Investigation of stress-induced (100) platelet formation and surface exfoliation in plasma hydrogenated Si

We have studied the mechanisms underlying stress-induced platelet formation during plasma hydrogenation. The stress is purposely introduced by a buried SiGe stained layer in a Si substrate. During plasma hydrogenation, diffusing H is trapped in the region of the SiGe layer and H platelets are formed. The platelet orientation is controlled by the in-plane compressive stress, which favors nucleation and growth of platelets in the plane of stress and parallel to the substrate surface, and ultimately leads to controlled fracture along the SiGe layer. Also, the SiSiGeSi structure is found to be more efficient in utilizing H for platelet formation and growth compared to H ion implanted Si because there are fewer defects to trap H (e.g., Vn Hm and In Hm); therefore, the total H dose needed for layer exfoliation is greatly reduced. © 2007 American Institute of Physics

Exciton formation and relaxation in GaAs epilayers

Exciton formation and relaxation in GaAs bulk epilayers have been studied by means of time-resolved photoluminescence techniques. It is found that the time evolution of the free exciton luminescence, nonresonantly excited at low temperature and low intensity, is extremely slow, with a rise time of the order of 1 ns and a decay time of several ns. Simulations based on Monte Carlo solution of the set of coupled Boltzmann-like equations for free carriers and excitons show a nice agreement with the experimental data, and suggest a dominant role played by acoustic phonons in the exciton relaxation

A practitioner's guide to Bayesian estimation of discrete choice dynamic programming models

This paper provides a step-by-step guide to estimating infinite horizon discrete choice dynamic programming (DDP) models using a new Bayesian estimation algorithm (Imai et al., Econometrica 77:1865–1899, 2009a) (IJC). In the conventional nested fixed point algorithm, most of the information obtained in the past iterations remains unused in the current iteration. In contrast, the IJC algorithm extensively uses the computational results obtained from the past iterations to help solve the DDP model at the current iterated parameter values. Consequently, it has the potential to significantly alleviate the computational burden of estimating DDP models. To illustrate this new estimation method, we use a simple dynamic store choice model where stores offer “frequent-buyer” type rewards programs. Our Monte Carlo results demonstrate that the IJC method is able to recover the true parameter values of this model quite precisely. We also show that the IJC method could reduce the estimation time significantly when estimating DDP models with unobserved heterogeneity, especially when the discount factor is close to 1

USEFULNESS OF CT COLONOGRAPHY IN PATIENTS WITH OCCLUSIVE COLORECTAL CANCER BEFORE METALLIC STENT PLACEMENT: A SINGLE ENTER EXPERIENCE

Up to 15% of patients with colorectal cancer (CRC) present with large bowel obstruction. Currently, computed tomography colonography (CTC) is regarded as a promising technique for complete evaluation of the proximal colon and simultaneous assessment of extraluminal status. Aim of this retrospective, observational study is to evaluate the feasibility of using CTC for preoperative examination of the proximal colon before metallic stgent placement in patients with colon obstruction caused by CRC. Sixteen patients who demonstrated colonic obstruction caused by CRC, underwent CTC immediately after incomplete colonoscopy. Per-patient sensitivity of CTC for lesion 5 mm larger in diameter in the colon proximal to the stent was 100% (95% CI: 0,4385-1). Per-patients specificity for lesions 5 mm and larger in the proximal colon was 92,3% (95% CI: 6669-0,9863). CTC did not generate any false diagnosis of synchronous cancer. false positive findings at CTC did not result in a change in surgical plan for asny patients. Although the small number of patient of our study, our data show that CTC is a safe and useful method for preoperative examination of the proximal colon before metallic stent placement in patients with acute colon obstruction caused by CRC

Blunted Neuronal Calcium Response to Hypoxia in Naked Mole-Rat Hippocampus

Naked mole-rats are highly social and strictly subterranean rodents that live in large communal colonies in sealed and chronically oxygen-depleted burrows. Brain slices from naked mole-rats show extreme tolerance to hypoxia compared to slices from other mammals, as indicated by maintenance of synaptic transmission under more hypoxic conditions and three fold longer latency to anoxic depolarization. A key factor in determining whether or not the cellular response to hypoxia is reversible or leads to cell death may be the elevation of intracellular calcium concentration. In the present study, we used fluorescent imaging techniques to measure relative intracellular calcium changes in CA1 pyramidal cells of hippocampal slices during hypoxia. We found that calcium accumulation during hypoxia was significantly and substantially attenuated in slices from naked mole-rats compared to slices from laboratory mice. This was the case for both neonatal (postnatal day 6) and older (postnatal day 20) age groups. Furthermore, while both species demonstrated more calcium accumulation at older ages, the older naked mole-rats showed a smaller calcium accumulation response than even the younger mice. A blunted intracellular calcium response to hypoxia may contribute to the extreme hypoxia tolerance of naked mole-rat neurons. The results are discussed in terms of a general hypothesis that a very prolonged or arrested developmental process may allow adult naked mole-rat brain to retain the hypoxia tolerance normally only seen in neonatal mammals

