N-dimensional static and evolving Lorentzian wormholes with cosmological constant

We present a family of static and evolving spherically symmetric Lorentzian wormhole solutions in N+1 dimensional Einstein gravity. In general, for static wormholes, we require that at least the radial pressure has a barotropic equation of state of the form $p_r=\omega_r \rho$, where the state parameter $\omega_r$ is constant. On the other hand, it is shown that in any dimension $N \geq 3$, with $\phi(r)=\Lambda=0$ and anisotropic barotropic pressure with constant state parameters, static wormhole configurations are always asymptotically flat spacetimes, while in 2+1 gravity there are not only asymptotically flat static wormholes and also more general ones. In this case, the matter sustaining the three-dimensional wormhole may be only a pressureless fluid. In the case of evolving wormholes with $N \geq 3$, the presence of a cosmological constant leads to an expansion or contraction of the wormhole configurations: for positive cosmological constant we have wormholes which expand forever and, for negative cosmological constant we have wormholes which expand to a maximum value and then recollapse. In the absence of a cosmological constant the wormhole expands with constant velocity, i.e without acceleration or deceleration. In 2+1 dimensions the expanding wormholes always have an isotropic and homogeneous pressure, depending only on the time coordinate.Comment: 10 pages, accepted for publication in Phys. Rev.

Evolving Lorentzian wormholes supported by phantom matter and cosmological constant

In this paper we study the possibility of sustaining an evolving wormhole via exotic matter made of phantom energy in the presence of a cosmological constant. We derive analytical evolving wormhole geometries by supposing that the radial tension of the phantom matter, which is negative to the radial pressure, and the pressure measured in the tangential directions have barotropic equations of state with constant state parameters. In this case the presence of a cosmological constant ensures accelerated expansion of the wormhole configurations. More specifically, for positive cosmological constant we have wormholes which expand forever and, for negative cosmological constant we have wormholes which expand to a maximum value and then recolapse. At spatial infinity the energy density and the pressures of the anisotropic phantom matter threading the wormholes vanish; thus these evolving wormholes are asymptotically vacuum $\Lambda$-Friedmann models with either open or closed or flat topologies.Comment: 8 pages. To appear in Physical Review

Design, analysis and test verification of advanced encapsulation systems, phase 2 program results

Optical, electrical isolation, thermal structural, structural deflection, and thermal tests are reported. The utility of the optical, series capacitance, and structural deflection models was verified

Supersymmetry, quark confinement and the harmonic oscillator

We study some quantum systems described by noncanonical commutation relations formally expressed as [q,p]=ihbar(I + chi H), where H is the associated (harmonic oscillator-like) Hamiltonian of the system, and chi is a Hermitian (constant) operator, i.e. [H,chi]=0 . In passing, we also consider a simple (chi=0 canonical) model, in the framework of a relativistic Klein-Gordon-like wave equation.Comment: To be published in Journal of Physics A: Mathematical and Theoretical (2007

A Semantic Problem Solving Environment for Integrative Parasite Research: Identification of Intervention Targets for Trypanosoma cruzi

Effective research in parasite biology requires analyzing experimental lab data in the context of constantly expanding public data resources. Integrating lab data with public resources is particularly difficult for biologists who may not possess significant computational skills to acquire and process heterogeneous data stored at different locations. Therefore, we develop a semantic problem solving environment (SPSE) that allows parasitologists to query their lab data integrated with public resources using ontologies. An ontology specifies a common vocabulary and formal relationships among the terms that describe an organism, and experimental data and processes in this case. SPSE supports capturing and querying provenance information, which is metadata on the experimental processes and data recorded for reproducibility, and includes a visual query-processing tool to formulate complex queries without learning the query language syntax. We demonstrate the significance of SPSE in identifying gene knockout targets for T. cruzi. The overall goal of SPSE is to help researchers discover new or existing knowledge that is implicitly present in the data but not always easily detected. Results demonstrate improved usefulness of SPSE over existing lab systems and approaches, and support for complex query design that is otherwise difficult to achieve without the knowledge of query language syntax

Trypanosoma cruzi Gene Expression in Response to Gamma Radiation

Trypanosoma cruzi is an organism highly resistant to ionizing radiation. Following a dose of 500 Gy of gamma radiation, the fragmented genomic DNA is gradually reconstructed and the pattern of chromosomal bands is restored in less than 48 hours. Cell growth arrests after irradiation but, while DNA is completely fragmented, RNA maintains its integrity. In this work we compared the transcriptional profiles of irradiated and non-irradiated epimastigotes at different time points after irradiation using microarray. In total, 273 genes were differentially expressed; from these, 160 were up-regulated and 113 down-regulated. We found that genes with predicted functions are the most prevalent in the down-regulated gene category. Translation and protein metabolic processes, as well as generation of precursor of metabolites and energy pathways were affected. In contrast, the up-regulated category was mainly composed of obsolete sequences (which included some genes of the kinetoplast DNA), genes coding for hypothetical proteins, and Retrotransposon Hot Spot genes. Finally, the tyrosyl-DNA phosphodiesterase 1, a gene involved in double-strand DNA break repair process, was up-regulated. Our study demonstrated the peculiar response to ionizing radiation, raising questions about how this organism changes its gene expression to manage such a harmful stress

