Suppression of Spin-Glass State in PrB6

2012 ◽  
Vol 190 ◽  
pp. 221-224 ◽  
Author(s):  
M.A. Anisimov ◽  
A.V. Bogach ◽  
V.V. Glushkov ◽  
S.V. Demishev ◽  
N.A. Samarin ◽  
...  

The comprehensive study of transverse magnetoresistance (MR) and magnetization has been carried out on the high quality single crystals of PrB6 in the wide range of temperatures 2-40K and magnetic fields up to 80kOe. In order to estimate the role of boron vacancies in the formation of the new spin-glass (SG) phase detected by Alekseev et al. below 20K the experiments were carried out on the ordinary (initial state) and annealed single crystals of PrB6. The data obtained demonstrate the appearance of spontaneous magnetization below TSG21.3K with M~1.6 emu/mol for initial state and the absence of spontaneous magnetization for the annealed PrB6 samples. On the contrary, quite similar behavior of MR was detected for various samples of PrB6. Our results suggest the existence of the aggregated boron vacancies which provoke the new SG phase formation in PrB6 at TSG.

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Yogesh Kumar ◽  
Rabia Sultana ◽  
Prince Sharma ◽  
V. P. S. Awana

AbstractWe report the magneto-conductivity analysis of Bi2Se3 single crystal at different temperatures in a magnetic field range of ± 14 T. The single crystals are grown by the self-flux method and characterized through X-ray diffraction, Scanning Electron Microscopy, and Raman Spectroscopy. The single crystals show magnetoresistance (MR%) of around 380% at a magnetic field of 14 T and a temperature of 5 K. The Hikami–Larkin–Nagaoka (HLN) equation has been used to fit the magneto-conductivity (MC) data. However, the HLN fitted curve deviates at higher magnetic fields above 1 T, suggesting that the role of surface-driven conductivity suppresses with an increasing magnetic field. This article proposes a speculative model comprising of surface-driven HLN and added quantum diffusive and bulk carriers-driven classical terms. The model successfully explains the MC of the Bi2Se3 single crystal at various temperatures (5–200 K) and applied magnetic fields (up to 14 T).


2020 ◽  
Vol 122 (10) ◽  
pp. 1-50
Author(s):  
Susan Bush-Mecenas ◽  
Julie A. Marsh ◽  
Katharine O. Strunk

Background/Context School leaders are central to state and district human-capital reforms (HCRs), yet they are rarely equipped with the skills to implement new evaluation, professional development, and personnel data systems. Although districts increasingly offer principals coaching and training, there has been limited empirical work on how these supports influence principals’ HCR-related practices. Purpose Drawing on a two-year, mixed-methods study in the Los Angeles Unified School District (LAUSD), this article examines the role of principal supervisors in HCRs. We ask: What role did principal supervisors (Instructional Directors [IDs]) play in the implementation of human-capital reforms? What did high-quality coaching on the part of IDs look like in this context? Research Design Our two-part analysis draws upon survey and interview data. First, we conducted descriptive analyses and significance testing using principal and ID survey data to examine the correlations among principals’ ratings of ID coaching quality, ID coaching practices, and principals’ implementation of HCRs. Second, we conducted in-depth interviews, using a think-aloud protocol, with two sets of IDs—those consistently highly-rated and those with mixed ratings—who were identified using principals’ reports of coaching quality. Following interview coding, we created various case-ordered metamatrix displays to analyze our qualitative data in order to identify patterns in coaching strategy and approach across IDs, content, and contexts. Findings First, our survey data indicate that receiving high-quality coaching from IDs is correlated with stronger principal support for and implementation of HCRs. Our survey findings further illustrate that IDs support a wide range of principals’ HCR activities. Second, our think-aloud interviews with case IDs demonstrate that coaching strategy and approach vary between consistently highly-rated and mixed-rated coaches: Consistently highly-rated IDs emphasize the importance of engaging in, or defining HCR problems as, joint work alongside principals, while mixed-rated IDs often emphasize the use of tools to guide principal improvement. We find that, on the whole, the consistently highly-rated IDs in our sample employ a nondirective approach to coaching more often than mixed-rated coaches. Conclusions These findings contribute to a growing literature on the crucial role of principal supervisors as coaches to improve principals’ instructional leadership and policy implementation. While exploratory, this study offers the first steps toward building greater evidence of the connections between high-quality coaching and policy implementation, and it may have implications for the design and implementation of professional development for principal supervisors and the selection and placement of supervisors with principals.


