1,068 research outputs found

    An artificially generated atmosphere near a lunar base

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    We discuss the formation of an artificial atmosphere generated by vigorous lunar base activity in this paper. We developed an analytical, steady-state model for a lunar atmosphere based upon previous investigations of the Moon's atmosphere from Apollo. Constant gas-injection rates, ballistic trajectories, and a Maxwellian particle distribution for an oxygen-like gas are assumed. Even for the extreme case of continuous He-3 mining of the lunar regolith, we find that the lunar atmosphere would not significantly degrade astronomical observations beyond about 10 km from the mining operation

    The anomalous Hall effect in non-collinear antiferromagnetic Mn3_{3}NiN thin films

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    We have studied the anomalous Hall effect (AHE) in strained thin films of the frustrated antiferromagnet Mn3_{3}NiN. The AHE does not follow the conventional relationships with magnetization or longitudinal conductivity and is enhanced relative to that expected from the magnetization in the antiferromagnetic state below TN=260T_{\mathrm{N}} = 260\,K. This enhancement is consistent with origins from the non-collinear antiferromagnetic structure, as the latter is closely related to that found in Mn3_{3}Ir and Mn3_{3}Pt where a large AHE is induced by the Berry curvature. As the Berry phase induced AHE should scale with spin-orbit coupling, yet larger AHE may be found in other members of the chemically flexible Mn3A_{3}AN structure

    Evaluation of a Fiber-Optic Based Pulsed Laser System for Fluorescence Spectroscopy

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    A fiber optic based continous wave laser setup has been developed to record the 5-aminolevulinic (5-ALA) induced Protoporfyrin IX (PpIX) fluorescence signals from cerebral gliomas. To reduce the energy delivered to the tissue as well as suppression of the ambient lamp artifact from the recorded spectra, a pulsed laser setup has been developed and evaluated. This setup has been calibrated and first evaluations were performed on the 5-ALA treated skin showing PpIX fluorescence peaks from the ALA treated skin at 635 and 704 nm wavelengths. The system controls laser pulses through a computer interface and labview software package. Pulses as short as 50 ms over a period time of 500 ms are generated and optimally detected. The results from primary measurements on skin show an effective suppression of room fluorescent lamp artifact from the recorded spectra

    Wage returns to university disciplines in Greece: are Greek Higher Education degrees Trojan Horses?

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    This paper examines the wage returns to qualifications and academic disciplines in the Greek labour market. Exploring wage responsiveness across various degree subjects in Greece is interesting, as it is characterised by high levels of graduate unemployment, which vary considerably by field of study, and relatively low levels of wage flexibility. Using micro-data from recently available waves (2002-2003) of the Greek Labour Force Survey (LFS), the returns to academic disciplines are estimated by gender and public/private sector. Quantile regressions and cohort interactions are also used to capture the heterogeneity in wage returns across the various disciplines. The results show considerable variation in wage premiums across the fields of study, with lower returns for those that have a marginal role to play in an economy with a rising services/shrinking public sector. Educational reforms that pay closer attention to the future prospects of university disciplines are advocated

    Identification and geographical distribution of pyrethroid resistance mutations in the poultry red mite Dermanyssus gallinae

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    The poultry red mite (PRM) Dermanyssus gallinae is the most common ectoparasite on poultry and causes high economic losses in poultry farming worldwide. Pyrethroid acaricides have been widely used for its control and, consequently, pyrethroid resistance has arisen. In this study we aim to investigate the occurrence of resistance and study the geographical distribution of pyrethroid resistance mutations across PRM populations in Europe

    Extending the voltage window in the characterization of electrical transport of large-area molecular junctions

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    A large bias window is required to discriminate between different transport models in large-area molecular junctions. Under continuous DC bias, the junctions irreversibly break down at fields over 9 MV/cm. We show that, by using pulse measurements, we can reach electrical fields of 35 MV/cm before degradation. The breakdown voltage is shown to depend logarithmically on both duty cycle and pulse width. A tentative interpretation is presented based on electrolysis in the polymeric top electrode. Expanding the bias window using pulse measurements unambiguously shows that the electrical transport exhibits not an exponential but a power-law dependence on bias. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3608154

    Alexithymia and its association with burnout, depression and family support among Greek nursing staff

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    <p>Abstract</p> <p>Background</p> <p>Few studies have examined the relation between alexithymia (i.e. the inability to recognize and verbalize emotions) and professional burnout. Considering the absence of relevant studies in the Greek scientific literature, the aim of this work was to examine the associations of alexithymia with the three facets of professional burnout, the perception of family support and depression in nursing personnel.</p> <p>Methods</p> <p>The study was performed in one of the largest hospitals in Greece and included 95 nurses. Assessments of alexithymia, burnout, depression and family support were made by means of the Toronto Alexithymia Scale, the Maslach Burnout Inventory, the Beck Depression Inventory and the Julkunen Family Support Scale, respectively. Student's t-test, Pearson's correlation and stepwise linear regression were used for the evaluation of data.</p> <p>Results</p> <p>Alexithymia was correlated positively with depression, emotional exhaustion and depersonalization, and negatively with sense of family support and personal achievement. Additionally, family support was correlated positively with personal achievement and negatively with depression.</p> <p>Conclusion</p> <p>In the scientific literature there is a debate as to whether alexithymia is a stable personality characteristic or if it is dependent on symptoms of mental disorders. We tried to interpret the associations of alexithymia with professional burnout, depressive symptoms and family support. From this study it appears very likely that alexithymia is directly associated with depression and personal achievement, but also indirectly with the sense of family support.</p

