2,925 research outputs found
Vertices of Lie Modules
Let Lie(n) be the Lie module of the symmetric group S_n over a field F of
characteristic p>0, that is, Lie(n) is the left ideal of FS_n generated by the
Dynkin-Specht-Wever element. We study the problem of parametrizing
non-projective indecomposable summands of Lie(n), via describing their vertices
and sources. Our main result shows that this can be reduced to the case when n
is a power of p. When n=9 and p=3, and when n=8 and p=2, we present a precise
answer. This suggests a possible parametrization for arbitrary prime powers.Comment: 26 page
Perturbation theories for the S=1/2 spin ladder with four-spin ring exchange
The isotropic S=1/2 antiferromagnetic spin ladder with additional four-spin
ring exchange is studied perturbatively in the strong coupling regime with the
help of cluster expansion technique, and by means of bosonization in the weak
coupling limit. It is found that a sufficiently large strength of ring exchange
leads to a second-order phase transition, and the shape of the boundary in the
vicinity of the known exact transition point is obtained. The critical exponent
for the gap is found to be , in agreement both with exact results
available for the dimer line and with the bosonization analysis. The phase
emerging for high values of the ring exchange is argued to be gapped and
spontaneously dimerized. The results for the transition line from strong
coupling and from weak coupling match with each other naturally.Comment: 8 pages, 4 figures, some minor changes in text and reference
Magnetic Phase Diagram of Spin-1/2 Two-Leg Ladder with Four-Spin Ring Exchange
We study the spin-1/2 two-leg Heisenberg ladder with four-spin ring exchanges
under a magnetic field. We introduce an exact duality transformation which is
an extension of the spin-chirality duality developed previously and yields a
new self-dual surface in the parameter space. We then determine the magnetic
phase diagram using the numerical approaches of the density-matrix
renormalization-group and exact diagonalization methods. We demonstrate the
appearance of a magnetization plateau and the Tomonaga-Luttinger liquid with
dominant vector-chirality quasi-long-range order for a wide parameter regime of
strong ring exchange. A "nematic" phase, in which magnons form bound pairs and
the magnon-pairing correlation functions dominate, is also identified.Comment: 18pages, 7 figure
Preclinical investigations using [177Lu]Lu-Ibu-DAB-PSMA toward its clinical translation for radioligand therapy of prostate cancer
[Lu]Lu-Ibu-DAB-PSMA was previously characterized with moderate albumin-binding properties enabling high tumor accumulation but reasonably low retention in the blood. The aim of this study was to investigate [Lu]Lu-Ibu-DAB-PSMA in preclinical in vivo experiments and compare its therapeutic efficacy and potential undesired side effects with those of [Lu]Lu-PSMA-617 and the previously developed [Lu]Lu-PSMA-ALB-56. BALB/c nude mice without tumors were investigated on Day 10 and 28 after injection of 10Â MBq radioligand. It was revealed that most plasma parameters were in the same range for all groups of mice and histopathological examinations of healthy tissue did not show any alternations in treated mice as compared to untreated controls. Based on these results, a therapy study over twelve weeks was conducted with PC-3 PIP tumor-bearing mice for comparison of the radioligandsâs therapeutic efficacy up to an activity of 10Â MBq (1Â nmol) per mouse. In agreement with the increased mean absorbed tumor dose, [Lu]Lu-Ibu-DAB-PSMA (~â6.6Â Gy/MBq) was more effective to inhibit tumor growth than [Lu]Lu-PSMA-617 (~â4.5Â Gy/MBq) and only moderately less potent than [Lu]Lu-PSMA-ALB-56 (~â8.1Â Gy/MBq). As a result, the survival of mice treated with 2Â MBq of an albumin-binding radioligand was significantly increased (pâ<â0.05) compared to that of mice injected with [Lu]Lu-PSMA-617 or untreated controls. The majority of mice treated with 5Â MBq or 10Â MBq [Lu]Lu-Ibu-DAB-PSMA or [Lu]Lu-PSMA-ALB-56 were still alive at study end. Hemograms of immunocompetent mice injected with 30Â MBq [Lu]Lu-Ibu-DAB-PSMA or 30Â MBq [Lu]Lu-PSMA-617 showed values in the same range as untreated controls. This was, however, not the case for mice treated with [Lu]Lu-PSMA-ALB-56 which revealed a drop in lymphocytes and hemoglobin at Day 10 and Day 28 after injection. The data of this study demonstrated a significant therapeutic advantage of [Lu]Lu-Ibu-DAB-PSMA over [Lu]Lu-PSMA-617 and a more favorable safety profile as compared to that of [Lu]Lu-PSMA-ALB-56. Based on these results, [Lu]Lu-Ibu-DAB-PSMA may has the potential for a clinical translation
Extraânigral pathological conditions are common in Parkinson's disease with freezing of gait: An in vivo positron emission tomography study
