On the appearance of hyperons in neutron stars

By employing a recently constructed hyperon-nucleon potential the equation of state of \beta-equilibrated and charge neutral nucleonic matter is calculated. The hyperon-nucleon potential is a low-momentum potential which is obtained within a renormalization group framework. Based on the Hartree-Fock approximation at zero temperature the densities at which hyperons appear in neutron stars are estimated. For several different bare hyperon-nucleon potentials and a wide range of nuclear matter parameters it is found that hyperons in neutron stars are always present. These findings have profound consequences for the mass and radius of neutron stars.Comment: 12 pages, 12 figures, RevTeX4; summary and conclusions are strengthened, to appear in PR

Клинико-морфологические доказательства влияния консервантов на поверхность глаза при первичной открытоугольной глаукоме

PURPOSE: To compare clinical features related to changes in the eye surface caused by long term use of prostaglandin antiglaucoma agents, containing and not containing preservatives, and to perform comparative morphological analysis of the conjunctival biopsies in the study groups. METHODS: The study was performed on 90 patients aged 36 to 89 years (mean age 64.5±11.3 years), including 36 males and 54 females. The first two groups were comprised of the patients with newly diagnosed primary open-angle glaucoma stage 1-3, who were prescribed Taflotan without preservatives produced by «Santen» (tafluprost 0.0015% solution in single use 0.3 ml dripping tubes) (1st group) and 0.005% latanoprost with 0.02% benzalkonium chloride or 0.004% travoprost with 0.015% benzalkonium chloride (2nd group). Mean duration of treatment within the frameworks of the study was 135 days, minimal - 90 days. The control group included patients with age-related cataract of various degree of maturation who did not receive local treatment. In the beginning and the end of the study, all patients underwent assessment of the eye surface condition for Dry Eye Syndrome (DES), including symptom scope according to the OSDI (Ocular Surface Disease Index); assessment of the conjunctival folds degree (LIPCOF); the tear film rapture time (TFRT); the degree of Rose Bengal staining of the eye surface (RB); and Schirmer 1 test. At the end of the study selective biopsies were performed during the surgery. RESULTS: Statistically significant gender differences in DES incidence were revealed: 78% of females (42/54) versus 39% of males (14/36). At the end of the study statistically significant decrease in OSDI score in both groups was revealed, compared to baseline data without differences between the groups, as well as Schirmer 1 test in the second group. Treatment complications (hyperemia, subcompensated intraocular pressure, DES and cataract progression) were noted in 3 eyes in the first group, and 11 eyes in the second group (the difference was statistically significant). Hyperemia was revealed in 6% (2 eyes) and 17% (6 eyes), in the first and second group, respectively. In the second group DES progression was revealed, showing correlation with decreased tear expression during Schirmer 1 test. CONCLUSION: Tafluprost without preservatives is an effective and safe hypotensive agent from the group of prostaglandin analogues. It is better tolerated, causes least complaints during instillation, and less adverse effects in the long term use (hyperemia, advancement of the preexisting Dry Eye Syndrome, etc.) when compared to other medications from the same pharmacologic group containing preservatives, which is confirmed by comparative morphological assessment of conjunctiva biopsies.ЦЕЛЬ. Сравнить клинические проявления изменения поверхности глаза, связанные с длительным применением антиглаукомных препаратов простагландинового ряда, содержащих и не содержащих консервант, провести сравнительный морфологический анализ биоптатов конъюнктивы в исследуемых группах. методы. в іриняло участие 90 паци ентов в возрасте от 35 до 89 лет (64,5±11,3 года), из них 36 мужчин и 54 женщины. Первые две группы составили пациенты с впервые выявленной первичной открытоугольной глаукомой (ПОУГ) I-III стадий, которым были назначены тафлотан без консерванта, фирмы «Santen» (0,0015% тафлупрост в одноразовых тюбиках-капельницах по 0,3 мл) (1-я группа) и 0,005% латанопрост с 0,02% бензалкония хлоридом или 0,004% травопрост с 0,015% бензалкония хлоридом (2-я группа). Средняя длительность лечения в рамках исследования составила 135 дней, минимальная - 90 дней. Контрольная группа состояла из пациентов с возрастной катарактой различной степени зрелости, не получавших местной терапии. Всем пациентам в начале и в конце исследования проведена оценка состояния поверхности глаза на наличие синдрома «сухого глаза» (ССГ), включавшая жалобы по опроснику OSDI (Ocular Surface Disease Index), определение степени конъюнктивальных складок (LIPCOF), времени разрыва слезной пленки (ВРСП), степени окрашивания глазной поверхности бенгальским розовым (БР), теста Ширмера 1. Выборочно в конце исследования во время выполнения хирургического лечения взяты биоптаты конъюнктивы для морфологического исследования. РЕЗУЛЬТАТЫ. Выя значимые ген дерные различия частоты встречаемости ССГ: у 78% женщин (42/54) и у 39% мужчин (14/36). В конце исследования отмечено статистически значимое снижение баллов OSDI в обеих группах по сравнению со стартовыми данными без межгрупповых различий, а также теста Ширмера 1 во 2-й группе. Осложнения лечения (гиперемия, увеличение стадии ССГ и прогрессирование катаракты) отмечены в трех глазах в 1-й группе и в 11 глазах во 2-й группе (разница статистически значима). В группах гиперемия отмечена у 6% (2 глаза) и 17% (6 глаз) соответственно. Во 2-й группе выявлено усиление стадии ССГ, коррелирующее со снижением теста Ширмера 1. ЗАКЛЮЧЕНИЕ. Тафлупрост без консерванта является эффективным и безопасным гипотензивным препаратом из ряда аналогов простагландинов. Он лучше переносится, вызывая наименьшее количество жалоб во время инстилляции, а при длительном применении - меньшие побочные эффекты (гиперемия, усиление имеющегося ССГ и др.) по сравнению с другими препаратами аналогичной фармакологической группы, содержащими консервант, что подтверждает и сравнительное морфологическое исследование биоптатов конъюнктивы

