1,312 research outputs found
A Possible Aoki Phase for Staggered Fermions
The phase diagram for staggered fermions is discussed in the context of the
staggered chiral Lagrangian, extending previous work on the subject. When the
discretization errors are significant, there may be an Aoki-like phase for
staggered fermions, where the remnant SO(4) taste symmetry is broken down to
SO(3). We solve explicitly for the mass spectrum in the 3-flavor degenerate
mass case and discuss qualitatively the 2+1-flavor case. From numerical results
we find that current simulations are outside the staggered Aoki phase. As for
near-future simulations with more improved versions of the staggered action, it
seems unlikely that these will be in the Aoki phase for any realistic value of
the quark mass, although the evidence is not conclusive.Comment: 27 pages, 8 figures, uses RevTe
Densovirus induces winged morphs in asexual clones of the rosy apple aphid, Dysaphis plantaginea
Winged morphs of aphids are essential for their dispersal and survival. We discovered that the production of the winged morph in asexual clones of the rosy apple aphid, Dysaphis plantaginea, is dependent on their infection with a DNA virus, Dysaphis plantaginea densovirus (DplDNV). Virus-free clones of the rosy apple aphid, or clones infected singly with an RNA virus, rosy apple aphid virus (RAAV), did not produce the winged morph in response to crowding and poor plant quality. DplDNV infection results in a significant reduction in aphid reproduction rate, but such aphids can produce the winged morph, even at low insect density, which can fly and colonize neighboring plants. Aphids infected with DplDNV produce a proportion of virus-free aphids, which enables production of virus-free clonal lines after colonization of a new plant. Our data suggest that a mutualistic relationship exists between the rosy apple aphid and its viruses. Despite the negative impact of DplDNV on rosy apple aphid reproduction, this virus contributes to their survival by inducing wing development and promoting dispersal
Numerical simulation of heavy fermions in an SU(2)_L x SU(2)_R symmetric Yukawa model
An exploratory numerical study of the influence of heavy fermion doublets on
the mass of the Higgs boson is performed in the decoupling limit of a chiral
symmetric Yukawa model with mirror fermions. The
behaviour of fermion and boson masses is investigated at infinite bare quartic
coupling on , and lattices. A first
estimate of the upper bound on the renormalized quartic coupling as a function
of the renormalized Yukawa-coupling is given.Comment: 15 pp + 11 Figures appended as Postscript file
OBSCN Mutations Associated with Dilated Cardiomyopathy and Haploinsufficiency
Studies of the functional consequences of DCM-causing mutations have been limited to a few cases where patients with known mutations had heart transplants. To increase the number of potential tissue samples for direct investigation we performed whole exon sequencing of explanted heart muscle samples from 30 patients that had a diagnosis of familial dilated cardiomyopathy and screened for potentially disease-causing mutations in 58 HCM or DCM-related genes.We identified 5 potentially disease-causing OBSCN mutations in 4 samples; one sample had two OBSCN mutations and one mutation was judged to be not disease-related. Also identified were 6 truncating mutations in TTN, 3 mutations in MYH7, 2 in DSP and one each in TNNC1, TNNI3, MYOM1, VCL, GLA, PLB, TCAP, PKP2 and LAMA4. The mean level of obscurin mRNA was significantly greater and more variable in healthy donor samples than the DCM samples but did not correlate with OBSCN mutations. A single obscurin protein band was observed in human heart myofibrils with apparent mass 960 ± 60 kDa. The three samples with OBSCN mutations had significantly lower levels of obscurin immunoreactive material than DCM samples without OBSCN mutations (45±7, 48±3, and 72±6% of control level).Obscurin levels in DCM controls, donor heart and myectomy samples were the same.OBSCN mutations may result in the development of a DCM phenotype via haploinsufficiency. Mutations in the obscurin gene should be considered as a significant causal factor of DCM, alone or in concert with other mutations
The supersymmetric Ward identities on the lattice
Supersymmetric (SUSY) Ward identities are considered for the N=1 SU(2) SUSY
Yang Mills theory discretized on the lattice with Wilson fermions (gluinos).