Cholinergic denervation has been associated with falls and slower gait speed and ÎČâamyloid deposition with greater severity of axial motor impairments in Parkinson disease (PD). However, little is known about the association between the presence of extraânigral pathological conditions and freezing of gait (FoG). Patients with PD (nâ=â143; age, 65.5â±â7.4 years, Hoehn and Yahr stage, 2.4â±â0.6; Montreal Cognitive Assessment score, 25.9â±â2.6) underwent [ 11 C]methylâ4âpiperidinyl propionate acetylcholinesterase and [ 11 C]dihydrotetrabenazine dopaminergic PET imaging, and clinical, including FoG, assessment in the dopaminergic âoffâ state. A subset of subjects (nâ=â61) underwent [ 11 C]Pittsburgh compoundâB ÎČâamyloid positron emission tomography (PET) imaging. Normative data were used to dichotomize abnormal ÎČâamyloid uptake or cholinergic deficits. Freezing of gait was present in 20 patients (14.0%). Freezers had longer duration of disease ( P â=â0.009), more severe motor disease ( P â<â0.0001), and lower striatal dopaminergic activity ( P â=â0.013) compared with nonâfreezers. Freezing of gait was more common in patients with diminished neocortical cholinergic innervation (23.9%, Ï 2 â=â5.56, P â=â0.018), but not in the thalamic cholinergic denervation group (17.4%, Ï 2 â=â0.26, P â=â0.61). Subgroup analysis showed higher frequency of FoG with increased neocortical ÎČâamyloid deposition (30.4%, Fisher Exact test: P â=â0.032). Frequency of FoG was lowest with absence of both pathological conditions (4.8%), intermediate in subjects with single extraânigral pathological condition (14.3%), and highest with combined neocortical cholinopathy and amyloidopathy (41.7%; CochranâArmitage trend test, Z â=â2.63, P â=â0.015). Within the group of freezers, 90% had at least one of the two extraânigral pathological conditions studied. Extraânigral pathological conditions, in particular the combined presence of cortical cholinopathy and amyloidopathy, are common in PD with FoG and may contribute to its pathophysiology. © 2014 International Parkinson and Movement Disorder SocietyPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108363/1/mds25929.pd
Spin Excitations in La2CuO4: Consistent Description by Inclusion of Ring-Exchange
We consider the square lattice Heisenberg antiferromagnet with plaquette ring
exchange and a finite interlayer coupling leading to a consistent description
of the spin-wave excitation spectrum in La2CuO4. The values of the in-plane
exchange parameters, including ring-exchange J_{\Box}, are obtained
consistently by an accurate fit to the experimentally observed in-plane
spin-wave dispersion, while the out-of-plane exchange interaction is found from
the temperature dependence of the sublattice magnetization at low temperatures.
The fitted exchange interactions J=151.9 meV and J_{\Box}=0.24 J give values
for the spin stiffness and the Neel temperature in excellent agreement with the
experimental data.Comment: 4 pages, 1 figure, RevTe
Combination of terbium-161 with somatostatin receptor antagonistsâa potential paradigm shift for the treatment of neuroendocrine neoplasms
Purpose: The ÎČÂŻ-emitting terbium-161 also emits conversion and Auger electrons, which are believed to be effective in killing single cancer cells. Terbium-161 was applied with somatostatin receptor (SSTR) agonists that localize in the cytoplasm (DOTATOC) and cellular nucleus (DOTATOC-NLS) or with a SSTR antagonist that localizes at the cell membrane (DOTA-LM3). The aim was to identify the most favorable peptide/terbium-161 combination for the treatment of neuroendocrine neoplasms (NENs).
Methods: The capability of the 161Tb- and 177Lu-labeled somatostatin (SST) analogues to reduce viability and survival of SSTR-positive AR42J tumor cells was investigated in vitro. The radiopeptides' tissue distribution profiles were assessed in tumor-bearing mice. The efficacy of terbium-161 compared to lutetium-177 was investigated in therapy studies in mice using DOTATOC or DOTA-LM3, respectively.
Results: In vitro, [161Tb]Tb-DOTA-LM3 was 102-fold more potent than [177Lu]Lu-DOTA-LM3; however, 161Tb-labeled DOTATOC and DOTATOC-NLS were only 4- to fivefold more effective inhibiting tumor cell viability than their 177Lu-labeled counterparts. This result was confirmed in vivo and demonstrated that [161Tb]Tb-DOTA-LM3 was significantly more effective in delaying tumor growth than [177Lu]Lu-DOTA-LM3, thereby, prolonging survival of the mice. A therapeutic advantage of terbium-161 over lutetium-177 was also manifest when applied with DOTATOC. Since the nuclear localizing sequence (NLS) compromised the in vivo tissue distribution of DOTATOC-NLS, it was not used for therapy.
