We present the first Atacama Large Millimeter/submillimeter Array (ALMA) observations of the closest known extrasolar debris disc. This disc orbits the star is an element of Eri, a K-type star just 3.2 pc away. Due to the proximity of the star, the entire disc cannot fit within the ALMA field of view. Therefore, the observations have been centred 18" North of the star, providing us with a clear detection of the Northern arc of the ring, at a wavelength of 1.3 mm. The observed disc emission is found to be narrow with a width of just 11-13 AU. The fractional disc width we find is comparable to that of the Solar system's Kuiper Belt and makes this one of the narrowest debris discs known. If the inner and outer edges are due to resonances with a planet then this planet likely has a semi-major axis of 48 AU. We find tentative evidence for clumps in the ring, although there is a strong chance that at least one is a background galaxy. We confirm, at much higher significance, the previous detection of an unresolved emission at the star that is above the level of the photosphere and attribute this excess to stellar chromospheric emission.

Nous abordons dans cette thèse une approche à deux niveaux pour un problème de transport longue distance à charge pleine. Dans cette approche, la problématique étant que le produit chargé dans un entrepôt est immédiatement et intégralement livré au client, laissant le véhicule vide pour passage à l’entrepôt du client suivant. Dans cet environnement, nous étudions la situation de deux transporteurs. Le premier, le transporteur B, possède une clientèle qu’il ne peut satisfaire en totalité, et devra se résoudre à sous-traiter une partie à la concurrence. Le deuxième transporteur, le transporteur A, concurrent mais partenaire privilégié du premier, propose des tarifs pour combler les demandes insatisfaites du transporteur B. Nous sommes donc en présence d’un problème séquentiel non coopératif que nous modélisons par une approche de programmation bi-niveau : au premier niveau le transport A représente le meneur, qui a pour objectif de maximiser son revenu en fixant des tarifs attractifs à B. Au second niveau, le transporteur B représente le suiveur qui a pour objectif de satisfaire toutes ses demandes à coût minimal. Le modèle proposé formulé en programme mathématique à deux niveaux en variables mixtes est NP difficile à résoudre en raison de sa complexité intrinsèque. Deux versions du problème sont étudiées : le modèle simplifié mono-objectif et le modèle complet bi- objectif. Nous développons des méthodes exactes pour résoudre les instances de petites tailles et des heuristiques afin d’obtenir de bonnes solutions en des temps raisonnables pour les instances de plus grande taille. / In this thesis, we discuss a bilevel approach for a full-load long-haul problem. In this type of issue, the product, loaded from a warehouse, is immediately and fully delivered to client, leaving the vehicle empty to visit the warehouse of the next customer. In this environnement, we consider the situation for two carriers. The first one, called carrier B, has a customer base that they cannot totally satisfy and they will be compelled to partial outsourcing to competitors. The second one, called carrier A, competitor but also key partner of the first carrier, offers rates to respond to requests unsatisfied by carrier B. We are dealing here with a non-cooperative sequential problem that we model with a bilevel programming approach : at the first level, carrier A is the leader, whose aim is to maximize their incomes by setting attractive prices to B. In the second level, carrier B is the follower whose aim is to respond to all demands at minimal cost. The proposed model is formulated as mathematical program with two levels and mixed variables. It is NP-hard to solve due to inherent complexity. Two versions of the problem are considered : the mono-objective simplified model and the multi-objective complete model. We develop exact method to solve small-scale instances and heuristics to obtain goog solutions within a reasonable amount of time for larger-scale instances.

In the need of computational tools for epsilon-multiplicity, we provide a criterion for a module with a rank E inside a free module F to have rational epsilon-multiplicity in terms of the finite generation of the saturation Rees algebra of E. In this case, the multiplicity can be related to a Hilbert multiplicity of certain graded algebra. A particular example of this situation is provided: it is shown that the epsilon-multiplicity of monomial modules is Noetherian. Numerical evidence is provided that leads to a conjecture formula for the epsilon-multiplicity of certain monomial curves in the 3-affine space.

