Photonic microstructures as laser mirrors

Deeply etched 1-D third-order Bragg reflectors have been used as mirrors for broad-area semiconductor lasers operating at 975-nm wavelength. From a threshold and efficiency analysis, we determine the mirror reflectivity to be approximately 95%. The design of the GaAs-based laser structure features three InGaAs quantum wells placed close (0.5 μm) to the surface in order to reduce the required etch depth and facilitate high-quality etching. Despite the shallow design and the proximity of the guided mode to the metal contact, the threshold current density (J_(th) = 220 A/cm^2 for infinite cavity length) and internal loss (α_i = 9±1 cm^(−1)) are very low

Effect of mild oxidation on the surface chemistry of bituminous coals under different humidity conditions

The influence of humidity conditions on the oxidation of four coals has been studied on the basis of their surface chemistry. A systematic study was carried out in which four coals of different rank were oxidised at 50 °C in two conditions of humidity (20 and 90% moisture levels) and in an air atmosphere. The changes in the surface functional groups were measured by means of diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and X-ray photoelectron spectroscopy (XPS). The lowest rank coals were the most affected by oxidation in all the humidity conditions applied. In the case of the higher rank coals, higher moisture levels promoted the oxidation process. The number of oxygen-containing structures increased after oxidation, the most abundant being the carbonyl and carboxyl groups

Baubles, Bangles, and Biotypes: A Critical Review of the use and Abuse of the Biotype Concept

Pest species of insects are notoriously prone to escape the weapons deployed in management efforts against them. This is particularly true in herbivorous insects. When a previously successful tactic fails the insect population has apparently adapted to it and is often considered to be a new or distinct entity, and given the non-formal category ‘biotype’. The entities falling under the umbrella term ‘biotype’ are not consistent either within or between biotypes, and their underlying genetic composition and origins, while generally unknown, are likely heterogeneous within and variable between biotypes. In some cases race or species may be more appropriate referents. Some examples of applications of the concept in the context of host plant resistance are discussed. It is argued here that the term ‘biotype’ and its applications are overly simplistic, confused, have not proved useful in current pest management, and lack predictive power for future management

Aggregation and travelling wave dynamics in a two-population model of cancer cell growth and invasion

Funding: Engineering and Physical Sciences Research Council (UK) grant numbers EP/L504932/1 (VB), EP/K033689/1 (RE).Cells adhere to each other and to the extracellular matrix (ECM) through protein molecules on the surface of the cells. The breaking and forming of adhesive bonds, a process critical in cancer invasion and metas- tasis, can be influenced by the mutation of cancer cells. In this paper, we develop a nonlocal mathematical model describing cancer cell invasion and movement as a result of integrin-controlled cell-cell adhesion and cell-matrix adhesion, for two cancer cell populations with different levels of mutation. The partial differential equations for cell dynamics are coupled with ordinary differential equations describing the extracellular matrix (ECM) degradation and the production and decay of integrins. We use this model to investigate the role of cancer mutation on the possibility of cancer clonal competition with alternating dominance, or even competitive exclusion (phenomena observed experimentally). We discuss different possible cell aggregation patterns, as well as travelling wave patterns. In regard to the travelling waves, we investigate the effect of cancer mutation rate on the speed of cancer invasion.Publisher PDFPeer reviewe

High-resolution structure of the M14-type cytosolic carboxypeptidase from <em>Burkholderia cenocepacia </em>refined exploiting <em>PDB_REDO </em>strategies

A potential cytosolic metallocarboxypeptidase from Burk­holderia cenocepacia has been crystallized and a synchrotron-radiation microfocus beamline allowed the acquisition of diffraction data to 1.9 Å resolution. The asymmetric unit comprises a tetramer containing over 1500 amino acids, and the high-throughput automated protocols embedded in PDB_REDO were coupled with model–map inspections in refinement. This approach has highlighted the value of such protocols for efficient analyses. The subunit is constructed from two domains. The N-terminal domain has previously only been observed in cytosolic carboxypeptidase (CCP) proteins. The C-terminal domain, which carries the Zn(2+)-containing active site, serves to classify this protein as a member of the M14D subfamily of carboxypeptidases. Although eukaryotic CCPs possess deglutamylase activity and are implicated in processing modified tubulin, the function and substrates of the bacterial family members remain unknown. The B. cenocepacia protein did not display deglutamylase activity towards a furylacryloyl glutamate derivative, a potential substrate. Residues previously shown to coordinate the divalent cation and that contribute to peptide-bond cleavage in related enzymes such as bovine carboxypeptidase are conserved. The location of a conserved basic patch in the active site adjacent to the catalytic Zn(2+), where an acetate ion is identified, suggests recognition of the carboxy-terminus in a similar fashion to other carboxypeptidases. However, there are significant differences that indicate the recognition of substrates with different properties. Of note is the presence of a lysine in the S1′ recognition subsite that suggests specificity towards an acidic substrate

