External-cavity diode lasers with different devices and collimating optics

Comparative operating characteristics of external-cavity diode lasers (ECDL's) with either a channel substrate planar device or a multi-quantum-well (MQW) device are presented. These include the output beam profile, which is significantly altered depending on the collimating lens used (either multielement or graded index), power versus injection-current characteristics, and the optical frequency and the rf spectra. The coherence lengths of the different laser diode-collimating-lens combinations in the ECDL are measured, and a new method for calculating the coupling coefficient and the coupled values of the internal quantum efficiency and the internal lumped loss is demonstrated for the MQW device.     

Photo Noise

Like past avant-garde movements, glitch and noise in the twenty-first century are used to reveal the materiality of the medium. But instead of providing insight or clarity into the politics or social conditions of a technology, they demarcate broader conditions of opacity and blockage, contributing to what Jodi Dean has called ‘communicative capitalism’. The work of German photographer Thomas Ruff alongside the Düsseldorf School, New Photography and JPEG technology are used in this article to illustrate this tendency as a move away from meaning and toward visual noise and communicative breakdown. I use three core analytic registers: the deliberate failure to adhere to visual norms, communicative failure and machine failure and breakdown. Ruff’s work uses visual noise as art to at once reaffirm pervasive conditions of breakdown, failure and decline in high-tech global capitalism, while simultaneously providing a temporary reprieve from these conditions through an emergent form of visual beauty.     

Amblyomma variegatum (Acari: Ixodidae): mechanism and control of arbovirus secretion in tick saliva

Saliva is considered to be the conduit by which pathogens are transmitted from blood-sucking arthropod vectors to their vertebrate hosts, but supporting evidence for this is fragmentary. To determine if Thogoto (THO) virus, a tick-borne member of the influenza virus family, is transmitted via tick saliva, and whether virus replication is a prerequisite for such transmission, two experimental conditions were compared: (1) "biological transmission" and (2) "mechanical transmission." In (1), THO virus was allowed to infect and replicate in a natural vector, Amblyomma variegatum: virus was detected in saliva collected from 3/22 (14%) ticks. In (2), virus was inoculated directly into the hemocoel with the drug used to induce salivation and saliva was collected immediately to preclude the possibility of virus replication: virus was detected in saliva collected from 31/170 (18%) ticks. The results demonstrate that THO virus is secreted in tick saliva and that virus can pass from the hemolymph to the salivary glands independently of viral replication within the tick. The comparatively low numbers of ticks that yielded virus-positive saliva samples together with the results from assays of serial saliva samples suggested that virus secretion may not be a continuous process during salivation. Ticks in which THO virus had established an infection showed an impaired secretory response compared with uninfected ticks and ticks used for mechanical transmission.     

Glu227-->Lys substitution in the acidic loop of major histocompatibility complex class I alpha 3 domain distinguishes low avidity CD8 coreceptor and avidity-enhanced CD8 accessory functions

Cytotoxic T lymphocyte (CTL) activation requires specific T cell receptor (TCR)-class I major histocompatibility complex (MHC) antigen complex interactions as well as the participation of coreceptor or accessory molecules on the surface of CTL. CD8 can serve as a coreceptor in that it binds to the same MHC class I molecules as the TCR to facilitate efficient TCR signaling. In addition, CD8 can be "activated" by TCR stimulation to bind to class I molecules with high avidity, including class I not recognized by the TCR as antigenic complexes (non-antigen [Ag] class I), to augment CTL responses and thus serve an accessory molecule function. A Glu/Asp227-->Lys substitution in the class I alpha 3 domain acidic loop abrogates lysis of target cells expressing these mutant molecules by alloreactive CD8-dependent CTL. Lack of response is attributed to the destruction of the CD8 binding site in the alpha 3 domain which is likely to disrupt CD8 coreceptor function. The relative importance of the class I alpha 3 domain acidic loop Glu227 in coreceptor as opposed to accessory functions of CD8 is unclear. To address this issue, we examined CTL adhesion and degranulation in response to immobilized class I-peptide complexes formed in vitro from antigenic peptides and purified class I molecules containing wild-type or Glu227-->Lys substituted alpha 3 domains. The alpha 3 domain mutant class I-peptide complexes were bound by CTL and triggered degranulation, however to much lower levels than wild-type class I-peptide complexes. In further experiments, it is directly demonstrated that the alpha 3 domain mutant class I molecules, which lack the Glu227 CD8 binding site, still serve as TCR-activated, avidity-enhanced CD8 accessory ligands. However, mutant class I peptide Ag complexes failed to effectively serve as CD8 coreceptor ligands to initiate TCR-dependent signals required to induce avidity-enhanced CD8 binding to coimmobilized non-Ag class I molecules. Thus the Glu227-->Lys mutation effectively distinguishes CD8 coreceptor and avidity-enhanced CD8 accessory functions.     