Conclusion: The use of membrane-localizing DOTA-LM3 was beneficial and profited from the short-ranged electrons emitted by terbium-161. Based on these preclinical data, [161Tb]Tb-DOTA-LM3 may outperform the clinically employed [177Lu]Lu-DOTATOC for the treatment of patients with NENs
The behaviour of political parties and MPs in the parliaments of the Weimar Republic
Copyright @ 2012 The Authors. This is the author's accepted manuscript. The final published article is available from the link below.Analysing the roll-call votes of the MPs of the Weimar Republic we find: (1) that party competition in the Weimar parliaments can be structured along two dimensions: an economic leftâright and a pro-/anti-democratic. Remarkably, this is stable throughout the entire lifespan of the Republic and not just in the later years and despite the varying content of votes across the lifespan of the Republic, and (2) that nearly all parties were troubled by intra-party divisions, though, in particular, the national socialists and communists became homogeneous in the final years of the Republic.Zukunftskolleg, University of Konstan
High-Order Coupled Cluster Method (CCM) Calculations for Quantum Magnets with Valence-Bond Ground States
In this article, we prove that exact representations of dimer and plaquette
valence-bond ket ground states for quantum Heisenberg antiferromagnets may be
formed via the usual coupled cluster method (CCM) from independent-spin product
(e.g. N\'eel) model states. We show that we are able to provide good results
for both the ground-state energy and the sublattice magnetization for dimer and
plaquette valence-bond phases within the CCM. As a first example, we
investigate the spin-half -- model for the linear chain, and we show
that we are able to reproduce exactly the dimerized ground (ket) state at
. The dimerized phase is stable over a range of values for
around 0.5. We present evidence of symmetry breaking by considering
the ket- and bra-state correlation coefficients as a function of . We
then consider the Shastry-Sutherland model and demonstrate that the CCM can
span the correct ground states in both the N\'eel and the dimerized phases.
Finally, we consider a spin-half system with nearest-neighbor bonds for an
underlying lattice corresponding to the magnetic material CaVO (CAVO).
We show that we are able to provide excellent results for the ground-state
energy in each of the plaquette-ordered, N\'eel-ordered, and dimerized regimes
of this model. The exact plaquette and dimer ground states are reproduced by
the CCM ket state in their relevant limits.Comment: 34 pages, 13 figures, 2 table
Antibody Response to SARS-CoV-2 Vaccination in Patients following Allogeneic Hematopoietic Cell Transplantation
Vaccines against SARS-CoV-2 have been rapidly approved. Although pivotal studies were conducted in healthy volunteers, little information is available on the safety and efficacy of mRNA vaccines in immunocompromised patients, including recipients of allogeneic hematopoietic cell transplantation (allo-HCT). Here we used a novel assay to analyze patient- and transplantation-related factors and their influence on immune responses to SARS-CoV-2 vaccination over an extended period (up to 6 months) in a large and homogenous group of allo-HCT recipients at a single center in Switzerland. We examined longitudinal antibody responses to SARS-CoV-2 vaccination with BNT162b2 (BioNTech/Pfizer) and mRNA-1273 (Moderna) in 110 allo-HCT recipients and 86 healthy controls. Seroprofiling recording IgG, IgA, and IgM reactivity against SARS-CoV-2 antigens (receptor-binding domain, spike glycoprotein subunits S1 and S2, and nucleocapsid protein) was performed before vaccination, before the second dose, and at 1, 3, and 6 months after the second dose. Patients were stratified to 3 groups: 3 to 6 months post-allo-HCT, 6 to 12 months post-allo-HCT, and >12 months post-allo-HCT. Patients in the 3 to 6 months and 6 to 12 months post-allo-HCT groups developed significantly lower antibody titers after vaccination compared with patients in the >12 months post-allo-HCT group and healthy controls (P 65 years (P = .030), those receiving immunosuppression for prevention or treatment of graft-versus-host disease (GVHD) (P = .033), and patients with relapsed disease (P = .014) displayed low humoral immune responses to the vaccine. In contrast, the intensity of the conditioning regimen, underlying disease (myeloid/lymphoid/other), and presence of chronic GVHD had no impact on antibody levels. Antibody titers achieved the highest levels at 1 month after the second dose of the vaccine but waned substantially in all transplantation groups and healthy controls over time. This analysis of long-term vaccine antibody response is of critical importance to allo-HCT recipients and transplant physicians to guide treatment decisions regarding revaccination and social behavior during the SARS-CoV-2 pandemic.
Keywords: Allogeneic hematopoietic cell transplantation; SARS-CoV-2; Vaccinatio
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