p-State Luminescence in CdSe Nanoplatelets: The Role of Lateral Confinement and an LO Phonon Bottleneck

We report excited state emission from p-states at excitation fluences well below ground state saturation in CdSe nanoplatelets. Size dependent exciton ground state-excited state energies and dynamics are determined by three independent methods, time-resolved photoluminescence (PL), time-integrated PL and Hartree renormalized k$\cdot$p calculations -- all in very good agreement. The ground state-excited state energy spacing strongly increases with the lateral platelet quantization. Our results suggest that the PL decay of CdSe platelets is governed by an LO-phonon bottleneck, related to the reported low exciton phonon coupling in CdSe platelets and only observable due to the very large oscillator strength and energy spacing of both states

Relationships Between Two Approaches: Rigged Configurations and 10-Eliminations

There are two distinct approaches to the study of initial value problem of the periodic box-ball systems. One way is the rigged configuration approach due to Kuniba--Takagi--Takenouchi and another way is the 10-elimination approach due to Mada--Idzumi--Tokihiro. In this paper, we describe precisely interrelations between these two approaches.Comment: 16 pages, final version, minor revisio

Structure of ternary additive hard-sphere fluid mixtures

Monte Carlo simulations on the structural properties of ternary fluid mixtures of additive hard spheres are reported. The results are compared with those obtained from a recent analytical approximation [S. B. Yuste, A. Santos, and M. Lopez de Haro, J. Chem. Phys. 108, 3683 (1998)] to the radial distribution functions of hard-sphere mixtures and with the results derived from the solution of the Ornstein-Zernike integral equation with both the Martynov-Sarkisov and the Percus-Yevick closures. Very good agreement between the results of the first two approaches and simulation is observed, with a noticeable improvement over the Percus-Yevick predictions especially near contact.Comment: 11 pages, including 8 figures; A minor change; accepted for publication in PR

Broadband repeatable <0.025 dB average loss rapid adiabatic based 3-dB coupler in a 45 nm SOI CMOS process

We demonstrate a 75 µm-long rapid adiabatic coupler (RAC) with an average insertion loss <0.025 dB/coupler and an average power splitting ratio of 50±1.09% over 40 nm bandwidth and 68 reticles across a 300 mm 45 nm SOI CMOS wafer.Accepted manuscrip

Inverse correlation between PDGFC expression and lymphocyte infiltration in human papillary thyroid carcinomas

<p>Abstract</p> <p>Background</p> <p>Members of the PDGF family have been suggested as potential biomarkers for papillary thyroid carcinomas (PTC). However, it is known that both expression and stimulatory effect of PDGF ligands can be affected by inflammatory cytokines. We have performed a microarray study in a collection of PTCs, of which about half the biopsies contained tumour-infiltrating lymphocytes or thyroiditis. To investigate the expression level of PDGF ligands and receptors in PTC we measured the relative mRNA expression of all members of the PDGF family by qRT-PCR in 10 classical PTC, eight clinically aggressive PTC, and five non-neoplastic thyroid specimens, and integrated qRT-PCR data with microarray data to enable us to link PDGF-associated gene expression profiles into networks based on recognized interactions. Finally, we investigated potential influence on PDGF mRNA levels by the presence of tumour-infiltrating lymphocytes.</p> <p>Methods</p> <p>qRT-PCR was performed on <it>PDGFA</it>, <it>PDGFB</it>, <it>PDGFC</it>, <it>PDGFD</it>, <it>PDGFRA PDGFRB </it>and a selection of lymphocyte specific mRNA transcripts. Semiquantitative assessment of tumour-infiltrating lymphocytes was performed on the adjacent part of the biopsy used for RNA extraction for all biopsies, while direct quantitation by qRT-PCR of lymphocyte-specific mRNA transcripts were performed on RNA also subjected to expression analysis. Relative expression values of PDGF family members were combined with a cDNA microarray dataset and analyzed based on clinical findings and PDGF expression patterns. Ingenuity Pathway Analysis (IPA) was used to elucidate potential molecular interactions and networks.</p> <p>Results</p> <p>PDGF family members were differentially regulated at the mRNA level in PTC as compared to normal thyroid specimens. Expression of <it>PDGFA </it>(p = 0.003), <it>PDGFB </it>(p = 0.01) and <it>PDGFC </it>(p = 0.006) were significantly up-regulated in PTCs compared to non-neoplastic thyroid tissue. In addition, expression of <it>PDGFC </it>was significantly up-regulated in classical PTCs as compared to clinically aggressive PTCs (p = 0.006), and <it>PDGFRB </it>were significantly up-regulated in clinically aggressive PTCs (p = 0.01) as compared to non-neoplastic tissue. Semiquantitative assessment of lymphocytes correlated well with quantitation of lymphocyte-specific gene expression. Further more, by combining TaqMan and microarray data we found a strong inverse correlation between <it>PDGFC </it>expression and the expression of lymphocyte specific mRNAs.</p> <p>Conclusion</p> <p>At the mRNA level, several members of the PDGF family are differentially expressed in PTCs as compared to normal thyroid tissue. Of these, only the <it>PDGFC </it>mRNA expression level initially seemed to distinguish classical PTCs from the more aggressive PTCs. However, further investigation showed that <it>PDGFC </it>expression level correlated inversely to the expression of several lymphocyte specific genes, and to the presence of lymphocytes in the biopsies. Thus, we find that <it>PDGFC </it>mRNA expression were down-regulated in biopsies containing infiltrated lymphocytes or thyroiditis. No other PDGF family member could be linked to lymphocyte specific gene expression in our collection of PTCs biopsies.</p

