12,374 research outputs found
Van der Waals spin valves
We propose spin valves where a 2D non-magnetic conductor is intercalated
between two ferromagnetic insulating layers. In this setup, the relative
orientation of the magnetizations of the insulating layers can have a strong
impact on the in-plane conductivity of the 2D conductor. We first show this for
a graphene bilayer, described with a tight-binding model, placed between two
ferromagnetic insulators. In the anti-parallel configuration, a band gap opens
at the Dirac point, whereas in the parallel configuration, the graphene bilayer
remains conducting. We then compute the electronic structure of graphene
bilayer placed between two monolayers of the ferromagnetic insulator CrI,
using density functional theory. Consistent with the model, we find that a gap
opens at the Dirac point only in the antiparallel configuration.Comment: 5 pages, 4 figure
Pulmonary hypertension in AIDS/HIV infection: a rare disease
A Hipertensão pulmonar (HTP) é uma patologia rara mas que condiciona elevada morbilidade e mortalidade. É conhecida
a sua associação com o VÃrus da Imunodeficiência Humana (VIH), mas muitos dos mecanismos implicados na sua patogénese
bem como o impacto da terapêutica antiretroviral (TARV) no tratamento e prognóstico desta doença ainda se encontram
por definir.
Apresenta-se um caso clÃnico de uma doente de 62 anos com infecção VIH internada por um quadro interpretado inicial-
mente como infecção respiratória. A má evolução e os exames adicionais permitiram o diagnóstico de Hipertensão pulmonar
grave que viria a determinar o falecimento da doente em poucos dias.
Atendendo à elevada prevalência de doentes com infecção VIH, é expectável o aumento do número de casos de Hipertensão
pulmonar, pelo que se chama a atenção para a necessidade de um diagnóstico precoce antes da evolução da mesma.info:eu-repo/semantics/publishedVersio
A Complex Case of Cholestasis in a Patient with ABCB4 and ABCB11 Mutations
The low-phospholipid-associated cholelithiasis (LPAC) syndrome is a form of symptomatic cholelithiasis occurring in young adults, characterized by recurrence of symptoms after cholecystectomy and presence of hepatolithiasis. The case refers to a healthy 39-year-old Caucasian male who presented with abdominal pain and jaundice. His blood tests showed conjugated hyperbilirubinemia and elevated liver enzymes (total bilirubin 6.65 mg/dL, γ-glutamyltransferase 699 IU/L) and abdominal computed tomography revealed dilation of common bile duct and left intrahepatic ducts. Magnetic resonance cholangiopancreatography identified choledocholithiasis, retrieved by endoscopic retrograde cholangiopancreatography, after which there was a worsening of jaundice (total bilirubin 23 mg/dL), which persisted for several weeks, possibly due to ciprofloxacin toxicity. After an extensive workup including liver biopsy, the identification of two foci of hepatolithiasis on reevaluation abdominal ultrasound raised the hypothesis of LPAC syndrome and the patient was started on ursodeoxycholic acid, with remarkable improvement. Genetic testing identified the mutation c.1954A>G (p.Arg652Gly) in ABCB4 gene (homozygous) and c.1331T>C (p.Val444Ala) in ABCB11 gene (heterozygous). In conclusion, we describe the unique case of an adult male with choledocholithiasis, hepatolithiasis, and persistent conjugated hyperbilirubinemia after retrieval of stones, fulfilling the criteria for LPAC syndrome and with possible superimposed drug-induced liver injury, in whom ABCB4 and ABCB11 mutations were found, both of which had not been previously described in association with LPAC.info:eu-repo/semantics/publishedVersio
Causes and characteristics of uveitis in dogs
A uveÃte é uma das afecções oculares mais frequente nos cães, muitas vezes associada a doença sistémica. O
trabalho que se apresenta é um estudo retrospetivo de casos de uveÃtes caninas e foi realizado com o objetivo de
fazer uma análise descritiva das uveÃtes nesta população e avaliar as suas causas, em especial a relação com doenças
sistémicas
Estoque de carbono na necromassa depositada no chão nos remanescentes florestais em Santa Catarina.
Resumo
A Comment on Quantum Distribution Functions and the OSV Conjecture
Using the attractor mechanism and the relation between the quantization of
and topological strings on a Calabi Yau threefold we define a
map from BPS black holes into coherent states. This map allows us to represent
the Bekenstein-Hawking-Wald entropy as a quantum distribution function on the
phase space . This distribution function is a mixed
Husimi/anti-Husimi distribution corresponding to the different normal ordering
prescriptions for the string coupling and deviations of the complex structure
moduli. From the integral representation of this distribution function in terms
of the Wigner distribution we recover the Ooguri-Strominger-Vafa (OSV)
conjecture in the region "at infinity" of the complex structure moduli space.
The physical meaning of the OSV corrections are briefly discussed in this
limit.Comment: 27 pages. v2:reference and footnote adde
Nernst branes from special geometry
We construct new black brane solutions in gauged
supergravity with a general cubic prepotential, which have entropy density
as and thus satisfy the Nernst Law. By using
the real formulation of special geometry, we are able to obtain analytical
solutions in closed form as functions of two parameters, the temperature
and the chemical potential . Our solutions interpolate between
hyperscaling violating Lifshitz geometries with at the
horizon and at infinity. In the zero temperature limit,
where the entropy density goes to zero, we recover the extremal Nernst branes
of Barisch et al, and the parameters of the near horizon geometry change to
.Comment: 37 pages. v2: numerical pre-factors of scalar fields q_A corrected in
Section 3. No changes to conclusions. References adde
Necrotizing Fasciitis Post- Acute Appendicitis
A FasceÃte 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 inÃcio de terapêutica adequada, é de extrema importância que este diagnóstico seja considerado
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