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1.
Phys Rev Lett ; 124(4): 042503, 2020 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-32058764

RESUMO

There is sparse direct experimental evidence that atomic nuclei can exhibit stable "pear" shapes arising from strong octupole correlations. In order to investigate the nature of octupole collectivity in radium isotopes, electric octupole (E3) matrix elements have been determined for transitions in ^{222,228}Ra nuclei using the method of sub-barrier, multistep Coulomb excitation. Beams of the radioactive radium isotopes were provided by the HIE-ISOLDE facility at CERN. The observed pattern of E3 matrix elements for different nuclear transitions is explained by describing ^{222}Ra as pear shaped with stable octupole deformation, while ^{228}Ra behaves like an octupole vibrator.

2.
Eur J Nutr ; 59(6): 2805-2812, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31605198

RESUMO

PURPOSE: Intermittent energy restriction (IER) is a popular weight loss (WL) strategy; however, its efficacy in clinical practice remains unknown. The present study compared the effects of IER compared to continuous energy restriction (CER) on WL and cardiometabolic risk factors in primary care. METHODS: A (self-selected) cohort study was conducted at the Rotherham Institute for Obesity (RIO), a primary care-based weight management service. 197(24% male) obese patients volunteered to participate and selected their diet group. IER participants (n = 99) consumed ~ 2600 kJ for two days/week. CER participants (n = 98) restricted their diet by ~ 2100 kJ/day below estimated requirements. Both interventions were delivered alongside RIO standard care. Changes in anthropometry and cardiometabolic disease risk markers (fasting biochemistry and blood pressure) were assessed after a 6-month intervention period and then participants were followed up again 6 months later (month 12). RESULTS: 27 IER patients (27%) and 39 CER patients (40%) completed the 6-month weight loss phase. Among completers, mean (SEM) WL was greater in the IER group at 6 months (5.4 ± 1.1% versus 2.8 ± 0.6%; p = 0.01), as were reductions in fat mass (p < 0.001) and improvements in systolic blood pressure (p < 0.001). Fasting insulin (p = 0.873) and diastolic blood pressure (p = 0.701) were reduced similarly in both groups. However, in the IER group, changes in anthropometry and blood pressure in the IER group had reverted to baseline by 12-month follow-up, whilst the CER group maintained weight loss but showed an increase in blood pressure. CONCLUSIONS: Among completers, IER resulted in superior short-term changes in anthropometry and some cardiometabolic risk factors. However, rates of attrition and weight regain were higher compared with standard care, providing important insights in the implementations of IER within a "real-life" NHS setting. TRIAL REGISTRATION NUMBER: ISRCTN31465600.


Assuntos
Restrição Calórica , Redução de Peso , Estudos de Coortes , Dieta Redutora , Feminino , Humanos , Masculino , Atenção Primária à Saúde
3.
Osteoporos Int ; 30(9): 1893-1896, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31147735

RESUMO

We describe a novel disease of diffuse skeletal histiocytosis associated with multiple fragility fractures and high osteoclast activity. Clinical, radiographic, biochemical, genetic, and histopathological investigations were performed to characterize the diagnosis of an Asian man who presented with hip fracture and diffuse skeletal lytic lesions. After excluding malignancy and other common metabolic bone diseases, open bone biopsy yielded several pathological samples all showing extensive skeletal histiocytosis likely to explain the diffuse axial and appendicular lytic lesions. Rare disorders such as Langerhans histiocytosis, Erdheim-Chester disease, and diffuse cystic skeletal angiomatosis were excluded through careful pathological examination and lack of CD1a and S-100 staining. Whole exome sequencing did not yield diagnostic findings to explain this likely acquired disease. High markers of osteoclast activity suggested excessive focal bone resorption but normalized after zoledronic acid treatment. A novel disease of skeletal histiocytosis with high bone turnover is differentiated from other histiocytic and lytic skeletal diseases.


