Defect investigations in InAs/GaSb type-II strained layer superlattice

InAs/GaSb type-II strained layer superlattices are a material used for infrared detection. By adjusting the thickness of the InAs and GaSb layers, the material bandgap can be tuned to absorb photons from 3-30 um. Compared to competing materials such as HgCdTe and InSb, InAs/GaSb superlattices are more mechanically robust, have reduced tunneling currents, and can use strain to suppress Auger recombination. In spite of these advantages, this material still faces several challenges, including low minority carrier lifetime, resulting from trap levels that cause Schockley-Read-Hall recombination. These low lifetimes lead to reduced signal-to-noise ratio and higher dark current. Therefore, increasing the lifetime is important for improving this material\\u27s performance. However, to increase the carrier lifetimes, the origin of the traps must first be understood. In this work, several key suspect causes of the killer defect were evaluated. A commonly explored suspect in literature, the interfaces, was studied using time-resolved photoluminescence for three different samples. This characterization method was also used to determine if the doping atom and its layer placement significantly impacted the minority carrier lifetime. There is a substantial amount of evidence that the presence of gallium, or the GaSb layer itself harbors the defect. Thus, the rest of the study focused on aspects of GaSb. Layer intermixing of the In and As atoms into the GaSb layer was studied by intentionally incorporating In and As in bulk GaSb and using photocapacitance characterization to observe any possible defect level formation. In addition, trap level formation for different GaSb growth temperatures was also explored with this characterization technique. Finally, in an attempt to reduce trap densities, GaSb was grown with an increased level of Sb monomers rather than dimers. This material was characterized using dark current density measurements and photoluminescence.\u2

Chromatin condensation and recruitment of PHD finger proteins to histone H3K4me3 are mutually exclusive

Histone post-translational modifications, and specific combinations they create, mediate a wide range of nuclear events. However, the mechanistic bases for recognition of these combinations have not been elucidated. Here, we characterize crosstalk between H3T3 and H3T6 phosphorylation, occurring in mitosis, and H3K4me3, a mark associated with active transcription. We detail the molecular mechanisms by which H3T3ph/K4me3/T6ph switches mediate activities of H3K4me3-binding proteins, including those containing plant homeodomain (PHD) and double Tudor reader domains. Our results derived from nuclear magnetic resonance chemical shift perturbation analysis, orthogonal binding assays and cell fluorescence microscopy studies reveal a strong anti-correlation between histone H3T3/T6 phosphorylation and retention of PHD finger proteins in chromatin during mitosis. Together, our findings uncover the mechanistic rules of chromatin engagement for H3K4me3-specific readers during cell division

High Magnetic Shear Gain in a Liquid Sodium Stable Couette Flow Experiment; A Prelude to an alpha-Omega Dynamo

The $\Omega$-phase of the liquid sodium $\alpha$-$\Omega$ dynamo experiment at NMIMT in cooperation with LANL has successfully demonstrated the production of a high toroidal field, $B_{\phi} \simeq 8\times B_r$ from the radial component of an applied poloidal magnetic field, $B_r$. This enhanced toroidal field is produced by rotational shear in stable Couette flow within liquid sodium at $Rm \simeq 120$. The small turbulence in stable Taylor-Couette flow is caused by Ekman flow where $(\delta v/v)^2 \sim 10^{-3}$. This high $\Omega$-gain in low turbulence flow contrasts with a smaller $\Omega$-gain in higher turbulence, Helmholtz-unstable shear flows. This result supports the ansatz that large scale astrophysical magnetic fields are created within semi-coherent large scale motions in which turbulence plays only a smaller diffusive role that enables magnetic flux linkage.Comment: 5 pages, 5 figures, submitted PRL revised version: add one author, minor typo'

Triplet lifetime in gaseous argon

MiniCLEAN is a single-phase liquid argon dark matter experiment. During the initial cooling phase, impurities within the cold gas ($<$140 K) were monitored by measuring the scintillation light triplet lifetime, and ultimately a triplet lifetime of 3.480 $\pm$ 0.001 (stat.) $\pm$ 0.064 (sys.) $\mu$s was obtained, indicating ultra-pure argon. This is the longest argon triplet time constant ever reported. The effect of quenching of separate components of the scintillation light is also investigated

An Acetyl-Methyl Switch Drives a Conformational Change in p53

Individual posttranslational modifications (PTMs) of p53 mediate diverse p53-dependent responses, however much less is known about the combinatorial action of adjacent modifications. Here, we describe crosstalk between the early DNA damage response mark p53K382me2 and the surrounding PTMs that modulate binding of p53 co-factors, including 53BP1 and p300. The 1.8 Å resolution crystal structure of the tandem Tudor domain (TTD) of 53BP1 in complex with p53 peptide acetylated at K381 and dimethylated at K382 (p53K381acK382me2) reveals that the dual PTM induces a conformational change in p53. The α-helical fold of p53K381acK382me2 positions the side chains of R379, K381ac, and K382me2 to interact with TTD concurrently, reinforcing a modular design of double PTM mimetics. Biochemical and NMR analyses show that other surrounding PTMs, including phosphorylation of serine/threonine residues of p53, affect association with TTD. Our findings suggest a novel PTM-driven conformation switch-like mechanism that may regulate p53 interactions with binding partners

Predicting Patterns of Distant Metastasis in Breast Cancer Patients following Local Regional Therapy Using Machine Learning

