RESUMO
We report measurements of the diffusion rate of isolated ion-implanted ^{8}Li^{+} within â¼120 nm of the surface of oriented single-crystal rutile TiO_{2} using a radiotracer technique. The α particles from the ^{8}Li decay provide a sensitive monitor of the distance from the surface and how the depth profile of ^{8}Li evolves with time. The main findings are that the implanted Li^{+} diffuses and traps at the (001) surface. The T dependence of the diffusivity is described by a bi-Arrhenius expression with activation energies of 0.3341(21) eV above 200 K, whereas at lower temperatures it has a much smaller barrier of 0.0313(15) eV. We consider possible origins for the surface trapping, as well the nature of the low-T barrier.
RESUMO
By measuring the prototypical antiferromagnet α-Fe_{2}O_{3}, we show that it is possible to determine the static spin orientation and dynamic spin correlations within nanometers from an antiferromagnetic surface using the nuclear spin polarization of implanted ^{8}Li^{+} ions detected with ß-NMR. Remarkably, the first-order Morin spin reorientation in single crystal α-Fe_{2}O_{3} occurs at the same temperature at all depths between 1 and 100 nm from the (110) surface; however, the implanted nuclear spin experiences an increased 1/T_{1} relaxation rate at shallow depths revealing soft-surface magnons. The surface-localized dynamics decay towards the bulk with a characteristic length of ε=11±1 nm, closely matching the finite-size thresholds of hematite nanostructures.
RESUMO
Bunched-beam collinear laser spectroscopy is performed on neutron deficient ^{52,53}Fe prepared through in-flight separation followed by a gas stopping. This novel scheme is a major step to reach nuclides far from the stability line in laser spectroscopy. Differential mean-square charge radii δ⟨r^{2}⟩ of ^{52,53}Fe are determined relative to stable ^{56}Fe as δ⟨r^{2}⟩^{56,52}=-0.034(13) fm^{2} and δ⟨r^{2}⟩^{56,53}=-0.218(13) fm^{2}, respectively, from the isotope shift of atomic hyperfine structures. The multiconfiguration Dirac-Fock method is used to calculate atomic factors to deduce δ⟨r^{2}⟩. The values of δ⟨r^{2}⟩ exhibit a minimum at the N=28 neutron shell closure. The nuclear density functional theory with Fayans and Skyrme energy density functionals is used to interpret the data. The trend of δ⟨r^{2}⟩ along the Fe isotopic chain results from an interplay between single-particle shell structure, pairing, and polarization effects and provides important data for understanding the intricate trend in the δ⟨r^{2}⟩ of closed-shell Ca isotopes.
RESUMO
We have measured the hyperfine splitting of the 7P_{1/2} state at the 100 ppm level in Fr isotopes (^{206g,206m,207,209,213,221}Fr) near the closed neutron shell (N=126 in ^{213}Fr). The measurements in five isotopes and a nuclear isomeric state of francium, combined with previous determinations of the 7S_{1/2} splittings, reveal the spatial distribution of the nuclear magnetization, i.e., the Bohr-Weisskopf effect. We compare our results with a simple shell model consisting of unpaired single valence nucleons orbiting a spherical nucleus, and find good agreement over a range of neutron-deficient isotopes (^{207-213}Fr). Also, we find near-constant proton anomalies for several even-N isotopes. This identifies a set of Fr isotopes whose nuclear structure can be understood well enough for the extraction of weak interaction parameters from parity nonconservation studies.
RESUMO
We report the observation of weak magnetism in superlattices of LaAlO(3)/SrTiO(3) using ß-detected nuclear magnetic resonance. The spin lattice relaxation rate of ^{8}Li in superlattices with a spacer layers of 8 and 6 unit cells of LaAlO(3) exhibits a strong peak near ~35 K, whereas no such peak is observed in a superlattice with spacer layer thickness of 3 unit cells. We attribute the observed temperature dependence to slowing down of weakly coupled electronic moments at the LaAlO(3)/SrTiO(3) interface. These results show that the magnetism at the interface depends strongly on the thickness of the spacer layer, and that a minimal thickness of ~4-6 unit cells is required for the appearance of magnetism. A simple model is used to determine that the observed relaxation is due to small fluctuating moments (~0.002µ(B)) in the two samples with a larger LaAlO(3) spacer thickness.
