Atoms in strong magnetic fields: The high field limit at fixed nuclear charge

Let E(B,Z,N) denote the ground state energy of an atom with N electrons and nuclear charge Z in a homogeneous magnetic field B. We study the asymptotics of E(B,Z,N) as $B\to \infty$ with N and Z fixed but arbitrary. It is shown that the leading term has the form $(\ln B)^2 e(Z,N)$, where e(Z,N) is the ground state energy of a system of N {\em bosons} with delta interactions in {\em one} dimension. This extends and refines previously known results for N=1 on the one hand, and $N,Z\to\infty$ with $B/Z^3\to\infty$ on the other hand

Propiedades de soluciones acuosas diluídas de poliestiren - sulfonato de sodio

Se han estudiado propiedades de soluciones acuosas diluídas (10-1 - 7x10-3 N) de poliestirén-sulfonato de sodio. Se determinó enprimer término la variación del factor de actividad del contración sodiocon la concentración del polielectrolito, utilizando una celda conelectrodo gotero de amalgama de sodio. Se encontró que a partir de concentracionesmayores que aproximadamente 4x10-2 N el factor de actividadpermanece practicamente constante, mientras que a concentracionesmenores aumenta al disminuir la concentración. Los resultados obtenidos en la zona diluída, o sea el aumentodel factor de actividad al aumentar la dilución, fueron confirmados haciendomedidas con electrodos de vidrio, especiales para determinar actividadesde ión sodio. De esta forma se estableció, por medio de dosmétodos experimentales diferentes, que el poliestirén-sulfonato de sodiose comporta "normalmente" en lo referente a la variación del coeficientede actividad del contraión con la concentración, es decir quetiende a la unidad a diluciones grandes, a diferencia de otros polielectrolitos,que muestran comportamientos diferentes. Se analizaron teóricamente los datos obtenidos con la celda conelectrodo gotero de amalgamade sodio, a través de la teoria de Oosawa,encontrándose un acuerdo satisfactorio entre la curva calculada y la experimental,lo cual demuestra la validez del modelo de Oosawa. A partirde ese modelo se llegó a la conclusión que el polielectrolito en estudiono puede ser clasificado dentro del grupo de polielectrolitos con densidadde carga alta sobre la cadena, ni tampoco en el grupo de los que tienendensidad de carga baja, sino que deben explicarse sus propiedadescon una transición de un grupo al otro al variar la concentración. También se hicieron determinaciones del factor de actividad delión sodio en soluciones de toluén-sulfonato de sodio, pudiendo compararsede esta forma las propiedades de polielectrolitos con las de electrolitos. En el mismo rango de concentraciones se determinó el número detransporte del ión poliestirén-sulfonato, a través de experiencias deelectrólisis, utilizando cloruro de sodio radioactivo. A partir de losmismos resultados experimentales se pudo determinar la llamada fracciónde iones libres, la que fue comparada con la fracción de iones librescalculada a partir de datos de coeficientes de autodifusión del ión sodioen soluciones de poliestirén-sulfonato de sodio, a través de la teoríade Lifson y Jackson, obteniéndose muy buen acuerdo. Esto permitióesclarecer desde un punto de vista teórico la naturaleza de la “asociación"de contraiones dicha asociación está gobernada por la densidadde carga global sobre el poliión y no por una distribución local de cargas. Finalmente se intentó dar una explicación cualitativa de la variacióndel número de transporte del poliión con la concentración, pudiendohacerlo en la parte más diluída, mientras que en 1a parte más concentradano fué posible encontrar una explicación satisfactoria.Fil: Baumgartner, Erwin Carlos. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Surveillance of adults with congenital heart disease:Current guidelines and actual clinical practice

Background and aim: Congenital heart disease (CHD) is the most common birth defect with prevalence of 0.8%. Thanks to tremendous progress in medical and surgical practice, nowadays, &gt;90% of children survive into adulthood. Recently European Society of Cardiology (ESC), American College of Cardiology (ACC)/ American Heart Association (AHA) issued guidelines which offer diagnostic and therapeutic recommendations for the different defect categories. However, the type of technical exams and their frequency of follow-up may vary largely between clinicians and centres. We aimed to present an overview of available diagnostic modalities and describe current surveillance practices by cardiologists taking care of adults with CHD (ACHD).Methods and results: A questionnaire was used to assess the frequency cardiologists treating ACHD for at least one year administrated the most common diagnostic tests for ACHD. The most frequently employed diagnostic modalities were ECG and echocardiography for both mild and moderate/severe CHD. Sixty-seven percent of respondents reported that they routinely address psychosocial well-being. Conclusion: Differences exist between reported current clinical practice and published guidelines. This is particularly true for the care of patients with mild lesions. In addition, some differences exist between ESC and American guidelines, with more frequent surveillance suggested by the Americans.</p

