276 research outputs found
't Hooft Loops, Electric Flux Sectors and Confinement in SU(2) Yang-Mills Theory
We use 't Hooft loops of maximal size on finite lattices to calculate the
free energy in the sectors of SU(2) Yang-Mills theory with fixed electric flux
as a function of temperature and (spatial) volume. Our results provide evidence
for the mass gap. The confinement of electric fluxes in the low temperature
phase and their condensation in the high temperature phase are demonstrated. In
a surprisingly large scaling window around criticality, the transition is
quantitatively well described by universal exponents and amplitude ratios
relating the properties of the two phases.Comment: 5 Pages, LaTeX 2.09 (uses revtex v3.1), 5 Figures (epsfig), revised
version to appear in Phys. Rev.
Intra-arterial induction high-dose chemotherapy with cisplatin for oral and oropharyngeal cancer: long-term results
Intra-arterial (IA) chemotherapy for curative treatment of head and neck cancer experienced a revival in the last decade. Mainly, it was used in concurrent combination with radiation in organ-preserving settings. The modern method of transfemoral approach for catheterisation, superselective perfusion of the tumour-feeding vessel, and high-dose (150 mg m−2) administration of cisplatin with parallel systemic neutralisation with sodium thiosulphate (9 g m−2) made preoperative usage feasible. The present paper presents the results of a pilot study on a population of 52 patients with resectable stage 1–4 carcinomas of the oral cavity and the oropharynx, who were treated with one cycle of preoperative IA chemotherapy executed as mentioned above and radical surgery. There have been no interventional complications of IA chemotherapy, and acute side effects have been low. One tracheotomy had to be carried out due to swelling. The overall clinical local response has been 69%. There was no interference with surgery, which was carried out 3–4 weeks later. Pathological complete remission was assessed in 25%. The mean observation time was 3 years. A 3-year overall and disease-free survival was 82 and 69%, respectively, and at 5 years 77 and 59%, respectively. Survival results were compared to a treatment-dependent prognosis index for the same population. As a conclusion, it can be stated that IA high-dose chemotherapy with cisplatin and systemic neutralisation in a neoadjuvant setting should be considered a feasible, safe, and effective treatment modality for resectable oral and oropharyngeal cancer. The low toxicity of this local chemotherapy recommends usage especially in stage 1–2 patients. The potential of survival benefit as indicated by the comparison to the prognosis index should be controlled in a randomised study
A homogeneous spectroscopic analysis of host stars of transiting planets
The analysis of transiting extra-solar planets provides an enormous amount of
information about the formation and evolution of planetary systems. A precise
knowledge of the host stars is necessary to derive the planetary properties
accurately. The properties of the host stars, especially their chemical
composition, are also of interest in their own right. Information about planet
formation is inferred by, among others, correlations between different
parameters such as the orbital period and the metallicity of the host stars.
The stellar properties studied should be derived as homogeneously as possible.
The present work provides new, uniformly derived parameters for 13 host stars
of transiting planets. Effective temperature, surface gravity, microturbulence
parameter, and iron abundance were derived from spectra of both high
signal-to-noise ratio and high resolution by assuming iron excitation and
ionization equilibria. For some stars, the new parameters differ from previous
determinations, which is indicative of changes in the planetary radii. A
systematic offset in the abundance scale with respect to previous assessments
is found for the TrES and HAT objects. Our abundance measurements are
remarkably robust in terms of the uncertainties in surface gravities. The iron
abundances measured in the present work are supplemented by all previous
determinations using the same analysis technique. The distribution of iron
abundance then agrees well with the known metal-rich distribution of planet
host stars. To facilitate future studies, the spectroscopic results of the
current work are supplemented by the findings for other host stars of
transiting planets, for a total dataset of 50 objects.Comment: accepted for publication in A&A, 7 pages, 6 figure
Fetal heart rate and fetal heart rate variability in Lipizzaner broodmares
Monitoring fetal heart rate (FHR) and fetal heart rate variability (FHRV) helps to understand and evaluate normal and pathological conditions in the foal. The aim of this study was to establish normal heart rate reference values for the ongoing equine pregnancy and to perform a heart rate variability (HRV) time-domain analysis in Lipizzaner mares. Seventeen middle- and late-term (days 121–333) pregnant Lipizzaner mares were examined using fetomaternal electrocardiography (ECG). The mean FHR (P = 0.004) and the standard deviation of FHR (P = 0.012) significantly decreased during the pregnancy. FHR ± SD values decreased from 115 ± 35 to 79 ± 9 bpm between months 5 and 11. Our data showed that HRV in the foal decreased as the pregnancy progressed, which is in contrast with the findings of earlier equine studies. The standard deviation of normal-normal intervals (SDNN) was higher (70 ± 25 to 166 ± 108 msec) than described previously. The root mean square of successive differences (RMSSD) decreased from 105 ± 69 to 77 ± 37 msec between the 5th and 11th month of gestation. Using telemetric ECG equipment, we could detect equine fetal heartbeat on day 121 for the first time. In addition, the large differences observed in the HR values of four mare-fetus pairs in four consecutive months support the assumption that there might be ‘high-HR’ and ‘low-HR’ fetuses in horses. It can be concluded that the analysis of FHR and FHRV is a promising tool for the assessment of fetal well-being but the applicability of these parameters in the clinical setting and in studs requires further investigation
A new search for planet transits in NGC 6791
Context. Searching for planets in open clusters allows us to study the
effects of dynamical environment on planet formation and evolution.
