Discovery of a remarkable subpulse drift pattern in PSR B0818-41

We report the discovery of a remarkable subpulse drift pattern in the relatively less studied wide profile pulsar, B0818-41, using high sensitivity GMRT observations. We find simultaneous occurrence of three drift regions with two different drift rates: an inner region with steeper apparent drift rate flanked on each side by a region of slower apparent drift rate. Furthermore, these closely spaced drift bands always maintain a constant phase relationship. Though these drift regions have significantly different values for the measured P2, the measured P3 value is the same and equal to 18.3 P1. We interpret the unique drift pattern of this pulsar as being created by the intersection of our line of sight (LOS) with two conal rings on the polar cap of a fairly aligned rotator (inclination angle alpha ~ 11 deg), with an ``inner'' LOS geometry (impact angle beta ~ -5.4 deg). We argue that both the rings have the same values for the carousel rotation periodicity P4 and the number of sparks Nsp. We find that Nsp is 19-21 and show that it is very likely that, P4 is the same as the measured P3, making it a truly unique pulsar. We present results from simulations of the radiation pattern using the inferred parameters, that support our interpretations and reproduce the average profile as well as the observed features in the drift pattern quite well.Comment: 5 pages and 7 figures, Accepted for publication in MNRAS Letter

The restitution of an oxalate-damaged epithelium

The renal inner medulla is responsible for the hydro-saline equilibrium maintenance through water and electrolyte excretionin urine. The collecting ducts, which are involved in the urine concentration, are immersed in an extracellular matrix with thehighest body osmolarity. The hyperosmolarity is a key signal for cell differentiation and for the establishment of the urineconcentration mechanism. Moreover, renal ducts are exposed to wastes coming from blood filtration. There are severalnephrotoxic agents such as antibiotics, diuretics, antineoplastic and cytostatic agents, and renal stones. Calcium oxalate stonesare the most common type of kidney stone. The crystal aggregates are harmful for epithelial renal cells and tubular structures,and that damage could lead to the development of chronic kidney disease. Our previous results showed that differentiated renalcells treated with oxalate (Ox) for 24 h lost the typical epithelial cobblestone morphology and showed a spindle-shapedmorphology characteristic of an epithelial mesenchymal transition. After 48 h of Ox, cells started to recover their morphologyand after 72 h of Ox the epithelium was almost reestablished. The aims of the present work were to evaluate whether epithelialintegrity is disrupted after 24 h of Ox and whether epithelial differentiated characteristics are restituted after 72 h of Ox. Todo that, the renal epithelial cells MDCK were grown in a hyperosmolar environment (512 mOsm/Kg H2O) for 72 h to get adifferentiated epithelium, and then subjected to 1.5 mM Ox for 24, 48 and 72 h. After treatments, cell morphology and theexpression of differentiated epithelia markers were evaluated by fluorescence microscopy. E-cadherin, a member of adherensjunctions, was localized to the cell periphery at 24, 48 and 72 h in control conditions. After 24 h of Ox, the protein wasinternalized and its label on the periphery decreased. After 48 h of Ox, E-cadherin was localized both to the cell membranesand to the cytoplasm, while after 72 h of Ox the label was mainly at the cell periphery. In control cells the apical marker gp135was localized at apical cell surface, while in cells treated with 24 h of Ox gp135 apical staining was reduced. After 48 h of Ox,the percentage of cells expressing apical gp135 started to increase reaching values like control conditions at 72 h. Finally,primary cilium was evidenced by acetylated-tubulin immunofluorescence. Control cells showed a high percentage of ciliatedcells, while it decreased upon treatment with 24 h of Ox. After 48 h of Ox, the cells started to recover the primary cilium, andafter 72 h of Ox, the percentage of ciliated cells reached control values. The results showed that the treatment with 24 h of Oxinduces dedifferentiation and after 72 h of the cell damage there is a restitution of the differentiated epithelia. The next goal isto elucidate the molecular mechanisms involved in the restitution of the oxalate-damaged epithelium.Fil: Sendyk, Dylan. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Ciencias Biológicas. Cátedra de Biología Celular y Molecular; ArgentinaFil: Pescio, Lucila Gisele. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Ciencias Biológicas. Cátedra de Biología Celular y Molecular; ArgentinaFil: Fernández Tomé, M. C.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Ciencias Biológicas. Cátedra de Biología Celular y Molecular; ArgentinaFil: Casali, Cecilia Irene. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Ciencias Biológicas. Cátedra de Biología Celular y Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaLVII Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology Research and XVI Annual Meeting of the Argentinean Society for General MicrobiologyVirtualArgentinaSociedad Argentina de Investigación Bioquímica y Biología MolecularAsociación Civil de Microbiología Genera

