ISS GN and C - First Year Surprises

Assembly of the International Space Station (ISS) began in late 1998 with the joining of the first two US and Russ ian elements. For more than two years, the outpost was served by two Russian Guidance, Navigation, and Control (GN&C) systems. The station requires orbital translation and attitude control functions for its 100+ configurations, from the nascent two-module station to the half million kilogram completed station owned and operated by seventeen nations. With the launch of the US Laboratory module in February 2001, the integration of the US GN&C system with its Russian counterpart laid the foundation for such a robust system. In its first year of combined operation, the ISS GN&C system has performed admirably, even better than many expected, but there have been surprises. Loss of command capability, loss of communication between segments, a control system force-fight, and "non-propulsive vents" that weren't - such events have repeatedly underscored the importance of thorough program integration, testing, and operation, both across subsystem boundaries and across international borders

An investigation of relationships between Approach Motivation, Attentional Bias to Positive Stimuli, and Hypomanic Personality

Underpinned by the Behavioural Approach System (BAS) dysregulation theory of bipolar disorder (BD), five studies were conducted in non-clinical samples to; refine the measurement of state Approach Motivation (AM); measure minor increases in AM; and then finally, to investigate how this relates to attentional biases for emotional stimuli. Study 1 attempted to clarify the phenomenology of state AM and revealed four separable factors that emerged from pooled AM questionnaire items. These structures loosely mapped on hypothesized components of the BAS (Depue & Iacono, 1989) that pertain to; cognitive elements of approach motivation (feeling determined and inspired); an energized, activated state; an affective structure relating to positive mood and outlook; and finally to feelings of excitement. Studies 2 and 3 investigated the validity of the four derived factors and their parent scales against a reward-oriented laboratory induction, a psychophysiological marker of AM, and a test of the discriminative power. The validity results suggested that the most well-established of the scales, the PANAS-PA, slightly outperformed the other measures by showing the greatest response to an AM induction. A second aim was to explore the substructure of a valid measure of mania risk - the hypomanic personality scale (HPS: Eckblad & Chapman, 1986) – in relation to AM responsivity. Unexpectedly, individuals who endorsed unpredictable and changeable moods (mood volatility) displayed elevated sympathetic arousal in response to control task. On this basis, and with a view to exploring the role selective attentional processes as a mediator of AM dysregulation that is relevant to bipolar disorder, study 4 and 5 utilised PANAS-PA to replicate a bi-directional congruency-effect found in the literature between elevations in AM and attentional information-processing biases to reward-related stimuli. Results in general did not support a causal influence of AM on attentional biases, nor did the attempted manipulation of attentional biases affect downstream AM. However, there was evidence that within a stratified sample of participants who reliably responded to the AM and control conditions, those at greater risk to mania exhibited an attentional bias for both positive and negative stimuli, relative those at lower risk to mania

Asylum in Ireland - a public health perspective

This report has two elements, first a review of the literature on refugees and asylum seekrs, with particular to the legal and practical situation in Ireland, and secondly a report of a survey of refugees and asylum seekers carried out in part fulfillment of the requirments for the MPH. The survey had two elements, one a quantitaitve stuy carried out in Dublin and Ennis, and the second a series of focus groups

The DNA-damage signature in Saccharomyces cerevisiae is associated with single-strand breaks in DNA

BACKGROUND: Upon exposure to agents that damage DNA, Saccharomyces cerevisiae undergo widespread reprogramming of gene expression. Such a vast response may be due not only to damage to DNA but also damage to proteins, RNA, and lipids. Here the transcriptional response of S. cerevisiae specifically induced by DNA damage was discerned by exposing S. cerevisiae to a panel of three "radiomimetic" enediyne antibiotics (calicheamicin γ(1)(I), esperamicin A1 and neocarzinostatin) that bind specifically to DNA and generate varying proportions of single- and double-strand DNA breaks. The genome-wide responses were compared to those induced by the non-selective oxidant γ-radiation. RESULTS: Given well-controlled exposures that resulted in similar and minimal cell death (~20–25%) across all conditions, the extent of gene expression modulation was markedly different depending on treatment with the enediynes or γ-radiation. Exposure to γ-radiation resulted in more extensive transcriptional changes classified both by the number of genes modulated and the magnitude of change. Common biological responses were identified between the enediynes and γ-radiation, with the induction of DNA repair and stress response genes, and the repression of ribosomal biogenesis genes. Despite these common responses, a fraction of the response induced by gamma radiation was repressed by the enediynes and vise versa, suggesting that the enediyne response is not entirely "radiomimetic." Regression analysis identified 55 transcripts with gene expression induction associated both with double- or single-strand break formation. The S. cerevisiae "DNA damage signature" genes as defined by Gasch et al. [1] were enriched among regulated transcripts associated with single-strand breaks, while genes involved in cell cycle regulation were associated with double-strand breaks. CONCLUSION: Dissection of the transcriptional response in yeast that is specifically signaled by DNA strand breaks has identified that single-strand breaks provide the signal for activation of transcripts encoding proteins involved in the DNA damage signature in S. cerevisiae, and double-strand breaks signal changes in cell cycle regulation genes

