Detailed analysis of quantum phase transitions within the u(2)u(2) algebra

We analyze in detail the quantum phase transitions that arise in models based on the $u(2)$ algebraic description for bosonic systems with two types of scalar bosons. First we discuss the quantum phase transition that occurs in hamiltonians that admix the two dynamical symmetry chains $u(2)\supset u(1)$ and $u(2)\supset so(2)$ by diagonalizing the problem exactly in the $u(1)$ basis. Then we apply the coherent state formalism to determine the energy functional. Finally we show that a quantum phase transition of a different nature, but displaying similar characteristics, may arise also within a single chain just by including higher order terms in the hamiltonian.Comment: 5 figure

Relapsing fever, a disappearing cause of fever and maternal death in Sengerema, Tanzania, east Africa

Objective: To study the incidence of tick borne relapsing fever (TBRF) during the last 50 years, once like malaria an endemic disease in Sengerema, Tanzania.Design: By analyzing the annual reports, focusing on the number of admissions, maternal deaths, blood smears of patients with fever for Borrelia.Setting: Sengerema district, Tanzania.Subject: Admissions in Sengerema Hospital due to TBRF.Main Outcome Measures: From 1960 to 2010, we analyzed the incidence of TBRF.Result: Forty annual admissions in the sixties/seventies, 200 in the eighties (range from 37 in 1964 to 455 in 1988), dropping to 30 in the nineties. For the last nine years no Borrelia spirochetes were found in blood smears at the laboratory anymore and no admissions for TBRF were  registered. The number of maternal deaths due to relapsing fever  decreased simultaneously; the last one recorded was in 2002.Conclusion: During the last century, we have witnessed the disappearing of tick borne relapsing fever in Sengerema. Increase of gold mining,  improved local economy, housing and standards of living after the nineties resulted in an almost complete eradication of the incidence of TBRF

Algebraic approach to the Hulthen potential

In this paper the energy eigenvalues and the corresponding eigenfunctions are calculated for Hulthen potential. Then we obtain the ladder operators and show that these operators satisfy SU(2) commutation relation.Comment: 8 Pages, 1 Tabl

Measurement of the local Jahn-Teller distortion in LaMnO_3.006

The atomic pair distribution function (PDF) of stoichiometric LaMnO_3 has been measured. This has been fit with a structural model to extract the local Jahn-Teller distortion for an ideal Mn(3+)O_6 octahedron. These results are compared to Rietveld refinements of the same data which give the average structure. Since the local structure is being measured in the PDF there is no assumption of long-range orbital order and the real, local, Jahn-Teller distortion is measured directly. We find good agreement both with published crystallographic results and our own Rietveld refinements suggesting that in an accurately stoichiometric material there is long range orbital order as expected. The local Jahn-Teller distortion has 2 short, 2 medium and 2 long bonds.Comment: 5 pages, 3 postscript figures, minor change

Design of a freeform two-reflector system to collimate and shape a point source distribution

In this paper we propose a method to compute a freeform reflector system for collimating and shaping a beam from a point source. We construct these reflectors such that the radiant intensity of the source is converted into a desired target. An important generalization in our approach compared to previous research is that the output beam can be in an arbitrary direction. The design problem is approached by using a generalized Monge-Amp\`ere equation. This equation is solved using a least-squares algorithm for non-quadratic cost functions. This algorithm calculates the optical map, from which we can then compute the surfaces. We test our algorithm on two cases. First we consider a uniform source and target distribution. Next, we use the model of a laser diode light source and a ring-shaped target distribution

Bacterium-like particles as multi-epitope delivery platform for Plasmodium berghei circumsporozoite protein induce complete protection against malaria in mice

Contains fulltext : 110364.pdf (publisher's version ) (Open Access)BACKGROUND: Virus-like particles have been regularly used as an antigen delivery system for a number of Plasmodium peptides or proteins. The present study reports the immunogenicity and protective efficacy of bacterium-like particles (BLPs) generated from Lactococcus lactis and loaded with Plasmodium berghei circumsporozoite protein (PbCSP) peptides. METHODS: A panel of BLP-PbCSP formulations differing in composition and quantity of B-cell, CD4+ and CD8+ T-cell epitopes of PbCSP were tested in BALB/c mice. RESULTS: BLP-PbCSP1 induced specific humoral responses but no IFN-gamma ELISPOT response, protecting 30-40% of the immunized mice. BLP-PbCSP2, with reduced length of the non-immunogenic part of the T-cell-epitopes construct, increased induction of IFN-gamma responses as well as protection up to 60-70%. Compared to controls, lower parasitaemia was observed in unprotected mice immunized with BLP-PbCSP1 or 2, suggestive for partial immunity. Finally, further increase of the number of B-cell epitopes and codon optimization (BLP-PbCSP4) induced the highest anti-CSP antibody levels and number of IFN-gamma spots, resulting in sterile immunity in 100% of the immunized mice. CONCLUSION: Presentation of Plasmodium-derived antigens using BLPs as a delivery system induced complete protection in a murine malaria model. Eventually, BLPs have the potential to be used as a novel versatile delivery platform in malaria vaccine development

Algebraic approach to molecular rotation‐vibration spectra. II. Triatomic molecules

The algebraic approach to molecular rotation‐vibration spectra introduced in a previous article is extended from di‐ to tri‐ and polyatomic molecules. The spectrum generating algebra appropriate to triatomic molecules U(4)⊗U(4) is explicitly constructed. Its dynamical symmetries and their relation to rigid, nonrigid, linear, and nonlinear structures are discussed. Applications to the spectra of HCN, CO2, and H+3 are considered. In particular, it is shown that the algebraic description can account for the Fermi resonances occurring in CO2. Some remarks are made on the spectrum generating algebras appropriate to polyatomic molecules