Surveillance of adults with congenital heart disease:Current guidelines and actual clinical practice

Background and aim: Congenital heart disease (CHD) is the most common birth defect with prevalence of 0.8%. Thanks to tremendous progress in medical and surgical practice, nowadays, &gt;90% of children survive into adulthood. Recently European Society of Cardiology (ESC), American College of Cardiology (ACC)/ American Heart Association (AHA) issued guidelines which offer diagnostic and therapeutic recommendations for the different defect categories. However, the type of technical exams and their frequency of follow-up may vary largely between clinicians and centres. We aimed to present an overview of available diagnostic modalities and describe current surveillance practices by cardiologists taking care of adults with CHD (ACHD).Methods and results: A questionnaire was used to assess the frequency cardiologists treating ACHD for at least one year administrated the most common diagnostic tests for ACHD. The most frequently employed diagnostic modalities were ECG and echocardiography for both mild and moderate/severe CHD. Sixty-seven percent of respondents reported that they routinely address psychosocial well-being. Conclusion: Differences exist between reported current clinical practice and published guidelines. This is particularly true for the care of patients with mild lesions. In addition, some differences exist between ESC and American guidelines, with more frequent surveillance suggested by the Americans.</p

MONOPOL - A traveling-wave magnetic neutron spin resonator for tailoring polarized neutron beams

We report on first experimental tests of a neutron magnetic spin resonator at a very cold neutron beam port of the high flux reactor at the ILL Grenoble. When placed between two supermirror neutron polarizers and operated in a pulsed traveling-wave mode it allows to decouple its time- and wavelength-resolution and can therefore be used simultaneously as electronically tunable monochromator and fast beam chopper. As a first ‘real’ scientific application we intend its implementation in the PERC (p roton and e lectron r adiation c hannel) project related to high-precision experiments in neutron beta decay

Bleeding and thrombotic risk in pregnant women with Fontan physiology

Background/objectives Pregnancy may potentiate the inherent hypercoagulability of the Fontan circulation, thereby amplifying adverse events. This study sought to evaluate thrombosis and bleeding risk in pregnant women with a Fontan.  Methods We performed a retrospective observational cohort study across 13 international centres and recorded data on thrombotic and bleeding events, antithrombotic therapies and pre-pregnancy thrombotic risk factors.  Results We analysed 84 women with Fontan physiology undergoing 108 pregnancies, average gestation 33 +/- 5 weeks. The most common antithrombotic therapy in pregnancy was aspirin (ASA, 47 pregnancies (43.5%)). Heparin (unfractionated (UFH) or low molecular weight (LMWH)) was prescribed in 32 pregnancies (30%) and vitamin K antagonist (VKA) in 10 pregnancies (9%). Three pregnancies were complicated by thrombotic events (2.8%). Thirty-eight pregnancies (35%) were complicated by bleeding, of which 5 (13%) were severe. Most bleeds were obstetric, occurring antepartum (45%) and postpartum (42%). The use of therapeutic heparin (OR 15.6, 95% CI 1.88 to 129, p=0.006), VKA (OR 11.7, 95% CI 1.06 to 130, p=0.032) or any combination of anticoagulation medication (OR 13.0, 95% CI 1.13 to 150, p=0.032) were significantly associated with bleeding events, while ASA (OR 5.41, 95% CI 0.73 to 40.4, p=0.067) and prophylactic heparin were not (OR 4.68, 95% CI 0.488 to 44.9, p=0.096). Conclusions Current antithrombotic strategies appear effective at attenuating thrombotic risk in pregnant women with a Fontan. However, this comes with high (>30%) bleeding risk, of which 13% are life threatening. Achieving haemostatic balance is challenging in pregnant women with a Fontan, necessitating individualised risk-adjusted counselling and therapeutic approaches that are monitored during the course of pregnancy

Diagnosis and medical care of raptors in a compilation of cases from 1985-1994

This article summarises the clinical findings in 554 birds of prey, that were admitted to the zoo animal and exotic pet clinic of the veterinary faculty in Zurich between 1 January 1985 and 31 December 1994. Details on the diagnosis, therapy and prognosis are intended to give the practitioner information on the possibilities for the management of diseased raptors. However, it has to be emphasized that the ultimate goal of treatment has to be the rehabilitation of an animal that will be able to survive to a suitable environment. The data presented shows that 31% of the birds of prey were successfully released. The most frequent reason for admission was trauma and 47% of the patients had one or more fractures. But only one out of three fractures was considered suitable for treatment. The management of birds that are starving is a challenge because they require a special dietary regimen. Successful work in the field of the treatment and rehabilitation of raptors requires detailed knowledge of their biology and medicine