10,487 research outputs found

    Electrochemical sintering process for producing electrodes from cadmium felt and a nickel or silver grid

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    Electrochemical sintering process produces cadmium felt electrodes. Two pieces of cadmium felt are sandwiched around a nickel screen or silver expanded metal grid, held together by mold compression, and electrochemically sinitered by being put through several charge and discharge cycles at low current density

    Role of the conduction electrons in mediating exchange interactions in Heusler alloys

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    Because of large spatial separation of the Mn atoms in Heusler alloys the Mn 3d states belonging to different atoms do not overlap considerably. Therefore an indirect exchange interaction between Mn atoms should play a crucial role in the ferromagnetism of the systems. To study the nature of the ferromagnetism of various Mn-based semi- and full-Heusler alloys we perform a systematic first-principles calculation of the exchange interactions in these materials. The calculation of the exchange parameters is based on the frozen-magnon approach. The calculations show that the magnetism of the Mn-based Heusler alloys depends strongly on the number of conduction electrons, their spin polarization and the position of the unoccupied Mn 3d states with respect to the Fermi level. Various magnetic phases are obtained depending on the combination of these characteristics. The Anderson's s-d model is used to perform a qualitative analysis of the obtained results. The conditions leading to diverse magnetic behavior are identified. If the spin polarization of the conduction electrons at the Fermi energy is large and the unoccupied Mn 3d states lie well above the Fermi level, an RKKY-type ferromagnetic interaction is dominating. On the other hand, the contribution of the antiferromagnetic superexchange becomes important if unoccupied Mn 3d states lie close to the Fermi energy. The resulting magnetic behavior depends on the competition of these two exchange mechanisms. The calculational results are in good correlation with the conclusions made on the basis of the Anderson s-d model which provides useful framework for the analysis of the results of first-principles calculations and helps to formulate the conditions for high Curie temperature.Comment: 16 pages, 9 figures, 2 table

    Social and spatial heterogeneity in psychosis proneness in a multilevel case-prodrome-control study

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    To test whether spatial and social neighbourhood patterning of people at ultra-high risk (UHR) of psychosis differs from first-episode psychosis (FEP) participants or controls and to determine whether exposure to different social environments is evident before disorder onset

    Reef response to sea-level and environmental changes during the last deglaciation: Integrated Ocean Drilling Program Expedition 310, Tahiti Sea Level

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    The last deglaciation is characterized by a rapid sea-level rise and coeval abrupt environmental changes. The Barbados coral reef record suggests that this period has been punctuated by two brief intervals of accelerated melting (meltwater pulses, MWP), occurring at 14.08-13.61 ka and 11.4-11.1 ka (calendar years before present), that are superimposed on a smooth and continuous rise of sea level. Although their timing, magnitude, and even existence have been debated, those catastrophic sea-level rises are thought to have induced distinct reef drowning events. The reef response to sea-level and environmental changes during the last deglacial sea-level rise at Tahiti is reconstructed based on a chronological, sedimentological, and paleobiological study of cores drilled through the relict reef features on the modern forereef slopes during the Integrated Ocean Drilling Program Expedition 310, complemented by results on previous cores drilled through the Papeete reef. Reefs accreted continuously between 16 and 10 ka, mostly through aggradational processes, at growth rates averaging 10 mm yr-1. No cessation of reef growth, even temporary, has been evidenced during this period at Tahiti. Changes in the composition of coralgal assemblages coincide with abrupt variations in reef growth rates and characterize the response of the upward-growing reef pile to nonmonotonous sea-level rise and coeval environmental changes. The sea-level jump during MWP 1A, 16 Ā± 2 m of magnitude in ~350 yr, induced the retrogradation of shallow-water coral assemblages, gradual deepening, and incipient reef drowning. The Tahiti reef record does not support the occurrence of an abrupt reef drowning event coinciding with a sea-level pulse of ~15 m, and implies an apparent rise of 40 mm yr-1 during the time interval corresponding to MWP 1B at Barbados. Ā© 2012 Geological Society of America

    First-principles calculation of the intersublattice exchange interactions and Curie temperatures of full Heusler alloys Ni2MnX (X=Ga, In, Sn, Sb)

