Heavy quasiparticles and cascades without symmetry breaking in twisted bilayer graphene.

Among the variety of correlated states exhibited by twisted bilayer graphene, cascades in the spectroscopic properties and in the electronic compressibility occur over larger ranges of energy, twist angle and temperature compared to other effects. This suggests a hierarchy of phenomena. Using a combined dynamical mean-field theory and Hartree calculation, we show that the spectral weight reorganisation associated with the formation of local moments and heavy quasiparticles can explain the cascade of electronic resets without invoking symmetry breaking orders. The phenomena reproduced here include the cascade flow of spectral weight, the oscillations of remote band energies, and the asymmetric jumps of the inverse compressibility. We also predict a strong momentum differentiation in the incoherent spectral weight associated with the fragile topology of twisted bilayer graphene.

Interface effects on acceptor qubits in silicon and germanium.

Dopant-based quantum computing implementations often require the dopants to be situated close to an interface to facilitate qubit manipulation with local gates. Interfaces not only modify the energies of the bound states but also affect their symmetry. Making use of the successful effective mass theory we study the energy spectra of acceptors in Si or Ge taking into account the quantum confinement, the dielectric mismatch and the central cell effects. The presence of an interface puts constraints to the allowed symmetries and leads to the splitting of the ground state in two Kramers doublets (Mol et al 2015 Appl. Phys. Lett. 106 203110). Inversion symmetry breaking also implies parity mixing which affects the allowed optical transitions. Consequences for acceptor qubits are discussed.

Theory of one and two donors in silicon.

We provide here a roadmap for modeling silicon nano-devices with one or two group V donors (D). We discuss systems containing one or two electrons, that is, D(0), D(-), D(+)(2) and D(0)(2) centers. The impact of different levels of approximation is discussed. The most accurate instances--for which we provide quantitative results--are within multivalley effective mass including the central cell correction and a configuration interaction account of the electron-electron correlations. We also derive insightful, yet less accurate, analytical approximations and discuss their validity and limitations--in particular, for a donor pair, we discuss the single orbital LCAO method, the Hückel approximation and the Hubbard model. Finally, we connect these results with recent experiments on devices with few dopants.

Magnetic-field probing of an SU(4) Kondo resonance in a single-atom transistor.

Semiconductor devices have been scaled to the point that transport can be dominated by only a single dopant atom. As a result, in a Si fin-type field effect transistor Kondo physics can govern transport when one electron is bound to the single dopant. Orbital (valley) degrees of freedom, apart from the standard spin, strongly modify the Kondo effect in such systems. Owing to the small size and the s-like orbital symmetry of the ground state of the dopant, these orbital degrees of freedom do not couple to external magnetic fields which allows us to tune the symmetry of the Kondo effect. Here we study this tunable Kondo effect and demonstrate experimentally a symmetry crossover from an SU(4) ground state to a pure orbital SU(2) ground state as a function of magnetic field. Our claim is supported by theoretical calculations that unambiguously show that the SU(2) symmetric case corresponds to a pure valley Kondo effect of fully polarized electrons.

[Psychopathological comorbidity of obesity]. / Comorbilidad psicopatológica en obesidad.

Obesity is one of the most important health problems in the early twenty-first century as it affects millions of people around the world and remains a major cause of mortality. At present there is no clear link between obesity and psychopathology, and whether the possible psychological disorders are a cause or a consequence of obesity has not yet been clarified either. This paper reviews some recent contributions (2007-2010) related to the comorbidity between psychopathology and obesity. It can be concluded from this analysis that certain psychological disorders seem to be more common in obese people, such as depression, anxiety, substance abuse, etc., although the direction of the explanatory relation is not clear; moreover, the opposite result has also been found. The evidence of likely comorbid psychopathology means that the practitioner must consider its assessment in obesity cases, and include a plan for a psychiatric and/or psychological therapeutic intervention.

Low magnetization and anisotropy in the antiferromagnetic state of undoped iron pnictides.

We examine the magnetic phase diagram of iron pnictides using a five-band model. For the intermediate values of the interaction expected to hold in the iron pnictides, we find a metallic low moment state characterized by antiparallel orbital magnetic moments. The anisotropy of the interorbital hopping amplitudes is the key to understanding this low moment state. This state accounts for the small magnetization measured in undoped iron pnictides and leads to the strong exchange anisotropy found in neutron experiments. Orbital ordering is concomitant with magnetism and produces the large zx orbital weight seen at Γ in photoemission experiments.

Conductivity anisotropy in the antiferromagnetic state of iron pnictides.

Recent experiments on iron pnictides have uncovered a large in-plane resistivity anisotropy with a surprising result: The system conducts better in the antiferromagnetic x direction than in the ferromagnetic y direction. We address this problem by calculating the ratio of the Drude weight along the x and y directions, D(x)/D(y), for the mean-field Q=(π,0) magnetic phase diagram of a five-band model for the undoped pnictides. We find that D(x)/D(y) ranges between 0.2

Carcinoma suprarrenal. Análisis retrospectivo de cinco casos / Adenocortical carcinoma. A retrospective analysis of five cases

