Theoretical analysis of modulation response and second-order harmonic distortion in vertical-cavity surface-emitting lasers

A rate-equation model is developed, with the consideration of size effects, to analyze the steady state and dynamic behavior of index-guided vertical-cavity surface-emitting lasers. The size dependence of spatial hole burning, cavity loss, as well as thermal resistance of device cavity are taken into account. Using this model, the influence of size effects on the amplitude modulation response and second-order harmonic distortion are studied. It is found that a laser with a small core radius exhibits better modulation response and less harmonic distortion than that of a large waveguide device, however, there is a tradeoff between the output power and modulation efficiency of the lasers.published_or_final_versio

Investigating Cell Surface Markers and Differentiation Potential of Compact Bone-Derived Mesenchymal Stem Cells

Background: The differentiation potential of mesenchymal stem cells (MSCs) derived from the bone-tissue to multiple lineages is not clear. Objective: This study was conducted to investigate the surface antigen expression and multilineage stem cell potential of the cells derived from culture of collagenase digested marrow-free compact bones of C57BL/6 mouse. Materials & Methods: Long bones of C57BL/6 mouse (n=6) were collected aseptically and bone marrow was flushed out. Collagenase-digested bone fragments were washed and cultured in plastic flasks. The plastic-adherent fibroblast-like spindle-shaped cells were cultured sequentially in multiple passages in low-glucose DMEM (Dulbecco’s Modified Eagle’s Medium) supplemented with 15% FBS (Foetal Bovine Serum) and antibiotics in a 37°C incubator with 5% CO2. Immunophenotyping for cell surface markers was done using flow cytometry. The cells were differentiated into the osteoblastic, adipogenic and chondrogenic lineages. Results: The culture of the adherent cells exhibited active proliferation and multiplication in consequent passages. The cultured cells revealed evidence of adipogenic and osteogenic differentiation confirmed by staining with oil red O and von Kossa stains. Under flow cytometry observation, a significant proportion of cultured cells expressed CD29 and stem cell antigen (Sca-1). Only 9.8% cells showed expression of CD105. These MSCs exhibited low ability in chondrogenic differentiation, which can potentially be attributed to their lack of CD105 expression. Lack of expression of CD45 showed evidence of absence of hematopoietic stem cells. Conclusion: This study showed that murine compact bone-chip culture can yield MSCs with significant proliferation capacity. The cells displayed the ability to differentiate into osteoblast and adipocyte lineages

Metal–organic frameworks in proton-exchange membrane for intermediate-to-high-temperature fuel-cell applications: a review

A proton-exchange membrane (PEM) is a vital component in fuel cells as a solid electrolyte that conducts ions. The high cost and degradation of Nafion® membrane in low-temperature fuel cells limits the technology’s commercialization. The development of intermediate (IT-PEMFCs) to high-temperature (HT-PEMFCs) fuel cells operating within the range of 80–200 °C has made progress over the last few decades, and improvements in water management addressing the issues of low-temperature PEMFCs have been observed. However, these types of PEM fuel cells (IT-PEMFCs and HT-PEMFCs) still face considerable challenges, such as unsatisfactory performance stability at high temperatures. Particularly, in HT-PEMFC, despite the high acid doping level (ADL) in membranes as a potential means to improve proton conductivity, high ADL decreases the membrane’s mechanical stability. Recently, metal–organic frameworks (MOFs) have achieved satisfactory results in applications of PEM modification. This manuscript reviews the development in applying MOFs in improving the properties of composite membranes in IT- and HT-PEMFCs by using SPEEK and PBI, respectively. The synthesis strategies using MOFs in the PEM are discussed together with the electrochemical properties obtained. The success of incorporating of MOFs into PEMs could shed light on the synthesis of new-generation IT- and HT-PEMFCs, which could improve several properties such as mechanical and thermal stability, oxidative stability, and acid-retention capacity