Assuntos
Doenças Ósseas Metabólicas/diagnóstico , Fraturas Espontâneas/diagnóstico , Histiocitose/diagnóstico , Doenças Ósseas Metabólicas/patologia , Diagnóstico Diferencial , Fraturas Espontâneas/patologia , Histiocitose/patologia , Humanos , Masculino , Pessoa de Meia-Idade , Radiografia , Recidiva
5.
Phys Rev Lett ; 121(25): 252501, 2018 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-30608829

RESUMO

The first 2^{+} and 3^{-} states of the doubly magic nucleus ^{132}Sn are populated via safe Coulomb excitation employing the recently commissioned HIE-ISOLDE accelerator at CERN in conjunction with the highly efficient MINIBALL array. The ^{132}Sn ions are accelerated to an energy of 5.49 MeV/nucleon and impinged on a ^{206}Pb target. Deexciting γ rays from the low-lying excited states of the target and the projectile are recorded in coincidence with scattered particles. The reduced transition strengths are determined for the transitions 0_{g.s.}^{+}→2_{1}^{+}, 0_{g.s.}^{+}→3_{1}^{-}, and 2_{1}^{+}→3_{1}^{-} in ^{132}Sn. The results on these states provide crucial information on cross-shell configurations which are determined within large-scale shell-model and Monte Carlo shell-model calculations as well as from random-phase approximation and relativistic random-phase approximation. The locally enhanced B(E2;0_{g.s.}^{+}→2_{1}^{+}) strength is consistent with the microscopic description of the structure of the respective states within all theoretical approaches. The presented results of experiment and theory can be considered to be the first direct verification of the sphericity and double magicity of ^{132}Sn.

6.
Phys Rev Lett ; 119(12): 122501, 2017 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-29341650

RESUMO

The isotope ^{163}Ho is in many ways the best candidate to perform experiments to investigate the value of the electron neutrino mass. It undergoes an electron capture process to ^{163}Dy with an energy available to the decay, Q_{EC}, of about 2.8 keV. According to the present knowledge, this is the lowest Q_{EC} value for such transitions. Here we discuss a newly obtained spectrum of ^{163}Ho, taken by cryogenic metallic magnetic calorimeters with ^{163}Ho implanted in the absorbers and operated in anticoincident mode for background reduction. For the first time, the atomic deexcitation of the ^{163}Dy daughter atom following the capture of electrons from the 5s shell in ^{163}Ho, the OI line, was observed with a calorimetric measurement. The peak energy is determined to be 48 eV. In addition, a precise determination of the energy available for the decay Q_{EC}=(2.858±0.010_{stat}±0.05_{syst}) keV was obtained by analyzing the intensities of the lines in the spectrum. This value is in good agreement with the measurement of the mass difference between ^{163}Ho and ^{163}Dy obtained by Penning-trap mass spectrometry, demonstrating the reliability of the calorimetric technique.

7.
J R Army Med Corps ; 163(5): 339-341, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28193747

RESUMO

Cutaneous myiasis is a well-described problem in travellers to endemic regions including military personnel. Realistic training is important to ensure that healthcare workers have the confidence and expertise to recognise cutaneous myiasis and safely remove larvae if required. A model is described here that is simple, reproducible and realistic, and will allow for training of military healthcare workers in safe surgical removal of larvae when required.


Assuntos
Educação Médica/métodos , Medicina Militar/educação , Modelos Biológicos , Miíase/parasitologia , Miíase/cirurgia , Animais , Humanos , Larva , Carne/parasitologia , Suínos
8.
Epidemiol Infect ; 143(9): 1964-71, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25387485

RESUMO

Blood culture contamination (BCC) has been associated with unnecessary antibiotic use, additional laboratory tests and increased length of hospital stay thus incurring significant extra hospital costs. We set out to assess the impact of a staff educational intervention programme on decreasing intensive care unit (ICU) BCC rates to <3% (American Society for Microbiology standard). BCC rates during the pre-intervention period (January 2006-May 2011) were compared with the intervention period (June 2011-December 2012) using run chart and regression analysis. Monthly ICU BCC rates during the intervention period were reduced to a mean of 3.7%, compared to 9.5% during the baseline period (P < 0.001) with an estimated potential annual cost savings of about £250,100. The approach used was simple in design, flexible in delivery and efficient in outcomes, and may encourage its translation into clinical practice in different healthcare settings.


