Depressed clad hollow optical fiber with fundamental LP01 mode cut-off

We propose a depressed clad hollow optical fiber with fundamental (LP01) mode cut-off suitable for high power short-wavelength, especially three-level, fiber laser operation by introducing highly wavelength dependent losses at longer wavelengths. The cut-off characteristic of such fiber structure was investigated. A Yb-doped depressed clad hollow optical fiber laser generating 59.1W of output power at 1046nm with 86% of slope efficiency with respect to the absorbed pump power was realised by placing the LP01 mode cut-off at ~1100nm

Large Area Roller Embossing of Multilayered Ceramic Green Composites

In this paper, we will report our achievements in developing large area patterning of multilayered ceramic green composites using roller embossing. The aim of our research is to pattern large area ceramic green composites using a modified roller laminating apparatus, which is compatible with screen printing machines, for integration of embossing and screen printing. The instrumentation of our roller embossing apparatus, as shown in Figure1, consists of roller 1 and rollers 2. Roller 1 is heated up to the desired embossing temperature ; roller 2 is, however, kept at room temperature. The mould is a nickel template manufactured by plating nickel-based micro patterns (height : 50 $\mu$m) on a nickel film (thickness : 70 $\mu$m) ; the substrate for the roller embossing is a multilayered Heraeus Heralock HL 2000 ceramic green composite. Comparing with the conventional simultaneous embossing, the advantages of roller embossing include : (1) low embossing force ; (2) easiness of demoulding ; (3) localized area in contact with heater ; and etc. We have demonstrated the capability of large area roller embossing with a panel size of 150mmx 150mm on the mentioned substrate. We have explored and confirmed the impact of parameters (feed speed, temperature of roller and applied pressure) to the pattern quality of roller embossing. Furthermore, under the optimized process parameters, we characterized the variations of pattern dimension over the panel area, and calculated a scaling factor in order to make the panel compatible with other processes. Figure 2 shows the embossed patterns on a 150mmx 150mm green ceramic panel.Comment: Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/handle/2042/16838

Catalytic Performance of Commercial Zeolites Y as Catalyst for Ethylene Production from Ethanol Dehydration

Catalytic dehydration of ethanol into ethylene was studied over commercial Zeolites-Y with different Si:Al ratios between 5.1:1 and 80:1, and temperature from 573 K to 773 K. The physicochemical properties of fresh and spent catalyst of Zeolite Y Si:Al 80:1 (best performing catalyst) were investigated using N2-physisorption, TGA, SEM-EDX, NH3-TPD, FTIR and XRD. Results showed that catalysts with higher Si:Al ratios exhibit better catalytic performance in terms of higher ethanol conversion and higher selectivity to ethylene. Indeed, zeolites-Y with Si:Al ratio 5.1:1 and 12:1 demonstrated low catalytic activity with ethanol conversion of 34% and 2%, respectively. However, ethylene selectivity of NH3-Y (5) was 84%, which was considerably higher than NH3-Y (12) which was 26%, indicated that this catalyst was not promoting the formation of other hydrocarbons i.e. methane and ethane. Albeit all of the catalysts namely H-Y (30), H-Y (60) and H-Y (80) showed favorable performance in ethanol dehydration, H-Y (80) attained almost total selectivity to ethylene and highest conversion of 73.0% among all the tested catalysts

Ethnicity and Consumption South Asian food shopping patterns in Britain, 1947-75

Authors' draft version also available on University of Surrey e-print repository. Final version published by Sage and available at http://joc.sagepub.com/This article reviews the literature that explores the relationship between ethnic identities and food consumption, with particular reference to business management studies. It focuses on the food shopping practices of south Asians in Britain in the period 1947 to 1975, to illustrate the need for more historically contextualized studies that can provide a more nuanced exploration of any interconnections between ethnic identity and shopping behaviour. The article draws on a reasonably long-standing interest in ethnicity and consumption in marketing studies, and explores the conceptual use of acculturation within this literature. The arguments put forward are framed by recent interdisciplinary studies of the broader relationship between consumption and identity, which stress the importance of contextualizing any influence of ethnic identifications through a wider consideration of other factors including societal status, gender and age, rather than giving it singular treatment. The article uses a body of empirical research drawn from recent oral histories, to explore how these factors informed everyday shopping practices among south Asians in Britain. It examines some of the shopping and wider food provisioning strategies adopted by early immigrants on arrival in Britain. It considers the interaction between the south Asian population and the changing retail structure, in the context of the development of self-service and the supermarket. Finally, it demonstrates how age, gender and socioeconomic status interacted with ethnic identities to produce variations in shopping patterns

