Optomechanical properties of GaAs/AlAs micropillar resonators operating in the 18 GHz range.

Recent experiments demonstrated that GaAs/AlAs based micropillar cavities are promising systems for quantum optomechanics, allowing the simultaneous three-dimensional confinement of near-infrared photons and acoustic phonons in the 18-100 GHz range. Here, we investigate through numerical simulations the optomechanical properties of this new platform. We evidence how the Poisson's ratio and semiconductor/vacuum boundary conditions lead to very distinct features in the mechanical and optical three-dimensional confinement. We find a strong dependence of the mechanical quality factor and strain distribution on the micropillar radius, in great contrast to what is predicted and observed in the optical domain. The derived optomechanical coupling constants g0 reach ultra-large values in the 106 rad/s range.

Pedunculated liposarcoma of the esophagus.

Polypoid tumours of the esophagus present diagnostic and therapeutic problems. Liposarcomas are infrequent among them. We report a recent case. A 73-year-old male patient was seen in May 1995 in the Ear, Nose and Throat (ENT) Department, Clinica Modelo de Morón, with intermittent dysphagia and dyspnoea due to recurrent vomiting. A laryngeal lineal tomography showed a subglottic obstruction due to extrinsic compression. The patient was referred to the Gastroenterology Department, where an upper gastrointestinal (upper GI) series demonstrated mega-esophagus with abundant retained food. Endoscopy showed a large intraluminal mass covered by normal mucosa which arose on the posterior wall. Videofluoroscopy and chest CT diagnosed a probable polypoid lipoma due to its densitometric characteristics. The tumour was resected by left cervicotomy and left esophagotomy. The patient's progress to date is favourable. Pathology studies showed a well-differentiated liposarcoma. According to the literature, the first case was reported in 1983, and ours is only the seventh case in the world to be documented.

The pineal complex in the cichlid Cichlasoma dimerus: effect of different photoperiods on its cell morphology.

This research describes the pineal complex histology in juvenile and adult Cichlasoma dimerus, and the effect of different photoperiods on its cell morphology. In both juveniles and adults, the pineal complex of C. dimerus has three components: the pineal organ, consisting of a pineal vesicle (PV) and a pineal stalk, the parapineal organ and the dorsal sac. Although a strong morphological resemblance exists between the two stages, different synthesis patterns of cone and rod opsins were detected in the two life stages. An effect of the photoperiod length was observed on putative pinealocytes' activity from the PV, measured indirectly through nuclear area morphometry. Individuals exposed to a natural photoperiod (14L:10D) had smaller nuclear areas (mean ± s.e. = 13·82 ± 1·52 µm(2) ) than those exposed to a short photoperiod (8:16) (21·45 ± 2·67 µm(2) ; P < 0·001). Eventually, the nuclear area of pinealocytes could be used as a putative indicator of melatonin synthesis in fishes where it is difficult to obtain plasma samples, e.g. due to its small size or age. This work constitutes one of the few comparative descriptions of the pineal complex of juvenile and adult teleost and suggests potential approaches for the study of melatonin synthesis in fish larvae or small adult fishes.

Patterns of DNA damage and photoinhibition in temperate South-Atlantic picophytoplankton exposed to solar ultraviolet radiation.

Natural marine phytoplankton assemblages from Bahía Bustamante (Chubut, Argentina, 45 degrees S, 66.5 degrees W), mainly consisting of cells in the picoplankton size range (0.2-2 microm), were exposed to various UVBR (280-315 nm) and UVAR (315-400 nm) regimes in order to follow wavelength-dependent patterns of cyclobutane pyrimidine dimer (CPD) induction and repair. Simultaneously, UVR induced photosynthetic inhibition was studied in radiocarbon incorporation experiments. Biological weighting functions (BWFs) for photoinhibition and for CPD induction, the latter measured in bare calf thymus DNA, differed in the UVAR region: carbon incorporation was reduced markedly due to UVAR, whereas no measurable UVAR effect was found on CPD formation. In contrast, BWFs for inhibition of photosynthesis and CPD accumulation were fairly similar in the UVBR region, especially above 300 nm. Incubation of phytoplankton under full solar radiation caused rapid CPD accumulation over the day, giving maximum damage levels exceeding 500 CPD MB(-1) at the end of the afternoon. A clear daily pattern of CPD accumulation was found, in keeping with the DNA effective dose measured by a DNA dosimeter. In contrast, UVBR induced photosynthetic inhibition was not dose related and remained nearly constant during the day. Screening of UVBR or UVR did not cause significant CPD removal, indicating that photoreactivation either by PAR or UVAR was of minor importance in these organisms. High CPD levels were found in situ early in the morning, which remained unaffected notwithstanding treatments favoring photorepair. These results imply that a proportion of cells had been killed by UVBR exposure prior to the treatments. Our data suggest that the limited potential for photoreactivation in picophytoplankton assemblages from the southern Atlantic Ocean causes high CPD accumulation as a result of UVBR exposure.