Assuntos
Coleta de Amostras Sanguíneas/normas , Sangue/microbiologia , Pessoal de Saúde/educação , Testes Hematológicos/normas , Competência Clínica , Reações Falso-Positivas , Humanos , Irlanda do Norte , Estudos Prospectivos , Estudos Retrospectivos
9.
Int J Obes (Lond) ; 38(1): 22-6, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23897219

RESUMO

OBJECTIVE: To investigate whether ventilatory factors limit exercise in overweight and obese children during a 6-min step test and to compare ventilatory responses during this test with those of healthy weight children. DESIGN: Cross-sectional, prospective comparative study. SUBJECTS: Twenty-six overweight/obese subjects and 25 healthy weight subjects with no known respiratory illness. MEASUREMENTS: Various fatness and fat distribution parameters (using air displacement plethysmography and anthropometry), pulmonary function tests, breath-by-breath gas analysis during exercise, perceived exertion. RESULTS: Young people who are overweight or obese are more likely to experience expiratory flow limitation (expFL) during submaximal exercise compared with their healthy weight peers [OR 7.2 (1.4, 37.3), P=0.019]. Subjects who had lower lung volumes at rest were even more likely to experience exercise-induced expFLs [OR 8.35 (1.4-49.3)]. Both groups displayed similar breathing strategies during submaximal exercise. CONCLUSION: Young people who are overweight/obese are more likely to display expFL during submaximal exercise compared with children of healthy weight . Use of compensatory breathing strategies appeared to enable overweight children to avoid the experience of breathlessness at this intensity of exercise.


Assuntos
Dispneia/etiologia , Teste de Esforço , Tolerância ao Exercício , Exercício Físico , Obesidade Infantil/complicações , Ventilação Pulmonar , Testes de Função Respiratória/métodos , Comportamento Sedentário , Adolescente , Peso Corporal , Criança , Estudos Transversais , Dispneia/fisiopatologia , Dispneia/prevenção & controle , Feminino , Humanos , Masculino , Obesidade Infantil/fisiopatologia , Obesidade Infantil/prevenção & controle , Estudos Prospectivos , Inquéritos e Questionários
10.
Parasite Immunol ; 36(10): 494-502, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24909063

RESUMO

The host inflammatory response to the Onchocerca volvulus endosymbiont, Wolbachia, is a major contributing factor in the development of chronic pathology in humans (onchocerciasis/river blindness). Recently, the toll-like pattern recognition receptor motif of the major inflammatory ligands of filarial Wolbachia, membrane-associated diacylated lipoproteins, was functionally defined in murine models of pathology, including mediation of neutrophil recruitment to the cornea. However, the extent to which human neutrophils can be activated in response to this Wolbachia pattern recognition motif is not known. Therefore, the responses of purified peripheral blood human neutrophils to a synthetic N-terminal diacylated lipopeptide (WoLP) of filarial Wolbachia peptidoglycan-associated lipoprotein (PAL) were characterized. WoLP exposure led to a dose-dependent activation of healthy, human neutrophils that included gross morphological alterations and modulation of surface expressed integrins involved in tethering, rolling and extravasation. WoLP exposure induced chemotaxis but not chemokinesis of neutrophils, and secretion of the major neutrophil chemokine, interleukin 8. WoLP also induced and primed the respiratory burst, and enhanced neutrophil survival by delay of apoptosis. These results indicate that the major inflammatory motif of filarial Wolbachia lipoproteins directly activates human neutrophils in vitro and promotes a molecular pathway by which human neutrophils are recruited to sites of Onchocerca parasitism.


