271 research outputs found
Capillary and anchoring effects in thin hybrid nematic films and connection with bulk behavior
By means of a molecular model, we examine hybrid nematic films with
antagonistic anchoring angles where one of the surfaces is in the strong
anchoring regime. If anchoring at the other surface is weak, and in the absence
of wetting by the isotropic phase, the anchoring transition may interact with
the capillary isotropic-nematic transition in interesting ways. For general
anchoring conditions on this surface we confirm the existence of the step-tilt,
biaxial phase and the associated transition to the linear,
constant-tilt-rotation, configuration. The step-like phase is connected with
the bulk isotropic phase for increasing film thickness so that the latter
transition is to be interpreted as the capillary isotropic-nematic transition.
Finally, we suggest possible global surface phase diagrams.Comment: 7 pages, 5 figure
SNOM characterization of a potential low cost thin gold coated micro-structured grating using a commercial CD substrate
In this work near-field optical measurements of a corrugated grating coated with a 30 nm thick gold film are presented. The grating was made using the polycarbonate corrugated substrate of a commercially available recordable CD as template. This has been proved to be a versatile and low cost technique in producing large 1.6 μm period gratings. The study was carried out using a Scanning Near-Field Optical Microscope (SNOM) working in both collection and reflection modes at two different wavelengths, 532 nm and 633 nm. The results illustrate that the intensity patterns of near-field images are strongly polarization-dependent, even showing different periodicity of the localized fields for orthogonal polarization states. When electric field of the light is polarized parallel to the grooves, the periodicity of the SNOM images is coincident with the grating period, whereas when the light is polarized perpendicular to the grooves the SNOM pattern shows a periodicity twice that of the corresponding topography of the grating. Numerical simulations of the SNOM data based on a two-dimensional Finite Difference Time-Domain (2D-FDTD) model have been realized. The results of the simulations are in good agreement with the experimental data, emphasizing the need of performing numerical simulation for the correct interpretation of SNOM data
The surgical management of acute upper GI bleeding: Experiences from a district general hospital
Single-channel transmission in gold one-atom contacts and chains
We induce superconductivity by proximity effect in thin layers of gold and
study the number of conduction channels which contribute to the current in
one-atom contacts and atomic wires. The atomic contacts and wires are
fabricated with a Scanning Tunneling Microscope. The set of transmission
probabilities of the conduction channels is obtained from the analysis of the
characteristic curve which is highly non-linear due to multiple Andreev
reflections. In agreement with theoretical calculations we find that there is
only one channel which is almost completely open.Comment: 4 pages, 2 figures. To be published in Phys. Rev. B, Rapid
Communications (2003
Lung adenocarcinoma originates from retrovirus infection of proliferating type 2 pneumocytes during pulmonary post-natal development or tissue repair
Jaagsiekte sheep retrovirus (JSRV) is a unique oncogenic virus with distinctive biological properties. JSRV is the only virus causing a naturally occurring lung cancer (ovine pulmonary adenocarcinoma, OPA) and possessing a major structural protein that functions as a dominant oncoprotein. Lung cancer is the major cause of death among cancer patients. OPA can be an extremely useful animal model in order to identify the cells originating lung adenocarcinoma and to study the early events of pulmonary carcinogenesis. In this study, we demonstrated that lung adenocarcinoma in sheep originates from infection and transformation of proliferating type 2 pneumocytes (termed here lung alveolar proliferating cells, LAPCs). We excluded that OPA originates from a bronchioalveolar stem cell, or from mature post-mitotic type 2 pneumocytes or from either proliferating or non-proliferating Clara cells. We show that young animals possess abundant LAPCs and are highly susceptible to JSRV infection and transformation. On the contrary, healthy adult sheep, which are normally resistant to experimental OPA induction, exhibit a relatively low number of LAPCs and are resistant to JSRV infection of the respiratory epithelium. Importantly, induction of lung injury increased dramatically the number of LAPCs in adult sheep and rendered these animals fully susceptible to JSRV infection and transformation. Furthermore, we show that JSRV preferentially infects actively dividing cell in vitro. Overall, our study provides unique insights into pulmonary biology and carcinogenesis and suggests that JSRV and its host have reached an evolutionary equilibrium in which productive infection (and transformation) can occur only in cells that are scarce for most of the lifespan of the sheep. Our data also indicate that, at least in this model, inflammation can predispose to retroviral infection and cancer
