A study on relativistic lagrangian field theories with non-topological soliton solutions

We perform a general analysis of the dynamic structure of two classes of relativistic lagrangian field theories exhibiting static spherically symmetric non-topological soliton solutions. The analysis is concerned with (multi-) scalar fields and generalized gauge fields of compact semi-simple Lie groups. The lagrangian densities governing the dynamics of the (multi-) scalar fields are assumed to be general functions of the kinetic terms, whereas the gauge-invariant lagrangians are general functions of the field invariants. These functions are constrained by requirements of regularity, positivity of the energy and vanishing of the vacuum energy, defining what we call "admissible" models. In the scalar case we establish the general conditions which determine exhaustively the families of admissible lagrangian models supporting this kind of finite-energy solutions. We analyze some explicit examples of these different families, which are defined by the asymptotic and central behaviour of the fields of the corresponding particle-like solutions. From the variational analysis of the energy functional, we show that the admissibility constraints and the finiteness of the energy of the scalar solitons are necessary and sufficient conditions for their linear static stability against small charge-preserving perturbations. Furthermore we perform a general spectral analysis of the dynamic evolution of the small perturbations around the statically stable solitons, establishing their dynamic stability. Next, we consider the case of many-components scalar fields, showing that the resolution of the particle-like field problem in this case reduces to that of the one-component case. The study of these scalar models is a necessary step in the analysis of the gauge fields.Comment: LaTeX (uses elsart.cls), 57 pages, 9 Postscript figures, final version to appear in Annals of Physics, some minor corrections adde

Chernitsky, Jaime and Shirley -- 1977-80 -- Correspondence, Individual -- letter, 1978-06-29

Letter from Chernitsky, Jaime to Sabin, Albert B. dated 1978-06-29.Sabin Collection Fair Use Policy</a

Mexico/PAHO -- 1973-74 -- OPV Production, International -- letter, 1973-11-23

Letter from Chernitsky, Jaime to Sabin, Albert B. dated 1973-11-23.Sabin Collection Fair Use Policy</a

Agmon, Yaacov Dr. -- 1974-79 -- Correspondence, Individual -- letter, 1978-06-29

Letter from Chernitsky, Jaime to Sabin, Albert B. dated 1978-06-29.Sabin Collection Fair Use Policy</a

Chernitsky, Jaime -- 1967-68 -- Correspondence, Individual -- letter, 1968-09-19

Letter from Chernitsky, Jaime to Sabin, Albert B. dated 1968-09-19.Sabin Collection Fair Use Policy</a

Search for fast optical transients using archival VERITAS data

Fast optical transient phenomena have been observed in the cosmos. Conventional optical telescopes typically lack the fine time resolution required to investigate sub-second transients. Ground based Cherenkov telescopes are powerful devices for finding optical transients as they are designed to capture optical lightbursts on nanosecond time scales. The Very Energetic Radiation Imaging Telescope Array System (VERITAS) is an array of four imaging atmospheric Cherenkov telescopes (IACTs) that has been collecting data since 2007. A significant portion of the archived data corresponds to background signals that can be surveyed to find transient events. We discuss a methodology for conducting an archival search for serendipitous transients. With the analysis employed we achieved a nominal time resolution of approximately 150 ms and a limiting blue band magnitude of 8.9. The archival search revealed signals from transients occurring in the atmosphere, including meteor-like events and satellite flares. No astrophysical or astronomical candidates were found.Des ph ́enomnes de transmissions optiques rapides ont été observer dans le cosmos. Cependant, les télescopes optiques conventionnels n'ont pas la résolution temporelle suffisante pour observer des transmissions de moins dune seconde. Nous utilisons Les télescopes de Tcherenkov pour ce faire, ce sont des outils puissants pour trouver ces transmissions optiques. Ils peuvent capter des impulsions de transmission optique à l'échelle de la nanoseconde. En fonction depuis 2007, VERITAS (Very Energetic Radiation Imaging Telescope Array System) est un réseau de 4 télescopes a imagerie Tcherenkov atmosphérique. Une grande partie des données d'archive corresponde à des signaux de fond qui peuvent être examiner pour trouver événement de transmission optique. Dans cette thèse, nous développons une méthodologie pour trouver des transmissions optiques fortuite dans les archives. L'analyse utilise permet d'atteindre une résolution nominale temporelle d'approximativement 150 ms et d'une limite dans la bande B de magnitude 8.9. Les recherches dans les archives ont révélé des signaux des transmissions optiques ayant eu lieu dans l'atmosphere, cela inclut les météorites et les satellites. Aucun candidat astrophysique ou astronomique n'a été observer

Chernitsky, Jaime and Shirley -- 1977-80 -- Correspondence, Individual -- letter, 1978-09-13

Letter from Chernitsky, Jaime to Sabin, Albert B. dated 1978-09-13.Sabin Collection Fair Use PolicySome personal information has been redacted from this item. See Sabin Redaction Policy.Redacted 2013-05-0

The role of counterions in the membrane-disruptive properties of pH-sensitive lysine-based surfactants

Surfactants are among the most versatile and widely used excipients in pharmaceuticals. This versatility, together with their pH-responsive membrane-disruptive activity and low toxicity, could also enable their potential application in drug delivery systems. Five anionic lysine-based surfactants which differ in the nature of their counterion were studied. Their capacity to disrupt the cell membrane was examined under a range of pH values, concentrations and incubation times, using a standard hemolysis assay as a model for endosomal membranes. The surfactants showed pH-sensitive hemolytic activity and improved kinetics at the endosomal pH range. Low concentrations resulted in negligible hemolysis at physiological pH and high membrane lytic activity at pH 5.4, which is in the range characteristic of late endosomes. With increasing concentration, the surfactants showed an enhanced capacity to lyse cell membranes, and also caused significant membrane disruption at physiological pH. This observation indicates that, at high concentrations, surfactant behavior is independent of pH. The mechanism of surfactant-mediated membrane destabilization was addressed, and scanning electron microscopy studies were also performed to evaluate the effects of the compounds on erythrocyte morphology as a function of pH. The in vitro cytotoxicity of the surfactants was assessed by MTT and NRU assays with the 3T3 cell line. The influence of different types of counterion on hemolytic activity and the potential applications of these surfactants in drug delivery are discussed. The possibility of using pH-sensitive surfactants for endosome disruption could hold great promise for intracellular drug delivery systems in future therapeutic applications