Cytokine induced transcription of the germline immunoglobulin heavy chain gene directs isotype switch recombination to that gene. Therefore, understanding the regulation of germline transcription is an important first step in understanding the class switching process. Treatment of human B cells with IL-4 results in germline epsilon transcription. Subsequent activation of a second signal is necessary for these cells to undergo class switch recombination and express surface IgE. In contrast, treatment of splenic murine B-cells with IL-4 alone does not induce germline epsilon transcription. However, treatment with IL-4 plus LPS does induces germline epsilon transcription, followed by class switching to the IgE isotype. In both human and mouse, IL-4 is absolutely required for induction of germline transcripts and expression of IgE. Therefore, IL-4 is considered to be an IgE switch factor. The murine B lymphoma line, I.29μ is an IgM+ B cell line which can be induced to switch to the IgE isotype by treatment with IL-4 plus LPS. In these cells, germline epsilon transcription is constitutive and can be further induced 5-20 fold with IL-4, whereas LPS has no effect at the RNA level. Thus, the I.29μ cell line provides a model system to study the regulatory effects of IL-4 on the murine germline epsilon promoter. The aim of this thesis is to characterize the murine germline epsilon promoter and identify the minimal DNA elements necessary and sufficient for IL-4 induction. To identify the promoter elements, two kb of the 5' flanking region to the first exon (Iε) of the germline epsilon transcript was cloned into a Luciferase reporter plasmid and assayed for promoter activity. Assay of successive 5' deletion mutations by transfections into two B cell lines, I.29μ and M12.4.1, identified the 213 bp promoter construct, -162Luc, as containing sufficient sequence to confer full promoter function. Assay of the linker scanning mutations in the -162Luc plasmid localized the IL-4 responsive effect to a 46 bp region of the promoter. This region contains three nuclear factor binding elements: a C/EBP site, a recently identified NF-IL-4 site and a NFкB/p50 site. In order to detect protein complexes that specifically interact with this active region of DNA, electrophoretic mobility shift assays were performed using double stranded, oligonucleotide probes of this IL-4 responsive region. An IL-4 inducible complex was identified in nuclear extracts of I.29μ as well as murine splenic B-cells. Competition experiments with mutant probes mapped this inducible complex to the NF-IL-4 site. Constitutive binding of both C/EBP and NFкB/p50 was demonstrated by cold competition and supershift experiments. Transfection experiments using a series of linker scanning mutations allowed identification of DNA elements necessary for IL-4 induction. In order to test if these elements are sufficent for IL-4 induction, double stranded oligonucleotides containing these elements were transfered to a minimal fos promoter plasmid and assayed for IL-4 responsiveness. A 27 bp fragment containing two DNA elements, a C/EBP and a NF-IL-4 site were sufficient to confer IL-4 inducibility to a minimal c-fos promoter. This study defined a different IL-4 response element in the murine germline epsilon promoter from that previously published. This IL-4 response element is identical to the IL-4 response element in the human germline epsilon promoter. The NF-IL-4 site is also present in the promoter of the IL-4 responsive gene, CD23b (FcεRII), and this element binds an IL-4 inducible complex present in the human monocytic cell line U937. Various reports demonstrate the presence of an IL-4 inducible complex by gel shift assays and indeed the binding activity of NF-IL-4 has been mapped to a 9 bp consensus sequence within a 19 bp fragment. However, the transfer of IL-4 inducibility has not been reported using fragments smaller than 123 bp, the importance of which is underscored by the fact that more than one factor is involved in this induction. The contribution of this thesis to the understanding of transcriptional induction by IL-4 is in the delineation of the factors involved - namely, a member of the C/EBP family and NF-IL-4 are required for IL-4 induction and NFкB/p5O modulates this induction.

We are developing a new spectrophotometric temperature index based on the Ca II H and K lines. Because these lines are present even in very cool stars and because the Ca II H line is blended with the H-epsilon line in hot stars, this index should cover a very broad range of spectral types. Our data set consisted of 95 stars with spectral types ranging from O9 to M1. We examined five different indices based on the Ca II H + H-epsilon and K lines, as well as single-wavelength indices centered on each of the H-delta and H-gamma lines, which are in the same region of the spectrum. We compared our new index value with the H-beta index values for the stars in our data set that had published H-beta values. We found that the Ca II K-H index was the best temperature indicator with the widest range in magnitude of the indices we examined.