2020 ◽  
Vol 1 (1) ◽  
pp. 63-91 ◽  
Author(s):  
Ambrogio Volonté ◽  
Peter A. Clark ◽  
Suzanne L. Gray

Abstract. Idealised simulations of Shapiro–Keyser cyclones developing a sting jet (SJ) are presented. Thanks to an improved and accurate implementation of thermal wind balance in the initial state, it was possible to use more realistic environments than in previous idealised studies. As a consequence, this study provides further insight into SJ evolution and dynamics and explores SJ robustness to different environmental conditions, assessed via a wide range of sensitivity experiments. The control simulation contains a cyclone that fits the Shapiro–Keyser conceptual model and develops a SJ whose dynamics are associated with the evolution of mesoscale instabilities along the airstream, including symmetric instability (SI). The SJ undergoes a strong descent while leaving the cloud-head banded tip and markedly accelerating towards the frontal-fracture region, revealed as an area of buckling of the already-sloped moist isentropes. Dry instabilities, generated by vorticity tilting via slantwise frontal motions in the cloud head, exist in similar proportions to moist instabilities at the start of the SJ descent and are then released along the SJ. The observed evolution supports the role of SI in the airstream’s dynamics proposed in a conceptual model outlined in a previous study. Sensitivity experiments illustrate that the SJ is a robust feature of intense Shapiro–Keyser cyclones, highlighting a range of different environmental conditions in which SI contributes to the evolution of this airstream, conditional on the model having adequate resolution. The results reveal that several environmental factors can modulate the strength of the SJ. However, a positive relationship between the strength of the SJ, both in terms of peak speed and amount of descent, and the amount of instability occurring along it can still be identified. In summary, the idealised simulations presented in this study show the robustness of SJ occurrence in intense Shapiro–Keyser cyclones and support and clarify the role of dry instabilities in SJ dynamics.


1993 ◽  
Vol 328 ◽  
Author(s):  
Rene Clement ◽  
Pascal G. Lacroix

ABSTRACTThe layered MIIPS3 compounds posess a unique cation exchange intercalation chemistry, which allows the synthesis of a wide range of air stable M1-xPS3G2x intercalates (G stands here for a Monocation). The positive charge of the guest cations is counterbalanced by intralayer metallic vacancies.Intercalation exerts a dramatic influence on the magnetic properties of these compounds. Whereas pristine MPS3 compounds order antiferromagnetically (M = Mn, Fe‥), Many intercalates become magnets below an ordering temperature that can be as high as 92 K. The role of intercalation is discussed in terms of the creation of intralayer metallic vacancies, which destroy the spin balance that prevails in pristine MPS3 compounds.The MPS3 host lattice has the capability of causing spontaneous poling of the dimethylamino-N-Methyl stilbazolium chromophore (DAMS), leading to materials that exhibit strong second harmonic generation. (SHG). Inserting DAMS into MnPS3 therefore leads to a composite that possess both spontaneous Magnetization (below Tc = 40 K) and a strong efficiency for SHG.


Author(s):  
Wilson McLeod

This the first comprehensive study of the Gaelic language in modern Scotland, covering the period from 1872 to the present. It considers in detail the changing role of Gaelic in modern Scotland - from the introduction of state education in 1872 up to the present day - including the policies of government and the work of activists and campaigners who have sought to maintain and promote Gaelic. In addition, it scrutinises the competing ideologies that have driven the decline, marginalisation and subsequent revitalisation of the language. Taking an interdisciplinary approach - at the boundary of history, law, language policy and sociolinguistics - the book draws upon a wide range of sources in both English and Gaelic to consider in detail the development of the language policy regime for Gaelic that was developed between 1975 and 1989. It examines the campaign for the Gaelic Language (Scotland) Act 2005 and analyses its contents and implementation. It also assesses the development and delivery of development and delivery of Gaelic education and media from the late 1980s to the present.