Up to 30% of breast cancer (BC) patients will develop distant metastases (DM), for which there is no cure. Here, statistical and machine learning (ML) models were developed to estimate the risk of site-specific DM following local-regional therapy. This retrospective study cohort included 175 patients diagnosed with invasive BC who later developed DM. Clinicopathological information was collected for analysis. Outcome variables were the first site of metastasis (brain, bone or visceral) and the time interval (months) to developing DM. Multivariate statistical analysis and ML-based multivariable gradient boosting machines identified factors associated with these outcomes. Machine learning models predicted the site of DM, demonstrating an area under the curve of 0.74, 0.75, and 0.73 for brain, bone and visceral sites, respectively. Overall, most patients (57%) developed bone metastases, with increased odds associated with estrogen receptor (ER) positivity. Human epidermal growth factor receptor-2 (HER2) positivity and non-anthracycline chemotherapy regimens were associated with a decreased risk of bone DM, while brain metastasis was associated with ER-negativity. Furthermore, non-anthracycline chemotherapy alone was a significant predictor of visceral metastasis. Here, clinicopathologic and treatment variables used in ML prediction models predict the first site of metastasis in BC. Further validation may guide focused patient-specific surveillance practices.</jats:p

A Competência Virtual Individual: Um estudo de caso na empresa Eletrosul Centrais Elétricas S.A.

TCC (graduação) - Universidade Federal de Santa Catarina, Centro Sócio Econômico, Curso de Administração.A virtualidade é uma característica presente em muitas das atividades rotineiras realizadas pelo indivíduo no contexto atual, tanto em âmbito da vida pessoal quando na vida profissional. Logo, na vertente profissional, aproveitando das novas tecnologias de informação e comunicação, as organizações utilizam novas modalidades de ensino para o aperfeiçoamento de competências exigidas para o negócio, sendo um exemplo disto, a educação a distância. Dito isto, esta pesquisa apresenta a análise do Programa de Educação a Distância da empresa Eletrosul Centrais Elétricas S.A., no tocante da Competência Virtual Individual - CVI aplicada aos participantes do programa. Sendo assim a pesquisa assume caráter descritivo e caracteriza-se como predominamente qualitativa utilizando como complemento métodos quantitativos. Logo, na coleta de dados houve pesquisa documental, bibliográfica e de campo, assim como foi realizada uma entrevista com o coordenador do programa e um questionário com participantes do programa selecionados pelo coordenador. A partir dos dados coletados foi descrito o sistema de educação corporativa o qual envolve o Programa de Educação a Distância, assim como foram analisadas as percepções dos atores envolvidos a fim de identificar de que forma a organização promove o desenvolvimento da CVI no programa. Como embasamento para análise foram utilizados conceitos de Wang e Haggerty (2011), a partir dos quais concluiu-se que a CVI está presente no programa em níveis satisfatórios, entretanto, existem resistências em relação à autoeficácia virtual e a habilidade social virtual no que tange a confiança no AVA assim como em atividades colaborativas. Por fim, apresenta-se os pontos fortes e fracos do programa assim como propõem-se ações corretivas a fim de contribuir para o desenvolvimento da CVI.Virtuality is a feature present in many of the routine activities carried out by the individual in the current context, both in personal life and in professional life. Therefore, in the professional field, taking advantage of the new information and communication technologies, the organizations use new teaching modalities to improve the skills required for the business, being an example of this distance education. That said, this research presents the analysis of the Distance Education Program of the company Eletrosul Centrais Elétricas S.A., regarding the Individual Virtual Competence - IVC applied to the participants of the program. Therefore, the research takes a descriptive character and is characterized as predominantly qualitative using as complement quantitative methods. Therefore, in the data collection there was documentary, bibliographical and field research, as well as an interview with the program coordinator and a questionnaire with program participants selected by the coordinator. Based on the collected data, the corporate education system, which involves the Distance Education Program, was described, as well as the perceptions of the users involved, in order to identify how the organization promotes the development of the IVC in the program. Wang and Haggerty (2011), from which it was concluded that the IVC is present in the program at satisfactory levels, however, there are resistance in relation to virtual self-efficacy and virtual social skills in regard to Confidence in an virtual learning environment as well as in collaborative activities. Finally, we present the strengths and weaknesses of the program as well as propose corrective actions to contribute to the development of the IVC

Integração inovadora entre empresas incubadas e universidades para geração contínua de vantagens competitivas em ambientes dinâmicos

Esse artigo apresenta uma abordagem de integração entre startups e universidade, tendo como objetivos: (i) difundir práticas gerenciais inovadoras em empresas ligadas à incubadoras de empresas, (ii) estreitar a relação entre teoria e prática no ensino da Administração sobretudo em ambiente dinâmicos, (iii) criar um ambiente propício ao desenvolvimento das competências dos alunos do curso de Administração em um enfoque de aprendizagem pela ação, ao mesmo tempo que os empresários das empresas incubadas possam refletir sobre seus processos de gestão. Tal intento é alcançado por meio de uma abordagem construtivista de aprendizagem ativa, com participação ativa dos alunos de graduação de um curso de administração, sob supervisão de um professor-facilitador e dos empresários das startups. Esse artigo apresenta resultados de casos exploratórios que visam entender problemas gerenciais de empresas incubadas na incubadora MIDI Tecnológico e propõe modelos de decisão para os empresários a partir de seus valores e preferências. Essa pesquisa apresenta inovação no aspecto gerencial, onde é apresentado o uso da abordagem Lean Startup junto ao apoio à decisão construtivista, para avaliar e criar alternativas de ações no tocante ao desenvolvimento de produto e mercado. E em adição, esse trabalho também apresenta uma abordagem de integração inovadora entre empresas incubadas e universidades, onde a primeira pode se valer de conhecimento gerenciais presentes nos cursos de administração para melhorar seu desempenho, bem como os acadêmicos podem se valer da aprendizagem vivencial para aplicar conhecimentos que precisarão ser melhor explorados durante sua vida acadêmica e profissional