RESUMO
We present precision Penning trap mass measurements of neutron-rich calcium and potassium isotopes in the vicinity of neutron number N=32. Using the TITAN system, the mass of 51K was measured for the first time, and the precision of the (51,52)Ca mass values were improved significantly. The new mass values show a dramatic increase of the binding energy compared to those reported in the atomic mass evaluation. In particular, 52Ca is more bound by 1.74 MeV, and the behavior with neutron number deviates substantially from the tabulated values. An increased binding was predicted recently based on calculations that include three-nucleon (3N) forces. We present a comparison to improved calculations, which agree remarkably with the evolution of masses with neutron number, making neutron-rich calcium isotopes an exciting region to probe 3N forces.
RESUMO
We report a precise determination of the (19)Ne half-life to be T(1/2)=17.262±0.007 s. This result disagrees with the most recent precision measurements and is important for placing bounds on predicted right-handed interactions that are absent in the current standard model. We are able to identify and disentangle two competing systematic effects that influence the accuracy of such measurements. Our findings prompt a reassessment of results from previous high-precision lifetime measurements that used similar equipment and methods.
RESUMO
Collinear-laser spectroscopy with the bunched-beams technique was used for the study of neutron deficient Rb isotopes, out to (74)Rb (N = Z = 37) at TRIUMF. The measured hyperfine coupling constants of (76,78m)Rb were in agreement with literature values. The nuclear spin of (75)Rb was confirmed to be I = 3/2, and its hyperfine coupling constants were measured for the first time. The mean-square charge radius of (74)Rb was determined for the first time. This result has improved the isospin symmetry breaking correction term used to calculate the Ft value, with implications for tests of the unitarity of the Cabibbo-Kobayashi-Maskawa matrix.
RESUMO
Penning trap mass measurements of short-lived nuclides have been performed for the first time with highly charged ions, using the TITAN facility at TRIUMF. Compared to singly charged ions, this provides an improvement in experimental precision that scales with the charge state q. Neutron-deficient Rb isotopes have been charge bred in an electron beam ion trap to q=8-12+ prior to injection into the Penning trap. In combination with the Ramsey excitation scheme, this unique setup creating low energy, highly charged ions at a radioactive beam facility opens the door to unrivaled precision with gains of 1-2 orders of magnitude. The method is particularly suited for short-lived nuclides such as the superallowed ß emitter 74Rb (T(1/2)=65 ms). The determination of its atomic mass and an improved Q(EC) value are presented.
RESUMO
A 1-year-old male Boxer dog presented with sustained supraventricular tachycardia and tachycardia-induced cardiomyopathy. Conversion to sinus rhythm was achieved initially with intravenous lignocaine and subsequently with oral procainamide. Oral procainamide treatment was relatively successful in maintaining normal sinus rhythm with no side effects apart from a reversible change in coat colour. Electrophysiological studies demonstrated the presence of an accessory pathway connecting the right atrium to the right ventricle and confirmed the diagnosis of orthodromic atrioventricular reciprocating tachycardia. Radiofrequency catheter ablation of the accessory pathway led to permanent resolution of the supraventricular tachycardia and for 9.5 years the dog has had no further signs of cardiac disease. The successful treatment of this condition highlights the importance of differentiating tachycardia-induced cardiomyopathy from dilated cardiomyopathy.
Assuntos
Cardiomiopatias/veterinária , Cardiomiopatia Dilatada/veterinária , Ablação por Cateter/veterinária , Doenças do Cão/diagnóstico , Taquicardia Supraventricular/veterinária , Animais , Cardiomiopatias/diagnóstico , Cardiomiopatias/etiologia , Cardiomiopatias/cirurgia , Cardiomiopatia Dilatada/diagnóstico , Cardiomiopatia Dilatada/cirurgia , Ablação por Cateter/métodos , Diagnóstico Diferencial , Doenças do Cão/cirurgia , Cães , Eletrocardiografia/veterinária , Masculino , Taquicardia Supraventricular/complicações , Taquicardia Supraventricular/diagnóstico , Taquicardia Supraventricular/cirurgia , Resultado do TratamentoRESUMO
The acute haemodynamic and metabolic repercussions of total venous inflow occlusion were evaluated in six normal dogs, each of which underwent two four minute occlusions and one eight minute occlusion at normothermia. A further three dogs underwent a single eight minute period of occlusion and were allowed to recover from anaesthesia. Total venous inflow occlusion was well tolerated by all animals. They remained in sinus rhythm at the completion of occlusion, and unassisted haemodynamic recovery occurred rapidly. Recovery was quicker after four minutes than after eight minutes. There was no clinically detectable neurological impairment in three dogs which were allowed to recover.