2018 ◽  
Vol 9 (15) ◽  
pp. 4221-4226 ◽  
Author(s):  
Jie Ding ◽  
Zhipeng Lian ◽  
Yu Li ◽  
Shufeng Wang ◽  
Qingfeng Yan

2018 ◽  
Vol 6 (3) ◽  
pp. 482-490 ◽  
Author(s):  
M. Klein ◽  
S. Majumdar ◽  
P. Zassowski ◽  
W. Stampor

A study of photocurrent in SQ based solar cells, using a wide range of magnetic fields and temperatures, reveals that depending on the electron acceptor content, the photocurrent generation is limited by dissociation/recombination of e–h pairs or CT states.


2019 ◽  
Vol 27 (2) ◽  
pp. 159-169 ◽  
Author(s):  
Petr I. Karpov ◽  
Tatyana Zakharova

AbstractThe inverse problem of magnetoencephalography is ill-posed and difficult for both analytical and numerical solutions. Additional complications arise from the volume (passive) currents and the associated magnetic fields, which strongly depend on the brain geometry. In this paper, we find approximate analytical solutions for the forward and the inverse problems in the spheroid geometry. We compare the obtained results with the exact solution of the forward problem and deduce that for a wide range of parameters our approximation is valid. The analysis sheds new light on the role of the volume magnetic fields for solving the inverse problem of magnetoencephalography.


2017 ◽  
Vol 8 (1) ◽  
pp. 3-10
Author(s):  
A. O. Mikheev

Infectious diseases that are caused by numerous pathogenic microorganisms – bacteria, viruses, protozoa or fungi – can be transmitted from patients or carriers to healthy people or animals. A large group of infectious disease is caused by pathogens of animal infections – zoonoses. The issue of zoonoses is of great significance in human pathology and requires comprehensive study. This is of particular relevance to Ukraine, as the question of prevalence, level within the population and threats to human life and health from zoonoses, though highly important, has remained insufficiently studied. Information about many of these pathogens is absent in the existing scientific literature accessible in Ukraine – both veterinary and medical. This applies, in particular, to a causative agent of viral zoonoses the Borna disease virus or Bornavirus. For this purpose, an analysis of the literature concerning the role of the Bornavirus in the pathology of animals and humans was conducted. It is well known that a large number of pathogens of animal infections (zoonoses), including viral, pose a potential threat to human health. Among these potential threats is the Borna disease virus belonging to the family of Bornaviridae, order Mononegavirales. This order includes representatives of deadly human diseases like rabies (family Rhabdoviridae), Ebola virus (family Filoviridae) and Nipah virus (family Paramyxoviridae). Borna virus disease affects mainly mammals, but can infect birds and even reptiles (Aspid bornavirus). It is established that Bornaviruses have a wide range of natural hosts (horses, sheeps, cats, bats and various birds), including domestic animals, which poses a potential threat to human health. This is evidenced by numerous, although contradictory, research into the role of the Borna disease virus in human pathologies such as schizophrenia, depression, prolonged fatigue syndrome, multiple sclerosis and others. Analysis of the literature clearly shows the important role of the Borna disease virus in a variety of mental and behavioural changes in animals, both wild and domestic. However, the large amount of contradictory data and studies cannot yet provide a clear picture of the role of this virus in human pathology. On the one hand, there are clear data of the presence of RNA of the Bourna disease virus and antibodies to it in patients with psychoneurotic changes. On the other, there is no clear understanding of the infectivity of the virus in humans and its transmission from animals to humans and from person to person. These questions require further research and comprehensive study, particularly on the territory of Ukraine. 


1977 ◽  
Vol 36 ◽  
pp. 143-180 ◽  
Author(s):  
J.O. Stenflo

It is well-known that solar activity is basically caused by the Interaction of magnetic fields with convection and solar rotation, resulting in a great variety of dynamic phenomena, like flares, surges, sunspots, prominences, etc. Many conferences have been devoted to solar activity, including the role of magnetic fields. Similar attention has not been paid to the role of magnetic fields for the overall dynamics and energy balance of the solar atmosphere, related to the general problem of chromospheric and coronal heating. To penetrate this problem we have to focus our attention more on the physical conditions in the ‘quiet’ regions than on the conspicuous phenomena in active regions.


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