    Laser for balloon uncrossable and undilatable chronic total occlusion interventions

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    BACKGROUND: There is limited information on use of laser in complex percutaneous coronary interventions (PCI). We examined the impact of laser on the outcomes of balloon uncrossable and balloon undilatable chronic total occlusion (CTO) PCI. METHODS: We reviewed baseline clinical and angiographic characteristics and procedural outcomes of 4845 CTO PCIs performed between 2012 and 2020 at 32 centers. RESULTS: Of the 4845 CTO lesions, 752 (15.5%) were balloon uncrossable (523 cases) or balloon undilatable (356 cases) and were included in this analysis. Mean patient age was 66.9 ± 10 years and 83% were men. Laser was used in 20.3% of the lesions. Compared with cases in which laser was not used, laser was more commonly used in longer length occlusions (33 [21, 50] vs. 25 [15, 40] mm, p = 0.0004) and in-stent restenotic lesions (41% vs. 20%, p \u3c 0.0001). Laser use was associated with higher technical (91.5% vs. 83.1%, p = 0.010) and procedural (88.9% vs. 81.6%, p = 0.033) success rates and similar incidence of major adverse cardiac events (3.92% vs. 3.51%, p = 0.805). Laser use was associated with longer procedural (169 [109, 231] vs. 130 [87, 199], p \u3c 0.0001) and fluoroscopy time (64 [40, 94] vs. 50 [31, 81], p = 0.003). CONCLUSIONS: In a contemporary, multicenter registry balloon uncrossable and balloon undilatable lesions represented 15.5% of all CTO PCIs. Laser was used in approximately one-fifth of these cases and was associated with high technical and procedural success and similar major complication rates

    Decreased Exercise-Induced Changes in Prefrontal Cortex Hemodynamics Are Associated With Depressive Symptoms

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    People with a depressed mood tend to perform poorly on executive function tasks, which require much of the prefrontal cortex (PFC), an area of the brain which has also been shown to be hypo-active in this population. Recent research has suggested that these aspects of cognition might be improved through physical activity and cognitive training. However, whether the acute effects of exercise on PFC activation during executive function tasks vary with depressive symptoms remains unclear. To investigate these effects, 106 participants were given a cardiopulmonary exercise test (CPET) and were administered a set of executive function tests directly before and after the CPET assessment. The composite effects of exercise on the PFC (all experimental blocks) showed bilateral activation changes in dorsolateral (BA46/9) and ventrolateral (BA44/45) PFC, with the greatest changes occurring in rostral PFC (BA10). The effects observed in right ventrolateral PFC varied depending on level of depressive symptoms (13% variance explained); the changes in activation were less for higher levels. There was also a positive relationship between CPET scores (VO2peak) and right rostral PFC, in that greater activation changes in right BA10 were predictive of higher levels of aerobic fitness (9% variance explained). Since acute exercise ipsilaterally affected this PFC subregion and the inferior frontal gyrus during executive function tasks, this suggests physical activity might benefit the executive functions these subregions support. And because physical fitness and depressive symptoms explained some degree of cerebral upregulation to these subregions, physical activity might more specifically facilitate the engagement of executive functions that are typically associated with hypoactivation in depressed populations. Future research might investigate this possibility in clinical populations, particularly the neural effects of physical activity used in combination with mental health interventions

    Learning curve of sutureless transconjunctival 20-gauge vitrectomy

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    Background To report the learning curve of transition from 20-gauge (20 G) conventional vitrectomy to a 20 G sutureless vitrectomy technique. Materials and methods This is a retrospective descriptive case study of 32 eyes from 32 consecutive patients who underwent sutureless 20 G pars plana vitrectomy. A 20 G microvitreoretinal blade was introduced, beveled transconjunctivally, slowly, parallel with the limbus, creating a conjunctivoscleral tunnel incision. Study participants were divided into three groups, and surgical time, induced astigmatism, and complications were compared. Results Of 32 consecutive patients, there was no significant difference in induced astigmatism or maneuvering between the early learning curve and other groups. The true learning curve was the first three patients. There were three cases where suturing the sclerotomy was necessary: one port in each case, three of 32 cases (9.3%), or three of 96 ports (2.9%). Conclusion There were no significant difficulties in surgical maneuvers while performing 20 g sutureless vitrectomy. Keywords: sutureless, vitrectomy, 20 G, learning curv
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