76 research outputs found
Shape and soft functions of HQET and SCET in the 't Hooft Model
The main application of Heavy Quark Effective Theory (HQET) and of Soft
Collinear Effective Theory (SCET) is in establishing factorization theorems for
exclusive and semi-inclusive decays of heavy mesons. However, the calculation
of the soft factors from the HQET or SCET factorization relations is, as usual,
impeded by the non-perturbative aspect of the strong interactions. In the hope
of gaining some insights into some of these quantities we compute them in the
't Hooft model. We find that the B-meson shape function is exactly given by the
square of the B-meson light-cone wave-function. The structure of the B-pi
structure function is more complicated: it is given by the product of
wave-functions or by a resonant sum depending on the kinematics. The result
simplifies dramatically in the chiral limit, where it can be compared with
general arguments based on Heavy Meson-Chiral Perturbation theory. No attempt
is made to use these results for applications to phenomenology.Comment: 17 pages, 5 figure
The dependence of Galactic outflows on the properties and orientation of zCOSMOS galaxies at z ~ 1
We present an analysis of cool outflowing gas around galaxies, traced by MgII
absorption lines in the co-added spectra of a sample of 486 zCOSMOS galaxies at
1 < z < 1.5. These galaxies span a range of stellar masses (9.45<
log[M*/Msun]<10.7) and star formation rates (0.14 < log [SFR/Msun/yr] < 2.35).
We identify the cool outflowing component in the MgII absorption and find that
the equivalent width of the outflowing component increases with stellar mass.
The outflow equivalent width also increases steadily with the increasing star
formation rate of the galaxies. At similar stellar masses the blue galaxies
exhibit a significantly higher outflow equivalent width as compared to red
galaxies. The outflow equivalent width shows strong effect with star formation
surface density ({\Sigma}SFR) of the sample. For the disk galaxies, the outflow
equivalent width is higher for the face-on systems as compared to the edge-on
ones, indicating that for the disk galaxies, the outflowing gas is primarily
bipolar in geometry. Galaxies typically exhibit outflow velocities ranging from
-200 km/s to -300 km/s and on average the face-on galaxies exhibit higher
outflow velocity as compared to the edge-on ones. Galaxies with irregular
morphologies exhibit outflow equivalent width as well as outflow velocities
comparable to face on disk galaxies. These galaxies exhibit minimum mass
outflow rates > 5-7 Msun/yr and a mass loading factor ({\eta} = dMout/dt /SFR)
comparable to the star formation rates of the galaxies.Comment: 12 pages, 14 figures, ApJ submitte
Whole-scalp EEG mapping of somatosensory evoked potentials in macaque monkeys
High-density scalp EEG recordings are widely used to study whole-brain neuronal networks in humans non-invasively. Here, we validate EEG mapping of somatosensory evoked potentials (SSEPs) in macaque monkeys (Macaca fascicularis) for the long-term investigation of large-scale neuronal networks and their reorganisation after lesions requiring a craniotomy. SSEPs were acquired from 33 scalp electrodes in five adult anaesthetized animals after electrical median or tibial nerve stimulation. SSEP scalp potential maps were identified by cluster analysis and identified in individual recordings. A distributed, linear inverse solution was used to estimate the intracortical sources of the scalp potentials. SSEPs were characterised by a sequence of components with unique scalp topographies. Source analysis confirmed that median nerve SSEP component maps were in accordance with the somatotopic organisation of the sensorimotor cortex. Most importantly, SSEP recordings were stable both intra- and interindividually. We aim to apply this method to the study of recovery and reorganisation of large-scale neuronal networks following a focal cortical lesion requiring a craniotomy. As a prerequisite, the present study demonstrated that a 300-mm2 unilateral craniotomy over the sensorimotor cortex necessary to induce a cortical lesion, followed by bone flap repositioning, suture and gap plugging with calcium phosphate cement, did not induce major distortions of the SSEPs. In conclusion, SSEPs can be successfully and reproducibly recorded from high-density EEG caps in macaque monkeys before and after a craniotomy, opening new possibilities for the long-term follow-up of the cortical reorganisation of large-scale networks in macaque monkeys after a cortical lesion
Das akral-lentiginose Melanom: die jungste Sonderform des malignen Melanoms der Haut. [Acral-lentiginous melanoma: the newest subgroup of malignant melanomas of the skin]
A new subgroup of malignant melanoma, acral-lentiginous melanoma (ALM), is presented, which the authors have diagnosed in 8% of their melanoma patients. In a retrospective study the clinical and pathological findings in 44 patients with ALM are reviewed. A relationship was found between age, tumor diameter and thickness, pigmentation, ulceration, vasoinvasion and mitoses. The author's patients had a 5-year survival rate of 58%
Digital 3D reconstruction of two parahissian accessory bundles in a case of Wolff-Parkinson White syndrome
Three-dimensional reconstruction of digitized histological serial sections of the cardiac conduction system yielded two accessory pathways in a case of a 24-day-old male infant who died after a short period of illness with ECG findings of Wolff-Parkinson-White syndrome. In infants, the differential diagnosis of possible accessory pathways connecting the AV conduction system, atrial or ventricular septum includes dispersed conduction system tissue without connecting features. This is why three-dimensional reconstruction is necessary in order to refute or establish connectivity of cell groups as found in histological serial slice images
Intravenous levetiracetam : treatment experience with the first 50 critically ill patients
Levetiracetam (LEV) is a broad-spectrum antiepileptic drug with no known interactions and a favorable profile of adverse events. These properties make it a good candidate for use in critically ill patients. An intravenous formulation of LEV was recently approved. The present study retrospectively assesses the safety and efficacy of LEV in the first 50 critically ill patients treated with intravenous LEV. Indications for use were seizure prophylaxis, acute symptomatic seizures, and all forms of status epilepticus. There were no major adverse effects, although less prominent changes may have been masked by the already severely compromised condition of these patients. Two patients (4%) had transiently lowered platelet counts (55,000 and 82,000, respectively). Efficacy, defined as cessation of seizure activity or prevention of its recurrence, was observed in 41 of 50 patients (82%). Antiepileptic treatment of critically ill patients with LEV seems to be effective and safe according to the data for this small cohort, but this observation warrants further prospective investigation in a larger number of patients
Melanoma in childhood : an EORTC-MCG multicenter study on the clinico-pathological aspects
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