8,193 research outputs found
The Complexity of Vector Spin Glasses
We study the annealed complexity of the m-vector spin glasses in the
Sherrington-Kirkpatrick limit. The eigenvalue spectrum of the Hessian matrix of
the Thouless-Anderson-Palmer (TAP) free energy is found to consist of a
continuous band of positive eigenvalues in addition to an isolated eigenvalue
and (m-1) null eigenvalues due to rotational invariance. Rather surprisingly,
the band does not extend to zero at any finite temperature. The isolated
eigenvalue becomes zero in the thermodynamic limit, as in the Ising case (m=1),
indicating that the same supersymmetry breaking recently found in Ising spin
glasses occurs in vector spin glasses.Comment: 4 pages, 2 figure
Origin of the Growing Length Scale in M-p-Spin Glass Models
Two versions of the M-p-spin glass model have been studied with the
Migdal-Kadanoff renormalization group approximation. The model with p=3 and M=3
has at mean-field level the ideal glass transition at the Kauzmann temperature
and at lower temperatures still the Gardner transition to a state like that of
an Ising spin glass in a field. The model with p=3 and M=2 has only the Gardner
transition. In the dimensions studied, d=2,3 and 4, both models behave almost
identically, indicating that the growing correlation length as the temperature
is reduced in these models -- the analogue of the point-to-set length scale --
is not due to the mechanism postulated in the random first order transition
theory of glasses, but is more like that expected on the analogy of glasses to
the Ising spin glass in a field.Comment: 5 pages, 3 figures, revised versio
First-Order Transition and Critical End-Point in Vortex Liquids in Layered Superconductors
We calculate various thermodynamic quantities of vortex liquids in a layered
superconductor by using the nonperturbative parquet approximation method, which
was previously used to study the effect of thermal fluctuations in
two-dimensional vortex systems. We find there is a first-order transition
between two vortex liquid phases which differ in the magnitude of their
correlation lengths. As the coupling between the layers increases,the
first-order transition line ends at a critical point. We discuss the possible
relation between this critical end-point and the disappearance of the
first-order transition which is observed in experiments on high temperature
superconductors at low magnetic fields.Comment: 9 pages, 5 figure
Robert Milton Zollinger, M.D., teacher, surgeon, soldier, and farmer.
From Humble roots, Dr. Robert Milton Zollinger worked his way to a position in history among the giants of American surgery. He was born on September 4, 1903, in the central Ohio town of Millersport, the son of Elmira and William Zollinger. Neither of his parents had a high school education, but they supported education and always expressed a confidence that young Robert would be successful at anything he attempted.1 He had aspirations of attending West Point, a dream that was never fulfilled when he decided to be a surgeon. On being informed of his son’s intentions, Zollinger’s father bestowed on him advice that he ostensibly adhered to throughout his career: ‘‘If you are going to be a doctor, be a good one.’
Baron Guillaume Dupuytren: when brilliance combats professionalism.
Baron Guilluame Dupuytren was a French anatomist and surgeon who practiced during the 1800s and is considered by some to be the most brilliant and gifted surgeons of his time. His contributions to the field of surgery are quite extensive, yet his eccentric personality and attitude toward his colleagues, students, and patients raises a very interesting question: could Dr. Dupuytren (Fig. 1) and his many contributions to the field of surgery have thrived in today’s era of professionalism? The concept of professionalism is emphasized to medical students starting from day one of their medical training. How would Dr. Dupuytren, an esteemed anatomist, react to the idea that students are introduced to the idea of professionalism before entering the cadaver laboratory
Modified Appleby Procedure with Arterial Reconstruction for Locally Advanced Pancreatic Adenocarcinoma: A Literature Review and Report of Three Unusual Cases.
BACKGROUND: Pancreatic body and tail ductal adenocarcinomas are often diagnosed with local vascular invasion of the celiac axis (CA) and its various branches. With such involvement, these tumors have traditionally been considered unresectable. The modified Appleby procedure allows for margin negative resection of some such locally advanced tumors. This procedure involves distal pancreatectomy with en bloc splenectomy and CA resection and relies on the presence of collateral arterial circulation via an intact pancreaticoduodenal arcade and the gastroduodenal artery to maintain prograde hepatic arterial perfusion. When the resultant collateral circulation is inadequate to provide sufficient hepatic and gastric arterial inflow, arterial reconstruction (AR) is necessary to supercharge the inflow. Herein, we review all reported cases of AR with modified Appleby procedures that we have identified in the literature, and we report our experience of three recent cases with arterial reconstruction including two cases with arterial bypasses not requiring interposition grafting.
