Symmetry of boundary conditions of the Dirac equation for electrons in carbon nanotubes.

We consider the effective mass model of spinless electrons in single wall carbon nanotubes that is equivalent to the Dirac equation for massless fermions. Within this framework we derive all possible energy independent hard wall boundary conditions that are applicable to metallic tubes. The boundary conditions are classified in terms of their symmetry properties and we demonstrate that the use of different boundary conditions will result in varying degrees of valley degeneracy breaking of the single particle energy spectrum

Predominant Golgi-residency of the plant K/HDEL receptor is essential for its function in mediating ER retention

Accumulation of soluble proteins in the endoplasmic reticulum (ER) of plants is mediated by a receptor termed ER RETENTION DEFECTIVE 2 (ERD2) or K/HDEL receptor. Using two gain-of-function assays and by complementing loss of function in Nicotiana benthamiana we discovered that compromising the lumenal N-terminus or the cytosolic C-terminus with fluorescent fusions abolishes its biological function and profoundly affects its subcellular localization. Based on the confirmed asymmetrical topology of ERD2 we engineered a new fluorescent ERD2 fusion protein that retains biological activity. Using this fusion, we show that ERD2 is exclusively detected at the Golgi apparatus, unlike non-functional C-terminal fusions which also label the ER. Moreover, ERD2 is confined to early Golgi compartments and does not show ligand-induced redistribution to the ER. We show that the cytosolic C-terminus of ERD2 plays a crucial role in its function. Two conserved Leucine residues that do not correspond to any known targeting motifs for ER-Golgi trafficking were shown to be essential for both ERD2 Golgi residency and its ability to mediate ER retention of soluble ligands. The results suggest that anterograde ER to Golgi transport of ERD2 is either extremely fast, well in excess of the bulk flow rate, or that ERD2 does not recycle in the way originally proposed

Imbibition in Disordered Media

The physics of liquids in porous media gives rise to many interesting phenomena, including imbibition where a viscous fluid displaces a less viscous one. Here we discuss the theoretical and experimental progress made in recent years in this field. The emphasis is on an interfacial description, akin to the focus of a statistical physics approach. Coarse-grained equations of motion have been recently presented in the literature. These contain terms that take into account the pertinent features of imbibition: non-locality and the quenched noise that arises from the random environment, fluctuations of the fluid flow and capillary forces. The theoretical progress has highlighted the presence of intrinsic length-scales that invalidate scale invariance often assumed to be present in kinetic roughening processes such as that of a two-phase boundary in liquid penetration. Another important fact is that the macroscopic fluid flow, the kinetic roughening properties, and the effective noise in the problem are all coupled. Many possible deviations from simple scaling behaviour exist, and we outline the experimental evidence. Finally, prospects for further work, both theoretical and experimental, are discussed.Comment: Review article, to appear in Advances in Physics, 53 pages LaTe

Integrated care for patients with advanced chronic obstructive pulmonary disease

Przewlekła obturacyjna choroba płuc (POChP) jest trzecią przyczyną zgonów i trzecią przyczyną niesprawności (mierzonej za pomocą wskaźnika DALY) u osób powyżej 60. roku życia. Ciężką lub bardzo ciężką postać POChP (wskaźnik FEV1, odpowiednio, poniżej 50% i 30% należnej wartości) rozpoznaje się u mniej więcej jednej piątej ogółu chorych. Chorzy na zaawansowaną POChP z reguły cierpią z powodu fizycznej i umysłowej niepełnosprawności, w wielu przypadkach źle radzą sobie z problemami wynikającymi z choroby i współistniejących schorzeń. To z kolei stwarza duże ryzyko zaostrzeń POChP, które prowadzą do pogorszenia przebiegu choroby, istotnego zwiększenia kosztów medycznej opieki oraz zwiększenia ryzyka zgonu. Obecna organizacja medycznej opieki dla tej grupy chorych nie zapewnia odpowiednich warunków zdrowotnych i socjalnych. Wydaje się jednak, że zastosowanie modelu zintegrowanej opieki, zalecanego przez Światową Organizację Zdrowia stworzyłoby możliwość poprawy sytuacji chorych na zaawansowane POChP. W Polsce ta forma opieki jest realizowana od kilkunastu lat w zakładach medycyny paliatywnej i hospicjach w odniesieniu do chorych na zaawansowane nowotwory. Wykorzystanie tych doświadczeń powinno pomóc w integracji działań wokół lekarzy rodzinnych i wyspecjalizowanej pielęgniarki, z jednoczesnym zapewnieniem dostępu do specjalistów w zależności od indywidualnych potrzeb chorego. Powinno także umożliwić szersze wykorzystanie pracowników pomocniczych, jak: pracownicy socjalni, pomocnicy medyczni oraz wolontariusze, a także psycholodzy i duchowni (zwłaszcza w końcowej fazie choroby). Pneumonol. Alergol. Pol. 2010; 78, 2: 126-132Chronic obstructive pulmonary disease (COPD) is the third cause of mortality and disability (assed by DALY) among patients above 60 year old. Severe and very severe COPD (FEV1 = equal or less than 50% and 30% of expected value, respectively) is estimated at 20% of all COPD patients. Advanced COPD usually leads to physical and mental deterioration, the patients often manage with the problems caused by the disease and other comorbidities poorly. This leads to increased risk of COPD exacerbations and further deterioration of the patient’s status, increased costs of medical care and eventually increased risk of death. Current organization of medical care for those patients does not provide adequate health and social support for them. However, it seems that introducing an integrated approach proposed by World Health Organization, could improve the situation of advanced COPD patients. In Poland, this kind of care has been provided in advanced cancer patients throughout stationary palliative care units and hospices during the last several years. This experience should be helpful in integrating actions of general practitioners and specialized nurses, as well as providing access for the specialists’ consultations according to the individual needs of the patients. It should also allow for broad cooperation with auxiliary staff, such as social workers, medical assistants and volunteers, as well as psychologists and clergymen (especially in the terminal phase of the disease). Pneumonol. Alergol. Pol. 2010; 78, 2: 126-13