Childhood intussusception in Uzbekistan: Analysis of retrospective surveillance data

<p>Abstract</p> <p>Background</p> <p>Estimates of baseline incidence of childhood intussusception could help safety monitoring after the introduction of rotavirus vaccines. We studied the incidence of intussusception in Uzbekistan, a GAVI-fund eligible state in Central Asia.</p> <p>Methods</p> <p>We retrospectively reviewed intussusception cases in children <2 years of age treated during 2004-2008 at 15 hospitals in the Bukhara region of Uzbekistan. Demographic and clinical data as well as information on diagnostic and treatment practices were obtained from hospital records. We categorized cases using the Brighton collaboration clinical case definition and calculated the national incidence rate.</p> <p>Results</p> <p>Over a 5-year study period, 67 confirmed cases were identified, of which 67% were boys. The median age was 12 months, and no seasonal trend in the distribution of cases was observed. The diagnostic methods used included abdominal radiography (87%) and ultrasonography (57%). Intussusception reduction by air enema was successful in 33 (49%) patients and 34 (50%) cases underwent surgery. A total of 4 deaths occurred, including 3 deaths in infants aged 0-6 months. The median length of hospital stay was 7.3 (range 0-37) days. The incidence of intussusception is estimated at 23 (95% CI 13.6-32.4) cases per 100,000 child-years, corresponding to approximately 237 cases annually.</p> <p>Conclusions</p> <p>This is the first study to estimate the incidence of childhood intussusception prior to the introduction of the rotavirus vaccination in Uzbekistan. A prospective surveillance system using a standardized case definition is needed in order to better examine the occurrence of intussusception in developing countries.</p

Directed emission of CdSe nanoplatelets originating from strongly anisotropic 2D electronic structure

ntrinsically directional light emitters are potentially important for applications in photonics including lasing and energy-efficient display technology. Here, we propose a new route to overcome intrinsic efficiency limitations in light-emitting devices by studying a CdSe nanoplatelets monolayer that exhibits strongly anisotropic, directed photoluminescence. Analysis of the two-dimensional k-space distribution reveals the underlying internal transition dipole distribution. The observed directed emission is related to the anisotropy of the electronic Bloch states governing the exciton transition dipole moment and forming a bright plane. The strongly directed emission perpendicular to the platelet is further enhanced by the optical local density of states and local fields. In contrast to the emission directionality, the off-resonant absorption into the energetically higher 2D-continuum of states is isotropic. These contrasting optical properties make the oriented CdSe nanoplatelets, or superstructures of parallel-oriented platelets, an interesting and potentially useful class of semiconductor-based emitters

Cholinergic Interneurons Mediate Fast VGluT3-Dependent Glutamatergic Transmission in the Striatum

The neurotransmitter glutamate is released by excitatory projection neurons throughout the brain. However, non-glutamatergic cells, including cholinergic and monoaminergic neurons, express markers that suggest that they are also capable of vesicular glutamate release. Striatal cholinergic interneurons (CINs) express the Type-3 vesicular glutamate transporter (VGluT3), although whether they form functional glutamatergic synapses is unclear. To examine this possibility, we utilized mice expressing Cre-recombinase under control of the endogenous choline acetyltransferase locus and conditionally expressed light-activated Channelrhodopsin2 in CINs. Optical stimulation evoked action potentials in CINs and produced postsynaptic responses in medium spiny neurons that were blocked by glutamate receptor antagonists. CIN-mediated glutamatergic responses exhibited a large contribution of NMDA-type glutamate receptors, distinguishing them from corticostriatal inputs. CIN-mediated glutamatergic responses were insensitive to antagonists of acetylcholine receptors and were not seen in mice lacking VGluT3. Our results indicate that CINs are capable of mediating fast glutamatergic transmission, suggesting a new role for these cells in regulating striatal activity

Reliability of the Evaluation of Students’ Answers to Essay-type Questions. (Confiabilidad de la Evaluación de las Respuestas de los Estudiantes a las Preguntas de Ensayo)