METHODS: Perioperative and oncologic outcomes from our Institutional Review Board-approved database of pancreatic resections at the Thomas Jefferson University were reviewed. Additionally, PubMed search for cases of distal or total pancreatectomy with celiac axis resection and concurrent AR was performed.
RESULTS: From the literature, 12 reports involving 28 patients were identified of distal and total pancreatectomy with AR after CA resection. The most common AR in the literature, performed in 12 patients, was a bypass from the aorta to the common hepatic artery (CHA) using a variety of interposition conduits. In our institutional experience, patient #1 had a primary side-to-end aorto-CHA bypass, patient #2 had a primary end-to-end bypass of the transected distal CHA to the left gastric artery in the setting a replaced left hepatic artery, and patient #3 required an aortic to proper hepatic artery bypass with saphenous vein graft and portal venous reconstruction. All patients recovered from their operations without ischemic complications, and they are currently 16, 15, and 13 months post-op, respectively.
CONCLUSIONS: The criteria for resectability in patients with locally advanced pancreatic body and tail neoplasms are expanding due to increasing experience with AR in the setting of the modified Appleby procedure. When performing AR, primary arterial re-anastomosis may be considered preferable to interposition grafting as it decreases the potential for the infectious and thrombotic complications associated with conduits and it reduces the number of vascular anastomoses from two to one. Consideration must also be given to normal variant anatomy of the hepatic circulation during operative planning as the origin of the left gastric artery is resected with the CA. The modified Appleby procedure with AR, when used in appropriately selected patients, offers the potential for safe, margin negative resection of locally advanced pancreatic body and tail tumors
Replica Symmetry Broken States of some Glass Models
We have studied in detail the - balanced spin glass model, especially
the case . These types of model have relevance to structural glasses. The
models possess two kinds of broken replica states; those with one-step replica
symmetry breaking (1RSB) and those with full replica symmetry breaking (FRSB).
To determine which arises requires studying the Landau expansion to quintic
order. There are 9 quintic order coefficients, and 5 quartic order
coefficients, whose values we determine for this model. We show that it is only
for that the transition at mean-field level is to a
state with FRSB, while for larger values there is either a continuous
transition to a state with 1RSB (when ) or a discontinuous
transition for . The Gardner transition from a 1RSB state at low
temperatures to a state with FRSB also requires the Landau expansion to be
taken to quintic order. Our result for the form of FRSB in the Gardner phase is
similar to that found when , but differs from that
given in the early paper of Gross et al. [Phys. Rev. Lett. 55, 304 (1985)].
Finally we discuss the effects of fluctuations on our mean-field solutions
using the scheme of H\"{o}ller and Read [Phys. Rev. E 101, 042114 (2020)}] and
argue that such fluctuations will remove both the continuous 1RSB transition
and discontinuous 1RSB transitions when leaving just the FRSB
continuous transition. We suggest values for and which might be used in
simulations to confirm whether fluctuation corrections do indeed remove the
1RSB transitions.Comment: Two new figures; 21 pages, 10 figure
Simple Ginzburg-Landau Theory for Vortices in a Crystal Lattice
We study the Ginzburg-Landau model with a nonlocal quartic term as a simple
phenomenological model for superconductors in the presence of coupling between
the vortex lattice and the underlying crystal lattice. In mean-field theory,
our model is consistent with a general oblique vortex lattice ranging from a
triangular lattice to a square lattice. This simple formulation enables us to
study the effect of thermal fluctuations in the vortex liquid regime. We
calculate the structure factor of the vortex liquid nonperturbatively and find
Bragg-like peaks with four-fold symmetry appearing in the structure factor even
though there is only a short-range crystalline order.Comment: Revised version with new title and additional results for the vortex
liquid regime, to be published in Phys. Rev. Lett. 5 pages RevTeX, 1 figure
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