Chemical Oscillations out of Chemical Noise

The dynamics of one species chemical kinetics is studied. Chemical reactions are modelled by means of continuous time Markov processes whose probability distribution obeys a suitable master equation. A large deviation theory is formally introduced, which allows developing a Hamiltonian dynamical system able to describe the system dynamics. Using this technique we are able to show that the intrinsic fluctuations, originated in the discrete character of the reagents, may sustain oscillations and chaotic trajectories which are impossible when these fluctuations are disregarded. An important point is that oscillations and chaos appear in systems whose mean-field dynamics has too low a dimensionality for showing such a behavior. In this sense these phenomena are purely induced by noise, which does not limit itself to shifting a bifurcation threshold. On the other hand, they are large deviations of a short transient nature which typically only appear after long waiting times. We also discuss the implications of our results in understanding extinction events in population dynamics models expressed by means of stoichiometric relations

Nuevos registros de los mixomicetos de Isla de Mona, Puerto Rico

Seven species of myxomycetes are reported as new records for the Mona Island Commonwealth Reserve, Puerto Rico. They are Ceratiomyxa, fruticulosa, Cribaria intricata, Dictydium cancellatum, Fuligo septica, Lycogala sp., Stemonitis axifera and Tubifera ferruginosa.Siete especies de mixomicetos son informados oomo nuevos registros para la Reserva Estatal Isla de Mona, Puerto Rico. Estos son Ceratiomyxa fruticulosa, Cribaria intricata, Dictydium cancellatum, Fuligo septica, Lycogala sp., Stemonitis axifera y Tubifera ferruginosa

Hongos acuáticos de los estuarios en Puerto Rico: Boca del Río Manatí

Aquatic fungi were isolated from sea foam, leaf litter, beach sand, and driftwood in an estuary known as "La Boca" (river mouth) of the Manatí River in Barceloneta, northern Puerto Rico. Observations of the baits (sterilized balsa wood) and incubated organic debris, revealed the presence of 28 species of aquatic fungi, 13 of which belong to the ascomycetes and 15 to the mitosporic fungi. The species Arenariomyces triseptatus, Corollospora cf. colossa, C. filiformis, Halosphaeria sp., Kirschsteiniothelia sp., Astrosphaeriella aff. mangrovei, Torpedospora radiata (Ascomycota), Brachiosphaera tropicalis, Campylospora sp., and Clavatospora bulbosa (Mitosporic fungi) were the most common in the samples. Eleven species are new records for Puerto Rico; six fungal isolates could not be identified. Se aislaron hongos acuáticos de la espuma de mar, hojarasca, arena playera y madera a la deriva de un estuario conocido como "La Boca" (boca de río) del Río Manatí en Barceloneta, al norte de Puerto Rico. Las observaciones de los cebos (madera de balsa esterilizada) y material orgánico incubado, revelaron la presencia de 28 especies de hongos acuáticos, de los cuales 13 pertenecen a los ascomicetos y 15 a los hongos mitospóricos. Las especies Arenariomyces triseptatus, Corollospora cf. colossa, C. filiformis, Halosphaeria sp., Kirschsteiniothelia sp., Astrosphaeriella aff. mangrovei, Torpedospora radiata (Ascomycota), Brachiosphaera tropicalis, Campylospora sp. y Clavatospora bulbosa (Hongos Mitospóricos) fueron las más comunes en las muestras. Once especies son registros nuevos para Puerto Rico y se aislaron seis hongos que no pudieron ser identificados

Thinking With and Against the Social Determinants of Health: The Latin American Social Medicine (Collective Health) Critique from Jaime Breilh

The concept of the social determinants of health has become increasingly accepted and mainstream in anglophone public health over the past three decades. Moreover, it has been widely adopted into diverse geographic, sociocultural, and linguistic contexts. By recognizing the role of social conditions in influencing health inequalities, the concept challenges narrow behavioral and reductive biological understandings of health. Despite this, scholars and activists have critiqued the concept of the social determinants of health for being incomplete and even misrepresenting the true nature of health inequities. Arguably, these critiques have been most thoroughly developed among those working in the Latin American social medicine and collective health traditions who formulated the “social determination of health” paradigm and the concept of interculturality decades prior to the advent of the social determinants of health. We draw on Jaime Breilh’s main works, with a focus on the recently published book, Critical Epidemiology and the People’s Health, to (1) provide a broad overview of the social determination of health paradigm and its approach to interculturality and (2) clarify how these ideas and the broader collective health movement challenge assumptions within the social determinants of health concept

Isolamento e detecção de Escherichia coli e Campylobacter jejuni potencialmente patogênicos em pombos selvagens de uma área urbana na cidade de Lima, Perú

Os pombos selvagens (Columbia livia) vivem em estreito contato com os seres humanos e outros animais. Podem transmitir agentes potencialmente patogênicos e zoonóticos. Os objetivos deste estudo foram isolar e detectar cepas de Escherichia coli diarreiogênica e Campylobacter jejuni de pombos selvagens urbanos de uma área de Lima, Peru. Amostras de fezes frescas foram coletadas em parques urbanos para o isolamento microbiológico para cepas de E. coli em ágar seletivo e Campylobacterpor método de filtração. Identificação molecular de patótipos diarreiogênicos de E. coli e Campylobacter jejuni foi realizado por PCR. Vinte e dois parques foram amostrados e 16 colônias de Campylobacter spp. foram isolados. O 100% dos isolados foram identificados como Campylobacter jejuni. Além disso, 102 colônias de E. coli foram isoladas e 5,88% resultaram como tipo enteropatogênico (EPEC) e 0,98% como produtora de toxina Shiga (STEC). Os pombos selvagens urbanos de Lima no Peru podem atuar como reservatório ou ser portador de agentes zoonóticos entéricos potencialmente patogênicos.Feral pigeons (Columbia livia) live in close contact with humans and other animals. They can transmit potentially pathogenic and zoonotic agents. The objective of this study was to isolate and detect strains of diarrheagenic Escherichia coli and Campylobacter jejuniof urban feral pigeons from an area of Lima, Peru. Fresh dropping samples from urban parks were collected for microbiological isolation of E. coli strains in selective agar, and Campylobacterby filtration method. Molecular identification of diarrheagenic pathotypes of E.coliand Campylobacter jejuni was performed by PCR. Twenty-two parks were sampled and 16 colonies of Campylobacter spp. were isolated. The 100% of isolates were identified as Campylobacter jejuni. Furthermore, 102 colonies of E. coli were isolated and the 5.88% resulted as Enteropathogenic (EPEC) type and 0.98% as Shiga toxin-producing E. coli (STEC). The urban feral pigeons of Lima in Peru can act as a reservoir or carriers of zoonotic potentially pathogenic enteric agents

