4,872 research outputs found
Evidence for existence of many pure ground states in 3d Spin Glasses
Ground states of 3d EA Ising spin glasses are calculated for sizes up to
using a combination of genetic algorithms and cluster-exact
approximation . The distribution of overlaps is calculated. For
increasing size the width of converges to a nonzero value, indicating
that many pure ground states exist for short range Ising spin glasses.Comment: 4 pages, 3 figures, 2 tables, 16 reference
Preoperative systemic inflammation predicts postoperative infectious complications in patients undergoing curative resection for colorectal cancer
The presence of systemic inflammation before surgery, as evidenced by the glasgow prognostic score (mGPS), predicts poor long-term survival in colorectal cancer. The aim was to examine the relationship between the preoperative mGPS and the development of postoperative complications in patients undergoing potentially curative resection for colorectal cancer. Patients (n=455) who underwent potentially curative resections between 2003 and 2007 were assessed consecutively, and details were recorded in a database. The majority of patients presented for elective surgery (85%) were over the age of 65 years (70%), were male (58%), were deprived (53%), and had TNM stage I/II disease (61%), had preoperative haemoglobin (56%), white cell count (87%) and mGPS 0 (58%) in the normal range. After surgery, 86 (19%) patients developed a postoperative complication; 70 (81%) of which were infectious complications. On multivariate analysis, peritoneal soiling (P<0.01), elevated preoperative white cell count (P<0.05) and mGPS (P<0.01) were independently associated with increased risk of developing a postoperative infection. In elective patients, only the mGPS (OR=1.75, 95% CI=1.17-2.63, P=0.007) was significantly associated with increased risk of developing a postoperative infection. Preoperative elevated mGPS predicts increased postoperative infectious complications in patients undergoing potentially curative resection for colorectal cancer
Insider trading and future stock returns in firms with concentrated ownership levels
Peer reviewedPostprin
Finite-Size Scaling of the Domain Wall Entropy Distributions for the 2D Ising Spin Glass
The statistics of domain walls for ground states of the 2D Ising spin glass
with +1 and -1 bonds are studied for square lattices with , and = 0.5, where is the fraction of negative bonds, using periodic
and/or antiperiodic boundary conditions. When is even, almost all domain
walls have energy = 0 or 4. When is odd, most domain walls have
= 2. The probability distribution of the entropy, , is found
to depend strongly on . When , the probability distribution
of is approximately exponential. The variance of this distribution
is proportional to , in agreement with the results of Saul and Kardar. For
the distribution of is not symmetric about zero. In
these cases the variance still appears to be linear in , but the average of
grows faster than . This suggests a one-parameter scaling
form for the -dependence of the distributions of for .Comment: 13 page
Demonstrating an absolute quantum advantage in direct absorption measurement
Engineering apparatus that harness quantum theory promises to offer practical advantages over current technology. A fundamentally more powerful prospect is that such quantum technologies could out-perform any future iteration of their classical counterparts, no matter how well the attributes of those classical strategies can be improved. Here, for optical direct absorption measurement, we experimentally demonstrate such an instance of an absolute advantage per photon probe that is exposed to the absorbative sample. We use correlated intensity measurements of spontaneous parametric downconversion using a commercially available air-cooled CCD, a new estimator for data analysis and a high heralding efficiency photon-pair source. We show this enables improvement in the precision of measurement, per photon probe, beyond what is achievable with an ideal coherent state (a perfect laser) detected with 100% efficient and noiseless detection. We see this absolute improvement for up to 50% absorption, with a maximum observed factor of improvement of 1.46. This equates to around 32% reduction in the total number of photons traversing an optical sample, compared to any future direct optical absorption measurement using classical light
Nature of the Spin Glass State
The nature of the spin glass state is investigated by studying changes to the
ground state when a weak perturbation is applied to the bulk of the system. We
consider short range models in three and four dimensions and the infinite range
Sherrington-Kirkpatrick (SK) and Viana-Bray models. Our results for the SK and
Viana-Bray models agree with the replica symmetry breaking picture. The data
for the short range models fit naturally a picture in which there are large
scale excitations which cost a finite energy but whose surface has a fractal
dimension, , less than the space dimension . We also discuss a possible
crossover to other behavior at larger length scales than the sizes studied.Comment: 4 pages, 4 postscript figures included. Final version, only minor
changes mad
Relationship between tumour PTEN/Akt/COX-2 expression, inflammatory response and survival in patients with colorectal cancer
In patients with colorectal cancer (CRC), local and systemic inflammatory responses have been extensively reported to associate with cancer survival. However, the specific signalling pathways responsible for inflammatory responses are not clear. The PTEN/Akt pathway is a plausible candidate as it may play a role in mediating inflammation via COX-2, and has been associated with cancer progression. This study therefore examined the relationship between tumour PTEN/Akt/COX-2 expression, inflammatory responses and survival in CRC patients using a tissue microarray.
In 201 CRC patients, activation of tumour-specific PTEN/Akt significantly associated with poorer CSS (12.0yrs v 7.3yrs, P=0.032), poorer differentiation (P=0.032), venous invasion (P=0.008) and peritoneal involvement (P=0.004). Patients were stratified for peri-nuclear expression of COX-2 to examine associations with inflammatory responses. In patients with absent peri-nuclear COX-2 expression, activation of tumour-specific PTEN/Akt significantly associated with poorer CSS (11.9yrs v 5.4yrs, P=0.001), poorer differentiation (P=0.018), venous invasion (P=0.003) and peritoneal involvement (P=0.001). However, no associations were seen with either the local or systemic inflammatory responses.
In CRC patients, tumour-specific PTEN/Akt pathway activation was significantly associated with poorer CSS, particularly when peri-nuclear COX-2 expression was absent. However, activation of the PTEN/Akt pathway appears not to be responsible for the regulation of inflammatory responses
Strong Enhancement of Superconducting Correlation in a Two-Component Fermion Gas
We study high-density electron-hole (e-h) systems with the electron density
slightly larger than the hole density. We find a new superconducting phase, in
which the excess electrons form Cooper pairs moving in an e-h BCS phase. The
coexistence of the e-h and e-e orders is possible because e and h have opposite
charges, whereas analogous phases are impossible in the case of two fermion
species that have the same charge or are neutral. Most strikingly, the e-h
order enhances the superconducting e-h order parameter by more than one order
of magnitude as compared with that given by the BCS formula, for the same value
of the effective e-e attractive potential \lambda^{ee}. This new phase should
be observable in an e-h system created by photoexcitation in doped
semiconductors at low temperatures.Comment: 5 pages including 5 PostScript figure
Random Fixed Point of Three-Dimensional Random-Bond Ising Models
The fixed-point structure of three-dimensional bond-disordered Ising models
is investigated using the numerical domain-wall renormalization-group method.
It is found that, in the +/-J Ising model, there exists a non-trivial fixed
point along the phase boundary between the paramagnetic and ferromagnetic
phases. The fixed-point Hamiltonian of the +/-J model numerically coincides
with that of the unfrustrated random Ising models, strongly suggesting that
both belong to the same universality class. Another fixed point corresponding
to the multicritical point is also found in the +/-J model. Critical properties
associated with the fixed point are qualitatively consistent with theoretical
predictions.Comment: 4 pages, 5 figures, to be published in Journal of the Physical
Society of Japa
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