86 research outputs found
Heisenberg model in a random field: phase diagram and tricritical behavior
By using the differential operator technique and the effective field theory
scheme we study the tricritical behavior of Heisenberg classical model of
spin-1/2 in a random field. The phase diagram in the T-h plane on a square and
simple cubic lattice for a cluster with two spins is obtained when the random
field is bimodal distributed.Comment: 10 pages, 1 figur
Study of the first-order phase transition in the classical and quantum random field Heisenberg model on a simple cubic lattice
The phase diagram of the Heisenberg ferromagnetic model in the presence of a
magnetic random field (we have used bimodal distribution) of spin S=1/2
(quantum case) and (classical case) on a simple cubic lattice is
studied within the framework of the effective-field theory in finite cluster
(we have chosen N=2 spins). Integrating out the part of order parameter
(equation of state), we obtained an effective Landau expansion for the free
energy written in terms of the order parameter . Using Maxwell
construction we have obtained the phase diagram in the plane for all
interval of field. The first-order transition temperature is calculated by the
discontinuity of the magnetization at , on the other hand in
the continuous transition the magnetization is null at . At null
temperature (T=0) we have found the \textbf{coexistence} field
that is independent of spin value. The transition temperature for
the classical case (), in the plane, is larger than the
quantum case (S=1/2).Comment: 10 pages, 1 figur
Magnetic Properties of the Metamagnet Ising Model in a three-dimensional Lattice in a Random and Uniform Field
By employing the Monte Carlo technique we study the behavior of Metamagnet
Ising Model in a random field. The phase diagram is obtained by using the
algorithm of Glaubr in a cubic lattice of linear size with values ranging
from 16 to 42 and with periodic boundary conditions.Comment: 4 pages, 6 figure
Acute Conjunctivitis with Episcleritis and Anterior Uveitis Linked to Adiaspiromycosis and Freshwater Sponges, Amazon Region, Brazil, 2005
Medscape, LLC is pleased to provide online continuing medical education (CME) for this journal article, allowing clinicians the opportunity to earn CME credit. This activity has been planned and implemented in accordance with the Essential Areas and policies of the Accreditation Council for Continuing Medical Education through the joint sponsorship of Medscape, LLC and Emerging Infectious Diseases. Medscape, LLC is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide CME for physicians. Medscape, LLC designates this educational activity for a maximum of 0.5 AMA PRA Category 1 Creditsâą. Physicians should only claim credit commensurate with the extent of their participation in the activity. All other clinicians completing this activity will be issued a certificate of participation. To participate in this journal CME activity: (1) review the learning objectives and author disclosures; (2) study the education content; (3) take the post-test and/or complete the evaluation at http://www.medscape.com/cme/eidExternal Web Site Icon; (4) view/print certificate.\ud
Learning Objectives\ud
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Upon completion of this activity, participants will be able to:\ud
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Describe the mechanism of infection for adiaspiromycosis.\ud
Identify the age group most susceptible to ocular adiaspiromycosis.\ud
Describe presenting symptoms associated with ocular adiaspiromycosis.\ud
Describe the frequency of ocular lesions associated with adiaspiromycosis.\ud
Identify risk factors for ocular adiaspiromycosis
Pervasive gaps in Amazonian ecological research
Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4
While the increasing availability of global databases on ecological communities has advanced our knowledge
of biodiversity sensitivity to environmental changes,5â7 vast areas of the tropics remain understudied.8â11 In
the American tropics, Amazonia stands out as the worldâs most diverse rainforest and the primary source of
Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13â15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazonâs biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus
crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced
environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian
Amazonia, while identifying the regionâs vulnerability to environmental change. 15%â18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by
2050. This means that unless we take immediate action, we will not be able to establish their current status,
much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio
A 119-125 GeV Higgs from a string derived slice of the CMSSM
The recent experimental hints for a relatively heavy Higgs with a mass in the range 119-125 GeV favour supersymmetric scenarios with a large mixing in the stop mass matrix. It has been shown that this is possible in the constrained Minimal Super-symmetric Standard Model (CMSSM), but only for a very specific relation between the trilinear parameter and the soft scalar mass, favouring Aââââ2m for a relatively light spectrum, and sizable values of tan ÎČ. We describe here a string-derived scheme in which the first condition is automatic and the second arises as a consequence of imposing radiative EW symmetry breaking and viable neutralino dark matter in agreement with WMAP constraints. More specifically, we consider modulus dominated SUSY-breaking in Type II string compactifications and show that it leads to a very predictive CMSSM-like scheme, with small departures due to background fluxes. Imposing the above constraints leaves only one free parameter, which corresponds to an overall scale. We show that in this construction A=â3/2ââmââ2mA=â3/2mââ2m and in the allowed parameter space tan ÎČâââ38âââ41, leading to 119 GeVâ<âmhâ <â125 GeV. The recent LHCb results on BR(BsâââÎŒ+ÎŒâ) further constrain this range, leaving only the region with mhâ~â125. GeV. We determine the detectability of this model and show that it could start being probed by the LHC at 7(8) TeV with a luminosity of 5(2) fbâ1, and the whole parameter space would be accessible for 14 TeV and 25 fbâ1. Furthermore, this scenario can host a long-lived stau with the right properties to lead to catalyzed BBN. We finally argue that anthropic arguments could favour the highest value for the Higgs mass that is compatible with neutralino dark matter, i.e., mh-125 GeV
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