Assuntos
Cães/fisiologia , Hemodinâmica , Fenômenos Fisiológicos do Sistema Nervoso , Veias Cavas/fisiologia , Animais , Arritmia Sinusal/etiologia , Arritmia Sinusal/veterinária , Pressão Sanguínea , Dióxido de Carbono/sangue , Débito Cardíaco , Pressão Venosa Central , Doenças do Cão/etiologia , Cães/sangue , Cães/metabolismo , Eletrocardiografia/veterinária , Frequência Cardíaca , Hematócrito/veterinária , Concentração de Íons de Hidrogênio , Lactatos/sangue , Oxigênio/sangue , Potássio/sangueRESUMO
The haemodynamic and metabolic effects of caudal vena cava occlusion were evaluated in six normal anaesthetised dogs. Each animal underwent a single eight minute episode of caudal vena cava occlusion. The procedure was well tolerated by all the dogs. Systolic arterial pressure was reduced by 62 +/- 5 per cent and the heart rate increased by 11 +/- 3 per cent. There was rapid haemodynamic recovery after the release of occlusion, all cardiovascular parameters returning to normal spontaneously within five minutes. Caudal vena cava occlusion is therefore safe for periods of up to eight minutes in normal dogs. This technique allows repair of caudal vena caval lesions without necessitating systemic heparinisation and the use of cavoatrial conduits.
Assuntos
Cães/cirurgia , Hemodinâmica , Veia Cava Inferior/cirurgia , Animais , Pressão Sanguínea , Dióxido de Carbono/sangue , Pressão Venosa Central , Cães/metabolismo , Cães/fisiologia , Eletrocardiografia/veterinária , Frequência Cardíaca , Concentração de Íons de Hidrogênio , Oxigênio/sangue , Potássio/sangue , Veia Cava Inferior/fisiologiaRESUMO
Cardiopulmonary bypass using cross-circulation was evaluated in dogs. In eight experiments a greyhound (the donor) was used to perfuse a small mongrel dog (the recipient). Recipients averaged 40 per cent of the donor's weight. Total cardiopulmonary bypass was successfully established in all eight experiments and maintained for 60 to 90 minutes. Haemodynamic values (mean arterial pressure, central venous pressure, cardiac output) and arterial blood gas tensions in the recipient and donor dogs remained at near-baseline levels for the duration of cardiopulmonary bypass. Seven of the eight recipient dogs were successfully weaned from cardiopulmonary bypass at the end of the procedure.
Assuntos
Ponte Cardiopulmonar/veterinária , Circulação Cruzada/veterinária , Cães , Hemodinâmica , Animais , Pressão Sanguínea , Dióxido de Carbono/sangue , Débito Cardíaco , Ponte Cardiopulmonar/métodos , Pressão Venosa Central , Circulação Cruzada/métodos , Coração/fisiologia , Coração/fisiopatologia , Frequência Cardíaca , Oxigênio/sangue , Pressão Parcial , Fibrilação Ventricular/fisiopatologiaRESUMO
Posterior sternoclavicular dislocation is a relatively rare form of trauma, but one that must be recognized by the emergency physician. Such a case is presented here. Due to the proximity of the clavicle to critical thoracic outlet structures, serious complications can arise from a posterior dislocation: impingement on and possible trauma to the trachea, pneumothorax, laceration of underlying great vessels, brachial plexus injury, esophageal trauma, and laryngeal trauma that may cause permanent vocal cord changes. Many of these potential complications are life-threatening, and it is important that this injury not be triaged in the emergency department as a minor injury, thereby leading to its improper or delayed treatment.
Assuntos
Luxações Articulares , Articulação Esternoclavicular/lesões , Adolescente , Futebol Americano/lesões , Humanos , Luxações Articulares/complicações , Luxações Articulares/diagnóstico , Luxações Articulares/terapia , Masculino , Manipulação OrtopédicaRESUMO
A modified open patch-graft technique was used to correct congenital pulmonic stenosis in 8 dogs. Pulmonary valve dysplasia was moderate to severe in all cases, based upon clinical and echocardiographic criteria, and 3 dogs were in right-sided congestive heart failure at the time of surgery. Seven of the 8 dogs survived the surgery. One surviving dog displayed cerebral cortical dysfunction, the remaining 6 had no detectable neurological sequelae. Right ventricular failure was alleviated in all 7 surviving dogs, but right ventricular dilatation persisted post-operatively. Pulmonary valvulectomy and open patch-grafting provides an effective means of alleviating signs of congestive heart failure caused by pulmonary valve dysplasia, even in the presence of severe infundibular hypertrophy and dynamic outflow obstruction.