Spark Model for Pulsar Radiation Modulation Patterns

A non-stationary polar gap model first proposed by Ruderman & Sutherland (1975) is modified and applied to spark-associated pulsar emission at radio wave-lengths. It is argued that under physical and geometrical conditions prevailing above pulsar polar cap, highly non-stationary spark discharges do not occur at random positions. Instead, sparks should tend to operate in well determined preferred regions. At any instant the polar cap is populated as densely as possible with a number of two-dimensional sparks with a characteristic dimension as well as a typical distance between adjacent sparks being about the polar gap height. Our model differs, however, markedly from its original 'hollow cone' version. The key feature is the quasi-central spark driven by pair production process and anchored to the local pole of a sunspot-like surface magnetic field. This fixed spark prevents the motion of other sparks towards the pole, restricting it to slow circumferential drift across the planes of field lines converging at the local pole. We argue that the polar spark constitutes the core pulsar emission, and that the annular rings of drifting sparks contribute to conal components of the pulsar beam. We found that the number of nested cones in the beam of typical pulsar should not excced three; a number also found by Mitra & Deshpande (1999) using a completely different analysis.Comment: 31 pages, 8 figures, accepted by Ap

Unraveling the drift behaviour of the remarkable pulsar PSR B0826-34

We present new results from high sensitivity GMRT observations of PSR B0826-34. We provide a model to explain the observed subpulse drift properties of this pulsar, including the apparent reversals of the drift direction. In this model, PSR B0826-34 is close to being an aligned rotator. We solve for the emission geometry of this pulsar and show that the angle between the rotation and the magnetic axes is less than 5 deg. We see evidence for as many as 6 to 7 drifting bands in the main pulse at 318 MHz, which are part of a circulating system of about 15 spark-associated subpulse emission beams. We provide quantitative treatments of the aliasing problem and various effects of geometry. The observed drift rate is an aliased version of the true drift rate, such that a subpulse drifts to the location of the adjacent subpulse (or a multiple thereof) in about one pulsar period. We show that small variations, of the order of 3-8%, in the mean drift rate are then enough to explain the apparent reversals of drift direction. We find the mean circulation time of the drift pattern to be significantly longer than the predictions of the original RS75 model and propose an explanation for this, based on modified models with temperature regulated partial ion flow in the polar vacuum gap. From the variation of the mean subpulse separation across the main pulse window, we show that the spark pattern is not centred around the dipole axis, but around a point much closer (within a degree or so) to the rotation axis -- we discuss the implication of this.Comment: 23 pages (including 9 figure). Submitted to Astronomy and Astrophysics on November 11, 200

Spectrum evolution in binary pulsar B1259-63/LS 2883 Be star and gigahertz-peaked spectra

We study the radio spectrum of PSR B1259-63 orbiting around the Be star LS 2883 and show that the shape of the spectrum depends on the orbital phase. At frequencies below 3 GHz PSR B1259-63 flux densities are lower when measured near the periastron passage than those measured far from periastron. We suggest that an interaction of the radio waves with the Be star environment accounts for this effect. While it is quite natural to explain the pulsar eclipse by the presence of an equatorial disk around LS 2883, this disk alone cannot be responsible for the observed spectral evolution of PSR B1259-63 and we, therefore, propose a qualitative model which explains this evolution. We consider two mechanisms that might influence the observed radio emission: free-free absorption and cyclotron resonance. We believe that this binary system can hold the clue to the understanding of gigahertz-peaked spectra of pulsars.Comment: 5 pages, 4 figures, MNRAS Letters, 418, L114-L118 (2011

Family with the Modified Internal Structure as the Source of Social Exclusion of the Youth

A family with the modified internal structure creates different life conditions for an adolescent from the conditions in full families. The research run on the junior high school students proves that the families suffer from difficulties more often - the difficulties connected both with the sphere of material existence and the sphere of mutual relationships. The students from incomplete families more frequently experience violent behaviour from parents and more often suffer from loneliness. Such a complicated family situation and accompanying problems cause the students more exposed to depression, difficulties at school and anti-social behaviour.Rodzina o zmienionej strukturze wewnętrznej stwarza odmienne niż w rodzinach pełnych warunki życia dorastającego dziecka. Badania młodzieży gimnazjalnej dowodzą, że rodziny te częściej przeżywają trudności - zarówno te związane ze sferą bytu materialnego, jak i sferą wzajemnych relacji. Uczniowie z rodzin innych niż pełna nieco częściej doświadczają także zachowań przemocowych ze strony rodziców i częściej przeżywają osamotnienie. Ta skomplikowana sytuacja rodzinna i towarzyszące jej problemy powodują, że uczniowie z rodzin o zmienionej strukturze narażeni są na obniżenie nastroju w postaci depresyjności, trudności w szkole, przejawiają także zachowania aspołeczne

Dental implant loss in older versus younger patients : a systematic review and meta-analysis of prospective studies

The aim of this systematic review was to evaluate implant loss in younger and older patients. An electronic search of four databases (MEDLINE, EMBASE, SCOPUS and the Cochrane Library) was undertaken until May 2016 without time restriction and was supplemented by manual searching. Prospective cohorts were included if they met the following criteria: (i) presence of an exposed group (older subjects) with a minimum age of 60 years; (ii) presence of a control group (younger subjects) with a maximum age of 59 years; and (iii) outcome data considering implant survival or loss. Meta-analyses were performed to evaluate the impact of ageing on implant failure. Of 4152 potentially eligible articles, four were included in the qualitative analysis and quantitative synthesis. The pooled estimates suggest that the risk of implant loss in older patients is not significantly higher (RR = 0.92; 95% CI 0.43-1.96, P = 0.83) when compared to younger subjects. This systematic review suggests that age is not a limiting factor for dental implant therapy