Intense high-order harmonic generation in giant fullerene molecule C240_{240}

In this work the extreme nonlinear optical response of a giant fullerene molecule C$_{240}$ in strong laser field is studied. The investigation of high-order harmonic generation in such quantum nanostructure is presented modeling the C$_{240}$ molecule and its interaction with the laser field in the scope of the tight-binding mean-field approach. Electron-electron interaction is modeled by the parametrized Ohno potentail, which takes into account long-range Coulomb interaction. The essential role of many body Coulomb interaction in determining of harmonics intensities is demonstrated. We also consider vacancy-deffected molecule C$_{240}$. The presence of a single vacancy breaks the icosahedral symmetry leading to the emergence of intense even-order harmonics. We examine the dependence of moderate harmonics on laser frequency that shows the multiphoton resonant nature of high harmonics generation. The dependence of cutoff harmonics on both laser intensity and frequency are examined too.Comment: 9 pages, 10 figure

Magnetic Properties of J-J-J' Quantum Heisenberg Chains with Spin S=1/2, 1, 3/2 and 2 in a Magnetic Field

By means of the density matrix renormalization group (DMRG) method, the magnetic properties of the J-J-J$^{\prime}$ quantum Heisenberg chains with spin $S=1/2$, 1, 3/2 and 2 in the ground states are investigated in the presence of a magnetic field. Two different cases are considered: (a) when $J$ is antiferromagnetic and $J^{\prime}$ is ferromagnetic (i.e. the AF-AF-F chain), the system is a ferrimagnet. The plateaus of the magnetization are observed. It is found that the width of the plateaus decreases with increasing the ferromagnetic coupling, and disappears when $$ passes over a critical value. The saturated field is observed to be independent of the ferromagnetic coupling; (b) when $J$ is ferromagnetic and $J^{\prime}$ is antiferromagnetic (i.e. the F-F-AF chain), the system becomes an antiferromagnet. The plateaus of the magnetization are also seen. The width of the plateaus decreases with decreasing the antiferromagnetic coupling, and disappears when $J^{\prime}/J$ passes over a critical value. Though the ground state properties are quite different, the magnetization plateaus in both cases tend to disappear when the ferromagnetic coupling becomes more dominant. Besides, no fundamental difference between the systems with spin half-integer and integer has been found.Comment: 8 pages, 9 figures, to be published in J. Phys.: Condens. Matte

Cryogenic mechanical loss of a single-crystalline GaP coating layer for precision measurement applications

The first direct observations of gravitational waves have been made by the Advanced LIGO detectors. However, the quest to improve the sensitivities of these detectors remains, and epitaxially grown single-crystal coatings show considerable promise as alternatives to the ion-beam sputtered amorphous mirror coatings typically used in these detectors and other such precision optical measurements. The mechanical loss of a 1 μm thick single-crystalline gallium phosphide (GaP) coating, incorporating a buffer layer region necessary for the growth of high quality epitaxial coatings, has been investigated over a broad range of frequencies and with fine temperature resolution. It is shown that at 20 K the mechanical loss of GaP is a factor of 40 less than an undoped tantala film heat-treated to 600 °C and is comparable to the loss of a multilayer GaP/AlGaP coating. This is shown to translate into possible reductions in coating thermal noise of a factor of 2 at 120 K and 5 at 20 K over the current best IBS coatings (alternating stacks of silica and titania-doped tantala). There is also evidence of a thermally activated dissipation process between 50 and 70 K

НОВЫЕ ТЕХНОЛОГИИ В ДИАГНОСТИКЕ И ВОССТАНОВИТЕЛЬНОМ ЛЕЧЕНИИ РАССТРОЙСТВ МОЧЕИСПУСКАНИЯ ПОСЛЕ ХИРУРГИЧЕСКОГО ЛЕЧЕНИЯ РАКА ПРЕДСТАТЕЛЬНОЙ ЖЕЛЕЗЫ

