Extraordinary linear dynamic range in laser-defined functionalized graphene photodetectors

This is the author accepted manuscript. The final version is available from AAAS via the DOI in this record.Graphene-based photodetectors have demonstrated mechanical flexibility, large operating bandwidth, and broadband spectral response. However, their linear dynamic range (LDR) is limited by graphene’s intrinsic hot-carrier dynamics, which causes deviation from a linear photoresponse at low incident powers. At the same time, multiplication of hot carriers causes the photoactive region to be smeared over distances of a few micrometers, limiting the use of graphene in high-resolution applications. We present a novel method for engineering photoactive junctions in FeCl3-intercalated graphene using laser irradiation. Photocurrent measured at these planar junctions shows an extraordinary linear response with an LDR value at least 4500 times larger than that of other graphene devices (44 dB) while maintaining high stability against environmental contamination without the need for encapsulation. The observed photoresponse is purely photovoltaic, demonstrating complete quenching of hot-carrier effects. These results pave the way toward the design of ultrathin photodetectors with unprecedented LDR for high-definition imaging and sensing.S.R. and M.F.C. acknowledge financial support from the Engineering and Physical Sciences Research Council (grant nos. EP/J000396/1, EP/K017160/1, EP/K010050/1, EP/G036101/1, EP/M001024/1, and EP/M002438/1), from the Royal Society’s International Exchanges Scheme 2012/R3 and 2013/R2, and from the European Commission (FP7-ICT-2013-613024-GRASP)

Desarrollo de un modelo de perfil de copa para Pinus cooperi Blanco en la UMAFOR 1008, Durango, México

A crown profile model for Pinus cooperi Blanco in UMAFOR 1008 (El Salto, Pueblo Nuevo, Durango) was developed from data corresponding to 92 sampled trees. Trees with well-formed crowns were selected from stands varying in age, density and site quality. Diameter at breast height, total height, crown width, crown length, and crown profile were measured in each tree. To predict the crown profile, basic geometric shapes and several mathematic models were evaluated. The model developed by Hann (1999) best described the experimental data of the total crown, light crown, and shaded crown, accounting for over 92 % of the observed variability.Se desarrolló un modelo de perfil de copa para Pinus cooperi Blanco a partir de 92 árboles en la UMAFOR 1008 (Región El Salto, Pueblo Nuevo, Durango). Se seleccionaron individuos con una copa bien conformada y de diferente edad, densidad y calidad de estación. En cada uno de los individuos se midieron las variables diámetro normal, altura total, diámetro, longitud y perfil de copa. Tanto formas geométricas sencillas como algunos modelos matemáticos se analizaron para predecir el perfil de la copa. El mejor modelo para describir el perfil de copa de P. cooperi fue el de Hann (1999), ya que tuvo mejor ajuste para la copa entera, copa de luz y copa de sombra, explicando más de 92 % de la variabilidad de los datos.S

High-density lipoprotein proteome dynamics in human endotoxemia

BACKGROUND: A large variety of proteins involved in inflammation, coagulation, lipid-oxidation and lipid metabolism have been associated with high-density lipoprotein (HDL) and it is anticipated that changes in the HDL proteome have implications for the multiple functions of HDL. Here, SELDI-TOF mass spectrometry (MS) was used to study the dynamic changes of HDL protein composition in a human experimental low-dose endotoxemia model. Ten healthy men with low HDL cholesterol (0.7+/-0.1 mmol/L) and 10 men with high HDL cholesterol levels (1.9+/-0.4 mmol/L) were challenged with endotoxin (LPS) intravenously (1 ng/kg bodyweight). We previously showed that subjects with low HDL cholesterol are more susceptible to an inflammatory challenge. The current study tested the hypothesis that this discrepancy may be related to differences in the HDL proteome. RESULTS: Plasma drawn at 7 time-points over a 24 hour time period after LPS challenge was used for direct capture of HDL using antibodies against apolipoprotein A-I followed by subsequent SELDI-TOF MS profiling. Upon LPS administration, profound changes in 21 markers (adjusted p-value < 0.05) were observed in the proteome in both study groups. These changes were observed 1 hour after LPS infusion and sustained up to 24 hours, but unexpectedly were not different between the 2 study groups. Hierarchical clustering of the protein spectra at all time points of all individuals revealed 3 distinct clusters, which were largely independent of baseline HDL cholesterol levels but correlated with paraoxonase 1 activity. The acute phase protein serum amyloid A-1/2 (SAA-1/2) was clearly upregulated after LPS infusion in both groups and comprised both native and N-terminal truncated variants that were identified by two-dimensional gel electrophoresis and mass spectrometry. Individuals of one of the clusters were distinguished by a lower SAA-1/2 response after LPS challenge and a delayed time-response of the truncated variants. CONCLUSIONS: This study shows that the semi-quantitative differences in the HDL proteome as assessed by SELDI-TOF MS cannot explain why subjects with low HDL cholesterol are more susceptible to a challenge with LPS than those with high HDL cholesterol. Instead the results indicate that hierarchical clustering could be useful to predict HDL functionality in acute phase responses towards LPS