Radiating Effectiveness of Annular-Finned Space Radiators, Including Mutual Irradiation between Radiator Elements

the authors also provide an approximate quantitative number for the accuracy of the numerical results. Based on the authors' results of Figs. 8 and 9, the fully developed periodic flow is achieved at x/L = 4 and 30 for Re = 200 and 1600 respectively for L/H = 1. Would the authors first quantitatively define the periodic fully developed flow, and then provide the tabular values of x/L as functions of L/H and Re for L/H = 0.2,0.5,1,2 and 5, and the covered range of Re. A research task remains further refining the analytical model to correlate better the performance of interrupted wall surface with the experimental results. Subsequently, the more complex heat exchanger surfaces could be analyzed. In the meanwhile, this paper by Prof. Sparrow and his colleagues serves as a reminder that the flow and heat transfer phenomena in a compact heat exchanger are too complex to analyze. A better quantitative understanding of the flow phenomena is essential for better correlations and improved heat exchanger design. Additional Reference Authors' Closure We are appreciative of the perspectives conveyed by Dr. Shah's Discussion. With regard to the role of vortices and wakes, there are, assuredly, conditions where they will affect both the heat transfer and friction. On the other hand, there are conditions for which no significant effect will be felt. Perspectives on these conditions are conveyed in references [11] and [12]. In connection with the identification of the periodically developed regime in Figs. 8 and 9, there is considerable latitude depending on the selected criterion. Since all portions of a velocity or temperature profile do not develop with equal rapidity, there are various criteria that can be employed. It was for this reason that we did not quote development lengths in the paper. Additional References 11 Kottke, V., Blenke, H., and Schmidt, K. G., "The Influence of Nose Section and Turbulence Intensity on the Flow Around Thick Plates in Parallel Flow," Warme-und Stoffubertragung, Vol. 10,1977, pp. 159-174. 12 Loehrke, R. I., Roadman, R. E., and Read, G. W" ASME Paper The purpose of this discussion is to point out how one of Minning's results can be generalized. In his analysis of the inverted conical frustrum, Minning has chosen to express his results in terms of four variables-the cone half angle fi, the height of the frustrum h, the radial location of the differential element p, and the vertical distance from the differential element to the extended frustrums' vertex s. In my view, this last choice is not the natural one and indeed it obscures the generality of the result expressed by equation It appears that a better choice of variable would be the radius of the frustrum in the plane of the element or ring, which is given by r = -s tan fi. If s is thereby eliminated from equation With respect to this latter point, one may note, as was done for a cylinder by Sparrow, et al. [1] that the shape factor in question can be considered as the sum of two parts-one being a circular segment and, in this case, the other being a tilted triangular plate frustrum. 1 By C. P. Minning, published in the August, 1977 issue of the JOURNAL OP HEAT TRANSFER, Vol. 99, No. 3, The Aerospace Corporation, El Segundo, CA 90245. Since the former is known [2], the latter can be readily obtained and subsequently expressed in variables more suitable for that configuration. This, of course, introduces new possibilities too numerous to mention. Finally, since Minning does not mention any analytical checks of his result, it is pointed out that, when /3 = 0, it reduces to a form equivalent to that for the cylinder [1]. Additional References 1 Sparrow, E. M., Miller, G. B., and Jonsson, V. K., "Radiating Effectiveness of Annular-Finned Space Radiators, Including Mutual Irradiation between Radiator Elements," Journal Aerospace Sciences, Vol. 29, 1962, pp. 1291-1299 2 Sparrow, E. M., "A New and Simpler Formulation for Radiative Angle Factors," ASME JOURNAL OF HEAT TRANSFER, Vol. 85,1963, pp. 81-88. Author's Closure I appreciate Dr. Nelson's pointing out that the applicability of equation An alternate expression that avoids this confusion can be derived by substitution of the relation r = -s tanjtf, as suggested by Dr. Nelson, and the relation a = (7r/2) -fi into equation C^)] [(h cot a + r) -In this expression, a is the angle between the plane of dAi and the sloping side of the conical frustrum. Values of a are always positive and lie in the range 0 < « < TT. For 0 < « < 7r/2, the frustrum opens upward away from the plane of dA\. For 7r/2 < a < w, the frustrum opens downward toward the plane of dAi. The special case, a = it 12