Introduction: This paper seeks to quantify the reliability of the assessment of students’ answers to essay-type questions, in an attempt to define the role of such questions in University examinations. Methods: The marks awarded for essay-type questions during three consecutive final undergraduate examinations in surgery were analyzed. The mean scores, 95% confidence intervals and the standard error of the mean were calculated to determine the distribution of the marks. Statistical analysis was used to determine the correlation of the marks awarded for the same answer by different markers and deduce the dependability of this method of testing. Results: The marks awarded to 233 answer papers were available for analysis. The marks awarded by each pair of examiners for student answers to individual questions coincided on only 46.3% of occasions, but varied within just ± 5% on 90.7% of occasions. Use of the kappa index to determine the agreement between markers produced a value of just 0.385, well short of the ideal of 1.0. Assessment of the overall reliability of this type of examination by Cronbach’s reliability coefficent gave a value of 0.672. Conclusion: There was a significant variation among markers in the evaluation of answers to essaytype questions. However, the overall test reliability was acceptable enough to justify continuation of this type of assessment as a supplement to other methods. (Confiabilidad de la Evaluación de las Respuestas de los Estudiantes a las Preguntas de Ensayo) RESUMEN Introducción: Este trabajo busca cuantificar la confiabilidad de la evaluación de las respuestas de los estudiantes a las preguntas de ensayo, en un intento por definir el papel de este tipo de preguntas en los exámenes de la Universidad. Métodos: Se analizaron las notas otorgadas en cirugía a las preguntas de ensayo durante los tres exámenes finales consecutivos de pregrado. Se calcularon los puntajes promedio, intervalos de confianza de 95%, y el error estándar de la media, con el fin de determinar la distribución de las notas. Se usó el análisis estadístico para determinar la correlación de las notas dadas a las mismas respuestas por diferentes evaluadores, y para deducir la confiabilidad de este método de evaluación. Resultados: Las notas otorgadas a 233 pruebas respondidas fueron puestas a disposición para su análisis. Las notas dadas por cada par de examinadores a las respuestas de los estudiantes a las preguntas individuales, coincidieron sólo en 46.3% de las ocasiones, pero variaron en justamente ±5% en 90.7% de las ocasiones. El uso del índice de Kappa para determinar el acuerdo entre evaluadores, produjo un valor de sólo 0.385, bien lejos del ideal 1.0. La evaluación de la confiabilidad general de este tipo de examen, mediante el coeficiente de confiabilidad de Cronbach, arrojó un valor de 0.672. Conclusión: Hubo una variación significativa entre los evaluadores a la hora de calificar las respuestas a las preguntas de ensayo. Sin embargo, la confiabilidad de la prueba en general fue suficientemente aceptable para justificar que se continúe con este tipo de evaluación como un complemento de otros métodos

Interstitial Cells of Cajal and Intestinal Function in Trinidadian Children:

Objective: This study was carried out to compare the density of the interstitial cells of Cajal (ICCs) in the bowel wall of children with Hirschsprung’s disease (HD), anorectal malformations (ARM) and normal controls in Trinidad and Tobago. Subjects and Method: Segments of bowel wall excised from eight children with HD, three controls and two children with ARM were immunostained with c-Kit primary antibody. Cells with features of ICCs were counted. Results: All three controls and the two children with ARM had dense distribution of ICCs. Most children (6/8;75%) with HD had markedly reduced counts in aganglionic bowel. Two (25%) also had a decrease in ganglionic bowel. Possible influences were patient age and gender and the level of bowel sectioned. Conclusion: Analysis of this sample suggests that immunostaining for c-Kit positive cells might be a useful screening test in the assessment of bowel motility disorders. The possible effects of age, gender and the level of bowel sampled await determination. "Células Intersticiales de Cajal y Función Intestinal en Niños Trinitenses" RESUMEN Objetivo: Este estudio se llevó a cabo con el propósito de comparar la densidad de las células intersticiales de Cajal (CIC) en las paredes intestinales de niños con la enfermedad de Hirschprung (EH), y malformaciones anorectales (MAR), frente a controles normales en Trinidad Tobago. Sujetos y Métodos: Segmentos de las paredes intestinales les fueron extirpados a ocho niños con EH; tres controles y dos niños con MAR fueron inmunoteñidos con anticuerpo primario c-kit. Se contaron las células con características de CIC. Resultados: Los tres controles y los dos niños con MAR presentaban una distribución densa de CICs. La mayor parte de los niños (6/8; 75%) con EH tuvieron conteos marcadamente reducidos de intestino agangliónico. Dos niños (25%) también tuvieron una disminución de intestino gangliónico. Entre las influencias posibles se cuentan la edad y el género del paciente así como el nivel de intestino seccionado. Conclusión: El análisis de esta muestra sugiere que la inmunotinción para células c-kit positivas podría ser un útil test de pesquisaje a la hora de evaluar desórdenes en la motilidad intestinal. Los efectos posibles de la edad, el género y el nivel de intestino muestreado, están pendientes de determinación