735 research outputs found
Women physicians and stress
Most women physicians enjoy better than average physical health and lead satisfying and productive lives. However, higher than average rates of depression, anxiety, marital problems, and substance abuse have been reported by some, but not all, authors. This quantitative survey of 196 women physicians and qualitative focus groups with 48 other women physicians was conducted to determine perceptions of their health, stress, satisfaction, knowledge, and abuse rates in medical practice. Eight specialties plus family practice physicians participated. The average age was 44.1 years (SD 8.8, range 23–77). Seventy-four percent of women physicians were married, with children. Specialists and family physicians were similar in all demographic characteristics except that family physicians were more significantly likely to be divorced, separated, or widowed (p ≤ 0.01). Specialists perceived their personal physical health to be better than that of family doctors (p ≤ 0.05), and family physicians rated their medical knowledge better than that of specialists (p ≤ 0.0001). Women physicians over age 50 or with children over age 19 reported the best mental health (p ≤ 0.0001 and 0.003, respectively). Overall, 49% of women physicians reported usually having high levels of stress, 44% felt mentally tired, and 17% took antidepressant drugs. Seventy-three percent reported verbal abuse at work (71% in the last year), and 33% reported physical assault at work (11% in the last year). Focus groups identified three major sources of stress: high expectations, multiple roles, and work environment. These results are discussed and compared with the literature. Both personal and systemic strategies are required to solve the problems identified. Women physicians can facilitate the adoption of some of these strategies by sharing information about successes, challenges, and solutions
Instanton operators in five-dimensional gauge theories
This article is distributed under the terms of the Creative Commons
Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in
any medium, provided the original author(s) and source are creditedN.L. is supported in part by STFC grant ST/J002798/1. C.P. is a Royal Society Research Fellow.N.L. is supported in part by STFC grant ST/J002798/1. C.P. is a Royal Society Research Fellow.N.L. is supported in part by STFC grant ST/J002798/1. OPen Aceess funded by SCOAP
Spin-lattice instability to a fractional magnetization state in the spinel HgCr2O4
Magnetic systems are fertile ground for the emergence of exotic states when
the magnetic interactions cannot be satisfied simultaneously due to the
topology of the lattice - a situation known as geometrical frustration.
Spinels, AB2O4, can realize the most highly frustrated network of
corner-sharing tetrahedra. Several novel states have been discovered in
spinels, such as composite spin clusters and novel charge-ordered states. Here
we use neutron and synchrotron X-ray scattering to characterize the fractional
magnetization state of HgCr2O4 under an external magnetic field, H. When the
field is applied in its Neel ground state, a phase transition occurs at H ~ 10
Tesla at which each tetrahedron changes from a canted Neel state to a
fractional spin state with the total spin, Stet, of S/2 and the lattice
undergoes orthorhombic to cubic symmetry change. Our results provide the
microscopic one-to-one correspondence between the spin state and the lattice
distortion
Matrix Models for Supersymmetric Chern-Simons Theories with an ADE Classification
We consider N=3 supersymmetric Chern-Simons (CS) theories that contain
product U(N) gauge groups and bifundamental matter fields. Using the matrix
model of Kapustin, Willett and Yaakov, we examine the Euclidean partition
function of these theories on an S^3 in the large N limit. We show that the
only such CS theories for which the long range forces between the eigenvalues
cancel have quivers which are in one-to-one correspondence with the simply
laced affine Dynkin diagrams. As the A_n series was studied in detail before,
in this paper we compute the partition function for the D_4 quiver. The D_4
example gives further evidence for a conjecture that the saddle point
eigenvalue distribution is determined by the distribution of gauge invariant
chiral operators. We also see that the partition function is invariant under a
generalized Seiberg duality for CS theories.Comment: 20 pages, 3 figures; v2 refs added; v3 conventions in figure 3
altered, version to appear in JHE
Experimental modulation of capsule size in Cryptococcus neoformans