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    The interatomic exchange interactions and Curie temperatures in Ni-based full Heusler alloys Ni2MnX with X=Ga, In, Sn and Sb are studied within the framework of the density-functional theory. The calculation of the exchange parameters is based on the frozen-magnon approach. Despite closeness of the experimental Curie temperatures for all four systems their magnetism appeared to differ strongly. This difference involves both the Mn-Mn and Mn-Ni exchange interactions. The Curie temperatures, Tc, are calculated within the mean-field approximation by solving a matrix equation for a multi-sublattice system. Good agreement with experiment for all four systems is obtained. The role of different exchange interactions in the formation of Tc of the systems is discussed.Comment: 6 pages, 4 figure

    Participant experiences of the DWELL programme: focus group findings on motivation, experiences, facilitators and barriers

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    Initiatives to increase effective, low-cost self-management are essential to the sustainability of care for type 2 diabetes (T2D), however research shows that there is currently no standard approach. The DWELL programme seeks to motivate and empower people with T2D to better self-manage their condition through focussed content underpinned by motivational interviewing. As part of the DWELL evaluation study, end-of-programme focus groups were conducted to elicit participant experiences. 33 focus groups with 153 participants (including a small number of partners) took place in the two UK DWELL delivery sites. The focus group data was subjected to thematic content analysis to elicit key themes. Findings indicate that DWELL participants are motivated through a desire for better knowledge and management of their diabetes. Facilitating factors of the programme include: facilitator and peer support; the holistic and autonomous approach which provides participants with the opportunity to better understand the condition and its impact on their whole lives; and a tailored individual approach. Barriers and suggested improvements include content and operational changes, which are fed back to DWELL facilitators as part of the process evaluation in order that they can continually update the programme. Participants report positive outcomes in terms of wellbeing, social and mental health, enhanced knowledge and positive lifestyle changes. These themes align with quantitative outcome measures for participants, including weight loss, reduced BMI and glycated haemoglobin (HbA1c), enhanced empowerment and improved eating behaviours and illness perceptions and control. Interim findings suggest that DWELL outcomes include improved health literacy, participant empowerment and self-management. These findings underscore the need to incorporate a holistic, tailored approach to structured patient education for T2D

    Identifying cues for self-organized nest wall-building behaviour in the rock ant, Temnothorax rugatulus, using hidden Markov models

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    Funding: E.I.ā€™s Ph.D. was funded by the John Templeton Foundation as part of the research collaboration grant ā€˜Putting the extended evolutionary synthesis to the testā€™ (grant no. 60501). The postdoctoral research project that followed this initial work was funded by an ASAB research grant to M.W. and E.I.EuropeanĀ Temnothorax albipennisĀ and its American counterpartĀ Temnothorax rugatulusĀ build circular walls to limit their nest area within a rock crevice. To determine wall position, workers are thought to rely on a distance template (from the cluster of brood and nurses at the nest centre) and on indirect social (i.e. stigmergic) information found in the aggregations of already-deposited building material. Analytical and simulation models of this behaviour predict that the combination of these two mechanisms can produce the observed wall structure, but there is so far no empirical evidence of either mechanism. Here, we find statistical evidence in support of the stigmergic relationship between stone density and deposition behaviour. We apply hidden Markov models (HMMs) to analyse wall-building data from four colonies ofĀ T.Ā rugatulus. We show that material deposition activity changes following a parabolic relationship with the density of building material at building sites, different from the linear relationship hypothesized previously. This parabolic curve is similar to behavioural response curves identified in the nest enlargement process of several ant species. In addition, HMM analysis indicates the existence of two distinct states inĀ T.Ā rugatulusĀ building activity. These states are associated with different mean building rates (that is, the two states can be described as a high and a low activity state) and might be caused by changes in task priorities during the colony process of settling into a new nest. This study updates one of the earliest models of self-organized animal behaviour.Peer reviewe

    The Dutch language short Anterior Cruciate Ligamentā€”Return to Sport after Injury scale has good to excellent construct validity, internal consistency, and test-retest reliability when assessing athletes undergoing rehabilitation after ACL injury or ACL reconstruction