Hospitalized poisonings after renal transplantation in the United States

BACKGROUND: The national incidence of and risk factors for hospitalized poisonings in renal transplant recipients has not been reported. METHODS: Historical cohort study of 39,628 renal transplant recipients in the United States Renal Data System between 1 July 1994 and 30 June 1998. Associations with time to hospitalizations for a primary diagnosis of poisonings (ICD-9 codes 960.x-989.x) within three years after renal transplant were assessed by Cox Regression. RESULTS: The incidence of hospitalized poisonings was 2.3 patients per 1000 person years. The most frequent causes of poisonings were immunosuppressive agents (25.3%), analgesics/antipyretics (14.1%), psychotropic agents (10.0%), and insulin/antidiabetic agents (7.1%). In Cox Regression analysis, low body mass index (BMI, <21.6 vs. >28.3 kg/m(2), adjusted hazard ratio (AHR), 3.02, 95% CI, 1.45–6.28, and allograft rejection, AHR 1.83, 95% CI, 1.15–2.89, were the only factors independently associated with hospitalized poisonings. Hospitalized poisonings were independently associated with increased mortality (AHR, 1.54, 95% CI 1.22–1.92, p = 0.002). CONCLUSIONS: Hospitalized poisonings were associated with increased mortality after renal transplantation. However, almost all reported poisonings in renal transplant recipients were due to the use of prescribed medications. Allograft rejection and low BMI were the only independent risk factors for poisonings identified in this population

Differences in Disease Severity but Similar Telomere Lengths in Genetic Subgroups of Patients with Telomerase and Shelterin Mutations

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

A prospective clinical trial on the influence of a triamcinolone/demeclocycline and a calcium hydroxide based temporary cement on pain perception

<p>Abstract</p> <p>Introduction</p> <p>The aim of this clinical trial was to compare the degree of short term post-operative irritation after application of a triamcinolone/demeclocycyline based or a calcium hydroxide based provisional cement.</p> <p>Methods</p> <p>A total of 109 patients (55 female and 54 male; mean age: 51 ± 14 years) with primary or secondary dentinal caries were randomly assigned to the two treatment groups of this biomedical clinical trial (phase III). Selection criteria were good systemic health and treated teeth, which were vital and showed no symptoms of pulpitis. Up to three teeth were prepared for indirect metallic restorations, and the provisional restorations were cemented with a triamcinolone/demeclocycyline (Ledermix) or a calcium hydroxide (Provicol) based material. The intensity of post-operative pain experienced was documented according to the VAS (4, 12, 20, 24, and 82 h) and compared to VAS baseline.</p> <p>Results</p> <p>A total of 159 teeth were treated (Ledermix: 83 teeth, Provicol: 76 teeth). The minor irritation of the teeth, experienced prior to treatment, was similar in both groups; however, 4 h after treatment this value was significantly higher in the Provicol group than in the Ledermix group (p < 0.005, t-test). After 12 h, the difference was no longer significant. The number of patients taking analgesics for post-treatment pain was higher in the Provicol group (n = 11/53) than in the Ledermix group (n = 3/56).</p> <p>Conclusions</p> <p>The patients had no long term post-operative pain experience in both groups. However, within the first hours after cementation the sensation of pain was considerably higher in the Provicol group than in the Ledermix group.</p

Profiling allele-specific gene expression in brains from individuals with autism spectrum disorder reveals preferential minor allele usage.

One fundamental but understudied mechanism of gene regulation in disease is allele-specific expression (ASE), the preferential expression of one allele. We leveraged RNA-sequencing data from human brain to assess ASE in autism spectrum disorder (ASD). When ASE is observed in ASD, the allele with lower population frequency (minor allele) is preferentially more highly expressed than the major allele, opposite to the canonical pattern. Importantly, genes showing ASE in ASD are enriched in those downregulated in ASD postmortem brains and in genes harboring de novo mutations in ASD. Two regions, 14q32 and 15q11, containing all known orphan C/D box small nucleolar RNAs (snoRNAs), are particularly enriched in shifts to higher minor allele expression. We demonstrate that this allele shifting enhances snoRNA-targeted splicing changes in ASD-related target genes in idiopathic ASD and 15q11-q13 duplication syndrome. Together, these results implicate allelic imbalance and dysregulation of orphan C/D box snoRNAs in ASD pathogenesis