Experimental modulation of capsule size is an important technique for the study of the virulence of the encapsulated pathogen Cryptococcus neoformans. In this paper, we summarize the techniques available for experimental modulation of capsule size in this yeast and describe improved methods to induce capsule size changes. The response of the yeast to the various stimuli is highly dependent on the cryptococcal strain. A high CO(2) atmosphere and a low iron concentration have been used classically to increase capsule size. Unfortunately, these stimuli are not reliable for inducing capsular enlargement in all strains. Recently we have identified new and simpler conditions for inducing capsule enlargement that consistently elicited this effect. Specifically, we noted that mammalian serum or diluted Sabouraud broth in MOPS buffer pH 7.3 efficiently induced capsule growth. Media that slowed the growth rate of the yeast correlated with an increase in capsule size. Finally, we summarize the most commonly used media that induce capsule growth in C. neoformans
From Necklace Quivers to the F-theorem, Operator Counting, and T(U(N))
The matrix model of Kapustin, Willett, and Yaakov is a powerful tool for
exploring the properties of strongly interacting superconformal Chern-Simons
theories in 2+1 dimensions. In this paper, we use this matrix model to study
necklace quiver gauge theories with {\cal N}=3 supersymmetry and U(N)^d gauge
groups in the limit of large N. In its simplest application, the matrix model
computes the free energy of the gauge theory on S^3. The conjectured F-theorem
states that this quantity should decrease under renormalization group flow. We
show that for a simple class of such flows, the F-theorem holds for our
necklace theories. We also provide a relationship between matrix model
eigenvalue distributions and numbers of chiral operators that we conjecture
holds more generally. Through the AdS/CFT correspondence, there is therefore a
natural dual geometric interpretation of the matrix model saddle point in terms
of volumes of 7-d tri-Sasaki Einstein spaces and some of their 5-d
submanifolds. As a final bonus, our analysis gives us the partition function of
the T(U(N)) theory on S^3.Comment: 3 figures, 41 pages; v2 minor improvements, refs adde
The ABCDEF's of Matrix Models for Supersymmetric Chern-Simons Theories
We consider N = 3 supersymmetric Chern-Simons gauge theories with product
unitary and orthosymplectic groups and bifundamental and fundamental fields. We
study the partition functions on an S^3 by using the Kapustin-Willett-Yaakov
matrix model. The saddlepoint equations in a large N limit lead to a constraint
that the long range forces between the eigenvalues must cancel; the resulting
quiver theories are of affine Dynkin type. We introduce a folding/unfolding
trick which lets us, at the level of the large N matrix model, (i) map quivers
with orthosymplectic groups to those with unitary groups, and (ii) obtain
non-simply laced quivers from the corresponding simply laced quivers using a
Z_2 outer automorphism. The brane configurations of the quivers are described
in string theory and the folding/unfolding is interpreted as the
addition/subtraction of orientifold and orbifold planes. We also relate the
U(N) quiver theories to the affine ADE quiver matrix models with a
Stieltjes-Wigert type potential, and derive the generalized Seiberg duality in
2 + 1 dimensions from Seiberg duality in 3 + 1 dimensions.Comment: 30 pages, 5 figure
Phases of planar 5-dimensional supersymmetric Chern-Simons theory
In this paper we investigate the large- behavior of 5-dimensional
super Yang-Mills with a level Chern-Simons term and an
adjoint hypermultiplet. As in three-dimensional Chern-Simons theories, one must
choose an integration contour to completely define the theory. Using
localization, we reduce the path integral to a matrix model with a cubic action
and compute its free energy in various scenarios. In the limit of infinite
Yang-Mills coupling and for particular choices of the contours, we find that
the free-energy scales as for gauge groups with large values
of the Chern-Simons 't\,Hooft coupling, . If we also
set the hypermultiplet mass to zero, then this limit is a superconformal fixed
point and the behavior parallels other fixed points which have known
supergravity duals. We also demonstrate that gauge groups cannot have
this scaling for their free-energy. At finite Yang-Mills coupling we
establish the existence of a third order phase transition where the theory
crosses over from the Yang-Mills phase to the Chern-Simons phase. The phase
transition exists for any value of , although the details differ
between small and large values of . For pure Chern-Simons
theories we present evidence for a chain of phase transitions as
is increased.