Aims. Considering the strong dependence of planet frequency on stellar
metallicity, we studied the metal rich old open cluster NGC 6791 and searched
for close-in planets using the transit technique.
Methods. A ten-night observational campaign was performed using the
Canada-France-Hawaii Telescope (3.6m), the San Pedro M\'artir telescope (2.1m),
and the Loiano telescope (1.5m). To increase the transit detection probability
we also made use of the Bruntt et al. (2003) eight-nights observational
campaign. Adequate photometric precision for the detection of planetary
transits was achieved.
Results. Should the frequency and properties of close-in planets in NGC 6791
be similar to those orbiting field stars of similar metallicity, then detailed
simulations foresee the presence of 2-3 transiting planets. Instead, we do not
confirm the transit candidates proposed by Bruntt et al. (2003). The
probability that the null detection is simply due to chance coincidence is
estimated to be 3%-10%, depending on the metallicity assumed for the cluster.
Conclusions. Possible explanations of the null-detection of transits include:
(i) a lower frequency of close-in planets in star clusters; (ii) a smaller
planetary radius for planets orbiting super metal rich stars; or (iii)
limitations in the basic assumptions. More extensive photometry with 3-4m class
telescopes is required to allow conclusive inferences about the frequency of
planets in NGC 6791.Comment: 23 pages, 23 figures, A&A accepte
Nothophytophthora gen. nov., a new sister genus of Phytophthora from natural and semi-natural ecosystem
During various surveys of Phytophthora diversity in Europe, Chile and Vietnam slow growing oomycete
isolates were obtained from rhizosphere soil samples and small streams in natural and planted forest stands.
Phylogenetic analyses of sequences from the nuclear ITS, LSU, β-tubulin and HSP90 loci and the mitochondrial
cox1 and NADH1 genes revealed they belong to six new species of a new genus, officially described here as
Nothophytophthora gen. nov., which clustered as sister group to Phytophthora. Nothophytophthora species share
numerous morphological characters with Phytophthora: persistent (all Nothophytophthora spp.) and caducous
(N. caduca, N. chlamydospora, N. valdiviana, N. vietnamensis) sporangia with variable shapes, internal differentiation
of zoospores and internal, nested and extended (N. caduca, N. chlamydospora) and external (all Nothophytophthora
spp.) sporangial proliferation; smooth-walled oogonia with amphigynous (N. amphigynosa) and paragynous
(N. amphigynosa, N. intricata, N. vietnamensis) attachment of the antheridia; chlamydospores (N. chlamydospora)
and hyphal swellings. Main differing features of the new genus are the presence of a conspicuous, opaque plug
inside the sporangiophore close to the base of most mature sporangia in all known Nothophytophthora species and
intraspecific co-occurrence of caducity and non-papillate sporangia with internal nested and extended proliferation
in several Nothophytophthora species. Comparisons of morphological structures of both genera allow hypotheses
about the morphology and ecology of their common ancestor which are discussed. Production of caducous sporangia
by N. caduca, N. chlamydospora and N. valdiviana from Valdivian rainforests and N. vietnamensis from a
mountain forest in Vietnam suggests a partially aerial lifestyle as adaptation to these humid habitats. Presence of
tree dieback in all forests from which Nothophytophthora spp. were recovered and partial sporangial caducity of
several Nothophytophthora species indicate a pathogenic rather than a saprophytic lifestyle. Isolation tests from
symptomatic plant tissues in these forests and pathogenicity tests are urgently required to clarify the lifestyle of the
six Nothophytophthora species.info:eu-repo/semantics/publishedVersio
Quantum Griffiths effects and smeared phase transitions in metals: theory and experiment
In this paper, we review theoretical and experimental research on rare region
effects at quantum phase transitions in disordered itinerant electron systems.