Assuntos
Lipopeptídeos/imunologia , Neutrófilos/imunologia , Onchocerca volvulus/microbiologia , Oncocercose Ocular/imunologia , Wolbachia/imunologia , Animais , Apoptose , Quimiotaxia , Humanos , Interleucina-8/imunologia , Neutrófilos/patologia , Oncocercose Ocular/parasitologia , Explosão Respiratória
11.
Int J Clin Pract ; 68(3): 379-87, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24372837

RESUMO

BACKGROUND: Effective weight loss treatment is important as obesity has severe health and socioeconomic repercussions. Emerging evidence suggests that rapid initial weight loss results in better long-term weight loss maintenance. This remains controversial and contradicts current recommendations for slower weight loss. AIM: To determine the effect of a very low calorie diet (VLCD) with group-based behaviour therapy on weight loss and long-term weight management by means of a retrospective database analysis. METHODS: Data for this retrospective analysis included participants who embarked on the LighterLife Total VLCD programme between 2007 and 2010, and whose weights at baseline and at least 12 months were available (n = 5965). RESULTS: Data were available for 5965 individuals at 1 year, 2044 at 2 years and 580 at 3 years. At baseline, the majority of individuals were Caucasian (n = 5155), female (n = 5419), ≥ 40 years old (n = 4272), 49% were within the body mass index (BMI) range of 30-35 kg/m(2) while 51% had a BMI > 35 kg/m(2) . The average initial weight of the whole cohort was 99.1 kg (SD 16.6). Initial weight and BMI at entry onto programme, as well as numbers of weeks of weight loss were all significantly associated with weight loss achieved on the first weight loss attempt. Weight lost during the initial weight loss phase was the only factor, which was significantly associated with percentage weight loss maintenance for years 1, 2, and 3. CONCLUSION: The findings of this retrospective analysis suggest that provided a longer term weight loss management programme is adhered to, large amounts of initial weight loss can result in important longer term weight loss maintenance in motivated individuals.


Assuntos
Restrição Calórica/métodos , Obesidade/dietoterapia , Redução de Peso/fisiologia , Adolescente , Adulto , Idoso , Terapia Comportamental/métodos , Índice de Massa Corporal , Terapia Combinada , Feminino , Humanos , Assistência de Longa Duração , Masculino , Pessoa de Meia-Idade , Psicoterapia de Grupo/métodos , Estudos Retrospectivos , Resultado do Tratamento , Adulto Jovem
12.
Artigo em Inglês | MEDLINE | ID: mdl-38964865

RESUMO

This study assesses the efficacy of low-field portable MR imaging in measuring ventricular volumes in the pediatric population in the hospital setting. We compared portable and standard of care MR images from the same patient. The estimated ventricular volumes had excellent agreement with a mean bias of 2.06% by Bland-Altman analysis and a correlation of 0.99. From this initial data set, our results suggest that low-field, portable MR imaging is a promising technique for imaging and quantifying ventricular volumes.

13.
Sci Rep ; 14(1): 3284, 2024 02 08.
Artigo em Inglês | MEDLINE | ID: mdl-38332245

RESUMO

Terbium-149 (T1/2 = 4.1 h, Eα = 3.98 MeV (16.7%), 28 µm range in tissue) is a radionuclide with potential for targeted alpha therapy. Due to the negligible emission of α-emitting daughter nuclides, toxicity to healthy tissue may be reduced in comparison with other α-particle emitters. In this study, terbium-149 was produced via 1.4 GeV proton irradiation of a tantalum target at the CERN-ISOLDE facility. The spallation products were mass separated and implanted on zinc-coated foils and, later, radiochemically processed. Terbium-149 was separated from the co-produced isobaric radioisotopes and the zinc coating from the implantation foil, using cation-exchange and extraction chromatographic techniques, respectively. At the end of separation, up to 260 MBq terbium-149 were obtained with > 99% radionuclidic purity. Radiolabeling experiments were performed with DOTATATE, achieving 50 MBq/nmol apparent molar activity with radiochemical purity > 99%. The chemical purity was determined by inductively coupled plasma-mass spectrometry measurements, which showed lead, copper, iron and zinc only at ppb level. The radiolabeling of the somatostatin analogue DOTATATE with [149Tb]TbCl3 and the subsequent in vivo PET/CT scans conducted in xenografted mice, showing good tumor uptake, further demonstrated product quality and its ability to be used in a preclinical setting.