A Quantitative Systems Approach Reveals Dynamic Control of tRNA Modifications during Cellular Stress

Decades of study have revealed more than 100 ribonucleoside structures incorporated as post-transcriptional modifications mainly in tRNA and rRNA, yet the larger functional dynamics of this conserved system are unclear. To this end, we developed a highly precise mass spectrometric method to quantify tRNA modifications in Saccharomyces cerevisiae. Our approach revealed several novel biosynthetic pathways for RNA modifications and led to the discovery of signature changes in the spectrum of tRNA modifications in the damage response to mechanistically different toxicants. This is illustrated with the RNA modifications Cm, m[superscript 5]C, and m[superscript 2][subscript 2]G, which increase following hydrogen peroxide exposure but decrease or are unaffected by exposure to methylmethane sulfonate, arsenite, and hypochlorite. Cytotoxic hypersensitivity to hydrogen peroxide is conferred by loss of enzymes catalyzing the formation of Cm, m[superscript 5]C, and m[superscript 2][subscript 2]G, which demonstrates that tRNA modifications are critical features of the cellular stress response. The results of our study support a general model of dynamic control of tRNA modifications in cellular response pathways and add to the growing repertoire of mechanisms controlling translational responses in cells.National Institute of Environmental Health Sciences (ES002109)National Institute of Environmental Health Sciences (ES017010)National Institute of Environmental Health Sciences (ES015037)National Cancer Institute (U.S.) (CA026731)National Center for Research Resources (U.S.) (RR023783)Singapore-MIT Alliance for Research and Technolog

Technology in the Pharmacy Learning Environment: Surveys of Use and Misuse

The use of technology in the classroom may have positive and negative effects on learning. The purpose of this investigation was twofold: to identify the effect technology is having on the pharmacy learning environment; and, to assess students’ use of technology during class time for non-academic purposes. This study included a national cross-sectional survey as well as a single, college-specific survey. The national survey had a faculty response rate of 71.2%. Of the responders, approximately 61% identified significant problems related to students’ use of technology in the pharmacy learning environment. Cell phones were a recognized concern and more than 90% of programs have chosen to restrict cell phone use in the classroom. The single college survey examining technology use during class for non-academic purposes had a student response rate of 87% and faculty response rate of 100%. Students and faculty members disagreed regarding the negative effects of technology use during class for non-academic purposes. Notably, 16% of students acknowledged their in-class use of technology for non-academic purposes had been disruptive to their learning, as compared to 95.7% of faculty. According to students, common reasons for off-task technology use included checking e-mail/text messages (75.1%), lack of engagement (58.1%), multitasking (56.2%), and accessing social media sites (33%). Faculty and students were asked about enforcement of technology policy. More faculty than students supported policy enforcement by faculty (65.2% versus 22.8%, respectively; p<0.001) as well as policy enforcement by students (78.3% versus 31.9%, respectively; p<0.001). Overall, technology use during class for non-academic purposes was common. Many schools and colleges of pharmacy are developing approaches to address these evolving issues by revising their technology use policies

Coherent optical wavelength conversion via cavity-optomechanics

We theoretically propose and experimentally demonstrate coherent wavelength conversion of optical photons using photon-phonon translation in a cavity-optomechanical system. For an engineered silicon optomechanical crystal nanocavity supporting a 4 GHz localized phonon mode, optical signals in a 1.5 MHz bandwidth are coherently converted over a 11.2 THz frequency span between one cavity mode at wavelength 1460 nm and a second cavity mode at 1545 nm with a 93% internal (2% external) peak efficiency. The thermal and quantum limiting noise involved in the conversion process is also analyzed, and in terms of an equivalent photon number signal level are found to correspond to an internal noise level of only 6 and 4x10-3 quanta, respectively.Comment: 11 pages, 7 figures, appendi