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    Objectives:Ā To examine the validity and reliability of the Dutch language short Anterior Cruciate Ligamentā€”Return to Sport after Injury scale (short ACL-RSI-NL) in recreational athletes undergoing rehabilitation after ACL injury or ACL reconstruction (ACLR).Ā Methods:Ā The original 12-item version of the ACL-RSI had been translated into Dutch. Short ACL-RSI-NL items were derived from this 12-item Dutch version. Content validity was evaluated by a team consisting of eight ACL experts and eight athletes. A cohort of 115 athletes with ACL injury or after ACLR completed the short ACL-RSI-NL and related questionnaires at various time points during their rehabilitation. Construct validity (hypothesis testing using Spearman correlations), internal consistency (Cronbach's alpha), floor and ceiling effects (percentage of athletes having the lowest or highest score possible), and structural validity (exploratory factor analysis) were evaluated in the entire ACL athlete group. Test-retest reliability (using intra-class correlation, ICC; standard error of measurement, SEM; smallest detectable change, SDC, at both group and individual levels) was investigated in a subgroup of athletes with a stable outcome on psychological readiness within a two-week interval (n ā€‹= ā€‹27).Ā Results:Ā The short ACL-RSI-NL demonstrated good construct validity (83% of hypotheses confirmed). Internal consistency was excellent (Cronbach's alpha 0.84), and there were no floor and ceiling effects (ā‰¤13.9% lowest or highest score). Test-retest reliability was good (ICC 0.89 with 95% CI 0.77ā€“0.95, SEM 6.93, SDC individual level 19.2, SDC group level 3.7). Exploratory factor analysis confirmed the presence of a single underlying factor (accounting for 56.4% of the total variance of the score).Ā Conclusion:Ā The short ACL-RSI-NL exhibited good to excellent construct validity, internal consistency, and test-retest reliability. An averaged score ranging from 0 to 100 can be used to measure psychological readiness to return to sport. The short ACL-RSI-NL has potential for use in day-to-day practice to assess the psychological readiness of recreational athletes to return to sport after ACL injury or ACLR during their rehabilitation process. Level of evidence: Level II.</p

    Surface Properties of the Half- and Full-Heusler Alloys

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    Using a full-potential \textit{ab-initio} technique I study the electronic and magnetic properties of the (001) surfaces of the half-Heusler alloys, NiMnSb, CoMnSb and PtMnSb and of the full-Heusler alloys Co2_2MnGe, Co2_2MnSi and Co2_2CrAl. The MnSb terminated surfaces of the half-Heusler compounds present properties similar to the bulk compounds and, although the half-metallicity is lost, an important spin-polarisation at the Fermi level. In contrast to this the Ni terminated surface shows an almost zero net spin-polarisation. While the bulk Co2_2MnGe and Co2_2MnSi are almost half-ferromagnetic, their surfaces lose the half-metallic character and the net spin-polarisation at the Fermi level is close to zero. Contrary to these compounds the CrAl terminated (001) surface of Co2_2CrAl shows a spin polarisation of about 84%.Comment: 14 pages, 6 figure

    Appearance of Half-Metallicity in the Quaternary Heusler Alloys

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    I report systematic first-principle calculations of the quaternary Heusler alloys like Co2_2[Cr1āˆ’x_{1-x}Mnx_x]Al, Co2_2Mn[Al1āˆ’x_{1-x}Snx_x] and [Fe1āˆ’x_{1-x}Cox_x]2_2MnAl. I show that when the two limiting cases (x=0 or 1) correspond to a half-metallic compound, so do the intermediate cases. Moreover the total spin moment MtM_t in Ī¼B\mu_B scales linearly with the total number of valence electrons ZtZ_t (and thus with the concentration xx) following the relation Mt=Ztāˆ’24M_t=Z_t-24, independently of the origin of the extra valence electrons, confirming the Slater-Pauling behavior of the normal Heusler alloys. Finally I discuss in all cases the trends in the atomic projected DOSs and in the atomic spin moments.Comment: 4 pages, 3 figures, 2 Table
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