1,619 research outputs found

    Novel hybrid method to additively manufacture denser graphite structures using Binder Jetting.

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    This study introduces two hybrid processes integrating an additive manufacturing technique with post-processing treatments namely (i) Binder Jetting Printing (BJP) + Cold Isostatic Pressing (CIP) + cycle and (ii) BJP + cycle where cycle refers to a sequence of Impregnation-Drying-Pyrolysis. These two new processes yielded additively manufactured parts with higher density and reduced defects/porosities. As a testbed, we used these new processes to fabricate graphite structures. The samples produced by both methods were compared with each other and benchmarked to the samples produced by (a) BJP alone and (b) Traditional uniaxial pressing like compaction moulding. Various characterisation methods were used to investigate the microstructure and mechanical properties which showed that the porosity of hybrid manufactured samples reduces from 55% to a record 7%. This technological pathway is expected to create a new avalanche of industrial applications that are hitherto unexplored in the arena of hybrid additive manufacturing with BJP method

    Covariant equations for the three-body bound state

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    The covariant spectator (or Gross) equations for the bound state of three identical spin 1/2 particles, in which two of the three interacting particles are always on shell, are developed and reduced to a form suitable for numerical solution. The equations are first written in operator form and compared to the Bethe-Salpeter equation, then expanded into plane wave momentum states, and finally expanded into partial waves using the three-body helicity formalism first introduced by Wick. In order to solve the equations, the two-body scattering amplitudes must be boosted from the overall three-body rest frame to their individual two-body rest frames, and all effects which arise from these boosts, including the Wigner rotations and rho-spin decomposition of the off-shell particle, are treated exactly. In their final form, the equations reduce to a coupled set of Faddeev-like double integral equations with additional channels arising from the negative rho-spin states of the off-shell particle.Comment: 57 pages, RevTeX, 6 figures, uses epsf.st

    Anticipatory nausea in cyclical vomiting

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    BACKGROUND: Cyclical Vomiting Syndrome (CVS) is characterised by discrete, unexplained episodes of intense nausea and vomiting, and mainly affects children and adolescents. Comprehending Cyclical Vomiting Syndrome requires awareness of the severity of nausea experienced by patients. As a subjective symptom, nausea is easily overlooked, yet is the most distressing symptom for patients and causes many behavioural changes during attacks. CASE PRESENTATION: This first-hand account of one patient's experience of Cyclical Vomiting Syndrome shows how severe nausea contributed to the development of anticipatory nausea and vomiting (ANV), a conditioned response frequently observed in chemotherapy patients. This conditioning apparently worsened the course of the patient's disease. Anticipatory nausea and vomiting has not previously been recognised in Cyclical Vomiting Syndrome, however predictors of its occurrence in oncology patients indicate that it could complicate many cases. CONCLUSION: We suggest a model whereby untreated severe and prolonged nausea provokes anxiety about further cyclical vomiting attacks. This anxiety facilitates conditioning, thus increasing the range of triggers in a self-perpetuating manner. Effective management of the nausea-anxiety feedback loop can reduce the likelihood of anticipatory nausea and vomiting developing in other patients

    Fine structure and optical pumping of spins in individual semiconductor quantum dots

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    We review spin properties of semiconductor quantum dots and their effect on optical spectra. Photoluminescence and other types of spectroscopy are used to probe neutral and charged excitons in individual quantum dots with high spectral and spatial resolution. Spectral fine structure and polarization reveal how quantum dot spins interact with each other and with their environment. By taking advantage of the selectivity of optical selection rules and spin relaxation, optical spin pumping of the ground state electron and nuclear spins is achieved. Through such mechanisms, light can be used to process spins for use as a carrier of information

    A New Supersymmetric CP Violating Contribution to Neutral Meson Mixing

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    We study the contribution to flavor changing neutral current processes from box diagrams with light higgsinos and squarks. Starting with just the Cabbibo Kobayashi Maskawa (CKM) phase, we find contributions to the K0K^0 and B0B^0 meson mass matrices that are out of phase with the Standard Model contributions in the case of substantial mixing between the up-type squarks. This difference in phase could be large enough to be detected at the proposed BB factories, with interesting implications for the unitarity triangle of CKM matrix elements.Comment: 1 reference added, 1 reference clarified, 2 typos corrected (QCD corrections to K meson mixing in Tables 1 and 3). To be published in Phys. Rev. D. 15 pages (Latex), 2 figures and epsfig.sty submitte

    "It’s sort of reaffirmed to me that I'm not a monster, I'm not a terrible person": sex offenders’ movements toward desistance via peer-support roles in prison

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    Individuals incarcerated in prisons across the United Kingdom and abroad are able to volunteer for a variety of peer-support roles, which are characterized by prisoner-to-prisoner helping. Some research has found that such roles can represent turning points in the lives of those who have offended and encourage movements toward desistance. This proposed redemptive influence is argued to result from the prosocial behaviors that such roles appear to elicit in their holders. The present study aims to explore the mechanics of this claimed influence. While a limited amount of research has attempted this on a general offending population, no research has done so with a sample of sexual offenders. Given the intensive treatment programs involved in such contexts, and the requirements for sexual offenders to demonstrate reduced risk, the authors believe those serving time for sexual offenses represent an important sample on which to explore the potentially redemptive properties of peer-support roles. To this end, 13 peer supporters participated in semistructured interviews. Transcripts were analyzed using a phenomenologically oriented thematic analysis. Results suggest that sexual offenders who adopt peer-support roles are able to live up to desired selves by “doing good” in prison, “giving back,” and consequently resisting negative labels. These benefits have been theoretically linked with better reintegration outcomes for sexual offenders, who are publicly denigrated in the extreme and find it especially difficult to (re)integrate. Suggestions regarding the future utility of such schemes are offered

    What’s Sex (Composition) Got to Do with It? The Importance of Sex Composition of Gangs for Female and Male Members’ Offending and Victimization

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    Sex composition of groups has been theorized in organizational sociology and found in prior work to structure female and male members’ behaviors and experiences. Peer group and gang literature similarly finds that the sex gap in offending varies across groups of differing sex ratios. Drawing on this and other research linking gang membership, offending, and victimization, we examine whether sex composition of gangs is linked to sex differences in offending in this sample, further assess whether sex composition similarly structures females’ and males’ victimization experiences, and if so, why. Self-report data from gang members in a multi-site, longitudinal study of 3,820 youths are employed. Results support previous findings about variations in member delinquency by both sex and sex composition of the gang and also indicate parallel variations in members’ victimization. These results are further considered within the context of facilitating effects such as gender dynamics, gang characteristics, and normative orientation

    Cognitive Function in Children With Type 1 Diabetes: A meta-analysis

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    OBJECTIVE—To quantify the magnitude and pattern of cognitive difficulties in pediatric type 1 diabetes as well as the effects associated with earlier disease onset and severe hypoglycemia
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