After summarizing a few basic concepts about phase transitions in the presence
of quenched randomness, we introduce the idea of rare regions and discuss their
importance. We then analyze in detail the different phenomena that can arise at
magnetic quantum phase transitions in disordered metals, including quantum
Griffiths singularities, smeared phase transitions, and cluster-glass
formation. For each scenario, we discuss the resulting phase diagram and
summarize the behavior of various observables. We then review several recent
experiments that provide examples of these rare region phenomena. We conclude
by discussing limitations of current approaches and open questions.Comment: 31 pages, 7 eps figures included, v2: discussion of the dissipative
Ising chain fixed, references added, v3: final version as publishe
Double-blind test program for astrometric planet detection with Gaia
We use detailed simulations of the Gaia observations of synthetic planetary
systems and develop and utilize independent software codes in double-blind mode
to analyze the data, including statistical tools for planet detection and
different algorithms for single and multiple Keplerian orbit fitting that use
no a priori knowledge of the true orbital parameters of the systems. 1) Planets
with astrometric signatures times the single-measurement error
and period yr can be detected reliably, with a very
small number of false positives. 2) At twice the detection limit, uncertainties
in orbital parameters and masses are typically . 3) Over 70% of
two-planet systems with well-separated periods in the range
yr, , and eccentricity are
correctly identified. 4) Favorable orbital configurations have orbital elements
measured to better than 10% accuracy of the time, and the value of the
mutual inclination angle determined with uncertainties \leq 10^{\degr}. 5)
Finally, uncertainties obtained from the fitting procedures are a good estimate
of the actual errors. Extrapolating from the present-day statistical properties
of the exoplanet sample, the results imply that a Gaia with = 8
as, in its unbiased and complete magnitude-limited census of planetary
systems, will measure several thousand giant planets out to 3-4 AUs from stars
within 200 pc, and will characterize hundreds of multiple-planet systems,
including meaningful coplanarity tests. Finally, we put Gaia into context,
identifying several areas of planetary-system science in which Gaia can be
expected to have a relevant impact, when combined with data coming from other
ongoing and future planet search programs.Comment: 32 pages, 24 figures, 6 tables. Accepted for pubolication in A&
Unraveling the role of local ablative therapies for patients with metastatic soft tissue sarcoma – a retrospective multicenter study of the Bavarian university hospitals
Background
Local ablative therapies (LAT) are increasingly used in patients with metastatic soft tissue sarcoma (STS), yet evidence-based standards are lacking. This study aimed to assess the impact of LAT on survival of metastatic STS patients and to identify prognostic factors.
Methods
In this retrospective multicenter study, 246 STS patients with metastatic disease who underwent LAT on tumor board recommendation between 2017 and 2021 were analyzed. A mixed effects model was applied to evaluate multiple survival events per patient.
Results
Median overall survival (OS) after first metastasis was 5.4 years with 1-, 2- and 5-year survival rates of 93.7, 81.7, and 53.1%, respectively. A treatment-free interval ≥12 months and treatment of liver metastases were positively correlated with progression-free survival (PFS) after LAT (HR=0.61, p=0.00032 and HR=0.52, p=0.0081, respectively). A treatment-free interval ≥12 months and treatment of metastatic lesions in a single organ site other than lung and liver were positive prognostic factors for OS after first LAT (HR=0.50, p=0.028 and HR=0.40, p=0.026, respectively) while rare histotypes and LAT other than surgery and radiotherapy were negatively associated with OS after first LAT (HR=2.56, p=0.020 and HR=3.87, p=0.025). Additional systemic therapy was independently associated with a PFS benefit in patients ≤60 years with ≥4 metastatic lesions (for max. diameter of treated lesions ≤2cm: HR=0.32, p=0.02 and >2cm: HR=0.20, p=0.0011, respectively).
Conclusion
This multicenter study conducted at six German university hospitals underlines the value of LAT in metastatic STS. The exceptionally high survival rates are likely to be associated with patient selection and treatment in specialized sarcoma centers
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