We also find the expectation values for supersymmetric circular Wilson loops
in these various scenarios and show that the Chern-Simons term leads to
different physical properties for fundamental and anti-fundamental Wilson
loops. Different choices of the integration contours also lead to different
properties for the loops.Comment: 40 pages, 17 figures, Minor corrections, Published versio
Blunt trauma as a suspected cause of delayed constrictive pericarditis: a case report
<p>Abstract</p> <p>Introduction</p> <p>Constrictive pericarditis is a heterogeneous disease with many causes. Traumatic hemopericardium is an uncommon initiating cause. We report the case of a man developing constrictive pericarditis after blunt chest trauma, in order to highlight an approach to diagnosing the condition and to raise awareness of the possibility of this condition developing after blunt trauma.</p> <p>Case presentation</p> <p>A 72-year-old Caucasian man presented initially to our outpatient clinic with a one-year history of progressively worsening dyspnea, and recent onset of edema of the legs. He was later taken to the emergency department and admitted to hospital. He had previously received unsuccessful treatment from his local primary physicians for suspected respiratory disorder and cellulitis of his legs. Echocardiography showed evidence of pericardial constriction, and computed tomography revealed nodular, lobulated thickening of the pericardium and pleura bilaterally. Interventional biopsies were taken, but gave inconclusive results. Thus, as pericarditis and/or advanced malignancy were suspected, diagnostic video-assisted thoracoscopic surgery was performed to take biopsies from the abnormal lung and pericardial tissue. Examination of these supported the diagnosis of pericarditis, as acute and chronic inflammation and fibrous thickening were found, with no evidence of malignancy. Our patient underwent cardiac catheterization, which revealed three-vessel coronary artery disease. Emergency total pericardiectomy and coronary bypass were performed. Having excluded other common initiating factors, we considered that a blunt trauma that our patient had previously sustained to his chest was the potential cause of the constrictive pericarditis.</p> <p>Conclusion</p> <p>This was an interesting case of blunt chest trauma followed by progressive pericardial and pleural thickening. Subsequent development of chronic constrictive pericarditis occurred, requiring treatment by surgical pericardiectomy, as the clinical course of constrictive pericarditis is usually progressive without surgical intervention. Diagnosis of constrictive pericarditis remains challenging. Although uncommon, blunt trauma should be considered as a possible initiating cause. Delayed presentation of constrictive pericarditis should also be considered as a possible morbidity in a patient who has sustained blunt chest trauma. Our case also highlights the importance of performing echocardiography promptly in patients experiencing ongoing symptoms of congestive heart failure to allow earlier diagnosis of constrictive pericarditis or other cardiac disorders, and avoid unnecessary treatments.</p
Massive type IIA string theory cannot be strongly coupled
Understanding the strong coupling limit of massive type IIA string theory is
a longstanding problem. We argue that perhaps this problem does not exist;
namely, there may be no strongly coupled solutions of the massive theory. We
show explicitly that massive type IIA string theory can never be strongly
coupled in a weakly curved region of space-time. We illustrate our general
claim with two classes of massive solutions in AdS4xCP3: one, previously known,
with N = 1 supersymmetry, and a new one with N = 2 supersymmetry. Both
solutions are dual to d = 3 Chern-Simons-matter theories. In both these massive
examples, as the rank N of the gauge group is increased, the dilaton initially
increases in the same way as in the corresponding massless case; before it can
reach the M-theory regime, however, it enters a second regime, in which the
dilaton decreases even as N increases. In the N = 2 case, we find
supersymmetry-preserving gauge-invariant monopole operators whose mass is
independent of N. This predicts the existence of branes which stay light even
when the dilaton decreases. We show that, on the gravity side, these states
originate from D2-D0 bound states wrapping the vanishing two-cycle of a
conifold singularity that develops at large N.Comment: 43 pages, 5 figures. v2: added reference
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