A white dwarf-neutron star relativistic binary model for soft gamma-ray repeaters

A scenario for SGRs is introduced in which gravitational radiation reaction effects drive the dynamics of an ultrashort orbital period X-ray binary embracing a high-mass donor white dwarf (WD) to a rapidly rotating low magnetised massive neutron star (NS) surrounded by a thick, dense and massive accretion torus. Driven by GR reaction, sparsely, the binary separation reduces, the WD overflows its Roche lobe and the mass transfer drives unstable the accretion disk around the NS. As the binary circular orbital period is a multiple integer number ($m$) of the period of the WD fundamental mode (Pons et al. 2002), the WD is since long pulsating at its fundamental mode; and most of its harmonics, due to the tidal interaction with its NS orbital companion. Hence, when the powerful irradiation glows onto the WD; from the fireball ejected as part of the disk matter slumps onto the NS, it is partially absorbed. This huge energy excites other WD radial ($p$-mode) pulsations (Podsiadlowski 1991,1995). After each mass-transfer episode the binary separation (and orbital period) is augmented significantly (Deloye & Bildsten 2003; Al\'ecyan & Morsink 2004) due to the binary's angular momentum redistribution. Thus a new adiabatic inspiral phase driven by GR reaction starts which brings the binary close again, and the process repeats. This model allows to explain most of SGRs observational features: their recurrent activity, energetics of giant superoutbursts and quiescent stages, and particularly the intriguing subpulses discovered by BeppoSAX (Feroci et al. 1999), which are suggested here to be {\it overtones} of the WD radial fundamental mode (see the accompanying paper: Mosquera Cuesta 2004b).Comment: This paper was submitted as a "Letter to the Editor" of MNRAS in July 17/2004. Since that time no answer or referee report was provided to the Author [MNRAS publication policy limits reviewal process no longer than one month (+/- half more) for the reviewal of this kind of submission). I hope this contribution is not receiving a similar "peer-reviewing" as given to the A. Dar and A. De Rujula's "Cannonball model for gamma-ray bursts", or to the R.K. Williams' "Penrose process for energy extraction from rotating black holes". The author welcomes criticisms and suggestions on this pape

Ischemic Stroke and Epilepsy in a Patient with Tourette´s Syndrome: Association with the Antiphospholipid Syndrome and Good Response to Levetiracetam

The role played by different humoral factors, including antiphospholipid antibodies, in the pathogenesis of Tourette syndrome (TS) is still presently unclear. We present a patient with chronic and severe TS who, at the age of 16 years, presented an ischemic stroke in the left posterior cerebral artery and/or postero-inferior temporal branch of the left medial cerebral artery. A complete study was negative with the exception of a positive lupus anticoagulant. The stroke was related with the primary antiphospholipid syndrome (APS). The stroke manifested visual abnormalities and thereafter by secondary generalized complex partial seizures. The epileptic syndrome was initially difficult to control but responded dramatically to levetiracetam. With this therapy, the manifestations of TS, especially the tics, improved. We conclude that some TS cases may present APS. In addition, levetiracetam may be useful in the management of TS. Further investigations should pursue both these facts

Early Universe Constraints on Time Variation of Fundamental Constants

We study the time variation of fundamental constants in the early Universe. Using data from primordial light nuclei abundances, CMB and the 2dFGRS power spectrum, we put constraints on the time variation of the fine structure constant $\alpha$, and the Higgs vacuum expectation value $$without assuming any theoretical framework. A variation in$$ leads to a variation in the electron mass, among other effects. Along the same line, we study the variation of $\alpha$ and the electron mass $m_e$. In a purely phenomenological fashion, we derive a relationship between both variations.Comment: 18 pages, 12 figures, accepted for publication in Physical Review

Lewis Base Behavior of Bridging Nitrido Ligands of Titanium Polynuclear Complexes

The Lewis base behavior of mu(3)-nitrido ligands of the polynuclear titanium complexes [{Ti(eta(5)-C(5)Me(5))(mu-NH)}(3)(mu(3)-N)] (1) and [{Ti(eta(5)-C(5)Me(5))}(4)-(mu(3)-N)(4)] (2) to MX Lewis acids has been observed for the first time. Complex 1 entraps one equivalent of copper(I) halide or copper(I) trifluorornethanesulfonate through the basal NH imido groups to give cube-type adducts [XCu{(mu(3)-NH)(3)Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)}] (X=Cl (3), Br (4), I (5), OSO(2)CF(3) (6)). However, the treatment of 1 with an excess (>= 2 equiv) of copper reagents afforded complexes [XCu{(mu(3)-NH)(3)Ti(3)(eta(5)-C(5)Me(5))(3)(mu(4)-N)(CuX)}] (X=Cl (7), Br (8), I (9) OSO(2)CF(3) (10)) by incorporation of an additional CuX fragment Lit the mu(3)-N nitrido apical group. Similarly, the tetranuclear cube-type nitrido derivative 2 is capable of incorporating one, two, or up to three CuX units at the mu(3)-N ligands to give complexes [{Ti(eta(5)-C(5)Me(5))}(4)(mu(3)-N)(4-n)-{(mu(4)-N)CuX}(n)] (X=Br (11), n=1; X=Cl (12) n=2; X=OSO(2)CF(3) (13), n=3). Compound 2 also reacts with silver(I) trifluoromethanesulfortate (>= 1 equiv) to give the adduct [{Ti(eta(5)-C(5)Me(5))}(4)(mu(3)-N)(3){(mu(4)-N)AgOSO(2)CF(3)}] (14). X-ray crystal structure determinations have been performed for complexes 8-13. Density functional theory calculations have been carried out to understand the nature and strength of the interactions of [{Ti(eta(5)-C(5)H(5))(mu-NH)}(3)(mu(3)-N)] (1') and [{Ti(eta(5)-C(5)H(5))}(4)-(mu(3)-N)(4)] (2') model complexes with copper and silver MX fragments. Although coordination through the three basal NH imido groups is thermodynamically preferred in the case of V, in both complexes the mu(3)-nitrido groups act as two-electron donor Lewis bases to the appropriate Lewis acids.MINISTERIO DE EDUCACIÓN Y CIENCIA, COMUNIDAD DE MADRID, UNIVERSIDAD DE ALCALÁ, GENERALITAT DE CATALUNY