Mesoscopic Phase Coherence in a Quantum Spin Fluid

Mesoscopic quantum phase coherence is important because it improves the prospects for handling quantum degrees of freedom in technology. Here we show that the development of such coherence can be monitored using magnetic neutron scattering from a one-dimensional spin chain Y2BaNiO5, a quantum spin fluid where no classical, static magnetic order is present. In the cleanest samples, the quantum coherence length is 20 nm, almost an order of magnitude larger than the classical antiferromagnetic correlation length of 3 nm. We also demonstrate that the coherence length can be modified by static and thermally activated defects in a quantitatively predictable manner

Understanding suicide attempts among gay men from their self-perceived causes

Gay men are at higher risk of suicidality. This paper describes the causes of suicide attempts as perceived by the men themselves and analyzes their impact on severity and recidivism. Mental health surveys conducted among gay men in Geneva, Switzerland, from two probability-based time-space samples in 2007 and 2011, were merged to yield a combined sample N = 762. Suicide ideation, plans, and attempts were assessed, and respondents who had ever attempted suicide answered open questions about perceived causes which were coded and categorized for analysis within the framework of cultural epidemiology. In all, 16.7% of the respondents reported a suicide attempt in their lifetime (59.5% of them with multiple attempts). At their latest attempt, over two thirds asserted intent to die, and half required medical assistance. There was a wide variety of perceived causes, with most individuals reporting multiple causes and many of the most common causes cited at both the first and most recent subsequent attempts. Social/inter-personal problems constitute the most prominent category. Problems with love/relationship and accepting one's homosexuality figure consistently among the top three causes. Whereas the former tend to be associated with weaker intent to die, the latter are associated with the strongest intent to die and reported at multiple attempts. Problems with family are among the most common perceived causes at first attempt but not at the most recent subsequent attempt. Nevertheless, they tend to be related to the strongest intent to die and the greatest medical severity of all the perceived causes. Ten percent of men attempting suicide cited depression as a cause. Although it tended to be associated with weaker intent to die, depression was most likely to be reported at multiple attempts. Respondent-driven assessment yielded both common and idiosyncratic causes of suicide and their distinct effects. Some of these perceived causes are not prominent in the curren literature, yet they have important implications for understanding risk and preventing suicide among gay men

A model for spin-polarized transport in perovskite manganite bi-crystal grain boundaries

We have studied the temperature dependence of low-field magnetoresistance and current-voltage characteristics of a low-angle bi-crystal grain boundary junction in perovskite manganite La_{2/3}Sr_{1/3}MnO_3 thin film. By gradually trimming the junction we have been able to reveal the non-linear behavior of the latter. With the use of the relation M_{GB} \propto M_{bulk}\sqrt{MR^*} we have extracted the grain boundary magnetization. Further, we demonstrate that the built-in potential barrier of the grain boundary can be modelled by V_{bi}\propto M_{bulk}^2 - M_{GB}^2. Thus our model connects the magnetoresistance with the potential barrier at the grain boundary region. The results indicate that the band-bending at the grain boundary interface has a magnetic origin.Comment: 9 pages, 5 figure

Mesoscale magnetism at the grain boundaries in colossal magnetoresistive films

We report the discovery of mesoscale regions with distinctive magnetic properties in epitaxial La$_{1-x}$Sr$_{x}$MnO$_{3}$ films which exhibit tunneling-like magnetoresistance across grain boundaries. By using temperature-dependent magnetic force microscopy we observe that the mesoscale regions are formed near the grain boundaries and have a different Curie temperature (up to 20 K {\it higher}) than the grain interiors. Our images provide direct evidence for previous speculations that the grain boundaries in thin films are not magnetically and electronically sharp interfaces. The size of the mesoscale regions varies with temperature and nature of the underlying defect.Comment: 4 pages of text, 4 figure