Geometric Phases generated by the non-trivial spatial topology of static vector fields coupled to a neutral spin-endowed particle. Application to 171Yb atoms trapped in a 2D optical lattice

We have constructed the geometric phases emerging from the non-trivial topology of a space-dependent magnetic field, interacting with the spin magnetic moment of a neutral particle. Our basic tool is the local unitary transformation which recasts the magnetic spin interaction under a diagonal form. Rewriting the kinetic term in the "rotated" frame requires the introduction of non-Abelian covariant derivatives, involving the gradients of the Euler angles which define the orientation of the local field. Within the rotated frame, we have built a perturbation scheme,assuming that the longitudinal non-Abelian field component dominates the transverse ones, to be evaluated to second-order. The geometry embedded in the longitudinal gauge vector field and its curl, the geometric magnetic field, is described by the associated Aharonov-Bohm phase. As an illustration, we study the physics of cold 171Yb atoms dressed by two sets of circularly polarized beams, forming square or triangular 2D optical lattices. The geometric field is computed explicitly from the Euler angles. The magnitude of 2nd-order corrections due to transverse fields can be reduced to the percent level by a choice of light intensity which keeps the dressed atom loss rate below 5 s^{-1}. An auxiliary optical lattice confines the atoms within 2D domains where the geometric field is pointing upward.Comment: 12 pages, 4 figures. Comments and one figure added about the effect of the additional scalar potential (sec. V.B). To be published in J. Phys. A:Math. Theo

Effect of 2-(4-fluorophenylamino)-5-(2,4-dihydroxyphenyl)-1,3,4-thiadiazole on the molecular organisation and structural properties of the DPPC lipid multibilayers

AbstractInteractions and complex formation between lipids and biologically active compounds are crucial for better understanding of molecular mechanisms occurring in living cells. In this paper a molecular organisation and complex formation of 2-(4-fluorophenylamino)-5-(2,4-dihydroxybenzeno)-1,3,4-thiadiazole (FABT) in DPPC multibilayers are reported. The simplified pseudo binary phase diagram of this system was created based on the X-ray diffraction study and fourier transform infrared spectroscopic data. The detailed analysis of the refraction effect indicates a much higher concentration of FABT in the polar zones during phase transition. Both the lipid and the complex ripple after cooling. It was found that FABT occupied not only the hydrophilic zones of the lipid membranes but also partly occupied the central part of the non polar zone. The infrared spectroscopy study reveals that FABT strongly interact with hydrophilic (especially PO2−) and hydrophobic (especially “kink” vibrations of CH2 group). The interactions of FABT molecules with these groups are responsible for changes of lipid multibilayers observed in X-ray diffraction study

Chronic mild stress alters the somatostatin receptors in the rat brain

RATIONALE: The involvement of somatostatin (SST) and its receptors in the pathophysiology of depression and stress has been evidenced by numerous studies. OBJECTIVES: The purpose of the present study was to find whether chronic mild stress (CMS), an animal model of depression, affects the SST receptors in the rat brain and pituitary, as well as the level of SST in plasma. METHODS: In CMS model, rats were subjected to 2 weeks of stress and behaviorally characterized using the sucrose consumption test into differently reacting groups based on their response to stress, i.e., stress-reactive (anhedonic), stress-non-reactive (resilient), and invert-reactive rats (characterized by excessive sucrose intake). We measured specific binding of [(125)I]Tyr(3)-Octreotide, expression of mRNA encoding sst2R receptors in the rat brains, expression of SST and its receptors in rat pituitary, and the level of SST in the plasma. RESULTS: The obtained results show decreases in binding of [(125)I]Tyr(3)-Octreotide in most of rat brain regions upon CMS and no significant differences between three stressed groups of animals, except for significant up-regulation of sst2 receptor in medial habenula (MHb) in the stress-reactive group. In the same group of animals, significant increase in plasma SST level was observed. CONCLUSIONS: There are two particularly sensitive sites distinguishing the response to stress in CMS model. In the brain, it is MHb, while on the periphery this predictor is SST level in plasma. These changes may broaden an understanding of the mechanisms involved in the stress response and point to the intriguing role of MHb

Constraints on a second planet in the WASP-3 system

There have been previous hints that the transiting planet WASP-3 b is accompanied by a second planet in a nearby orbit, based on small deviations from strict periodicity of the observed transits. Here we present 17 precise radial velocity measurements and 32 transit light curves that were acquired between 2009 and 2011. These data were used to refine the parameters of the host star and transiting planet. This has resulted in reduced uncertainties for the radii and masses of the star and planet. The radial-velocity data and the transit times show no evidence for an additional planet in the system. Therefore, we have determined the upper limit on the mass of any hypothetical second planet, as a function of its orbital period.Comment: Accepted for publication in The Astronomical Journa

Structural basis of transposon end recognition explains central features of Tn7 transposition systems

Tn7 is a bacterial transposon with relatives containing element-encoded CRISPR-Cas systems mediating RNA-guided transposon insertion. Here, we present the 2.7 Å cryoelectron microscopy structure of prototypic Tn7 transposase TnsB interacting with the transposon end DNA. When TnsB interacts across repeating binding sites, it adopts a beads-on-a-string architecture, where the DNA-binding and catalytic domains are arranged in a tiled and intertwined fashion. The DNA-binding domains form few base-specific contacts leading to a binding preference that requires multiple weakly conserved sites at the appropriate spacing to achieve DNA sequence specificity. TnsB binding imparts differences in the global structure of the protein-bound DNA ends dictated by the spacing or overlap of binding sites explaining functional differences in the left and right ends of the element. We propose a model of the strand-transfer complex in which the terminal TnsB molecule is rearranged so that its catalytic domain is in a position conducive to transposition

Hexatic-Herringbone Coupling at the Hexatic Transition in Smectic Liquid Crystals: 4-ϵ\epsilon Renormalization Group Calculations Revisited

Simple symmetry considerations would suggest that the transition from the smectic-A phase to the long-range bond orientationally ordered hexatic smectic-B phase should belong to the XY universality class. However, a number of experimental studies have constantly reported over the past twenty years "novel" critical behavior with non-XY critical exponents for this transition. Bruinsma and Aeppli argued in Physical Review Letters {\bf 48}, 1625 (1982), using a $4-\epsilon$ renormalization-group calculation, that short-range molecular herringbone correlations coupled to the hexatic ordering drive this transition first order via thermal fluctuations, and that the critical behavior observed in real systems is controlled by a `nearby' tricritical point. We have revisited the model of Bruinsma and Aeppli and present here the results of our study. We have found two nontrivial strongly-coupled herringbone-hexatic fixed points apparently missed by those authors. Yet, those two new nontrivial fixed-points are unstable, and we obtain the same final conclusion as the one reached by Bruinsma and Aeppli, namely that of a fluctuation-driven first order transition. We also discuss the effect of local two-fold distortion of the bond order as a possible missing order parameter in the Hamiltonian.Comment: 1 B/W eps figure included. Submitted to Physical Review E. Contact: [email protected]

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