Presentamos cinco casos de carcinoma suprarrenal, diagnosticados en nuestro hospital y describimos su presentación clínica, métodos diagnósticos y tratamiento empleados. Es un tumor poco frecuente, muy agresivo y con mal pronostico. Clínicamente se presentan como tumores caracterizados por efecto masa, síntomas debidos a invasión de vecindad o por una variedad de síndromes hormonales entre los que destacan el hipercortisolismo y la virilización. El diagnóstico se fundamenta en la caracterización bioquímica del síndrome hormonal y en las técnicas de imagen, especialmente la TAC y la RM. Anatomopatológicamente suelen ser tumores de gran tamaño con tendencia a invadir las estructuras vecinas Su tratamiento es fundamentalmente quirúrgico y de los distintos fármacos de quimioterapia, los más efectivos son los adrenolíticos (mitotane) solos o asociados a doxorubicina, cisplatino y etopósido

We present five cases of adrenal cortical carcinoma, diagnosed in our hospital and we describe the clinical presentation, diagnostic methods and treatement. It is a rare tumor, highly aggressive and prognosis is poor. The clinical presentation is characterized by a mass effect, symptoms caused by the invasion of the structures nearby or by a variety of hormonal changes, especially hypercortisolism and virilization. The diagnosis is based on the biochemical characterization of the hormonal profile and on imaging techniques, especially computed tomography and magnetic resonance. The treatment is generally surgical and the most effective chemotherapeutic agents are the adrenolytics (mitotane) alone or associated with doxorubicin, cisplatin and etoposide

Quantum control of donor electrons at the Si-SiO2 interface.

Prospects for the quantum control of electrons in the silicon quantum computer architecture are considered theoretically. In particular, we investigate the feasibility of shuttling donor-bound electrons between the impurity in the bulk and the Si-SiO2 interface by tuning an external electric field. We calculate the shuttling time to range from subpicoseconds to nanoseconds depending on the distance (approximately 10-50 nm) of the donor from the interface. Our results establish that quantum control in such nanostructure architectures could, in principle, be achieved.

Infiltrados pulmonares en paciente en tratamiento con glucocorticoides / Pulmonary infiltrates in patients under treatment with glucocorticoids

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Mujer de 75 años de edad con síndrome constitucional y febril de 3 meses de evolución, con deterioro rápidamente progresivo / 75 year old woman with constitutional and pyretic syndrome with 3 month course and rapidly progressive deterioration

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[Adrenocortical carcinoma. A retrospective analysis of five cases]. / Carcinoma suprarrenal. Análisis retrospectivo de cinco casos.

We present five cases of adrenal cortical carcinoma, diagnosed in our hospital and we describe the clinical presentation, diagnostic methods and treatment. It is a rare tumor, highly aggressive and prognosis is poor. The clinical presentation is characterized by a mass effect, symptoms caused by the invasion of the structures nearby or by a variety of hormonal changes, especially hypercortisolism and virilization. The diagnosis is based on the biochemical characterization of the hormonal profile and on imaging techniques, especially computed tomography and magnetic resonance. The treatment is generally surgical and the most effective chemotherapeutic agents are the adrenolytics (mitotane) alone or associated with doxorubicin, cisplatin and etoposide.

[Intravascular lymphomatosis. A report of three cases]. / Linfomatosis intravascular. Descripción de tres casos.

Intravascular lymphomatosis (IVL) is a rare malignancy characterized by a proliferation of atypical lymphoid cells occluding small blood vessels (venules, capillaries and small arteries). The symptoms are caused by embolisms due to massive proliferation. Nervous system and skin are the most common sites of involvement but all organs may be involved, although it is typified by the absence of malignant cells in lymphoid tissues. We describe three cases of IVL: first patient was a 57 years old man with rapidly progressive dementia and neurological involvements and second case of a 69 years old man hospitalised with predominant symptoms in the lung (cough, dyspnea and fever), and a woman presenting as fever of unknown origin (FUO) with systemic inflammatory response syndrome. In all cases that we reported have been diagnosed post-mortem because of rapid progression of a multisystem disease and the absence of pathognomonic clinical manifestations. Diagnosis can be made using biopsy of one of the involved organs. In conclusion, we propose that IVL should be included in the differential diagnosis of acute confusional state, dementia or other unexplained neurological manifestations, fever of unknown origin, vasculitis, occult neoplasia or infections with signs of a systemic disease and marked elevation of serum lactate dehydrogenase (LDH).

Electronically soft phases in manganites.

The phenomenon of colossal magnetoresistance in manganites is generally agreed to be a result of competition between crystal phases with different electronic, magnetic and structural order; a competition which can be strong enough to cause phase separation between metallic ferromagnetic and insulating charge-modulated states. Nevertheless, closer inspection of phase diagrams in many manganites reveals complex phases where the two order parameters of magnetism and charge modulation unexpectedly coexist. Here we show that such experiments can be naturally explained within a phenomenological Ginzburg-Landau theory. In contrast to models where phase separation originates from disorder or as a strain-induced kinetic phenomenon, we argue that magnetic and charge modulation coexist in new thermodynamic phases. This leads to a rich diagram of equilibrium phases, qualitatively similar to those seen experimentally. The success of this model argues for a fundamental reinterpretation of the nature of charge modulation in these materials, from a localized to a more extended 'charge-density wave' picture. The same symmetry considerations that favour textured coexistence of charge and magnetic order may apply to many electronic systems with competing phases. The resulting 'electronically soft' phases of matter with incommensurate, inhomogeneous and mixed order may be general phenomena in correlated systems.