Assuntos
Doenças do Cão/cirurgia , Insuficiência Cardíaca/veterinária , Pericárdio/transplante , Estenose da Valva Pulmonar/veterinária , Valva Pulmonar/cirurgia , Animais , Arritmias Cardíacas/etiologia , Arritmias Cardíacas/veterinária , Reanimação Cardiopulmonar/veterinária , Doenças do Cão/etiologia , Cães , Feminino , Seguimentos , Insuficiência Cardíaca/etiologia , Insuficiência Cardíaca/cirurgia , Massagem Cardíaca/veterinária , Complicações Intraoperatórias/veterinária , Masculino , Complicações Pós-Operatórias/veterinária , Edema Pulmonar/etiologia , Edema Pulmonar/veterinária , Estenose da Valva Pulmonar/complicações , Estenose da Valva Pulmonar/cirurgia , Convulsões/etiologia , Convulsões/veterináriaRESUMO
A haemodynamically significant ventricular septal defect was diagnosed in a 3-month-old male Cavalier King Charles Spaniel. A median sternotomy was performed and the 6.5 kg dog placed on cardiopulmonary bypass using pump-assisted cross-circulation. A 10 mm diameter peri-membranous ventricular septal defect was closed using a continuous suture of 4-0 polypropylene, via a 2.5 cm incision in the right ventricular outflow tract. The duration of cardiopulmonary bypass was 90 minutes. Complications in the immediate postoperative period were mild and easily managed.
Assuntos
Ponte Cardiopulmonar/veterinária , Circulação Cruzada/veterinária , Cães/anormalidades , Comunicação Interventricular/veterinária , Animais , Ponte Cardiopulmonar/métodos , Circulação Cruzada/métodos , Cães/cirurgia , Ecocardiografia/veterinária , Coração/fisiopatologia , Comunicação Interventricular/diagnóstico por imagem , Comunicação Interventricular/fisiopatologia , Comunicação Interventricular/cirurgia , Hemodinâmica/fisiologia , Masculino , Complicações Pós-Operatórias/veterináriaRESUMO
Responses (486) were collared from a survey of 5054 Australian veterinarians on their use of anti-inflammatory and analgesic drugs in dogs and cats. Almost all respondents used glucocorticoids (usually prednisolone) to treat allergic, pruritic dermatoses in dogs, while two-thirds also gave fatty acid supplements and one-half used antihistamines. Almost 60% of respondents initially injected a glucocorticoid (frequently a long-acting preparation) when treating inflammatory skin diseases in dogs. More than 90% of respondents used glucocorticoids to treat immune-mediated haemolytic anaemia or thrombocytopenia, and about one-third also gave cytotoxic drugs. Administration of prednisolone on alternate days was generally favoured for long-term enteral steroid therapy. Phenylbutazone was the most preferred treatment for painful or inflammatory musculoskeletal disorders of dogs, but aspirin and pentosan polysulphate were also used widely. Regarding the use of analgesics drugs generally, both narcotic analgesics and non-steroidal anti-inflammatory drugs (NSAIDs) were used more widely in dogs than in cats, but alpha-2 agonists were used similarly in both species. The most commonly used narcotic analgesics were pethidine and buprenorphine in both species, while the NSAIDs used most often were flunixin and dipyrone in dogs and ketoprofen in cats. More than 80% of respondents generally used analgesic drugs with potentially painful surgical procedures, with doses given usually before anaesthetic recovery. Analgesic use rates varied with the condition, ranging from 94% for patients with acute severe trauma, through 60% for cruciate ligament repair and 29% for perineal herniorrahphy, to about 5% for ovariohysterectomy and dog castration. The three clinical signs most frequently nominated as indicators of pain in dogs and cats were (in descending order) vocalisation, response to handling or palpating the affected area, and mental depression. Other items mentioned frequently were behavioural changes and immobility (in both species), inappetence/anorexia in cats, and altered respiration in dogs.