Assuntos
Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Melhoria de Qualidade , Térbio , Animais , Camundongos , Radioisótopos/uso terapêutico , Zinco
14.
Phys Rev Lett ; 110(1): 012502, 2013 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-23383783

RESUMO

An experiment with a newly developed high-resolution kaon spectrometer and a scattered electron spectrometer with a novel configuration was performed in Hall C at Jefferson Lab. The ground state of a neutron-rich hypernucleus, (Λ)(7)He, was observed for the first time with the (e, e'K+) reaction with an energy resolution of ~0.6 MeV. This resolution is the best reported to date for hypernuclear reaction spectroscopy. The (Λ)(7)He binding energy supplies the last missing information of the A = 7, T = 1 hypernuclear isotriplet, providing a new input for the charge symmetry breaking effect of the ΛN potential.

15.
Phys Rev Lett ; 111(14): 141803, 2013 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-24152148

RESUMO

The Q(weak) experiment has measured the parity-violating asymmetry in ep elastic scattering at Q(2)=0.025(GeV/c)(2), employing 145 µA of 89% longitudinally polarized electrons on a 34.4 cm long liquid hydrogen target at Jefferson Lab. The results of the experiment's commissioning run, constituting approximately 4% of the data collected in the experiment, are reported here. From these initial results, the measured asymmetry is A(ep)=-279±35 (stat) ± 31 (syst) ppb, which is the smallest and most precise asymmetry ever measured in ep scattering. The small Q(2) of this experiment has made possible the first determination of the weak charge of the proton Q(W)(p) by incorporating earlier parity-violating electron scattering (PVES) data at higher Q(2) to constrain hadronic corrections. The value of Q(W)(p) obtained in this way is Q(W)(p)(PVES)=0.064±0.012, which is in good agreement with the standard model prediction of Q(W)(p)(SM)=0.0710±0.0007. When this result is further combined with the Cs atomic parity violation (APV) measurement, significant constraints on the weak charges of the up and down quarks can also be extracted. That PVES+APV analysis reveals the neutron's weak charge to be Q(W)(n)(PVES+APV)=-0.975±0.010.

16.
Nanotechnology ; 24(2): 025606, 2013 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-23238021

RESUMO

A homologous series of Au coated iron oxide nanoparticles with hydrodynamic diameters smaller than 60 nm was synthesized with very low Au-to-iron mass ratios, as low as 0.15. The hydrodynamic diameter was determined by dynamic light scattering and the composition by atomic absorption spectroscopy and energy dispersive x-ray spectroscopy. Unusually low Au precursor supersaturation levels were utilized to nucleate and grow Au coatings on iron oxide relative to the formation of pure Au nanoparticles. This approach produced unusually thin coatings by lowering autocatalytic growth of Au on Au, as shown by transmission electron microscopy. Nearly all of the nanoparticles were attracted by a magnet, indicating a minimal number of pure Au particles. The coatings were sufficiently thin to shift the surface plasmon resonance to the near infrared with large extinction coefficients, despite the small particle hydrodynamic diameters observed from dynamic light scattering to be less than 60 nm.