The bird species diversity in the wintering season is negatively associated with precipitation, tree species diversity and stand density in the Sierra Madre Occidental, Durango, Mexico

Bird migration constitutes a redistribution of bird diversity that radically changes the composition of the bird community worldwide. It comprises about 19% of the world’s bird species. Several studies have indicated that changes in avian community structure and differences in bird richness in different seasons are mainly driven by seasonality and by winter harshness, and that the associated costs increase with the distance involved. Western Mexico is an important wintering area for most passerines that breed in western North America, and that travel long on the long-distance Central and Pacific migration routes. In this study, we examined bird species richness and diversity during the breeding and wintering seasons in the Central Sierra Madre Occidental (SMO), North Durango (Mexico) in relation to i) tree species diversity, ii) tree dimension, iii) forest stand density and site quality, iv) density and dimension of snag trees, and v) various climate variables. The overall aim of the study was to determine how the observed associations between bird species diversity and variables i-v are affected by the season considered (breeding or wintering). The diversity of bird species in the breeding season was not affected by any of the climate and forest stand variables considered. In contrast, bird species diversity in the wintering season was significantly and weakly to moderately associated with climate variables, tree species diversity and stand density, although not with density or dimension of snag trees. Bird species diversity was higher at lower elevations and in drier and warmer locations of the SMO. The association detected is therefore mainly a local migratory phenomenon. | Supporting Information Supporting Information </supplementary-material

Purity of transferred CD8+ T cells is crucial for safety and efficacy of combinatorial tumor immunotherapy in the absence of SHP-1

Adoptive transfer of tumor-specific cytotoxic T cells is a promising advance in cancer therapy. Similarly, checkpoint inhibition has shown striking clinical results in some patients. Here we combine adoptive cell transfer with ablation of the checkpoint protein Src homology 2-domain-containing phosphatase 1 (SHP-1, Ptpn6). Naturally occurring motheaten mice lack SHP-1 and do not survive weaning due to extensive immunopathology. To circumvent this limitation, we created a novel SHP-1(null) mouse that is viable up to 12 weeks of age by knocking out IL1r1. Using this model, we demonstrate that the absence of SHP-1 augments the ability of adoptively transferred CD8(+) T cells to control tumor growth. This therapeutic effect was only observed in situations where T-cell numbers were limited, analogous to clinical settings. However, adoptive transfer of non-CD8(+) SHP-1(null) hematopoietic cells resulted in lethal motheaten-like pathology, indicating that systemic inhibition of SHP-1 could have serious adverse effects. Despite this caveat, our findings support the development of SHP-1 inhibition strategies in human T cells to complement adoptive transfer therapies in the clinic

Generating informative trajectories by using bounds on the return of control policies