The paper deals with the latest neurophysiological technologies for the recognition and treatment of neurogenic disorders of urination and erection in a group of patients operated on for prostate cancer (PC). Acicular electromyography of pelvic floor muscles with transcranial magnetic stimulation of micturition and erectile centers has been put into practice to examine this category of patients. The basic neurophysiological parameters of the muscles examined (cortical and segmental evoked motor response the latency, central motor conduction time (CMCT), and motor unit potential (MUP) amplitude and duration) were estimated. To develop a normative base, the neurophysiological features of the pelvic floor were studied in healthy volunteers (n = 12) who formed a control group. Examinations were made in 17 patients who had undergone operations for PC at Moscow hospitals 3 to 18 months before, such as retropubic prostatectomy (n = 11) and transurethral resection plus high-intensity focused ultrasound (HIFU) ablation (n = 6). Spontaneous urination was absent in 4 (23.5%) of cases; urinary incontinence was observed in 6 (35.2%) patients. The study group patients were found to have significant disorders of corticospinal tract conduction and those of perineal muscle contraction as potential fibrillation and positive pointed waves, as well as considerable CMCM prolongation and MUP polyphasia. Denervation alterations in PC patients after surgery and delayed reinnervation processes, nerve control recovery are determined by not only the surgery itself, but also by the features of the course of the underlying cancer process. Pelvic floor muscle studies indicated that HIFU was a very traumatic treatment for PC due to the fact that physical exposure spread outside the prostate to the neuromuscular structures. The denervation alterations detected in the pelvic floor muscles became essential in the elaboration of adequate treatment policy. The use of agents improving the function and trophicity of peripheral nerves in combination therapy and the introduction of extracorporeal magnetic stimulation methods could largely improve the results of treatment for dysuria.Статья посвящена новейшим нейрофизиологическим технологиям распознавания и лечения нейрогенных расстройств мочеиспускания и эрекции в группе пациентов, оперированных по поводу рака предстательной железы (РПЖ). В практику обследования пациентов данной категории внедрена игольчатая электромиография мышц тазового дна с транскраниальной магнитной стимуляцией центров мочеиспускания и эрекции. Оценены основные нейрофизиологические параметры изученных мышц — латентность коркового и сегментарного вызванного моторного ответа, время центрального моторного проведения (ВЦМП), амплитуда и длительность потенциала двигательной единицы (ПДЕ). С целью разработки нормативной базы изучены нейрофизиологические особенности тазового дна у здоровых добровольцев (n = 12), составивших контрольную группу. Обследованы 17 пациентов, которые в сроки от 3 до 18 мес назад перенесли операции по поводу РПЖ в стационарах Москвы: радикальная позадилонная простатэктомия (n = 11), трансуретральная резекция плюс высокоинтенсивная сфокусированная ультразвуковая аблация (HIFU) (n = 6). В 4 (23,5 %) наблюдениях самостоятельное мочеиспускание отсутствовало, недержание мочи отмечено у 6 (35,2 %) пациентов. В изученной группе больных выявлены значительные расстройства проводимости по кортикоспинальному тракту и сократительной способности мышц промежности в виде потенциальной фибрилляции и положительных острых волн, а также значительного удлинения ВЦМП, полифазия ПДЕ. Денервационные изменения у пациентов с РПЖ после операции и задержка процессов реиннервации, восстановления нервного контроля, определяются не только самим фактом операции, но и особенностями течения основного онкологического процесса. Исследования мышц тазового дна показали, что HIFU — весьма травматичный способ лечения РПЖ вследствие распространения физического воздействия за пределы предстательной железы на нервно-мышечные структуры. Выявляемые денервационные изменения в мышцах дна таза стали ключевыми в выработке адекватной лечебной тактики. Назначение в комплексной терапии препаратов, улучшающих проводящую функцию и трофику периферических нервов,а также внедрение методов экстракорпоральной магнитной стимуляции позволили в значительной степени улучшить результаты лечения при нарушениях мочеиспускания

Imaging Single Retrovirus Entry through Alternative Receptor Isoforms and Intermediates of Virus-Endosome Fusion

A large group of viruses rely on low pH to activate their fusion proteins that merge the viral envelope with an endosomal membrane, releasing the viral nucleocapsid. A critical barrier to understanding these events has been the lack of approaches to study virus-cell membrane fusion within acidic endosomes, the natural sites of virus nucleocapsid capsid entry into the cytosol. Here we have investigated these events using the highly tractable subgroup A avian sarcoma and leukosis virus envelope glycoprotein (EnvA)-TVA receptor system. Through labeling EnvA pseudotyped viruses with a pH-sensitive fluorescent marker, we imaged their entry into mildly acidic compartments. We found that cells expressing the transmembrane receptor (TVA950) internalized the virus much faster than those expressing the GPI-anchored receptor isoform (TVA800). Surprisingly, TVA800 did not accelerate virus uptake compared to cells lacking the receptor. Subsequent steps of virus entry were visualized by incorporating a small viral content marker that was released into the cytosol as a result of fusion. EnvA-dependent fusion with TVA800-expressing cells occurred shortly after endocytosis and delivery into acidic endosomes, whereas fusion of viruses internalized through TVA950 was delayed. In the latter case, a relatively stable hemifusion-like intermediate preceded the fusion pore opening. The apparent size and stability of nascent fusion pores depended on the TVA isoforms and their expression levels, with TVA950 supporting more robust pores and a higher efficiency of infection compared to TVA800. These results demonstrate that surface receptor density and the intracellular trafficking pathway used are important determinants of efficient EnvA-mediated membrane fusion, and suggest that early fusion intermediates play a critical role in establishing low pH-dependent virus entry from within acidic endosomes