Assuntos
Cristalização/métodos , Ouro/química , Nanopartículas de Magnetita/química , Nanopartículas de Magnetita/ultraestrutura , Absorção , Adsorção , Raios Infravermelhos , Substâncias Macromoleculares/química , Teste de Materiais , Conformação Molecular , Tamanho da Partícula , Propriedades de Superfície
17.
Can J Surg ; 56(6): 405-8, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24284148

RESUMO

BACKGROUND: The use of administrative databases in vascular injury research has been increasing, but the validity of the diagnosis codes used in this research is uncertain. We assessed the positive predictive value (PPV) of International Classification of Diseases, tenth revision (ICD-10), vascular injury codes in administrative claims data in Ontario. METHODS: We conducted a retrospective validation study using the Canadian Institute for Health Information Discharge Abstract Database, an administrative database that records all hospital admissions in Canada. We evaluated 380 randomly selected hospital discharge abstracts from the 2 main trauma centres in Toronto, Ont., St.Michael's Hospital and Sunnybrook Health Sciences Centre, between Apr. 1, 2002, and Mar. 31, 2010. We then compared these records with the corresponding patients' hospital charts to assess the level of agreement for procedure coding. We calculated the PPV and sensitivity to estimate the validity of vascular injury diagnosis coding. RESULTS: The overall PPV for vascular injury coding was estimated to be 95% (95% confidence interval [CI] 92.3-96.8). The PPV among code groups for neck, thorax, abdomen, upper extremity and lower extremity injuries ranged from 90.8 (95% CI 82.2-95.5) to 97.4 (95% CI 91.0-99.3), whereas sensitivity ranged from 90% (95% CI 81.5-94.8) to 98.7% (95% CI 92.9-99.8). CONCLUSION: Administrative claims hospital discharge data based on ICD-10 diagnosis codes have a high level of validity when identifying cases of vascular injury. LEVEL OF EVIDENCE: Observational Study Level III.


CONTEXTE: L'utilisation des bases de données administratives pour la recherche sur les lésions vasculaires est en hausse, mais la validité des codes diagnostiques utilisés dans ces recherches est incertaine. Nous avons évalué la valeur prédictive positive (VPP) des codes de lésions vasculaires de la dixième édition de la Classification internationale des maladies (CIM-10) qui figurent dans une base de données administrative ontarienne. MÉTHODES: Nous avons réalisé une étude de validation rétrospective à partir de la base de données de l'Institut canadien d'information sur la santé (ICIS) sur les congés des patients, une base de données administrative qui enregistre toutes les hospitalisations au Canada. Nous avons évalué 380 congés hospitaliers de 2 grands centres de traumatologie de Toronto, en Ontario, soit l'Hôpital St. Michael's et le Centre des sciences de la santé Sunnybrook, entre le 1er avril 2002 et le 31 mars 2010. Nous avons ensuite comparé ces dossiers aux dossiers hospitaliers des patients correspondants pour vérifier la concordance des codes attribués aux interventions. Nous avons calculé la VPP et la sensibilité pour estimer la validité des codes diagnostiques appliqués aux lésions vasculaires. RÉSULTATS: La VPP globale pour les codes de lésions vasculaires a été estimée à 95% (intervalle de confiance [IC] de 95% 92,3­96,8). Parmi les groupes de codes attribués aux lésions affectant le cou, le thorax, l'abdomen, les membres supérieurs et inférieurs, la VPP a varié de 90,8 (IC de 95% 82,2­95,5) à 97,4 (IC de 95% 91.0­99,3), tandis que la sensibilité a varié de 90% (IC de 95% 81,5­94,8) à 98,7% (IC de 95% 92,9­99,8). CONCLUSION: Les données administratives sur les congés hospitaliers basées sur les codes diagnostiques de la CIM 10 ont un degré de validité élevé pour ce qui est des lésions vasculaires. NIVEAU DE PREUVE: Étude d'observation Niveau III.


