RESUMO
Several long-period radio transients have recently been discovered, with strongly polarized coherent radio pulses appearing on timescales between tens to thousands of seconds1,2. In some cases, the radio pulses have been interpreted as coming from rotating neutron stars with extremely strong magnetic fields, known as magnetars; the origin of other, occasionally periodic and less-well-sampled radio transients is still debated3. Coherent periodic radio emission is usually explained by rotating dipolar magnetic fields and pair-production mechanisms, but such models do not easily predict radio emission from such slowly rotating neutron stars and maintain it for extended times. On the other hand, highly magnetic isolated white dwarfs would be expected to have long spin periodicities, but periodic coherent radio emission has not yet been directly detected from these sources. Here we report observations of a long-period (21 min) radio transient, which we have labelled GPM J1839-10. The pulses vary in brightness by two orders of magnitude, last between 30 and 300 s and have quasiperiodic substructure. The observations prompted a search of radio archives and we found that the source has been repeating since at least 1988. The archival data enabled constraint of the period derivative to <3.6 × 10-13 s s-1, which is at the very limit of any classical theoretical model that predicts dipolar radio emission from an isolated neutron star.
RESUMO
It is thought that neutron stars in low-mass binary systems can accrete matter and angular momentum from the companion star and be spun-up to millisecond rotational periods. During the accretion stage, the system is called a low-mass X-ray binary, and bright X-ray emission is observed. When the rate of mass transfer decreases in the later evolutionary stages, these binaries host a radio millisecond pulsar whose emission is powered by the neutron star's rotating magnetic field. This evolutionary model is supported by the detection of millisecond X-ray pulsations from several accreting neutron stars and also by the evidence for a past accretion disc in a rotation-powered millisecond pulsar. It has been proposed that a rotation-powered pulsar may temporarily switch on during periods of low mass inflow in some such systems. Only indirect evidence for this transition has hitherto been observed. Here we report observations of accretion-powered, millisecond X-ray pulsations from a neutron star previously seen as a rotation-powered radio pulsar. Within a few days after a month-long X-ray outburst, radio pulses were again detected. This not only shows the evolutionary link between accretion and rotation-powered millisecond pulsars, but also that some systems can swing between the two states on very short timescales.
RESUMO
Massive stars end their short lives in spectacular explosions--supernovae--that synthesize new elements and drive galaxy evolution. Historically, supernovae were discovered mainly through their 'delayed' optical light (some days after the burst of neutrinos that marks the actual event), preventing observations in the first moments following the explosion. As a result, the progenitors of some supernovae and the events leading up to their violent demise remain intensely debated. Here we report the serendipitous discovery of a supernova at the time of the explosion, marked by an extremely luminous X-ray outburst. We attribute the outburst to the 'break-out' of the supernova shock wave from the progenitor star, and show that the inferred rate of such events agrees with that of all core-collapse supernovae. We predict that future wide-field X-ray surveys will catch each year hundreds of supernovae in the act of exploding.
Assuntos
Hidrocistoma , Neoplasias das Glândulas Sudoríparas , Humanos , México/epidemiologia , Hidrocistoma/patologia , Hidrocistoma/tratamento farmacológico , Hidrocistoma/diagnóstico , Feminino , Masculino , Pessoa de Meia-Idade , Neoplasias das Glândulas Sudoríparas/patologia , Neoplasias das Glândulas Sudoríparas/diagnóstico , Adulto , Encaminhamento e Consulta , Neoplasias Orbitárias/tratamento farmacológico , Neoplasias Orbitárias/diagnóstico , Idoso , Toxinas Botulínicas Tipo A/administração & dosagem , Toxinas Botulínicas/administração & dosagemRESUMO
METHODS: We studied a group of 36 fertile women affected with moderate-to-severe cyclical mastalgia (mean age: 26.0 years) showing a normal menstrual history and normal basal levels of circulating hormones, including prolactin (PRL), luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol (E2), progesterone (P), testosterone (T), dehydroepiandrosterone sulphate (delta HEAs), androstenedione (A). Using serial measurements of PRL plasma levels after an intravenous injection of thyrotropin-releasing hormone (TRH), (TRH test), patients were divided in two groups: 19 patients with abnormal PRL response to TRH and the remaining 17 with normal response. RESULTS: Bromocriptine treatment, 2.5 mg b.i.d. for 3-6 months, was effective in 73.6% of patients with abnormal TRH test and in 23.5% of patients with normal TRH test: the difference was statistically significant. On the other hand, 76.9% of patients with either normal TRH test or resistant to bromocriptine therapy had a favourable response to percutaneous progesterone and systemic non-steroidal antiinflammatory drugs (NSAIDs). CONCLUSIONS: These results seem to confirm the hypothesis that PRL response to TRH could be used to identify patients affected with cyclical mastalgia that are likely to benefit by bromocriptine treatment.