Periodic Pattern in the Residual-Velocity Field of OB Associations

An analysis of the residual-velocity field of OB associations within 3 kpc of the Sun has revealed periodic variations in the radial residual velocities along the Galactic radius vector with a typical scale length of lambda=2.0(+/-0.2) kpc and a mean amplitude of fR=7(+/-1) km/s. The fact that the radial residual velocities of almost all OB-associations in rich stellar-gas complexes are directed toward the Galactic center suggests that the solar neighborhood under consideration is within the corotation radius. The azimuthal-velocity field exhibits a distinct periodic pattern in the region 0<l<180 degrees, where the mean azimuthal-velocity amplitude is ft=6(+/-2) km/s. There is no periodic pattern of the azimuthal-velocity field in the region 180<l<360 degrees. The locations of the Cygnus arm, as well as the Perseus arm, inferred from an analysis of the radial- and azimuthal-velocity fields coincide. The periodic patterns of the residual-velocity fields of Cepheids and OB associations share many common features.Comment: 21 page

Stellar structure and compact objects before 1940: Towards relativistic astrophysics

Since the mid-1920s, different strands of research used stars as "physics laboratories" for investigating the nature of matter under extreme densities and pressures, impossible to realize on Earth. To trace this process this paper is following the evolution of the concept of a dense core in stars, which was important both for an understanding of stellar evolution and as a testing ground for the fast-evolving field of nuclear physics. In spite of the divide between physicists and astrophysicists, some key actors working in the cross-fertilized soil of overlapping but different scientific cultures formulated models and tentative theories that gradually evolved into more realistic and structured astrophysical objects. These investigations culminated in the first contact with general relativity in 1939, when J. Robert Oppenheimer and his students George Volkoff and Hartland Snyder systematically applied the theory to the dense core of a collapsing neutron star. This pioneering application of Einstein's theory to an astrophysical compact object can be regarded as a milestone in the path eventually leading to the emergence of relativistic astrophysics in the early 1960s.Comment: 83 pages, 4 figures, submitted to the European Physical Journal

