Discovery of coherent millisecond X-ray pulsations in Aql X-1

We report the discovery of an episode of coherent millisecond X-ray pulsation in the neutron star low-mass X-ray binary Aql X-1. The episode lasts for slightly more than 150 seconds, during which the pulse frequency is consistent with being constant. No X-ray burst or other evidence of thermonuclear burning activity is seen in correspondence with the pulsation, which can thus be identified as occurring in the persistent emission. The pulsation frequency is 550.27 Hz, very close (0.5 Hz higher) to the maximum reported frequency from burst oscillations in this source. Hence we identify this frequency with the neutron star spin frequency. The pulsed fraction is strongly energy dependent, ranging from 10% (16-30 keV). We discuss possible physical interpretations and their consequences for our understanding of the lack of pulsation in most neutron star low-mass X-ray binaries. If interpreted as accretion-powered pulsation, Aql X-1 might play a key role in understanding the differences between pulsating and non-pulsating sources.Comment: 5 pages, 3 figures, accepted by ApJ Letters after minor revisions. Slightly extended discussion. One author added. Uses emulateapj.cl

Measurement of the Fermi Constant by FAST

An initial measurement of the lifetime of the positive muon to a precision of 16 parts per million (ppm) has been performed with the FAST detector at the Paul Scherrer Institute. The result is tau_mu = 2.197083 (32) (15) microsec, where the first error is statistical and the second is systematic. The muon lifetime determines the Fermi constant, G_F = 1.166353 (9) x 10^-5 GeV^-2 (8 ppm).Comment: 15 pages, 6 figure

Necrotizing Fasciitis Post- Acute Appendicitis

A Fasceíte Necrotizante (FN) é um processo infeccioso da fascia profunda, de evolução rápida e progressiva com necrose secundária do tecido celular subcutâneo. Os autores apresentam um caso de FN da parede abdominal, como complicação extremamente rara de apendicite aguda. Trata-se de uma criança, apendicectomizada por apendicite aguda gangrenada, que evolui para quadro infeccioso grave, com dor e processo inflamatório da parede abdominal. Após diagnóstico, foi submetido a desbridamento cirúrgico da parede abdominal e drenagem de abcesso intraperitoneal. Realizada terapêutica antibiótica, desbridamentos cirúrgicos e pensos sucessivos da lesão e ao 22º dia efectuou-se enxerto dermo-epidérmico de área cruenta residual da parede abdominal. Porque o prognóstico está intimamente relacionado com o tempo decorrido até ao diagnóstico correcto e início de terapêutica adequada, é de extrema importância que este diagnóstico seja considerado

Oral liquid L-thyroxine (L-t4) may be better absorbed compared to L-T4 tablets following bariatric surgery.

Drug malabsorption is a potential concern after bariatric surgery. We present four case reports of hypothyroid patients who were well replaced with thyroxine tablets to euthyroid thyrotropin (TSH) levels prior to Roux-en-Y gastric bypass surgery. These patients developed elevated TSH levels after the surgery, the TSH responded reversibly to switching from treatment with oral tablets to a liquid formulation

Neutron Acceleration in Uniform Electromagnetic Fields

The question as to whether neutron acceleration can occur in uniform electromagnetic fields is examined. Although such an effect has been predicted using the canonical equations of motion some doubt has been raised recently as to whether it is in principle observable for a spin 1/2 particle. To resolve this issue a gedanken experiment is proposed and analyzed using a wave packet construction for the neutron beam. By allowing arbitrary orientation for the neutron spin as well as for the electric and magnetic fields a non vanishing acceleration of the center of the neutron wave packet is found which confirms the predictions of the canonical formalism.Comment: 11 page

Oncological safety of stromal vascular fraction enriched fat grafting in two-stage breast reconstruction after nipple sparing mastectomy: long-term results of a prospective study

OBJECTIVE: Autologous fat transfer (AFT) is commonly used to treat implant palpability and prevent fibrosis and thinning in mastectomy skin flaps. A major limit to this procedure is volume retention over time, leading to the introduction of fat enrichment with stromal vascular fraction (SVF+AFT). Oncological concerns have been raised over the injection of an increased concentration of progenitors cells (ASCs) in the SVF. The aim of the study is to evaluate the long-term cancer recurrence risk of SVF+AFT cases compared to AFT, in patients undergoing Nipple Sparing Mastectomy (NSM). PATIENTS AND METHODS: A prospective study was designed to compare three groups of patients undergoing NSM followed by SVF+AFT, AFT or none (control group), after a two-stage breast reconstruction. Patients were strictly followed-up for at least 5-years from the second stage reconstructive procedure. Loco-regional and systemic recurrence rate were evaluated over time as the primary outcome. Logistic regression was used to investigate which factors were associated with recurrence events and independent variables of interest were: surgical technique, age above 50 years old, lympho-vascular invasion, oncological stage, adjuvant or neoadjuvant chemotherapy, adjuvant radiotherapy and adjuvant hormone therapy. RESULTS: 41 women were included in G1 (SVF+AFT), 64 in G2 (AFT), and 64 in G3 (control group). Loco-regional recurrence rate was 2.4% for G1, 4.7% for G2, and 1.6% for G3. Systemic recurrence was 7.3%, 3.1%, and 3.1%, respectively. Among the variables included, there were no significant risk factors influencing a recurrence event, either loco-regional or systemic. In particular, SVF+AFT (G1) did not increase the oncological recurrence. CONCLUSIONS: Our data suggest that both centrifuged and SVF-enhanced fat transfer have a similar safety level in comparison to patients who did not undergo fat grafting in breast reconstruction after NSM

Persistence of Left Superior Vena Cava Associated to Esophageal Atresia: Presentation of 5 Cases

Objectivos: A atresia do esófago está associada a uma variedade de malformações congénitas de outros órgãos. A persistência da veia cava superior esquerda e uma das malformações venosas torácicas mais comuns, ocorrendo em 0,3% da população. O objectivo deste estudo é caracterizar a persistência da veia cava superior esquerda nos doentes com atresia do esófago tratados no Hospital Dona Estefânia. Métodos: Estudo retrospectivo dos doentes admitidos por atresia do esófago desde Janeiro 2002 a Dezembro 2013. As seguintes variáveis foram estudadas, considerando, idade gestacional, o peso à nascença, o sexo, tipo de atresia do esófago, ecocardiograma no pré-operatório, malformações associadas, abordagem cirúrgica, eventual ecocardiograma no pós-operatório e angioressonância. Resultados: De um total de 107 doentes, em cinco casos foi diagnosticada persistência da veia cava superior esquerda. Destes, apenas um tinha diagnostico pré-natal. A restante investigação revelou um doente com atresia duodenal e outro com malformação do aparelho urinário, coloboma e malformação bilateral dos pavilhões auriculares. Todos os cinco doentes foram submetidos a toracotomia, esofagoesofagostomia primária após laqueação da fístula traqueo-esofágica e angio-ressonância para caracterizar a malformação vascular. Não houve registo de complicações, quer intra-operatórias quer pós-operatórias. Conclusão: Apesar do estudo pré-operatório, apenas se diagnosticou persistência da veia cava superior esquerda num dos doentes. O diagnóstico é geralmente feito de forma incidental durante a colocação rotineira de catéteres venosos centrais à esquerda. É importante identificar estes doentes e caracterizar o seu padrão de retorno venoso cardíaco, pelo risco de complicações embó1icas paradoxais para o sistema arterial