They are used in order to compute non-perturbatively a subtracted gluino mass
and the mixing coefficient of the SUSY current. The computations were performed
at gauge coupling =2.3 and hopping parameter =0.1925, 0.194,
0.1955 using the two-step multi-bosonic dynamical-fermion algorithm. Our
results are consistent with a scenario where the Ward identities are satisfied
up to O(a) effects. The vanishing of the gluino mass occurs at a value of the
hopping parameter which is not fully consistent with the estimate based on the
chiral phase transition. This suggests that, although SUSY restoration appears
to occur close to the continuum limit of the lattice theory, the results are
still affected by significant systematic effects.Comment: 34 pages, 7 figures. Typo corrected, last sentence reformulated,
reference added. To appear in Eur. Phys. J.
Psoas hematoma in the elderly patient, a diagnostic challenge, a case report
Background: A psoas hematoma is an uncommon condition in patients on anticoagulant therapy and patients with bleeding disorders. It can present itself with non-specific symptoms, as anemia, pain and hemodynamically instability. The CT angioscan is the diagnostic test of choice. Case presentation: We report a series of 3 cases of iliopsoas hematoma in older patients. These patients were all on anticoagulant therapy and presented with non-specific symptoms as pain in back or groin, anemia and weakness of the leg. These symptoms could be well explained by other, concurrent diseases. Moreover in one case it was not possible to obtain a reliable history due to cognitive impairment of the patient. In our cases the diagnosis of a psoas hematoma was made after performing many diagnostics or found fortuitously. All three patients recovered well after (temporarily) ceasing of anticoagulant therapy. Discussion: The diagnosis of a psoas hematoma is difficult, especially in elderly patients as illustrated in these cases. The symptoms of a psoas hematoma are often aspecific and can also be explained by other, comorbid diseases. Moreover, elderly patients often have an unusual presentation of illness and the presence of cognitive impairment compromises the reliability of a patients history. It is important to be aware of this diagnosis and perform a CT-scan when a psoas hematoma is possible. Conclusion: A psoas hematoma is easily overlooked in older patients due to an unusual presentation of illness, comorbidity and cognitive impairment
Randomizing a clinical trial in neuro-degenerative disease
The paper studies randomization rules for a sequential two-treatment, two-site clinical trial in Parkinson’s disease. An important feature is that we have values of responses and five potential prognostic factors from a sample of 144 patients similar to those to be enrolled in the trial. Analysis of this sample provides a model for trial analysis. The comparison of allocation rules is made by simulation yielding measures of loss due to imbalance and of potential bias. A major novelty of the paper is the use of this sample, via a two-stage algorithm, to provide an empirical distribution of covariates for the simulation; sampling of a correlated multivariate normal distribution is followed by transformation to variables following the empirical marginal distributions. Six allocation rules are evaluated. The paper concludes with some comments on general aspects of the evaluation of such rules and provides a recommendation for two allocation rules, one for each site, depending on the target number of patients to be enrolled
Goals and outcomes of hospitalised older people:does the current hospital care match the needs of older people?
Background Due to the rising number of acutely hospitalised older people in the coming years, there is increased interest in tailoring care to the individual goals and preferences of patients in order to reach patient-centred care. Aims To investigate the goals of older hospitalised patients and the extent to which these goals were reached during hospitalisation. Methods A single-centre prospective cohort study was performed in The Netherlands between December 2017 and January 2018. Participants aged 70 years or older were included. In the first 3 days of hospitalisation, a semi-structured interview was conducted to assess the patient goals regarding the hospital admission. At 1-2 weeks after discharge, patients were asked to what extent the recent hospitalisation had contributed to reaching their goals. Results One hundred and four patients were included and follow up was completed for 86 patients. The main goals reported at hospital admission were 'remaining alive' (72.1%), 'feeling better' (71.2%) and 'improving condition' (65.4%). Hospitalisation seemed to have a positive contribution to reaching the goals 'remaining alive', 'knowing what is wrong', 'feeling better', 'reducing pain' and 'controlling disease'. Hospitalisation seemed to contribute little to reaching the goals in the categories 'enjoying life', 'independency and freedom', 'improving daily functioning', 'hobbies and work' and 'social functioning'. Conclusions It is important for healthcare professionals to know the goals of their patients. The majority of these goals were not achieved at hospital discharge. It is important to be aware of this, so sufficient aftercare can be arranged and patients can be prepared
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