Sub-Doppler spectroscopy of the near-UV Cs atom 6S1/2_{1/2}-7P1/2_{1/2} transition in a microfabricated vapor cell

We report on the characterization of sub-Doppler resonances detected by probing the 6S$_{1/2}$-7P$_{1/2}$ transition of Cs atom at 459 nm in a microfabricated vapor cell. The dependence of the sub-Doppler resonance (linewidth, amplitude) on some key experimental parameters, including the laser intensity and the cell temperature, is investigated. These narrow atomic resonances are of interest for high-resolution spectroscopy, instrumentation, and may constitute the basis of a near-UV microcell optical standard

Estructura poblacional de Morpho sulkowskyi Kollar, 1850 (Lepidoptera: Nymphalidae) en un sector de la cordillera occidental, departamento del Cauca (Colombia).

PRIETO C, TAKEGAMI C, RIVERA JM. 2005. Population structure of Morpho sulkowskyi Kollar, 1850 (Lepidoptera: Nymphalidae) in the western Cordillera, Cauca department (Colombia). Entomotropica 20(1): 15-22. Between the months of April and August of 2003 we stimated the Morpho sulkowskyi population size in a site of the western mountain range in the department of the Cauca by means of three methodologies of mark-release-recapture (MRR): Peterson, Jolly-Seber and Schnabel compared with the method of abundance by observation of Pollard. We captured 152 individuals with a recapture success of 23.68%. The ages structure and the recapture success showed that this is a nonconfined population with an emergency tip between July and August. The size of the population varied between 9 and 348 individuals. The residence time average was 3 days and the maximum observed measured for males was 8 days. The number of captured and recaptured individuals showed a positive correlation with the monthly average temperature. The individuals flew mainly between 9:00 and 14:00 hours; and when the temperature was higher than 15 \ub0 C.PRIETO C, TAKEGAMI C, RIVERA JM. 2005. Estructura poblacional de Morpho sulkowskyi Kollar, 1850 (Lepidoptera: Nymphalidae) en un sector de la cordillera occidental, departamento del Cauca (Colombia). Entomotropica 20(1): 15-22. Entre los meses de abril y agosto de 2003 se estim\uf3 el tama\uf1o de una poblaci\uf3n de Morpho sulkowskyi conocida para la cordillera occidental en el departamento del Cauca por medio de tres metodolog\uedas de Marcaje-recaptura (MRR): Peterson, Jolly-Seber y Schnabel comparadas con el m\ue9todo de abundancia por observaci\uf3n de Pollard. Se capturaron 152 individuos y se obtuvo un \ue9xito de recaptura del 23.68%. La estructura de edades y el \ue9xito de recaptura muestran que esta es una poblaci\uf3n no confinada con un pico de emergencia entre julio y agosto. El tama\uf1o de la poblaci\uf3n vari\uf3 entre 9 y 348 individuos. El tiempo de residencia promedio fue de 3 d\uedas y el m\ue1ximo observado fue de 8 d\uedas para machos. El n\ufamero de individuos capturados y recapturados mostr\uf3 una correlaci\uf3n positiva con la temperatura media mensual. Los individuos vuelan principalmente entre las 9:00 y 14:00 horas y cuando la temperatura ambiental es superior a 15 \ub0 C

EFFECT OF ESTROGEN IN THE ELIMINATION OF SEXUAL ODOR IN BOARS

EFFECT OF ESTROGEN IN THE ELIMINATION OF SEXUAL ODOR IN BOAR

Notas sobre los Agaricales del Páramo de Guasca, departamento de Cundinamarca, Colombia

Se han informado pocas especies de los Agaricales (Basidiomycota) de los páramos colombianos. Guzmán y Yarda (1978), Pulido (1983), Saldarriaga et al. (1988) y Guzmán et al. (1994) entre otros, ofrecen valiosa información sobre la taxonomía y distribución de éstos

Yttria-stabilized zirconia/SrTiO_(3) oxide heteroepitaxial interface with symmetry discontinuity

We show that yttria-stabilized zirconia (YSZ) films deposited on structurally dissimilar SrTiO_(3)(110) substrates exhibit two-dimensional layer-by-layer growth. We observed that, up to a thickness of about 15 nm, the square (001) basal plane of the cubic YSZ grows epitaxially on the rectangular (110) crystallographic plane of SrTiO3 substrates, with [110]YSZ(001)//[001]SrTiO_(3)(110) epitaxial relationship. Thus, the heterointerface presents symmetry discontinuity between the YSZ(001) film and the lower surface symmetry SrTiO_(3)(110) substrate. Beyond this specific case, we envisage similar approaches to develop other innovative oxide interfaces showing similar crystal symmetry discontinuities