Surveillance of SARS-CoV-2 virus circulation using Acute Respiratory Infections sentinel system of Catalonia (PIDIRAC) during the 2019-2020 season: A retrospective observational study

Background: In the context of COVID-19 pandemic in Catalonia (Spain), the present study analyses respiratory samples collected by the primary care network using Acute Respiratory Infections Sentinel Surveillance System (PIDIRAC) during the 2019-2020 season to complement the pandemic surveillance system in place to detect SARS-CoV-2. The aim of the study is to describe whether SARS-CoV-2 was circulating before the first confirmed case was detected in Catalonia, on February 25th, 2020. Methods: The study sample was made up of all samples collected by the PIDIRAC primary care network as part of the Influenza and Acute Respiratory Infections (ARI) surveillance system activities. The study on respiratory virus included coronavirus using multiple RT-PCR assays. All positive samples for human coronavirus were subsequently typed for HKU1, OC43, NL63, 229E. Every respiratory sample was frozen at-80°C and retrospectively studied for SARS-CoV-2 detection. A descriptive study was performed, analysing significant differences among variables related to SARS-CoV- 2 cases comparing with rest of coronaviruses cases through a bivariate study with Chi-squared test and statistical significance at 95%. Results: Between October 2019 and April 2020, 878 respiratory samples from patients with acute respiratory infection or influenza syndrome obtained by PIDIRAC were analysed. 51.9% tested positive for influenza virus, 48.1% for other respiratory viruses. SARS-CoV-2 was present in 6 samples. The first positive SARS-CoV-2 case had symptom onset on 2 March 2020. These 6 cases were 3 men and 3 women, aged between 25 and 50 years old. 67% had risk factors, none had previous travel history nor presented viral coinfection. All of them recovered favourably. Conclusion: Sentinel Surveillance PIDIRAC enhances global epidemiological surveillance by allowing confirmation of viral circulation and describes the epidemiology of generalized community respiratory viruses' transmission in Catalonia. The system can provide an alert signal when identification of a virus is not achieved in order to take adequate preparedness measures

Anisotropic Pressures in Very Dense Magnetized Matter

The problem of anisotropic pressures arising as a consequence of the spatial symmetry breaking introduced by an external magnetic field in quantum systems is discussed. The role of the conservation of energy and momentum of external fields as well as of systems providing boundary conditions in quantum statistics is considered. The vanishing of the average transverse momentum for an electron-positron system in its Landau ground state is shown, which means the vanishing of its transverse pressure. The situation for neutron case and Strange Quark Matter (SQM) in $\beta$-equilibrium is also briefly discussed. Thermodynamical relations in external fields as well as the form of the stress tensor in a quantum relativistic medium are also discussed. The ferromagnetic symmetry breaking is briefly discussed.Comment: 10 page

Quark stars and quantum-magnetically induced collapse

Quark matter is expected to exist in the interior of compact stellar objects as neutron stars or even the more exotic strange stars, based on the Bodmer-Witten conjecture. Bare strange quark stars and (normal) strange quark-matter stars, those possessing a baryon (electron-supported) crust, are hypothesized as good candidates to explain the properties of a set of peculiar stellar sources as the enigmatic X-ray source RX J1856.5-3754, some pulsars as PSR B1828-11 and PSR B1642-03, and the anomalous X-ray pulsars and soft gamma-ray repeaters. In the MIT bag model, quarks are treated as a degenerate Fermi gas confined to a region of space having a vacuum energy density $B_{bag}$ (the Bag constant). In this note, we modif{}y the MIT Bag Model by including the electromagnetic interaction. We also show that this version of the MIT model implies the anisotropy of the Bag pressure due to the presence of the magnetic field. The equations of state of degenerate quarks gases are studied in the presence of ultra strong magnetic fields. The behavior of a system made-up of quarks having (or not) anomalous magnetic moment is reviewed. A structural instability is found, which is related to the anisotropic nature of the pressures in this highly magnetized matter. The conditions for the collapse of this system are obtained and compared to a previous model of neutron stars build-up on a neutron gas having anomalous magnetic moment.Comment: 11 pages, 2 figure

El nicho ecológico de los hominidos del Pleistoceno Medio de Atapuerca.

Sin resume

Paroxysmal bradyarrhythmias are frequent among heart transplant recipients with unexplained syncope: a study based on implantable loop recorders

Research lette