Polymorphisms in the IL2, IL2RA and IL2RB genes in multiple sclerosis risk
Interleukin (IL)-2/IL-2R signalling promotes proliferation and survival of activated T cells and has an essential non-redundant role in the production of regulatory T cells. Associations with different autoimmune diseases of polymorphisms in a linkage disequilibrium block in which the IL2/IL21 genes map (4q27), and also in genes encoding the IL2RA and IL2RB subunits (located in 10p15 and 22q13, respectively), were identified through genome-wide studies. Polymorphisms in these three genes were studied in 430 multiple sclerosis (MS) patients and in 550 ethnically matched controls from Madrid (Spain). Replication and meta-analysis with results from an independent cohort of 771 MS patients and 759 controls from AndalucÃa (Spain) confirmed the association of polymorphisms in the IL2RA gene (PMantel-Haenszel, odds ratio (OR) M-H (95% confidence interval, CI) for rs2104286: 0.0001, 0.75 (0.65-0.87); for rs11594656/rs35285258: 0.004, 1.19 (1.06-1.34); for rs41295061: 0.03, 0.77 (0.60-0.98)); showed a trend for association of the IL2/IL21 rs6822844 (P M-H 0.07, OR M-H (95% CI)0.86 (0.73-1.01)), but did not corroborate the association for IL2RB. Regression analyses of the combined Spanish cohort revealed the independence of two IL2RA association signals: rs2104286 and rs11594656/rs35285258. The relevant role of the IL2RA gene on MS susceptibility adds support to its common effect on autoimmune risk and the suggestive association of IL2/IL21 warrants further investigation. © 2010 Macmillan Publishers Limited All rights reserved.Concepción Núñez holds a research contract from Fondo Investigaciones Sanitarias (CA06/0163) and Elena Urcelay works for the Fundación para la Investigación Biomédica-Hospital ClÃnico San Carlos. This study was supported by grants from: Alfonso MartÃn Escudero Foundation and Fondo Investigaciones Sanitarias FIS PI07/0353, FIS PI07/0369, PI08/1636 and Plan Nacional PN-SAF2006-02023.Peer Reviewe
The Spanish Pancreatic Club's recommendations for the diagnosis and treatment of chronic pancreatitis: Part 2 (treatment)
Chronic pancreatitis (CP) is a complex disease with a wide range of clinical manifestations. This range
comprises from asymptomatic patients to patients with disabling symptoms or complications. The
management of CP is frequently different between geographic areas and even medical centers. This is
due to the paucity of high quality studies and clinical practice guidelines regarding its diagnosis and
treatment. The aim of the Spanish Pancreatic Club was to give current evidence-based recommendations
for the management of CP. Two coordinators chose a multidisciplinary panel of 24 experts on this
disease. These experts were selected according to clinical and research experience in CP. A list of
questions was made and two experts reviewed each question. A draft was later produced and discussed
with the entire panel of experts in a face-to-face meeting. The level of evidence was based on the ratings
given by the Oxford Centre for Evidence-Based Medicine. In the second part of the consensus, recommendations were given regarding the management of pain, pseudocysts, duodenal and biliary stenosis,
pancreatic fistula and ascites, left portal hypertension, diabetes mellitus, exocrine pancreatic insufficiency,
and nutritional support in CP
Influence de la densité du peuplement et de la fertilité de la station sur la dynamique de reproduction de Pinus halepensis Mill., dix ans après d’importants incendies
The Spanish Pancreatic Club recommendations for the diagnosis and treatment of chronic pancreatitis: Part 1 (diagnosis)
Chronic pancreatitis (CP) is a relatively uncommon, complex and heterogeneous disease. The absence of
a gold standard applicable to the initial phases of CP makes its early diagnosis difficult. Some of its
complications, particularly chronic pain, can be difficult to manage. There is much variability in the
diagnosis and treatment of CP and its complications amongst centers and professionals. The Spanish
Pancreatic Club has developed a consensus on the management of CP. Two coordinators chose a multidisciplinary
panel of 24 experts on this disease. A list of questions was drafted, and two experts reviewed
each question. Then, a draft was produced and shared with the entire panel of experts and discussed in
a face-to-fac
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