Energy-efficient full-range oscillation analysis of parallel-plate electrostatically actuated MEMS resonators

This is the peer reviewed version of the following article: “Fargas Marques, A., Costa Castelló, R. (2017) Energy-efficient full-range oscillation analysis of parallel-plate electrostatically actuated MEMS resonators, 1-13.” which has been published in final form at [doi: 10.1007/s11071-017-3633-8]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."Electrostatic parallel-plate actuators are a common way of actuating microelectromechanical systems, both statically and dynamically. Nevertheless, actuation voltages and oscillations are limited by the nonlinearity of the actuator that leads to the pull-in phenomena. This work presents a new approach to obtain the electrostatic parallel-plate actuation voltage, which allows to freely select the desired frequency and amplitude of oscillation. Harmonic Balance analysis is used to determine the needed actuation voltage and to choose the most energy-efficient actuation frequency. Moreover, a new two-sided actuation approach is presented that allows to actuate the device in all the stable range using the Harmonic Balance Voltage.Peer ReviewedPostprint (author's final draft

Financial wellbeing of Asian Americans

The Asian American population in the United States has been increasing. Research on the economic wellbeing of this minority group is far from being adequate. It is generally found that Asian Americans are more highly educated and have more wealth. Although the homeownership rate of this population is lower than the national average rate, the gap is gradually narrowing. Asian Americans are found to have more confidence in their financial future and have better management in their financial lives. In addition, Asian-owned businesses have been an important part of the U.S. economy and, as such, the self-employment status of Asian Americans has stimulated great interest for research. Large differences in financial behaviors exist among different groups in Asian Americans. This chapter serves the purpose to summarize past research on Asian American consumer finances and provide directions for future research.Includes bibliographical references

Nature and consequences of interactions between Salmonella enterica serovar Dublin and host cells in cattle

International audienceAbstractSalmonella enterica is a veterinary and zoonotic pathogen of global importance. While murine and cell-based models of infection have provided considerable knowledge about the molecular basis of virulence of Salmonella, relatively little is known about salmonellosis in naturally-affected large animal hosts such as cattle, which are a reservoir of human salmonellosis. As in humans, Salmonella causes bovine disease ranging from self-limiting enteritis to systemic typhoid-like disease and exerts significant economic and welfare costs. Understanding the nature and consequences of Salmonella interactions with bovine cells will inform the design of effective vaccines and interventions to control animal and zoonotic infections. In calves challenged orally with S. Dublin expressing green fluorescent protein (GFP) we observed that the bacteria were predominantly extracellular in the distal ileal mucosa and within gut-associated lymph nodes 48 h post-infection. Intracellular bacteria, identified by flow cytometry using the GFP signal, were predominantly within MHCII+ macrophage-like cells. In contrast to observations from murine models, these S. Dublin-infected cells had elevated levels of MHCII and CD40 compared to both uninfected cells from the same tissue and cells from the cognate tissue of uninfected animals. Moreover, no gross changes of the architecture of infected lymph nodes were observed as was described previously in a mouse model. In order to further investigate Salmonella-macrophage interactions, net replication of S. enterica serovars that differ in virulence in cattle was measured in bovine blood-derived macrophages by enumeration of gentamicin-protected bacteria and fluorescence dilution, but did not correlate with host-specificity

Couple-oriented prenatal HIV counseling for HIV primary prevention: an acceptability study

<p>Abstract</p> <p>Background</p> <p>A large proportion of the 2.5 million new adult HIV infections that occurred worldwide in 2007 were in stable couples. Feasible and acceptable strategies to improve HIV prevention in a conjugal context are scarce. In the preparatory phase of the ANRS 12127 Prenahtest multi-site HIV prevention trial, we assessed the acceptability of couple-oriented post-test HIV counseling (COC) and men's involvement within prenatal care services, among pregnant women, male partners and health care workers in Cameroon, Dominican Republic, Georgia and India.</p> <p>Methods</p> <p>Quantitative and qualitative research methods were used: direct observations of health services; in-depth interviews with women, men and health care workers; monitoring of the COC intervention and exit interviews with COC participants.</p> <p>Results</p> <p>In-depth interviews conducted with 92 key informants across the four sites indicated that men rarely participated in antenatal care (ANC) services, mainly because these are traditionally and programmatically a woman's domain. However men's involvement was reported to be acceptable and needed in order to improve ANC and HIV prevention services. COC was considered by the respondents to be a feasible and acceptable strategy to actively encourage men to participate in prenatal HIV counseling and testing and overall in reproductive health services.</p> <p>Conclusions</p> <p>One of the keys to men's involvement within prenatal HIV counseling and testing is the better understanding of couple relationships, attitudes and communication patterns between men and women, in terms of HIV and sexual and reproductive health; this conjugal context should be taken into account in the provision of quality prenatal HIV counseling, which aims at integrated PMTCT and primary prevention of HIV.</p