Solar ultraviolet radiation and its impact on aquatic systems of Patagonia, South America.

Solar ultraviolet radiation (UVR, 280-400 nm) is known to cause a number of detrimental effects in aquatic organisms. The area of Patagonia, which is sometimes under the influence of the Antarctic ozone "hole", occasionally receives enhanced levels of ultraviolet B radiation (UV-B, 280-315 nm). Great efforts have been put into creating a database for UVR climatology by installing a variety of instruments in several localities in the region. However, no comparable effort has been made to determine the impact of normal and enhanced levels of solar UVR upon organisms. Most of the photobiological research in aquatic systems of Patagonia has focused on determining the effects of solar UVR in phytoplankton photosynthesis, DNA damage, and mortality, fecundity and repair mechanisms in zooplanktonic species. Some work has also been done with fish larvae and interactions between species at low trophic levels of the aquatic food web. The results of these studies indicate that in order to assess the overall impact of UVR in a certain waterbody, it is also necessary to consider other variables, such as changes in cloudiness, ozone concentrations, differential sensitivity of organisms, and depth of the upper mixed layer/epilimnion. All factors that can preclude or benefit the acclimation of species to solar radiation.

[Plasma clearance of alpha 1-antitrypsin. A simple method for the study of intestinal protein loss]. / Depuración plasmática de alfa-1-antitripsina. Método simple para el estudio de la perdida proteica intestinal.

We tried to evaluate the value of the alpha-1-antitrypsin clearance in order to search for the protein loss through the digestive tract. Twenty-two patients were studied, 11 with protein losing enteropathy and 11 normal controls. Alpha-1-antitrypsin concentration was determined in serum and feces to obtain the clearance of such protein. The values were always abnormal in patients with protein losing enteropathy, and normal in control patients. We consider this method simple and safe for the evaluation of intestinal protein loss, besides having the advantage of not using radioactive material.

[Chronic calcified pancreatitis. Our experience]. / Pancreatitis crónica calcificada. Nuestra experiencia.

Forty five cases of chronic pancreatitis have been diagnosed between January 1966 to July 1983 in the Hospital A. Posadas. The diagnosis was confirmed by the presence of one or more of the following data: pancreatic calcifications positive in 35, abnormal secretin test 37, ultrasonography and computed tomography pathological findings 10. Surgical operations were carried out in 25 patients and biopsy taken in 5. Thirty nine (86.6%) were males, 6 (13.3%) females, the mean age in each group was 47.4 and 39.8 years. Chronic alcoholism was certain in 41 (91.9) patients, in the remainder 4 no other etiologic factors were found. The main clinical data were: Weight loss 38 (84.4%) diabetes 34 (75.5%) pain 33 (73.3% in 7 as acute pancreatitis) Steatorrhea 23 (51.1%) jaundice 16 (35.5%- 11 by extrahepatic biliary tree obstruction, 5 by hepatic cirrhosis) pseudocysts 12 (26.6%). The more common associated diseases were: hepatic cirrhosis 6, fatty liver 2 (17.7%) gastroduodenal ulcer 6 (13.3%) cancer 4 (8.8%--gastric 1, pancreatic 3). In order to study the frequency of the clinical data the patients were grouped according to the presence or absence of calcifications and the etiologic factor Symptoms and signs were matched and statistic analysis (coefficient association phi) was made. Only a moderate association between acute pancreatitis in no calcified group and diabetes in calcified group were found. The chronologic study of certains clinical data shows that acute pancreatitis, jaundice, pseudo-cyst and surgical operations were significative more frequent in the first five years while diabetes has little more frequency in the second five year period. Twenty six surgical operations were carried out in 25 patients; 20 (76.9%) due to complications, 6 (23.1%) secondary to pain (pancreatic resection 3, pancreatoyeyunostomy 2, exploration 1). Twenty three patients were lost to follow-up, 12 died and 10 are still alive. This last group was followed at regular period, 8 remained asymptomatic and 2 have intermittent abdominal pain related to alcoholic ingestion.

Photochemical responses of three marine phytoplankton species exposed to ultraviolet radiation and increased temperature: role of photoprotective mechanisms.

