RESUMO
Nearly a century ago it was recognized that radiation absorption by stellar matter controls the internal temperature profiles within stars. Laboratory opacity measurements, however, have never been performed at stellar interior conditions, introducing uncertainties in stellar models. A particular problem arose when refined photosphere spectral analysis led to reductions of 30-50 per cent in the inferred amounts of carbon, nitrogen and oxygen in the Sun. Standard solar models using the revised element abundances disagree with helioseismic observations that determine the internal solar structure using acoustic oscillations. This could be resolved if the true mean opacity for the solar interior matter were roughly 15 per cent higher than predicted, because increased opacity compensates for the decreased element abundances. Iron accounts for a quarter of the total opacity at the solar radiation/convection zone boundary. Here we report measurements of wavelength-resolved iron opacity at electron temperatures of 1.9-2.3 million kelvin and electron densities of (0.7-4.0) × 10(22) per cubic centimetre, conditions very similar to those in the solar region that affects the discrepancy the most: the radiation/convection zone boundary. The measured wavelength-dependent opacity is 30-400 per cent higher than predicted. This represents roughly half the change in the mean opacity needed to resolve the solar discrepancy, even though iron is only one of many elements that contribute to opacity.
RESUMO
The first systematic study of opacity dependence on atomic number at stellar interior temperatures is used to evaluate discrepancies between measured and modeled iron opacity [J. E. Bailey et al., Nature (London) 517, 56 (2015)NATUAS0028-083610.1038/nature14048]. High-temperature (>180 eV) chromium and nickel opacities are measured with ±6%-10% uncertainty, using the same methods employed in the previous iron experiments. The 10%-20% experiment reproducibility demonstrates experiment reliability. The overall model-data disagreements are smaller than for iron. However, the systematic study reveals shortcomings in models for density effects, excited states, and open L-shell configurations. The 30%-45% underestimate in the modeled quasicontinuum opacity at short wavelengths was observed only from iron and only at temperature above 180 eV. Thus, either opacity theories are missing physics that has nonmonotonic dependence on the number of bound electrons or there is an experimental flaw unique to the iron measurement at temperatures above 180 eV.
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BACKGROUND: Deep hypothermic circulatory arrest (DHCA) is used during the repair of congenital heart disease in neonates. However, because of concern about neurologic injury after DHCA, there is increasing use of continuous deep hypothermic low-flow cardiopulmonary bypass (DHCPB). This study examines the effects of DHCPB versus DHCA on pulmonary dynamics in 1-week-old piglets (weight range, 2.5 to 3.5 kg). METHODS: Animals were placed on CPB (37 degrees C) at 100 mL.kg-1.min-1, cooled to 18 degrees C, and then assigned to one of two groups: DHCPB (n = 7), 25 to 50 mL.kg-1.min-1 DHCPB for 90 minutes; or DHCA (n = 8), DHCA for 90 minutes. Animals were rewarmed to 37 degrees C, weaned from CPB, and observed for 30 minutes. Static pulmonary compliance and pulmonary vascular resistance index were assessed before CPB, 5 minutes after CPB, and 30 minutes after CPB. RESULTS: There was greater impairment of static pulmonary compliance after DHCPB compared with 90 minutes of DHCA. There was a trend toward higher pulmonary vascular resistance index in the DHCPB group; however, significance was not reached. CONCLUSIONS: Deep hypothermic low flow cardiopulmonary bypass produces greater pulmonary dysfunction than DHCA, manifested by decreased static pulmonary compliance. If DHCPB is used in place of DHCA in congenital heart operations, close attention to ventilatory and fluid management is mandatory in the postoperative period to prevent further worsening of pulmonary dysfunction.
Assuntos
Ponte Cardiopulmonar/efeitos adversos , Parada Cardíaca Induzida/efeitos adversos , Circulação Pulmonar , Fatores Etários , Animais , Animais Recém-Nascidos , Gasometria , Modelos Animais de Doenças , Hipotermia Induzida , Complacência Pulmonar , Suínos , Fatores de Tempo , Resistência VascularRESUMO
Adult budgerigars (Melopsittacus undulatus) with 2 years of breeding experience were removed from an aviary with enzootic avian polyomavirus (APV) disease and maintained in an isolation unit. Following a 7-month respite from breeding, these birds were allowed to breed without interruption for 2 years. Although the adults were seropositive both at the beginning and end of the experiment, all 102 of their offspring were seronegative. These data suggest that APV can be eliminated from a budgerigar aviary with the use of simple management techniques.
