1,193 research outputs found
Scaling dimensions of higher-charge monopoles at deconfined critical points
The classical cubic dimer model has a columnar ordering transition that is continuous and described by a critical Anderson–Higgs theory containing an SU(2)-symmetric complex field minimally coupled to a noncompact U(1) gauge theory. Defects in the dimer constraints correspond to monopoles of the gauge theory, with charge determined by the deviation from unity of the dimer occupancy. By introducing such defects into Monte Carlo simulations of the dimer model at its critical point, we determine the scaling dimensions y2 = 1:48 _ 0:07 and y3 = 0:20 _ 0:03 for the operators corresponding to defects of charge q = 2 and 3 respectively. These results, which constitute the first direct determination of the scaling dimensions, shed light on the deconfined critical point of spin-12 quantum antiferromagnets, thought to belong to the same universality class. In particular, the positive value of y3 implies that the transition in the JQ model on the honeycomb lattice is of first order
The effect of irradiation-induced disorder on the conductivity and critical temperature of the organic superconductor -(BEDT-TTF)Cu(SCN)
We have introduced defects into clean samples of the organic superconductor
-(BEDT-TTF)Cu(SCN) in order to determine their effect on the
temperature dependence of the conductivity and the critical temperature . We find a violation of Matthiessen's rule that can be explained by a model
of the conductivity involving a defect-assisted interlayer channel which acts
in parallel with the band-like conductivity. We observe an unusual dependence
of on residual resistivity which is not consistent with the
generalised Abrikosov-Gor'kov theory for an order parameter with a single
component, providing an important constraint on models of the superconductivity
in this material
Towards Structure-Property-Function Relationships for Eumelanin
We discuss recent progress towards the establishment of important
structure-property-function relationships in eumelanins - key functional
bio-macromolecular systems responsible for photo-protection and immune response
in humans, and implicated in the development of melanoma skin cancer. We focus
on the link between eumelanin's secondary structure and optical properties such
as broad band UV-visible absorption and strong non-radiative relaxation; both
key features of the photo-protective function. We emphasise the insights gained
through a holistic approach combining optical spectroscopy with first
principles quantum chemical calculations, and advance the hypothesis that the
robust functionality characteristic of eumelanin is related to extreme chemical
and structural disorder at the secondary level. This inherent disorder is a low
cost natural resource, and it is interesting to speculate as to whether it may
play a role in other functional bio-macromolecular systems.Comment: 19 pages, 8 figures, Invited highlight article for Soft Matte
Order by Disorder in Spin-Orbit Coupled Bose-Einstein Condensates
Motivated by recent experiments, we investigate the system of
isotropically-interacting bosons with Rashba spin-orbit coupling. At the
non-interacting level, there is a macroscopic ground-state degeneracy due to
the many ways bosons can occupy the Rashba spectrum. Interactions treated at
the mean-field level restrict the possible ground-state configurations, but
there remains an accidental degeneracy not corresponding to any symmetry of the
Hamiltonian, indicating the importance of fluctuations. By finding analytical
expressions for the collective excitations in the long-wavelength limit and
through numerical solution of the full Bogoliubov- de Gennes equations, we show
that the system condenses into a single momentum state of the Rashba spectrum
via the mechanism of order by disorder. We show that in 3D the quantum
depletion for this system is small, while the thermal depletion has an infrared
logarithmic divergence, which is removed for finite-size systems. In 2D, on the
other hand, thermal fluctuations destabilize the system.Comment: 5 page
The pre treatment systemic inflammatory response is an important determinant of poor pathologic response for patients undergoing neoadjuvant therapy for rectal cancer
Background
Not all patients respond equally to neoadjuvant chemoradiotherapy (nCRT), with subsequent effects on survival. The systemic inflammatory response has been shown to predict long-term outcomes in colorectal cancer. The current study examined the association between systemic inflammation and nCRT in patients with rectal cancer.
Methods
Between 1999 and 2010, patients who underwent nCRT were identified. Serum measurements of hemoglobin, C-reactive protein, albumin, modified Glasgow prognostic score (mGPS), and differential white cell counts were obtained before and after nCRT. The Rödel scoring system measured pathologic tumor regression, and magnetic resonance imaging and computed tomography determined radiologic staging.
Results
The study included 79 patients. Of these patients, 37% were radiologically downstaged, and 44% were categorized as showing a good pathologic response (Rödel scores 3 and 4). As a validated measure of the systemic inflammatory response, mGPS (P = 0.022) was associated with a poor pathologic response to nCRT. A radiologic response was associated with a good pathologic response to treatment (P = 0.003). A binary logistic regression model identified mGPS (odds ratio [OR] 0.27; 95% confidence interval [CI] 0.07–0.96; P = 0.043) and radiologic response (OR 0.43; 95% CI 0.18–0.99; P = 0.048) as strong independent predictors of a pathologic response to treatment.
Conclusion
The current study showed that a systemic inflammatory response before nCRT is associated with a poor pathologic response. Further study in a prospective controlled trial setting is warranted.
Stephan B. Dreyer and Arfon G. M. T. Powell—contributed equally.
Colorectal cancer (CRC) is the third most common cancer and the second highest cause of cancer death in the United Kingdom.1 The 5-year survival rate for CRC still is less than 60% with surgery alone, offering the only chance of cure.
Rectal cancers comprise about one third of surgical resections for colorectal cancer.2 The widely adapted surgical technique of total mesorectal excision (TME), increased centralization, specialization of rectal surgery, and earlier disease detection have led to improved survival in the last 30 years.3,4 Preoperative neoadjuvant radiotherapy with or without chemotherapy currently is accepted as a standard of care for patients with margin-threatening rectal cancer. This increases disease-free survival (DFS) and sphincter preservation rates and improves circumferential resection margins and local recurrence rates.5–8
Current management of CRC in the United Kingdom involves evaluating patients using magnetic resonance imaging (MRI) and computed tomography (CT) before treatment to identify those with margin-threatening disease (T3 or T4).9 These patients are offered neoadjuvant chemoradiotherapy (nCRT) before surgical resection.10
Not all patients respond to nCRT, and there is a need to identify biomarkers of response because treatment is associated with significant morbidity. Rödel et al.11 have shown that the presence of spontaneous apoptosis in the resected specimen is a good marker of tumor regression and improved prognosis.
The prognostic value of the systemic inflammatory response (SIR) has been widely studied in gastrointestinal cancers, particularly in the operative setting, using measurements of circulating markers including C-reactive protein (CRP), albumin, the modified Glasgow prognostic score (mGPS), the neutrophil lympocyte ratio (NLR), the platelet-to-lymphocyte ratio (PLR), and more recently, the neutrophil-platelet score (NPS) and the derived neutrophil-to-lymphocyte ratio (dNLR).12–16
This study investigated the association between markers of the systemic inflammatory response and the pathologic response to nCRT in patients with rectal cancer
Genetic Background and Allorecognition Phenotype in Hydractinia symbiolongicarpus
The Hydractinia allorecognition complex (ARC) was initially identified as a single chromosomal interval using inbred and congenic lines. The production of defined lines necessarily homogenizes genetic background and thus may be expected to obscure the effects of unlinked allorecognition loci should they exist. Here, we report the results of crosses in which inbred lines were out-crossed to wild-type animals in an attempt to identify dominant, codominant, or incompletely dominant modifiers of allorecognition. A claim for the existence of modifiers unlinked to ARC was rejected for three different genetic backgrounds. Estimates of the genetic map distance of ARC in two wild-type haplotypes differed markedly from one another and from that measured in congenic lines. These results suggest that additional allodeterminants exist in the Hydractinia ARC
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