We carried out experiments using long-term (5-7 days) exposure of marine phytoplankton species to solar radiation, in order to assess the joint effects of ultraviolet radiation (UVR) and temperature on the photochemical responses and photoprotective mechanisms. In the experiments, carried out at Atlantic coast of Patagonia (43°18.7'S; 65°2.5'W) in spring-summer 2011, we used three species as model organisms: the dinoflagellate Prorocentrum micans, the chlorophyte Dunaliella salina and the haptophyte Isochrysis galbana. They were exposed under: (1) two radiation quality treatments (by using different filters): P (PAR, >400 nm) and PAB (PAR+UV-A+UV-B, >280 nm); (2) two radiation intensities (100% and 50%) and (3) two experimental temperatures: 18 °C and 23 °C during summer and 15 °C and 20 °C in spring experiments, simulating a 5 °C increase under a scenario of climate change. In addition, short-term (4h) artificial radiation exposure experiments were implemented to study vertical migration of cells pre- and non-acclimated to solar radiation. We observed species-specific responses: P. micans displayed a better photochemical performance and a lower inhibition induced by UVR than D. salina and I. galbana. In accordance, P. micans was the only species that showed a synthesis of UV-absorbing compounds (UVACs) during the experiment. On the other hand, non-photochemical quenching (NPQ) was activated in D. salina at noon throughout the exposure, while I. galbana did not show a regular NPQ pattern. This mechanism was almost absent in P. micans. Regarding vertical migration, I. galbana showed the most pronounced displacement to deepest layers since the first two hours of exposure in pre- and non-acclimated cells, while only non-acclimated D. salina cells moved to depth at the end of the experiment. Finally, temperature partially counteracted solar radiation inhibition in D. salina and I. galbana, whereas no effect was observed upon P. micans. In particular, significant UVR and temperature interactive effects were found in I. galbana, the most UVR sensitive species. The joint effects on UVR and temperature, and the species-specific photoprotective responses will affect the trophodynamics and production of aquatic ecosystems in a way that is difficult to predict; however the specificity of the responses suggests that not all phytoplankton would be equally benefited by temperature increases therefore affecting the balance and interaction among species in the water column.

Temperature benefits the photosynthetic performance of the diatoms Chaetoceros gracilis and Thalassiosira weissflogii when exposed to UVR.

The aim of this study was to assess the combined effects of temperature and UVR on the photosynthesis performance of two diatoms -Chaetoceros gracilis and Thalassiosira weissflogii. In particular, we evaluated the role of UVR in inducing photoinhibition and the potential mitigation of this negative effect by an increase in temperature. Cultures were pre-acclimated at two temperatures - 18°C and 23°C - and exposed to different radiation treatments - UVR+PAR (280-700nm); UV-A+PAR (315-700nm) and PAR only (400-700nm) under two temperatures: 18°C (local surface summer water temperature) and 23°C (simulating a potential increase estimated by the year 2100). Exposure to natural solar radiation resulted in UVR-induced photoinhibition that was significantly higher in T. weissflogii than in C. gracilis. Both species benefited from the higher temperature (23°C) resulting in a lower photoinhibition as compared to samples exposed at 18°C. Inter-specific differences were determined in regard to the heat dissipation processes (NPQ) which were higher at high temperatures, and much more evident in C. gracilis than in T. weissflogii. The analyses of inhibition and recovery rates under different irradiances indicate that the balance between negative (inhibition) and positive (repair-dissipation) effects shifted towards a more positive balance with increasing temperature. Our results highlight for a beneficial effect of temperature on photosynthesis performance during exposure to UVR, although important inter-specific differences are found, probably due to differences in cell size as well as in their distribution within the oceanic realm (i.e., coastal versus oceanic species).

Pedunculated liposarcoma of the esophagus.

Polypoid tumors of the esophagus present diagnostic and therapeutic problems. Liposarcomas are infrequent among them. We report a recent case. A 73-year-old male patient was seen in May 1995 in the Ear, Nose and Throat (ENT) Department, Clínica Modelo de Morón, with intermittent dysphagia and dyspnoea due to recurrent vomiting. A laryngeal lineal tomography showed a subglottic obstruction due to extrinsic compression. The patient was referred to the Gastroenterology Department, where an upper gastrointestinal (upper GI) series demonstrated mega-esophagus with abundant retained food. Endoscopy showed a large intraluminal mass covered by normal mucosa which arose on the posterior wall. Videofluoroscopy and chest CT diagnosed a probable polypoid lipoma due to its densitometric characteristics. The tumour was resected by left cervicotomy and left esophagotomy. The patient's progress to date is favourable. Pathology studies showed a well-differentiated liposarcoma. According to the literature, the first case was reported in 1983, and ours is only the seventh case in the world to be documented.

Depuración plasmática de alfa-1-antitripsina, método simple para el estudio de la pérdida proteica intestinal / Plasma clearance of alpha 1-antitrypsin, a simple method for the study of intestinal protein losing

Tratamos de corroborar el valor del clearence de alfa-antitripsina como una técnica eficaz para objetivar la pérdida de proteínas a través del tubo digestivo y su aplicación como método de diagnóstico en tal patología. Se estudiaron 22 individuos; 11 con patología intestinal capaz de producir pérdida proteica y 11 controles sin daño de la mucosa intestinal. Se determinó la concentración de alfa-1-antitripsina tanto en suero como en materia fecal en días consecutivos y pesando la materia fecal de 24 horas se pudo obtener el clearence intestinal de dicha proteína. En los pacientes con enfermedad perdedora de proteínas el valor del clearence fue siempre patológico mientras que en los controles se obtuvieron valores normales. Este método es útil para diagnosticar la pérdida proteica intestinal y tiene la ventaja de no utilizar material radioactivo para su determinación