CLINICAL OUTCOMES OF SELF-EXPAMDABLE METALLIC STENTS IN PALLIATION OF MALIGNANT ANASTOMOTIC STRICTURES: A SINGLE CENTER EXPERIENCE

Background: self-expandable metallic stents (SEMS) are employed as the preferred non surgical palliative treatment for gastric outlet obstruction due to malignancies. Metallic stents are often employed to treat malignant anastomotic obstructions after surgicsl interventions as esophagojejunostomy, gastrojejunostomy and esophagogastrojejunostomy. Methods: this case series reports prospectively the clinical outcomes of SEMS in the palliative care of malignant anastomotic strictures caused by the recurrence gastric cancer follwing gastric surgery as oncological curative treatment, in a series of nine consecutive patients, treated between January 2009 and december 2012 in our center. Results: Nine patients (M:F=8:1) were enrolled in the study. The operation was a total gastrectomy with esophagogastrojejunostomy (n=4), subtotal gastrectomy with Bilroth-II reconstruction (n=4), subtotal gastrectomy with Billroth-II reconstruction (n=3), and subtotal gastrectomy with esophagogastrostomy (n=2). The technical success rate was 88,9%, and the clinical success rate was 88.9%. The reostruction of the stent, due to the ingrowth of the tumor, occurred in 1 patient (11,1%) within 1 month after stent placement. the migration of the stent occurred after the placement of a covered stent in 1 patient who underwent a subtotal gastrectomy (with Billroth-II reconstruction). A case o partial stent dislodgement was treated with the placement of a second stent. The median survival period was 180 days (range, 30-240 days) and the median stent patency was 45 days 8range, 30-90 days). Conclusions: Although the number of the patients treated with SEMS results, in this series, almost small to certainly judge the safety and feasibility of SEMS, we believe that the endoscopic insertion of SEMS seems to be a safe, easily feasible, and effective treatment in the palliative care of malignant anastomotic strictures caused by the recurrence of gastric cancer following gastric surgery. The technical and clinical success, and the onset of complications of this procedure are influenced by several factors, such as the type of anastomosis, the technical features of the stent, and the extent of the underlying tumor

Cultivares de batata para sistemas orgânicos de produção.

Informações a respeito de cultivares adaptadas ao sistema de cultivo orgânico são escassas. O objetivo deste estudo foi avaliar, sob sistema de cultivo orgânico, genótipos nacionais e estrangeiros desenvolvidos para o cultivo convencional, quanto ao potencial produtivo, em condições de campo. O experimento foi conduzido em 2008, no Pólo APTA Leste Paulista, em Monte Alegre do Sul-SP. O delineamento experimental foi em blocos ao acaso, com 18 tratamentos e quatro repetições. Cada parcela foi constituída por 80 batatas-semente, dispostas em quatro linhas de 5 m de comprimento, espaçadas de 80 cm, com 25 cm entre tubérculos. Os genótipos avaliados foram Agata, Asterix, Caesar, Cupido, Éden, Melody, Novella e Vivaldi, de origem estrangeira; e Apuã, Aracy, Catucha, IAC Aracy Ruiva, Itararé, Monte Alegre 172, IAC 6090, APTA 16.5, APTA 15.20 e APTA 21.54, nacionais. Foram avaliadas as características de produtividade total e comercial de tubérculos, massa média total e comercial de tubérculos, teor de matéria seca e severidade da pinta-preta (Alternaria solani). Os clones APTA 16.5, APTA 21.54 e IAC 6090, e as cultivares Cupido, Apuã, Itararé e Monte Alegre 172 foram os mais produtivos. ‘APTA 21.54’ superou os demais em relação a produtividade comercial (18,07 t ha-1), sendo que ‘APTA 16.5’, ‘Cupido’, ‘IAC 6090’ e ‘Itararé’ formaram o segundo grupo. As maiores massas médias de tubérculos foram apresentadas pelas cultivares Itararé e Cupido. O clone IAC 6090 e as cultivares Aracy e Aracy Ruiva foram as que apresentaram maiores teores de matéria seca, com valor médio de 22,91%. ‘APTA 16.5’, ‘Apuã’, ‘Aracy’, ‘Aracy Ruiva’, ‘Éden’, ‘Ibituaçú’ e ‘Monte Alegre 172’ apresentaram alto nível de resistência à pinta-preta. As cultivares Itararé, Apuã e Cupido são adaptadas ao cultivo orgânico, e os clones avançados APTA 16.5, APTA 21.54 e IAC 6090 apresentam potencial de cultivo no sistema orgânico