Assuntos
Anti-Inflamatórios não Esteroides/uso terapêutico , Doenças do Gato/tratamento farmacológico , Doenças do Cão/tratamento farmacológico , Dor/veterinária , Anemia Hemolítica/complicações , Anemia Hemolítica/tratamento farmacológico , Anemia Hemolítica/veterinária , Animais , Austrália/epidemiologia , Doenças do Gato/epidemiologia , Doenças do Gato/etiologia , Gatos , Doenças do Cão/epidemiologia , Doenças do Cão/etiologia , Cães , Glucocorticoides/uso terapêutico , Doenças Musculoesqueléticas/complicações , Doenças Musculoesqueléticas/tratamento farmacológico , Doenças Musculoesqueléticas/veterinária , Dor/tratamento farmacológico , Dor/etiologia , Complicações Pós-Operatórias/tratamento farmacológico , Complicações Pós-Operatórias/veterinária , Padrões de Prática Médica , Dermatopatias/complicações , Dermatopatias/tratamento farmacológico , Dermatopatias/veterinária , Inquéritos e Questionários , Ferimentos e Lesões/complicações , Ferimentos e Lesões/tratamento farmacológico , Ferimentos e Lesões/veterináriaRESUMO
Records of 146 dogs and 41 cats that underwent thoracic surgery at The University of Sydney Veterinary Teaching Hospital were reviewed for age, sex, breed, disease, operation date, periods of pre- and post-operative hospitalisation, use of surgical drains and outcome. Animals were assigned to 16 disease categories, the most common being patent ductus arteriosus, traumatic diaphragmatic hernia and oesophageal foreign body in dogs and traumatic diaphragmatic hernia in cats. Differences were observed between disease categories in all the criteria examined. There were almost equal numbers of male (72) and female (74) dogs, the median (range) age was 2.0 (0.2 to 14.0) years, the median pre-operative stay was 1 (0 to 14) days, the median post-operative stay was 4 (0 to 28) days and the overall survival to discharge rate was 78%. There were 24 male and 15 female cats (sex not recorded in 2 cats). The median (range) age was 3 (0.1 to 12) years, pre-operative stay 1 (0 to 6) days, post-operative stay 5 (0 to 15) days and the overall survival to discharge rate was 85%. Causes of post-operative deaths among animals in the most common categories are recorded and discussed.
Assuntos
Doenças do Gato/cirurgia , Doenças do Cão/cirurgia , Cirurgia Torácica/estatística & dados numéricos , Fatores Etários , Animais , Doenças do Gato/mortalidade , Gatos , Doenças do Cão/mortalidade , Cães , Drenagem/veterinária , Permeabilidade do Canal Arterial/cirurgia , Permeabilidade do Canal Arterial/veterinária , Esôfago , Feminino , Corpos Estranhos/cirurgia , Corpos Estranhos/veterinária , Hérnia Diafragmática Traumática/cirurgia , Hérnia Diafragmática Traumática/veterinária , Tempo de Internação , Ligadura/veterinária , Masculino , Derrame Pleural/cirurgia , Derrame Pleural/veterinária , Estudos Retrospectivos , Fatores Sexuais , Análise de Sobrevida , Resultado do TratamentoRESUMO
Prinzmetal's angina, a form of angina precipitated by vasoconstriction or spasm, appears to be a somatic phenomenon, but there is evidence, from research and case reports, of a major psychological component. In this study, individuals with Prinzmetal's angina were interviewed to determine the nature of their interpersonal relationships and their intrapsychic state at the time of onset of their chest pain. In addition, short developmental histories were obtained. The authors found that onset of chest pain was related to experiencing intense affect, and multiple levels of interpersonal and intrapsychic conflict, with strong conscious and unconscious, emotional and ideational links to previous traumas.
Assuntos
Angina Pectoris Variante/psicologia , Emoções , Interpretação Psicanalítica , Transtornos Psicofisiológicos/psicologia , Adulto , Angina Pectoris Variante/diagnóstico , Nível de Alerta , Conflito Psicológico , Vasoespasmo Coronário/psicologia , Feminino , Humanos , Relações Interpessoais , Masculino , Pessoa de Meia-Idade , Determinação da Personalidade , Desenvolvimento da Personalidade , Terapia Psicanalítica , Transtornos Psicofisiológicos/diagnóstico , Papel do DoenteRESUMO
TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN) constitutes the only high precision mass measurement setup coupled to a rare isotope facility capable of increasing the charge state of short-lived nuclides prior to the actual mass determination in a Penning trap. Recent developments around TITAN's charge breeder, the electron beam ion trap, form the basis for several successful experiments on radioactive isotopes with half-lives as low as 65 ms and in charge states as high as 22+.