Genome of the Avirulent Human-Infective Trypanosome—Trypanosoma rangeli

Background: Trypanosoma rangeli is a hemoflagellate protozoan parasite infecting humans and other wild and domestic mammals across Central and South America. It does not cause human disease, but it can be mistaken for the etiologic agent of Chagas disease, Trypanosoma cruzi. We have sequenced the T. rangeli genome to provide new tools for elucidating the distinct and intriguing biology of this species and the key pathways related to interaction with its arthropod and mammalian hosts.  Methodology/Principal Findings: The T. rangeli haploid genome is ,24 Mb in length, and is the smallest and least repetitive trypanosomatid genome sequenced thus far. This parasite genome has shorter subtelomeric sequences compared to those of T. cruzi and T. brucei; displays intraspecific karyotype variability and lacks minichromosomes. Of the predicted 7,613 protein coding sequences, functional annotations could be determined for 2,415, while 5,043 are hypothetical proteins, some with evidence of protein expression. 7,101 genes (93%) are shared with other trypanosomatids that infect humans. An ortholog of the dcl2 gene involved in the T. brucei RNAi pathway was found in T. rangeli, but the RNAi machinery is non-functional since the other genes in this pathway are pseudogenized. T. rangeli is highly susceptible to oxidative stress, a phenotype that may be explained by a smaller number of anti-oxidant defense enzymes and heatshock proteins.  Conclusions/Significance: Phylogenetic comparison of nuclear and mitochondrial genes indicates that T. rangeli and T. cruzi are equidistant from T. brucei. In addition to revealing new aspects of trypanosome co-evolution within the vertebrate and invertebrate hosts, comparative genomic analysis with pathogenic trypanosomatids provides valuable new information that can be further explored with the aim of developing better diagnostic tools and/or therapeutic targets

Functional recombinant protein is present in the pre-induction phases of Pichia pastoris cultures when grown in bioreactors, but not shake-flasks

Background - Pichia pastoris is a widely-used host for recombinant protein production; expression is typically driven by methanol-inducible alcohol oxidase (AOX) promoters. Recently this system has become an important source of recombinant G protein-coupled receptors (GPCRs) for structural biology and drug discovery. The influence of diverse culture parameters (such as pH, dissolved oxygen concentration, medium composition, antifoam concentration and culture temperature) on productivity has been investigated for a wide range of recombinant proteins in P. pastoris. In contrast, the impact of the pre-induction phases on yield has not been as closely studied. In this study, we examined the pre-induction phases of P. pastoris bioreactor cultivations producing three different recombinant proteins: the GPCR, human A2a adenosine receptor (hA2aR), green fluorescent protein (GFP) and human calcitonin gene-related peptide receptor component protein (as a GFP fusion protein; hCGRP-RCP-GFP). Results - Functional hA2aR was detected in the pre-induction phases of a 1 L bioreactor cultivation of glycerol-grown P. pastoris. In a separate experiment, a glycerol-grown P. pastoris strain secreted soluble GFP prior to methanol addition. When glucose, which has been shown to repress AOX expression, was the pre-induction carbon source, hA2aR and GFP were still produced in the pre-induction phases. Both hA2aR and GFP were also produced in methanol-free cultivations; functional protein yields were maintained or increased after depletion of the carbon source. Analysis of the pre-induction phases of 10 L pilot scale cultivations also demonstrated that pre-induction yields were at least maintained after methanol induction, even in the presence of cytotoxic concentrations of methanol. Additional bioreactor data for hCGRP-RCP-GFP and shake-flask data for GFP, horseradish peroxidase (HRP), the human tetraspanins hCD81 and CD82, and the tight-junction protein human claudin-1, demonstrated that bioreactor but not shake flask cultivations exhibit recombinant protein production in the pre-induction phases of P. pastoris cultures. Conclusions - The production of recombinant hA2aR, GFP and hCGRP-RCP-GFP can be detected in bioreactor cultivations prior to methanol induction, while this is not the case for shake-flask cultivations of GFP, HRP, hCD81, hCD82 and human claudin-1. This confirms earlier suggestions of leaky expression from AOX promoters, which we report here for both glycerol- and glucose-grown cells in bioreactor cultivations. These findings suggest that the productivity of AOX-dependent bioprocesses is not solely dependent on induction by methanol. We conclude that in order to maximize total yields, pre-induction phase cultivation conditions should be optimized, and that increased specific productivity may result in decreased biomass yields