Assuntos
Doenças das Aves , Transmissão Vertical de Doenças Infecciosas/veterinária , Papagaios/virologia , Infecções por Polyomavirus/veterinária , Polyomavirus , Infecções Tumorais por Vírus/veterinária , Criação de Animais Domésticos , Animais , Feminino , Abrigo para Animais , Transmissão Vertical de Doenças Infecciosas/prevenção & controle , Masculino , Papagaios/fisiologia , Infecções por Polyomavirus/prevenção & controle , Infecções por Polyomavirus/transmissão , Infecções Tumorais por Vírus/prevenção & controle , Infecções Tumorais por Vírus/transmissãoRESUMO
This article describes the imaging of aortic dissection from the perspective of a multidisciplinary imaging team. The relative merits of radiography, aortography, computed tomography, magnetic resonance imaging, ultrasound and nuclear medicine are described. Each technique has unique advantages for initial diagnosis, confirmation and follow-up. In recent years, ultrasound, computed tomography and magnetic resonance imaging have seen increased use for diagnosis of the condition.
Assuntos
Aneurisma Aórtico/diagnóstico , Dissecção Aórtica/diagnóstico , Diagnóstico por Imagem , Dissecção Aórtica/diagnóstico por imagem , Aneurisma Aórtico/diagnóstico por imagem , Aneurisma da Aorta Abdominal/diagnóstico , Aneurisma da Aorta Torácica/diagnóstico , Aortografia , Ecocardiografia , Humanos , Imageamento por Ressonância Magnética , Cintilografia , Tomografia Computadorizada por Raios XAssuntos
Amiloidose/complicações , Doenças do Colo/complicações , Perfuração Intestinal/etiologia , Doenças do Colo Sigmoide/etiologia , Dor Abdominal/etiologia , Dor Abdominal/cirurgia , Idoso , Idoso de 80 Anos ou mais , Amiloidose/patologia , Amiloidose/cirurgia , Doenças do Colo/patologia , Doenças do Colo/cirurgia , Humanos , Perfuração Intestinal/patologia , Perfuração Intestinal/cirurgia , Masculino , Doenças do Colo Sigmoide/patologia , Doenças do Colo Sigmoide/cirurgiaAssuntos
Ética Médica , Radiografia , Tecnologia Radiológica/educação , Códigos de Ética , Cultura , Currículo , Tomada de Decisões , Análise Ética , Teoria Ética , Humanos , Jurisprudência , Resolução de Problemas , Religião , Ciência , Valores SociaisRESUMO
Autoradiographic techniques were used to measure rate of replication and length of the replication unit in cultured cells of Scaphiopus couchi, Bufo cognatus, Rana clamitans, and Triturus viridescens, having nuclear DNA amounts in the ratio 1:4:7:39 respectively. The autoradiographic experiments were designed to show whether the larger amounts of nuclear DNA are correlated with more rapid rates of synthesis and/or with longer replication units. -- The DNA replication rate was 2.5 mu/minute (corrected for two growing points) with 10 minutes 3H-thymidine label at 22 degrees C, but decreased with longer labelling durations. The length of the replication unit (estimated by the distance from the center of one autoradiograph to the center of the next in sequence) was most commonly in the 10-25 mu range with a 30 minute label, in all four species. The average center-to-center distance was 8 mu at 10 minutes and increased with label duration, to over 45 mu with 24 hours label. Replication was predominantly but not exclusively bidirectional. Neither rate of replication nor length of the replication unit was proportional to the amount of DNA in these species.
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Anfíbios , Replicação do DNA , Animais , Anuros , Autorradiografia , Bufonidae , Replicação do DNA/efeitos dos fármacos , Floxuridina/metabolismo , Floxuridina/farmacologia , Marcação por Isótopo/métodos , Ranidae , Timidina/metabolismo , Trítio , Triturus , Uridina/metabolismoRESUMO
Appendicular carcinoid tumours in 147 patients are presented. Two patients had evidence of metastatic spread at the time of presentation. Both patients had primary tumours less than 2 cm in diameter. Size remains the most reliable guide to the malignant potential of these tumours. If, after simple appendicectomy, a carcinoid tumour is found with a post-formalin fixation diameter greater than 1.5 cm then a subsequent right hemicolectomy should be considered.
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Neoplasias do Apêndice/cirurgia , Tumor Carcinoide/cirurgia , Adolescente , Adulto , Idoso , Neoplasias do Apêndice/patologia , Tumor Carcinoide/patologia , Criança , Colectomia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fatores SexuaisRESUMO
Small bowel is the commonest site of gastrointestinal metastases from cutaneous malignant melanoma. Five patients with malignant melanoma involving the small bowel are reported. One patient was operated on for suspected acute appendicitis, two patients for gastrointestinal bleeding and two patients for small bowel obstruction. Two patients remain well 4 and 5 years after surgery.
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Neoplasias Intestinais/secundário , Melanoma/secundário , Adulto , Feminino , Humanos , Intestino Delgado , Masculino , Pessoa de Meia-IdadeRESUMO
The majority of splenic cysts occur as a result of parasitic infection, most commonly in countries where hydatid disease is endemic. In the Western world however, their occurrence is extremely rare and aetiology less clear. Approximately 800 cases of non-parasitic splenic cysts have been reported in the world literature to date. Their presentation ranges from that of an incidental finding on abdominal examination to catastrophic intraperitoneal haemorrhage. The methods of treatment of splenic cysts are protean with no universally accepted policy. We report a case of a massive splenic cyst in an adolescent female treated by partial splenectomy. We also present a review of the pertinent literature on this subject paying special attention to the role of conservative surgery with preservation of normal splenic tissue.