Abstract We propose new methods for guiding the generation of informative trajectories when solving discrete-time optimal control problems. These methods exploit recently published results that provide ways for computing bounds on the return of control policies from a set of trajectories. Keywords: reinforcement learning, optimal control, sampling strategies Introduction. Discrete-time optimal control problems arise in many fields such as finance, medicine, engineering as well as artificial intelligence. Whatever the techniques used for solving such problems, their performance is related to the amount of information available on the system dynamics and the reward function of the optimal control problem. In this paper, we consider settings in which information on the system dynamics must be inferred from trajectories and, furthermore, due to cost and time constraints, only a limited number of trajectories can be generated. We assume that a regularity structure -given in the form of Lipschitz continuity assumptions -exists on the system dynamics and the reward function. Under such assumptions, we exploit recently published methods for computing bounds on the return of control policies from a set of trajectorie

Diversidad de macromicetos en bosques de pino en el municipio Madera, Chihuahua

El municipio Madera cuenta con una gran diversidad de ecosistemas que albergan una alta riqueza de especies fúngicas, de las cuales se tiene poco conocimiento debido a la falta de investigación para esa zona. El objetivo del presente estudio fue determinar y comparar la diversidad, hábitos y comestibilidad de los macromicetos. El muestreo se realizó en siete parcelas de 100 m × 100 m, en seis ejidos del municipio Madera, Chihuahua, durante los meses de julio y agosto del año 2016; se determinó número efectivo de especies, abundancia de frutos y diversidad alfa, mediante los índices de Shannon (Hˈ) y Margalef (DMG). Los resultados mostraron un total de 69 taxa de macromicetos, pertenecientes a 27 familias y 46 géneros; de acuerdo al hábito de desarrollo, 53.62 % son saprobias, 43.50 % micorrízicas y 2.90 % patógenas. En cuanto a la comestibilidad, 28.98 % tienen potencial alimenticio. La mayor diversidad se presentó en el ejido Socorro Rivera (H’=2.44 y DMG=3.58). Las especies con mayor distribución en las localidades de estudio pertenecen a Amanita; el porcentaje más alto de similitud de especies se registró en los ejidos Nicolás Bravo (paraje El Pedregoso) y Madera, con 18 %. Los taxones fúngicos registrados se suman a los citados previamente; con ello, aumenta el conocimiento para el estado de Chihuahua

Random subwindows and extremely randomized trees for image classification in cell biology

Background: With the improvements in biosensors and high-throughput image acquisition technologies, life science laboratories are able to perform an increasing number of experiments that involve the generation of a large amount of images at different imaging modalities/scales. It stresses the need for computer vision methods that automate image classification tasks. Results: We illustrate the potential of our image classification method in cell biology by evaluating it on four datasets of images related to protein distributions or subcellular localizations, and red-blood cell shapes. Accuracy results are quite good without any specific pre-processing neither domain knowledge incorporation. The method is implemented in Java and available upon request for evaluation and research purpose. Conclusion: Our method is directly applicable to any image classification problems. We foresee the use of this automatic approach as a baseline method and first try on various biological image classification problems

ADAM17-dependent proteolysis of L-selectin promotes early clonal expansion of cytotoxic T cells

L-selectin on T-cells is best known as an adhesion molecule that supports recruitment of blood-borne naïve and central memory cells into lymph nodes. Proteolytic shedding of the ectodomain is thought to redirect activated T-cells from lymph nodes to sites of infection. However, we have shown that activated T-cells re-express L-selectin before lymph node egress and use L-selectin to locate to virus-infected tissues. Therefore, we considered other roles for L-selectin proteolysis during T cell activation. In this study, we used T cells expressing cleavable or non-cleavable L-selectin and determined the impact of L-selectin proteolysis on T cell activation in virus-infected mice. We confirm an essential and non-redundant role for ADAM17 in TCR-induced proteolysis of L-selectin in mouse and human T cells and show that L-selectin cleavage does not regulate T cell activation measured by CD69 or TCR internalisation. Following virus infection of mice, L-selectin proteolysis promoted early clonal expansion of cytotoxic T cells resulting in an 8-fold increase over T cells unable to cleave L-selectin. T cells unable to cleave L-selectin showed delayed proliferation in vitro which correlated with lower CD25 expression. Based on these results, we propose that ADAM17-dependent proteolysis of L-selectin should be considered a regulator of T-cell activation at sites of immune activity