Achieving Diagnosis by Consensus

This paper provides an analysis of the collaborative work conducted at a multidisciplinary medical team meeting, where a patient’s definitive diagnosis is agreed, by consensus. The features that distinguish this process of diagnostic work by consensus are examined in depth. The current use of technology to support this collaborative activity is described, and experienced deficiencies are identified. Emphasis is placed on the visual and perceptual difficulty for individual specialities in making interpretations, and on how, through collaboration in discussion, definitive diagnosis is actually achieved. The challenge for providing adequate support for the multidisciplinary team at their meeting is outlined, given the multifaceted nature of the setting, i.e. patient management, educational, organizational and social functions, that need to be satisfied.

One-sided multiple comparisons for treatment means with a control mean

We study comparisons of several treatments with a common control when it is believed a priori that the treatment means, μ_i, are at least as large as the control mean, μ₀. In this setting, which is called a tree ordering, we study multiple comparisons that determine whether μ_i>μ₀ or μ_i=μ₀ for each treatment. The classical procedure by Dunnett (1955) and the step-down and step-up techniques by [Dunnett and Tamhane, 1991] and [Dunnett and Tamhane, 1992] are well known. The results in Marcus and Talpaz (1992) provide multiple comparisons based on the maximum likelihood estimates restricted by the tree ordering. We also study two-stage procedures that consist of the likelihood ratio test of homogeneity with the alternative constrained by the tree ordering followed by two-sample t comparisons with possibly different critical values for the two-sample comparisons. Marcus et al. (1976) discuss the use of closed tests in such situations and propose using a closed version of the restricted likelihood ratio test. We describe step-down versions of the Marcus-Talpaz, the two-stage, and the likelihood ratio procedures, as well as a closed version of the Marcus-Talpaz multiple comparison procedure. Using Monte Carlo techniques, we study the familywise errors and powers of these procedures and make some recommendations concerning techniques that perform well for all tree ordered mean vectors.     

Impedance cardiography used to assess patterns of cardiovascular response to behavioral stressors

This paper presents two examples of how impedance cardiography may be used to interpret the hemodynamic influences on blood pressures measured during behavioral stress. In Study 1, blood pressure changes which were similar during two tasks were shown to have important differences in their cardiac output and vascular resistance components. During work on a reaction time task having aversive incentives compared with a neutral task, the blood pressure changes were seen to be associated with lowered vascular resistance and raised cardiac activity, a "fight-flight" pattern. In Study 2, blood pressure response differences between two subject groups working on an identical task were found to have blood pressure changes differing in their underlying cardiac and vascular components as measured by impedance. Such uses impedance cardiography have widespread potential application in psychophysiological research with humans.     

Working memory capacity and the top-down control of visual search: Exploring the boundaries of "executive attention".

The executive attention theory of working memory capacity (WMC) proposes that measures of WMC broadly predict higher order cognitive abilities because they tap important and general attention capabilities (R. W. Engle & M. J. Kane, 2004). Previous research demonstrated WMC-related differences in attention tasks that required restraint of habitual responses or constraint of conscious focus. To further specify the executive attention construct, the present experiments sought boundary conditions of the WMC-attention relation. Three experiments correlated individual differences in WMC, as measured by complex span tasks, and executive control of visual search. In feature-absence search, conjunction search, and spatial configuration search, WMC was unrelated to search slopes, although they were large and reliably measured. Even in a search task designed to require the volitional movement of attention (J. M. Wolfe, G. A. Alvarez, & T. S. Horowitz, 2000), WMC was irrelevant to performance. Thus, WMC is not associated with all demanding or controlled attention processes, which poses problems for some general theories of WMC. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Beam position measurements of Indus-2 using X-Ray beam position monitor

A staggered pair metal blade X-ray beam position monitor (XBPM) is designed, fabricated and commissioned on Indus-2 bending magnet front end. Calibration of XBPM is done by scanning the metal blades in the path of synchrotron radiation and by giving controlled electron asymmetric bump. The vertical beam position stability of the source measured during various injections and storages are reported.