126 research outputs found
Nuclear Polarization of Molecular Hydrogen Recombined on a Non-metallic Surface
The nuclear polarization of molecules formed by recombination
of nuclear polarized H atoms on the surface of a storage cell initially coated
with a silicon-based polymer has been measured by using the longitudinal
double-spin asymmetry in deep-inelastic positron-proton scattering. The
molecules are found to have a substantial nuclear polarization, which is
evidence that initially polarized atoms retain their nuclear polarization when
absorbed on this type of surfac
Estimation of surface potential of lymphocytes from patients with leukemia using Kelvin probe mode
Precision bond lengths for Rydberg Matter clusters KN (N = 19, 37, 61 and 91) in excitation levels n = 4 - 8 from rotational radio-frequency emission spectra
Clusters of the electronically excited condensed matter Rydberg Matter (RM)
are planar and six-fold symmetric with magic numbers N = 7, 19, 37, 61 and 91.
The bond distances in the clusters are known with a precision of +- 5% both
from theory and Coulomb explosion experiments. Long series of up to 40
consecutive lines from rotational transitions in such clusters are now observed
in emission in the radio-frequency range 7-90 MHz. The clusters are produced in
five different vacuum chambers equipped with RM emitters. The most prominent
series with B = 0.9292 +- 0.0001 MHz agrees accurately with expectation (within
2%) for the planar six-fold symmetric cluster K19 in excitation level n = 4.
Other long series agree even better with K19 at n = 5 and 6. The ratio between
the interatomic distance and the theoretical electron orbit radius (the
dimensional ratio) for K19 in n = 4 is found to be 2.8470 +- 0.0003. For
clusters K19 (n = 6) and K37 (n = 7 and 8) the dimensional ratio 2.90 is the
highest value that is found, which happens to be exactly the theoretical value.
Clusters K61 and K91 in n = 5 and 6 have slightly lower dimensional ratios.
This is expected since the edge effects are smaller. Intensity alternations are
observed of approximately 7:3. The nuclear spins interact strongly with the
magnetic field from the orbiting electrons. Spin transitions are observed with
energy differences corresponding accurately (within 0.6%) to transitions with
apparent total (delta)F = -3 at excitation levels n = 5 and 6. The angular
momentum coupling schemes in the clusters are complex but well understood.Comment: 37 pages, 14 figure
The HERMES Polarized Hydrogen and Deuterium Gas Target in the HERA Electron Storage Ring
The HERMES hydrogen and deuterium nuclear-polarized gas targets have been in
use since 1996 with the polarized electron beam of HERA at DESY to study the
spin structure of the nucleon. Polarized atoms from a Stern-Gerlach Atomic Beam
Source are injected into a storage cell internal to the HERA electron ring.
Atoms diffusing from the center of the storage cell into a side tube are
analyzed to determine the atomic fraction and the atomic polarizations. The
atoms have a nuclear polarization, the axis of which is defined by an external
magnetic holding field. The holding field was longitudinal during 1996-2000,
and was changed to transverse in 2001. The design of the target is described,
the method for analyzing the target polarization is outlined, and the
performance of the target in the various running periods is presented
Response of the ATLAS tile calorimeter prototype to muons
A study of high energy muons traversing the ATLAS hadron Tile calorimeter in the barrel region in the energy range between 10 and 300~GeV is presented. Both test beam experimental data and Monte Carlo simulations are given and show good agreement. The Tile calorimeter capability of detecting isolated muons over the above energy range is demonstrated. A signal to background ratio of about 10 is expected for the nominal LHC luminosity (). The photoelectron statistics effect in the muon shape response is shown. The e/mip ratio is found to be ; the e/ ratio is in the range 0.91 - 0.97. The energy loss of a muon in the calorimeter, dominated by the energy lost in the absorber, can be correlated to the energy loss in the active material. This correlation allows one to correct on an event by event basis the muon energy loss in the calorimeter and therefore reduce the low energy tails in the muon momentum distribution
Evaluation of Fermi Read-out of the ATLAS Tilecal Prototype
Prototypes of the \fermi{} system have been used to read out a prototype of the \atlas{} hadron calorimeter in a beam test at the CERN SPS. The \fermi{} read-out system, using a compressor and a 40 MHz sampling ADC, is compared to a standard charge integrating read-out by measuring the energy resolution of the calorimeter separately with the two systems on the same events. Signal processing techniques have been designed to optimize the treatment of \fermi{} data. The resulting energy resolution is better than the one obtained with the standard read-out
Results from a combined test of an electromagnetic liquid argon calorimeter with a hadronic scintillating-tile calorimeter
The first combined test of an electromagnetic liquid argon accordion calorimeter and a hadronic scintillating-tile calorimeter was carried out at the CERN SPS. These devices are prototypes of the barrel calorimeter of the future ATLAS experiment at the LHC. The energy resolution of pions in the energy range from 20 to 300~GeV at an incident angle of about 11 is well-described by the expression \sigma/E = ((46.5 \pm 6.0)\%/\sqrt{E} +(1.2 \pm 0.3)\%) \oplus (3.2 \pm 0.4)~\mbox{GeV}/E. Shower profiles, shower leakage, and the angular resolution of hadronic showers were also studied
A measurement of the energy loss spectrum of 150 GeV muons in iron