Enhanced Fluctuations of the Tunneling Density of States near the Bottom of a Landau Band Measured by a Local Spectrometer

We have found that the local density of state fluctuations (LDOSF) in a disordered metal, detected using an impurity in the barrier as a spectrometer, undergo enhanced (with respect to Shubnikov -de Haas and de Haas -van Alphen effects) oscillations in strong magnetic fields, v c t 1. We attribute this to the dominant role of the states near the bottom of Landau bands which give the major contribution to the LDOSF and are most strongly affected by disorder. We also demonstrate that in intermediate fields the LDOSF increase with field B in accordance with the results obtained in the diffusion approximation. PACS numbers: 73.23.Hk, 72.15.Gd, 73.20.Fz, 73.40.Ty Resonant tunneling through individual impurities has been identified and studied in vertical In this paper, we study the evolution with magnetic field of the LDOSF in a 3D disordered metal, a heavily doped semiconductor, and discuss the results from the point of view of the fluctuation and correlation properties of single-particle wave functions in disordered media. We have measured the fingerprint of the LDOSF, dn͑´͒, in the differential conductance G͑V ͒ dI dV ͑V ͒ in a broad range of magnetic fields, B, and analyzed its variance, ͗dG 2 ͘, and correlation parameters. In intermediate fields, v c t ϳ 1, we have detected an increase of the fluctuation magnitude, in agreement with the theoretically predicted behavior [11]: ͗͑dG͒ 2 ͘ B ͗͑͞dG͒ 2 ͘ B0 ഠ 1 1 ͑v c t͒ 2 . At higher fields, v c t 1, we have observed large 1͞B periodic oscillations in ͗dG 2 ͘. We conclude that LDOSF in strong fields are dominated by the states near the minimum of the Landau bands which play a distinguished role relative to the rest of the spectrum. Notably, the observed oscillations are significantly stronger than those in other oscillatory effects in metals, such as de Haas-van Alphen effect. The investigated structure consists of a 50 Å GaAs well imbedded between two 81 Å Al 0.33 Ga 0.67 As barriers. Each Si-doped GaAs contact consists of three layers: 4800 Å with nominal doping 10 18 cm 23 is followed by 4800 Å with 2 3 10 17 cm 23 , and the latter is separated from the barrier by an undoped spacer of 300 Å and 200 Å, for top and bottom contact, respectively. The lateral area of the nominally undoped quantum well is reduced to a 700 Å diameter disk using the ion bombardment technique At zero bias, the spectrometer level S is above the Fermi level m of the emitter with 3D metallic conduction. The alignment of S and m with increasing bias is registered as a step in IV . In the differential conductance G͑V ͒ shown in and its width is related to the energetic width of the spectrometer G Ӎ G max Ӎ 120 meV determined by the tunneling coupling between the impurity and the contacts. The values of G min,max depend on the transparencies of the two barriers, so that G max corresponds to the lower (collector) barrier and G min corresponds to the higher (emitter) barrier, G min ϳ 5 3 10 23 G max , as estimated from the value of G G . The relation between bias V and the energy scale of the spectrometer is established by the coefficientf b dE d͑eV ͒ 0.24, found for the selected 0031-9007͞00͞84(7)͞1563(4)$15.0

Anorexia nervosa and Wernicke-Korsakoff syndrome: a case report

<p>Abstract</p> <p>Introduction</p> <p>Wernicke's encephalopathy is an acute, potentially fatal, neuropsychiatric syndrome resulting from thiamine deficiency. The disorder is still greatly under-diagnosed, and failure to promptly identify and adequately treat the condition can lead to death or to the chronic form of the encephalopathy - Korsakoff's syndrome. Wernicke's encephalopathy has traditionally been associated with alcoholism but, in recent years, there has been an increase in the number of clinical settings in which the disorder is observed.</p> <p>Case presentation</p> <p>We report the case of a 45-year-old Caucasian woman who arrived at the emergency room presenting signs of marked malnutrition and mental confusion, ataxic gait and ophthalmoplegia. Main laboratory test findings included low serum magnesium and megaloblastic anemia. Brain magnetic resonance imaging revealed increased T2 signal in the supratentorial paraventricular region, the medial regions of the thalamus and the central and periaqueductal midbrain. The diagnosis of Wernicke's encephalopathy was made at once and immediate reposition of thiamine and magnesium was started. The patient had a long history of recurrent thoughts of being overweight, severe self-imposed diet restrictions and self-induced vomiting. She had also been drinking gin on a daily basis for the last eight years. One day after admittance the acute global confusional state resolved, but she presented severe memory deficits and confabulation. After six months of outpatient follow-up, memory deficits remained unaltered.</p> <p>Conclusion</p> <p>In this case, self-imposed long-lasting nutritional deprivation is thought to be the main cause of thiamine deficiency and subsequent encephalopathy, but adjunct factors, such as magnesium depletion and chronic alcohol misuse, might have played an important role, especially in the development of Korsakoff's syndrome. The co-morbidity between eating disorders and substance abuse disorders has emerged as a significant health issue for women, and the subgroup of patients with anorexia nervosa who also misuse alcohol is probably at a particular risk of developing Wernicke-Korsakoff syndrome. The present case report highlights this relevant issue.</p