Assuntos
Doenças Mamárias/tratamento farmacológico , Dor/tratamento farmacológico , Síndrome Pré-Menstrual/tratamento farmacológico , Prolactina/sangue , Hormônio Liberador de Tireotropina , Adolescente , Adulto , Androstenodiona/sangue , Anti-Inflamatórios não Esteroides/uso terapêutico , Doenças Mamárias/sangue , Doenças Mamárias/etiologia , Bromocriptina/administração & dosagem , Bromocriptina/uso terapêutico , Interpretação Estatística de Dados , Sulfato de Desidroepiandrosterona/sangue , Agonistas de Dopamina/uso terapêutico , Estradiol/sangue , Feminino , Hormônio Foliculoestimulante/sangue , Antagonistas de Hormônios/administração & dosagem , Antagonistas de Hormônios/uso terapêutico , Humanos , Hormônio Luteinizante/sangue , Dor/sangue , Dor/etiologia , Síndrome Pré-Menstrual/complicações , Progesterona/sangue , Progesterona/uso terapêutico , Prolactina/antagonistas & inibidores , Radioimunoensaio , Testosterona/sangueRESUMO
Warthin's tumor is a debated pathological condition. There are many controversies concerning this disease such as its origin (hereditary or acquired), its nature (whether neoplastic or no), its topographical relation with the salivary glands, its relationship with possible concomitant pathologies (dysmetabolic, infective, neoplastic, etc.), the problems of diagnosis and of differential diagnosis with all possible causes of cervical swelling, and also the problems of surgical treatment in relation to the possible involvement of the salivary glands. In this paper two clinical cases are described. The first one is characterized by a latero-cervical bilateral Warthin's tumor, apparently independent of the salivary glands, associated with rhinopharyngeal lymphatic hyperplasia and nodular colloid goiter. The second case is characterized by a latero-cervical uni-lateral Warthin's tumor, linked by a slender layer with the ipsilateral parotid gland, associated with breast cancer. Starting point from the discussion of these two cases, the Authors make remarks in order to answer some of the aforementioned questions.
Assuntos
Adenolinfoma , Neoplasias de Cabeça e Pescoço , Neoplasias Primárias Múltiplas , Neoplasias Parotídeas , Adenolinfoma/diagnóstico por imagem , Adenolinfoma/etiologia , Adenolinfoma/patologia , Adenolinfoma/cirurgia , Idoso , Neoplasias da Mama/cirurgia , Carcinoma Ductal de Mama/cirurgia , Feminino , Neoplasias de Cabeça e Pescoço/diagnóstico por imagem , Neoplasias de Cabeça e Pescoço/etiologia , Neoplasias de Cabeça e Pescoço/patologia , Neoplasias de Cabeça e Pescoço/cirurgia , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias Primárias Múltiplas/diagnóstico por imagem , Neoplasias Primárias Múltiplas/etiologia , Neoplasias Primárias Múltiplas/patologia , Neoplasias Primárias Múltiplas/cirurgia , Neoplasias Parotídeas/diagnóstico por imagem , Neoplasias Parotídeas/etiologia , Neoplasias Parotídeas/patologia , Neoplasias Parotídeas/cirurgia , Neoplasias da Glândula Tireoide/terapia , Tomografia Computadorizada por Raios XRESUMO
Soft gamma repeaters (SGRs) and anomalous x-ray pulsars form a rapidly increasing group of x-ray sources exhibiting sporadic emission of short bursts. They are believed to be magnetars, that is, neutron stars powered by extreme magnetic fields, B ~ 10(14) to 10(15) gauss. We report on a soft gamma repeater with low magnetic field, SGR 0418+5729, recently detected after it emitted bursts similar to those of magnetars. X-ray observations show that its dipolar magnetic field cannot be greater than 7.5 × 10(12) gauss, well in the range of ordinary radio pulsars, implying that a high surface dipolar magnetic field is not necessarily required for magnetar-like activity. The magnetar population may thus include objects with a wider range of B-field strengths, ages, and evolutionary stages than observed so far.
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PIP: The sexual problem of the handicapped, individuals who are physically, intellectually, emotionally, or socially handicapped in any way, is discussed. Certain considerations which must be faced include 1) the restrictive activity of the handicapped, 2) the degree of isolation because of the "difference" from other people, and 3) the way people feel about the handicapped. These factors must be kept in mind in the work the IPPF does with the handicapped. The kinds of contraceptive advice which may be offered may be limited because of physical incapacities make certain methods inappropriate. Handicapped people must be dealt with as human beings. They require the same care and concern as other people so that they will not become too isolated. Contraceptive counseling and sex education cannot be the complete responsibility of the parents of the handicapped. They are not equipped to carry out such activities. Planned parenthood organizations should join with parents, parents' organizations, health and social organizations, teachers, and others working with the handicapped to benefit from their experience with handicapped persons.^ieng
Assuntos
Anticoncepção , Aconselhamento , Instituições de Assistência Ambulatorial , Serviços de Planejamento Familiar , Planejamento em Saúde , Organização e AdministraçãoRESUMO
A compact scanning microscope that uses a semiconductor laser both to illuminate a specimen and to detect the signal reflected from it is described. It is demonstrated that the spatial filtering performed by the laser detector ensures confocal operation. Two detection regimes, one employing a laser power monitor and the other using the diode junction voltage as a signal, are compared.