Compact stars made of fermionic dark matter

Compact stars consisting of fermions with arbitrary masses and interaction strengths are studied by solving the structure equation of general relativity, the Tolman-Oppenheimer-Volkoff equations. Scaling solutions are derived for a free and an interacting Fermi gas and tested by numerical calculations. We demonstrate that there is a unique mass-radius relation for compact stars made of free fermions which is independent of the fermion mass. For sufficiently strong interactions, the maximum stable mass of compact stars and its radius are controlled by the parameter of the interaction, both increasing linearly with the interaction strength. The mass-radius relation for compact stars made of strongly interacting fermions shows that the radius remains approximately constant for a wide range of compact star masses.Comment: 19 pages, 8 figures, refs. added, version to appear in Physical Review

The Role of Strangeness in Astrophysics - an Odyssey through Strange Phases

The equation of state for compact stars is reviewed with special emphasis on the role of strange hadrons, strange dibaryons and strange quark matter. Implications for the properties of compact stars are presented. The importance of neutron star data to constrain the properties of hypothetic particles and the possible existence of exotic phases in dense matter is outlined. We also discuss the growing interplay between astrophysics and heavy-ion physics.Comment: invited talk given at Strange Quark Matter 2001, Frankfurt, Germany, 8 pages, uses iopart.cls, minor modifications, version to appear in J. Phys.

Spectral correlations in a random distributed feedback fibre laser

Random distributed feedback fibre lasers belong to the class of random lasers, where the feedback is provided by amplified Rayleigh scattering on sub-micron refractive index inhomogenities randomly distributed over the fibre length. Despite the elastic nature of Rayleigh scattering, the feedback mechanism has been insofar deemed incoherent, which corresponds to the commonly observed smooth generation spectra. Here, using a real-time spectral measurement technique based on a scanning Fabry-Pérot interferometer, we observe long-living narrowband components in the random fibre laser's spectrum. Statistical analysis of the ∼104 single-scan spectra reveals a preferential interspacing for the components and their anticorrelation in intensities. Furthermore, using mutual information analysis, we confirm the existence of nonlinear correlations between different parts of the random fibre laser spectra. The existence of such narrowband spectral components, together with their observed correlations, establishes a long-missing parallel between the fields of random fibre lasers and conventional random lasers

Gravitational-wave research as an emerging field in the Max Planck Society. The long roots of GEO600 and of the Albert Einstein Institute

On the occasion of the 50th anniversary since the beginning of the search for gravitational waves at the Max Planck Society, and in coincidence with the 25th anniversary of the foundation of the Albert Einstein Institute, we explore the interplay between the renaissance of general relativity and the advent of relativistic astrophysics following the German early involvement in gravitational-wave research, to the point when gravitational-wave detection became established by the appearance of full-scale detectors and international collaborations. On the background of the spectacular astrophysical discoveries of the 1960s and the growing role of relativistic astrophysics, Ludwig Biermann and his collaborators at the Max Planck Institute for Astrophysics in Munich became deeply involved in research related to such new horizons. At the end of the 1960s, Joseph Weber's announcements claiming detection of gravitational waves sparked the decisive entry of this group into the field, in parallel with the appointment of the renowned relativist Juergen Ehlers. The Munich area group of Max Planck institutes provided the fertile ground for acquiring a leading position in the 1970s, facilitating the experimental transition from resonant bars towards laser interferometry and its innovation at increasingly large scales, eventually moving to a dedicated site in Hannover in the early 1990s. The Hannover group emphasized perfecting experimental systems at pilot scales, and never developed a full-sized detector, rather joining the LIGO Scientific Collaboration at the end of the century. In parallel, the Max Planck Institute for Gravitational Physics (Albert Einstein Institute) had been founded in Potsdam, and both sites, in Hannover and Potsdam, became a unified entity in the early 2000s and were central contributors to the first detection of gravitational waves in 2015.Comment: 94 pages. Enlarged version including new results from further archival research. A previous version appears as a chapter in the volume The Renaissance of General Relativity in Context, edited by A. Blum, R. Lalli and J. Renn (Boston: Birkhauser, 2020

Astrophysics in 2005

We bring you, as usual, the Sun and Moon and stars, plus some galaxies and a new section on astrobiology. Some highlights are short (the newly identified class of gamma-ray bursts, and the Deep Impact on Comet 9P/ Tempel 1), some long (the age of the universe, which will be found to have the Earth at its center), and a few metonymic, for instance the term "down-sizing" to describe the evolution of star formation rates with redshift