Abstract: Under normal sealing and storage conditions, Nylon-6, poly-caprolactam-based plastic laminates may release impurities to packaged foods and liquids and the application of heat for cooking often increases the rate of migration. Epsilon-caprolactam is one of the main contaminates found to migrate from a Nylon-6 poly-caprolactam plastic film. The objectives of this study were to determine the effects of solvent, transportation and storage time on the migration of ε-caprolactam from a Nylon-6-based lidding material into water or a white wine substitute (12% ethanol). Polypropylene plastic cups were filled, sealed, packaged, stacked and exposed to a simulated 3-day cross-country shipment. Cups were sampled with or without simulated shipment after 0, 7, 14 and 28 days at 20.6°C. Epsilon-caprolactam was determined using a GC equipped with FID and a Restek Rtx 1301 megabore column. Results of the study indicated migration of ε-caprolactam into containers at the time of sealing with significantly higher levels (4.42 ppm average) occurring in cups containing 12% ethanol vs. water (0.01 ppm average). After the cups were sealed, neither simulated cross-country shipment nor storage increased levels of ε-caprolactam in either solvent. The results indicate that wine sealed in packages lined with Nylon-6-based plastic could contain significant amounts of ε-caprolactam. However, it is not understood how the alcohol, whether as liquid or vapor, interacted with the lidding material to increase migration at the time of sealing. No delamination of the polypropylene layer in the lidding material was observed after sealing. Future research needs to be conducted to study the effects of alcohol, alcohol vapor, sealing time and temperature on ε-caprolactam migration.

In this dissertation we have studied nearield phenomena in dipole radiation. We have studied first the energy flow patterns of the radiation emitted by an electric dipole located in between parallel mirrors. The field lines of the Poynting vector have intricate structures, including many singularities and vortices. For a dipole parallel to the mirror surfaces, vortices appear close to the dipole. Vortices are located where the magnetic field vanishes. Also, a radiating electric dipole near the joint of two orthogonal mirrors is considered, and also here we find numerous singularities and vortices in the energy flow patterns. We have also studied the current density in the mirrors. Next we have studied the reflection of radiation by and the transmission of radiation through an interface with an  -near-zero (ENZ) material. For p polarization, we find that the reflection coefficient is -1, and the transmission coefficient is zero for all angles of incidence. The transmitted electric field is evanescent and circularly polarized. The transmitted magnetic field is identically zero. For s polarization, the transmitted electric field is s polarized and the transmitted magnetic field is circularly polarized. The next topic was the study of the force exerted on the dipole by its own reflected field near an ENZ interface. We found that, under certain circumstances, it could be possible that the dipole would levitate in its reflected field. This levitation is brought about by evanescent reflected waves. Finally, power emission by an electric dipole near an interface was considered. We have derived expressions for the emitted power crossing an interface. The power splits in contributions from traveling and evanescent incident waves. We found that for an ENZ interface, only evanescent dipole waves penetrate the material, but there is no net power flow into the material.

No description available.

No description available.

Polymeric bone scaffolds are a promising tissue engineering approach for the repair of critical-size bone defects. Porous three-dimensional (3D) scaffolds play an essential role as templates to guide new tissue formation. However, there are critical challenges arising from the poor mechanical properties and low bioactivity of bioresorbable polymers, such as poly(epsilon-caprolactone) (PCL) in bone tissue engineering applications. This research investigates the potential use of cellulose nanocrystals (CNCs) as multi-functional additives that enhance the mechanical properties and increase the biomineralization rate of PCL. To this end, an in vitro biomineralization study of both sulfuric acid hydrolyzed-CNCs (SH-CNCs) and surface oxidized-CNCs (SO-CNCs) has been performed in simulated body fluid in order to evaluate the bioactivity of the surface functional groups, sulfate and carboxyl groups, respectively. PCL nanocomposites were prepared with different SO-CNC contents and the chemical/physical properties of the nanocomposites were analyzed. 3D porous scaffolds with fully interconnected pores and well-controlled pore sizes were fabricated from the PCL nanocomposites with a 3D printer. The mechanical stability of the scaffolds were studied using creep test under dry and submersion conditions. Lastly, the biocompatibility of CNCs and 3D printed porous scaffolds were assessed in vitro. The carboxyl groups on the surface of SO-CNCs provided a significantly improved calcium ion binding ability which could play an important role in the biomineralization (bioactivity) by induction of mineral formation for bone tissue engineering applications. In addition, the mechanical properties of porous PCL nanocomposite scaffolds were pronouncedly reinforced by incorporation of SO-CNCs. Both the compressive modulus and creep resistance of the PCL scaffolds were enhanced either in dry or in submersion conditions at 37 degrees Celsius. Lastly, the biocompatibility study demonstrated that both the CNCs and material fabrication processes (e.g., PCL nanocomposites and 3D printing) were not toxic to the preosteoblasts (MC3T3 cells). Also, the SO-CNCs showed a positive effect on biomineralization of PCL scaffolds (i.e., accelerated calcium or mineral deposits on the surface of the scaffolds) during in vitro study. Overall, the SO-CNCs could play a critical role in the development of scaffold materials as a potential candidate for reinforcing nanofillers in bone tissue engineering applications. / Ph. D.