The energy loss spectrum of 150 GeV muons has been measured with a prototype of the ATLAS hadron calorimeter in the H8 beam of the CERN SPS.\\ The differential probability per radiation length of a fractional energy loss has been measured in the range ; it is then compared with the theoretical predictions for energy losses due to bremsstrahlung and production of electron-positron pairs or of energetic knock-on electrons.\\ The integrated probability is in agreement with the theoretical predictions of and . %7.8.96 - start Agreement with theory is also found in two intervals of where production of electron-positron pairs and knock-on electrons dominates. In the region of bremsstrahlung dominance () the measured integrated probability is in agreement with the theoretical value of , obtained using Petrukhin and Shestakov's \cite{PS} description of the bremsstrahlung process. The same result is about 3.6 standard deviations (defined as the quadratic sum of statistical and systematic errors) lower than the theoretical prediction of , obtained using Tsai's \cite{TS} description of bremsstrahlung
Терапевтическая эффективность внутриартериального введения нейральных прогениторных клеток, полученных из индуцированных плюрипотентных стволовых клеток, при остром экспериментальном ишемическом инсульте у крыс
Aim. Neural progenitor cells (NPC) are used for the development of cell therapies of neurological diseases. Their stereotaxic transplantation in the middle cerebral artery occlusion (MCAO) model imitating ischemic stroke results in symptom aleviation. However, exploration of less invasive transplantation options is essential, because stereotaxic transplantation is a complex procedure and can be applied to humans only by vital indications in a specialized neurological ward. The aim of the present study was to evaluate the efficacy of cell therapy of the experimental ischemic stroke by the intra-arterial transplantation of NPC.Materials and methods. NPC for transplantation (IPSC-NPC) were derived by two-stage differentiation of cells of a stable line of human induced pluripotent stem cells. Stroke modeling in rats was carried out by transitory 90 min endovascular MCAO by a silicon-tipped filament. NPC were transplanted 24 hours after MCAO. Repetitive magnetic resonance tomography of experimental animals was made with the Bruker BioSpin ClinScan tomograph with 7 Tl magnetic field induction. Animal survival rate and neurological deficit (using mNSS standard stroke severity scale) were evaluated at the 1st (before IPSC-NPC transplantation), 7th and 14th day after transplantation. Histological studies were carried out following standard protocols.Results. Intra-arterial transplantation of 7 × 105 IPSC-NPC in 1 ml at a constant 100 l/min rate in case of secured blood flow through the internal carotid artery did not cause brain capillary embolism, additional cytotoxic brain tissue edemas or other complications, while inducing increase of animal survival rate and enhanced revert of the neurological deficit. IPSC-NPC accumulation in brain after intra-arterial infusion was demonstrated. Some cells interacted with the capillary endothelium and probably penetrated through the blood-brain barrier.Conclusion. Therapeutic efficacy of the systemic, intra-arterial administration of NPC in ischemic stroke has been experimentally proven. A method of secure intra-arterial infusion of cell material into the internal carotid artery middle in rats has been developed and tested.Цель. Нейральные прогениторные клетки (НПК) используются при разработке технологий клеточной терапии неврологических заболеваний. Их стереотаксическое введение в мозг крыс после имитирующей ишемический инсульт операции окклюзии средней мозговой артерии (ОСМА) приводит к облегчению симптоматики. Однако стереотаксическое введение является сложной процедурой и для лечения болезней человека может быть применено только в специализированной клинике по жизненным показаниям, что делает необходимым исследование возможности менее травматичных способов трансплантации. Цель настоящей работы – исследование возможности проведения клеточной терапии экспериментального инсульта путем внутриартериального введения НПК.Материалы и методы. НПК для трансплантации (ИПСК-НПК) получали путем двухступенчатой дифференцировки клеток стабильной линии индуцированных плюрипотентных стволовых клеток человека. Моделирование инсульта у крыс производилось методом транзиторной (90 мин) эндоваскулярной ОСМА филаментом с силиконовым наконечником. Внутриартериальная трансплантация НПК выполнялась через 24 часа после ОСМА. Магнитно-резонансная томография экспериментальных животных в динамике проводилась на МР-томографе ClinScan фирмы Bruker BioSpin с индукцией магнитного поля 7 Тл. На 1 (до введения ИПСК-НПК), 7 и 14-е сутки после трансплантации оценивались выживаемость животных и неврологический дефицит с использованием стандартной шкалы оценки тяжести инсульта mNSS для грызунов. Гистологические исследования проводили, пользуясь стандартными методами.Результаты. Внутриартериальная трансплантация ИПСК-НПК в дозе 7 × 105 НПК в 1 мл с равномерной скоростью100 мкл/мин и поддержанием кровотока по внутренней сонной артерии не вызывала эмболии капилляров мозга, появления новых зон цитотоксического отека вещества головного мозга или других осложнений и приводила к достоверному повышению выживаемости животных и более быстрому восстановлению неврологического статуса. Продемонстрировано накопление ИПСК-НПК в мозге после их внутриартериальной инфузии. Часть клеток взаимодействовала с эндотелием капилляров и, вероятно, способна проникать через ГЭБ.Заключение. Получено экспериментальное подтверждение терапевтической эффективности НПК при ишемическом инсульте при системной, внутриартериальной трансплантации. Отработан и протестирован метод безопасной внутриартериальной инфузии клеточного материала в бассейн внутренней сонной артерии у крыс
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