Relationship of an hRAD54 gene polymorphism (2290 C/T) in an Ecuadorian population with chronic myelogenous leukemia

The hRAD54 gene is a key member of the RAD52 epistasis group involved in repair of double-strand breaks (DSB) by homologous recombination (HR). Thus, alterations of the normal function of these genes could generate genetic instability, shifting the normal process of the cell cycle, leading the cells to develop into cancer. In this work we analyzed exon 18 of the hRAD54 gene, which has been previously reported by our group to carry a silent polymorphism, 2290 C/T (Ala730Ala), associated to meningiomas. We performed a PCR-SSCP method to detect the polymorphism in 239 samples including leukemia and normal control population. The results revealed that the 2290 C/T polymorphism has frequencies of 0.1 for the leukemia and 0.1 for the control group. These frequencies show no statistical differences. Additionally, we dissected the leukemia group in chronic myelogenous leukemia (CML) and acute lymphoblastic leukemia (ALL) to evaluate the polymorphism. The frequencies found in these subgroups were 0.14 for CML and 0.05 for ALL. We found statistically significant differences between CML patients and the control group (p < 0.05) but we did not find significant differences between ALL and the control group (p > 0.05). These results suggest a possible link between the 2290 C/T polymorphism of the hRAD54 gene and CML

Is there a relationship between pain intensity and postural sway in patients with non-specific low back pain?

Background Increased center of pressure excursions are well documented in patients suffering from non-specific low back pain, whereby the altered postural sway includes both higher mean sway velocities and larger sway area. No investigation has been conducted to evaluate a relationship between pain intensity and postural sway in adults (aged 50 or less) with non-specific low back pain. Methods Seventy-seven patients with non-specific low back pain and a matching number of healthy controls were enrolled. Center of pressure parameters were measured by three static bipedal standing tasks of 90sec duration with eyes closed in narrow stance on a firm surface. The perceived pain intensity was assessed by a numeric rating scale (NRS-11), an equal number of patients (n=11) was enrolled per pain score. Results Generally, our results confirmed increased postural instability in pain sufferers compared to healthy controls. In addition, regression analysis revealed a significant and linear increase in postural sway with higher pain ratings for all included COP parameters. Statistically significant changes in mean sway velocity in antero-posterior and medio lateral direction and sway area were reached with an incremental change in NRS scores of two to three points. Conclusions COP mean velocity and sway area are closely related to self-reported pain scores. This relationship may be of clinical use as an objective monitoring tool for patients under treatment or rehabilitation

In Vitro Downregulation of Matrix Metalloproteinase-9 in Rat Glial Cells by CCR5 Antagonist Maraviroc: Therapeutic Implication for HIV Brain Infection

BACKGROUND: Matrix metalloproteinases (MMPs) released by glial cells are important mediators of neuroinflammation and neurologic damage in HIV infection. The use of antiretroviral drugs able to combat the detrimental effect of chronic inflammation and target the exaggerated MMP activity might represent an attractive therapeutic challenge. Recent studies suggest that CCR5 antagonist maraviroc (MVC) exerts immunomodulant and anti-inflammatory activity beyond its anti-HIV properties. We investigated the in vitro effect of MVC on the activity of MMPs in astrocyte and microglia cultures. METHODOLOGY/PRINCIPAL FINDINGS: Primary cultures of rat astrocytes and microglia were activated by exposure to phorbol myristate acetate (PMA) or lypopolysaccharide (LPS) and treated in vitro with MVC. Culture supernatants were subjected to gelatin zymography and quantitative determination of MMP-9 and MMP-2 was done by computerized scanning densitometry. MMP-9 levels were significantly elevated in culture supernatants from both LPS- and PMA-activated astrocytes and microglia in comparison to controls. The treatment with MVC significantly inhibited in a dose-dependent manner the levels and expression of MMP-9 in PMA-activated astrocytes (p&lt;0,05) and, to a lesser extent, in PMA-activated microglia. By contrast, levels of MMP-2 did not significantly change, although a tendency to decrease was seen in PMA-activated astrocytes after treatment with MVC. The inhibition of levels and expression of MMP-9 in PMA-activated glial cells did not depend on cytotoxic effects of MVC. No inhibition of MMP-9 and MMP-2 were found in both LPS-activated astrocytes and microglia. CONCLUSIONS: The present in vitro study suggests that CCR5 antagonist compounds, through their ability to inhibit MMP-9 expression and levels, might have a great potential for the treatment of HIV-associated neurologic damage