Assuntos
Codificação Clínica , Lesões do Sistema Vascular/classificação , Canadá , Humanos , Estudos Retrospectivos , Centros de Traumatologia
18.
Appl Radiat Isot ; 202: 111044, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37797447

RESUMO

Terbium-152 is one of four terbium radioisotopes that together form a potential theranostic toolbox for the personalised treatment of tumours. As 152 Tb decay by positron emission it can be utilised for diagnostics by positron emission tomography. For use in radiopharmaceuticals and for activity measurements by an activity calibrator a high radionuclide purity of the material and an accurate and precise knowledge of the half-life is required. Mass-separation and radiochemical purification provide a production route of high purity 152Tb. In the current work, two mass-separated samples from the CERN-ISOLDE facility have been assayed at the National Physical Laboratory to investigate the radionuclide purity. These samples have been used to perform four measurements of the half-life by three independent techniques: high-purity germanium gamma-ray spectrometry, ionisation chamber measurements and liquid scintillation counting. From the four measurement campaigns a half-life of 17.8784(95) h has been determined. The reported half-life shows a significant difference to the currently evaluated half-life (ζ-score = 3.77), with a relative difference of 2.2 % and an order of magnitude improvement in the precision. This work also shows that under controlled conditions the combination of mass-separation and radiochemical separation can provide high-purity 152Tb.

19.
Nature ; 440(7086): 896-9, 2006 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-16612375

RESUMO

Vega, the second brightest star in the northern hemisphere, serves as a primary spectral type standard. Although its spectrum is dominated by broad hydrogen lines, the narrower lines of the heavy elements suggested slow to moderate rotation, giving confidence that the ground-based calibration of its visible spectrum could be safely extrapolated into the ultraviolet and near-infrared (through atmosphere models), where it also serves as the primary photometric calibrator. But there have been problems: the star is too bright compared to its peers and it has unusually shaped absorption line profiles, leading some to suggest that it is a distorted, rapidly rotating star seen pole-on. Here we report optical interferometric observations that show that Vega has the asymmetric brightness distribution of the bright, slightly offset polar axis of a star rotating at 93 per cent of its breakup speed. In addition to explaining the unusual brightness and line shape peculiarities, this result leads to the prediction of an excess of near-infrared emission compared to the visible, in agreement with observations. The large temperature differences predicted across its surface call into question composition determinations, adding uncertainty to Vega's age and opening the possibility that its debris disk could be substantially older than previously thought.

20.
J Environ Qual ; 41(6): 1818-34, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23128739

RESUMO

This study investigates the use of a mineral processing by-product, neutralized used acid (NUA), primarily composed of gypsum and Fe-oxyhydroxide, as a soil amendment. A 1489-d turf farm field trial assessed nutrient, trace element, and radionuclide mobility of a soil amended with ∼5% by mass to a depth of 15 cm of NUA. Average PO-P fluxes collected as subsoil leachates were 0.7 and 26.6 kg ha yr for NUA-amended and control sites, respectively, equating to a 97% reduction in PO-P loss after 434 kg P ha was applied. Total nitrogen fluxes in NUA-amended soil leachates were similarly reduced by 82%. Incorporation of NUA conferred major changes in leachate geochemistry with a diverse suite of trace elements depleted within NUA-amended leachates. Gypsum dissolution from NUA resulted in an increase from under- to oversaturation of the soil leachates for a range of Fe- and Ca-minerals including calcite and ferrihydrite, many of which have a well-documented ability to assimilate PO-P and trace elements. Isotopic analysis indicated little Pb addition from NUA. Both Sr and Nd isotope results revealed that NUA and added fertilizer became an important source of Ca to leachate and turf biomass. The NUA-amended soils retained a range of U-Th series radionuclides, with little evidence of transfer to soil leachate or turf biomass. Calculated radioactivity dose rates indicate only a small increment due to NUA amendment. With increased nutrient, trace element, and solute retention, and increased productivity, a range of potential agronomic benefits may be conferred by NUA amendment of soils, in addition to the potential to limit offsite nutrient loss and eutrophication.


Assuntos
Elementos Químicos , Resíduos Industriais/análise , Mineração , Eliminação de Resíduos/métodos , Solo/química , Fenômenos Geológicos , Modelos Teóricos , Folhas de Planta/química , Poaceae/química , Radioisótopos/química , Poluentes do Solo/química , Fatores de Tempo , Oligoelementos/química
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