A Cryogenic Silicon Interferometer for Gravitational-wave Detection

The detection of gravitational waves from compact binary mergers by LIGO has opened the era of gravitational wave astronomy, revealing a previously hidden side of the cosmos. To maximize the reach of the existing LIGO observatory facilities, we have designed a new instrument that will have 5 times the range of Advanced LIGO, or greater than 100 times the event rate. Observations with this new instrument will make possible dramatic steps toward understanding the physics of the nearby universe, as well as observing the universe out to cosmological distances by the detection of binary black hole coalescences. This article presents the instrument design and a quantitative analysis of the anticipated noise floor

Gravitational Waves From Known Pulsars: Results From The Initial Detector Era

We present the results of searches for gravitational waves from a large selection of pulsars using data from the most recent science runs (S6, VSR2 and VSR4) of the initial generation of interferometric gravitational wave detectors LIGO (Laser Interferometric Gravitational-wave Observatory) and Virgo. We do not see evidence for gravitational wave emission from any of the targeted sources but produce upper limits on the emission amplitude. We highlight the results from seven young pulsars with large spin-down luminosities. We reach within a factor of five of the canonical spin-down limit for all seven of these, whilst for the Crab and Vela pulsars we further surpass their spin-down limits. We present new or updated limits for 172 other pulsars (including both young and millisecond pulsars). Now that the detectors are undergoing major upgrades, and, for completeness, we bring together all of the most up-to-date results from all pulsars searched for during the operations of the first-generation LIGO, Virgo and GEO600 detectors. This gives a total of 195 pulsars including the most recent results described in this paper.United States National Science FoundationScience and Technology Facilities Council of the United KingdomMax-Planck-SocietyState of Niedersachsen/GermanyAustralian Research CouncilInternational Science Linkages program of the Commonwealth of AustraliaCouncil of Scientific and Industrial Research of IndiaIstituto Nazionale di Fisica Nucleare of ItalySpanish Ministerio de Economia y CompetitividadConselleria d'Economia Hisenda i Innovacio of the Govern de les Illes BalearsNetherlands Organisation for Scientific ResearchPolish Ministry of Science and Higher EducationFOCUS Programme of Foundation for Polish ScienceRoyal SocietyScottish Funding CouncilScottish Universities Physics AllianceNational Aeronautics and Space AdministrationOTKA of HungaryLyon Institute of Origins (LIO)National Research Foundation of KoreaIndustry CanadaProvince of Ontario through the Ministry of Economic Development and InnovationNational Science and Engineering Research Council CanadaCarnegie TrustLeverhulme TrustDavid and Lucile Packard FoundationResearch CorporationAlfred P. Sloan FoundationAstronom

A First Search for coincident Gravitational Waves and High Energy Neutrinos using LIGO, Virgo and ANTARES data from 2007

We present the results of the first search for gravitational wave bursts associated with high energy neutrinos. Together, these messengers could reveal new, hidden sources that are not observed by conventional photon astronomy, particularly at high energy. Our search uses neutrinos detected by the underwater neutrino telescope ANTARES in its 5 line configuration during the period January - September 2007, which coincided with the fifth and first science runs of LIGO and Virgo, respectively. The LIGO-Virgo data were analysed for candidate gravitational-wave signals coincident in time and direction with the neutrino events. No significant coincident events were observed. We place limits on the density of joint high energy neutrino - gravitational wave emission events in the local universe, and compare them with densities of merger and core-collapse events.Comment: 19 pages, 8 figures, science summary page at http://www.ligo.org/science/Publication-S5LV_ANTARES/index.php. Public access area to figures, tables at https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=p120000