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Cistos/cirurgia , Esplenectomia/métodos , Esplenopatias/cirurgia , Adolescente , Cistos/patologia , Feminino , Humanos , Esplenopatias/patologia , Técnicas de SuturaRESUMO
The incidental finding of a rare appendiceal tumour in a previously healthy male patient is described. He presented as an emergency with a self-inflicted abdominal stab injury. At laparotomy, there was no visceral damage but the appendix was hugely distended and appendectomy was performed. Subsequent histological examination of the appendix revealed a low-grade mucinous cystadenocarcinoma. A right hemicolectomy was performed two months later which demonstrated no residual tumour.
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Traumatismos Abdominais/complicações , Neoplasias do Apêndice/complicações , Cistadenocarcinoma Mucinoso/complicações , Ferimentos Perfurantes/complicações , Adulto , Neoplasias do Apêndice/patologia , Neoplasias do Apêndice/cirurgia , Cistadenocarcinoma Mucinoso/patologia , Cistadenocarcinoma Mucinoso/cirurgia , Humanos , MasculinoRESUMO
Forty-two patients with complete rectal prolapse have been treated using the Ivalon sponge rectopexy. There was no operative mortality in this series and only one complete recurrence after an average follow-up of more than 4 years. Pelvic sepsis occurred in one patient and required removal of the sponge. The majority of the patients were satisfied with the results of surgery, despite some remaining incontinent.
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Polivinil , Prolapso Retal/cirurgia , Reto/cirurgia , Adulto , Idoso , Feminino , Seguimentos , Humanos , Masculino , Métodos , Pessoa de Meia-Idade , Complicações Pós-Operatórias , RecidivaRESUMO
OBJECTIVE: To assess the results and cost implications of laparoscopic nephrectomy. PATIENTS AND METHODS: Ten patients underwent attempted laparoscopic nephrectomy and nephro-ureterectomy. The cost of the laparoscopic procedures was estimated to allow comparison with that of open surgery. RESULTS: Two patients required conversion to an open procedure, one for a colonic tear, the other for irretrievable loss of pneumoperitoneum. The median operating time for successful cases was 3 h (range 2.5-4). The mean morphine equivalent of analgesia delivered per patient was 18 mg (range 10-28). There was no mortality. Post-operative complications consisted of one case of prolonged ileus and another of chest infection. The median hospital stay of successful cases was 5 days (range 4-17), and the mean time to return to normal activity was 4 weeks (range 3-6). The cost of the procedure using re-usable instruments was approximately 2000 pounds, comprising 100 pounds for equipment. 900 pounds theatre costs and 1000 pounds for hospital stay. Using disposable equipment adds up to 900 pounds to the cost. In comparison an open nephrectomy typically costs around 2300 pounds. CONCLUSION: Laparoscopic nephrectomy is associated with lower analgesia requirements, shorter hospital stay and quicker return to work than equivalent open procedures. The cost, particularly when performed with re-usable instruments, is not prohibitive being comparable with that of open nephrectomy. With further experience it should become part of the armamentarium of urological surgeons.
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Nefropatias/cirurgia , Laparoscopia/economia , Nefrectomia/economia , Adolescente , Adulto , Idoso , Feminino , Custos de Cuidados de Saúde , Humanos , Nefropatias/economia , Laparoscopia/reabilitação , Tempo de Internação , Masculino , Pessoa de Meia-Idade , Nefrectomia/métodos , Nefrectomia/reabilitação , Fatores de TempoRESUMO
We present the first x-ray spectroscopic measurements of the ionization balance in inertial confinement fusion hohlraums supported by 4omega Thomson scattering diagnostics. The experimental data show agreement with non-LTE radiation-hydrodynamic calculations of the averaged Au charge state and electron temperatures. These findings are consistent with the successful integrated modeling of the hohlraum radiation fields. Comparisons with detailed synthetic spectra calculations show that the experimental ionization distribution is slightly shifted indicating nonsteady state kinetics.
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The reported incidence of gastrointestinal endocrine tumours is variable. In Northern Ireland circumstances allowing such an assessment are favourable with a central diagnostic laboratory and register established to collect data on tumours from a well-defined population of 1.5 million people. From 1970 to 1985, 368 cases were recorded of which 85 per cent were carcinoid tumours. The annual incidence of carcinoid tumours was 1.3 per 100,000 of the population and the majority occurred in the appendix (61 per cent). No patients presented with the carcinoid syndrome. The annual incidence for other tumours was 0.12 per 100,000 for insulinomas; islet cell tumours of unknown type 0.07; Zollinger-Ellison syndrome 0.05; and multiple endocrine neoplasia (MEN) 0.05. There were two cases of VIPoma, one glucagonoma, one neurotensinoma and one tumour producing ACTH. It is possible that some tumours are more uncommon than others because of difficulty in diagnosis.