.5 ml of distilled water to the control group. The marker used was activated carbon, orally supplied to every mice 30 min after the administration of the aqueous extract. The animals are decapitated and the measurement of the carbon motion in the small intestine was done after 30 min. Both dose increased the intestinal movement compared to the control group, but only the 1,000 mg/kg dose showed a statistically significant difference (p < or = 0.05).

[Cardiovascular effects of aqueous extracts of the leaves of Clusia coclensis (Guttiferae)]

Aqueous extracts of the leaves of Clusia coclensis, (Guttiferae) injected intravenously to 42 normal Sprague-Dawley rats and to 42 Spontaneous Hypertensive rats, in 7 different doses, induced a rapid and transitory decrease in blood pressure and heart frequency. The magnitude of blood pressure decrease was dose-dependent. The effect was statistically significant (p < or = 0.01), probably due to sympathetic stimuli.