RESUMO
We investigate the structural relaxation of a soft-sphere liquid quenched isochorically (Ï = 0.7) and instantaneously to different temperatures Tf above and below the glass transition. For this, we combine extensive Brownian dynamics simulations and theoretical calculations based on the non-equilibrium self-consistent generalized Langevin equation (NE-SCGLE) theory. The response of the liquid to a quench generally consists of a sub-linear increase of the α-relaxation time with system's age. Approaching the ideal glass-transition temperature from above (Tf > Ta), sub-aging appears as a transient process describing a broad equilibration crossover for quenches to nearly arrested states. This allows us to empirically determine an equilibration timescale teq(Tf) that becomes increasingly longer as Tf approaches Ta. For quenches inside the glass (Tf ≤ Ta), the growth rate of the structural relaxation time becomes progressively larger as Tf decreases and, unlike the equilibration scenario, τα remains evolving within the whole observation time-window. These features are consistently found in theory and simulations with remarkable semi-quantitative agreement and coincide with those revealed in a previous and complementary study [P. Mendoza-Méndez et al., Phys. Rev. 96, 022608 (2017)] that considered a sequence of quenches with fixed final temperature Tf = 0 but increasing Ï toward the hard-sphere dynamical arrest volume fraction ÏHS a=0.582. The NE-SCGLE analysis, however, unveils various fundamental aspects of the glass transition, involving the abrupt passage from the ordinary equilibration scenario to the persistent aging effects that are characteristic of glass-forming liquids. The theory also explains that, within the time window of any experimental observation, this can only be observed as a continuous crossover.
Assuntos
Vidro , Simulação de Dinâmica Molecular , Temperatura , Temperatura de Transição , Vidro/químicaRESUMO
The Amejeiras strain of Blatella germanica (Dictyoptera: Blattellidae) kept in lab conditions since 1994 and susceptible to arpocarb, malathion and cipermethrin insecticides, was studied. This strain was treated with 4 diflubenzuron (Dimilin OMS 1804) concentrations supplied by feeding nymphs at their first stage of development, with the purpose of determining their effect on the survival, phenotype and period of nynmphal development of this species. The dosage-mortality line of regression was determined and the values of CE50 = 0.042% and CE95 = 0.357% were obtained. Sublethal effects were observed in the nymphs treated with the 4 tested concentrations whereas the morphogenetic effects in adult insects only occurred when they were exposed to higher concentrations (0.25% and 0.4%). The nymph development stage showed a highly significant increase when the diflubenzuron concentration was raised. (F = 11.64; p < 0.001).
Assuntos
Blattellidae/efeitos dos fármacos , Diflubenzuron/farmacologia , Animais , Relação Dose-Resposta a DrogaRESUMO
An analysis was made on the incidence of Culicidae in Boyeros municipality, City of Havana from 1994 to 1996 based on the requirements of the national program for eradication of Aedes aegypti. A total of 13 species was detected in which Aedes mediovittatus predominated during 3 years of study, followed by Culex quinquefasciatus whereas for the first time Aedes albopictus species was found in the territory. People's Councils Wajay, Santiago de las Vegas and Armada exhibited the highest values of infestation by Culicidae in the municipality, therefore, they required that anti-Aedes program, operators paid more attention to this situation. It was found that depots preferred by Culicidae for breeding were larval traps followed by low tanks in 1994 and 1995 and by other reservoirs in 1996. A mediovittatus preferred larval traps whereas Cx. quinquefasciatus preferred low tanks except in 1996 when this species was mostly found in other tanks. 93% of all test-positive reservoirs found were colonized by only one species, whereas 7% presented larvae from 2 species or more. A. mediovittatus and C. quinquefasciatus were the most related, above all in low tanks.
Assuntos
Aedes , Anopheles , Culex , Ecossistema , Insetos Vetores , Animais , Distribuição de Qui-Quadrado , Intervalos de Confiança , Cuba , Larva , Dinâmica PopulacionalRESUMO
The results of the entomologic surveillance carried out from 1991 to 1996 in Boyeros municipality, City of Havana within the Program for Eradication of Aedes aegypti were analyzed. Data on mosquitoes fauna collected in the municipality by various sampling methods, larval survey, human bait, capture at rest and larval traps. Culex quinquefasciatus, Aedes mediovittatus and Aedes aegypti species were the most found by the different methods. It was proved that water tanks, man-made deposits, other kinds of tanks and low tanks were the most exploited resources by mosquitoes for their breeding in this municipality whereas larval surveys were the most sensitive method for detecting species since it contributed a greater variety of species. Reference is made to the search for a mechanism that help estimate adult populations from larval indices provided by surveys and the method of capture at rest is stressed as the most sensitive method for adult mosquitoes, particularly for dengue vector within the surveillance system aimed at this species.
Assuntos
Aedes , Anopheles , Culex , Insetos Vetores , Animais , Cuba , Dengue/transmissão , Ecossistema , Humanos , Larva , Densidade Demográfica , Estações do Ano , Estatísticas não ParamétricasRESUMO
A typing of the habitats of Aedes albopictus in Cuba was made after its detection in 1995. It was observed in suburban areas of the Boyeros Municipality, in Havana City, where a study was conducted from October, 1995, to July, 1998. Most of the positive repositories were found outside the houses. Tins, tires, trees and plants were the places preferred for its breeding. It was found in the breeding places associated with Aedes mediovittatus and Culex quinquefasciatus, dominant species in these places. It was also observed a trend towards an increase of the number of repositories colonized only by the species under study. Reference was made to the phenomenon of competence between this species and the indigenous species present in such places.
Assuntos
Aedes , Culex , Aedes/classificação , Animais , Cuba , Comportamento de Retorno ao Território Vital , Dinâmica PopulacionalRESUMO
An analysis was made on the incidence of Culicidae present in Playa Municipality, Havana City, during the intensive stage of the anti-aegypti campaign from June to July, 1997, according to its requirements. Culex quinquefasciatus was the predominant species with a total of 269 focuses. It was collected in all the People's Councils and in every type of repository, excepting clay repositories. The second most abundant species was the Aedes aegypti with 199 focuses, followed by Aedes mediovittatus with 67. The Almendares-Sierra, Ampliación-Almendares and Miramar People's Councils showed the highest values of Culicidae infestation in the municipality. The Aedes aegypti prevailed in the first and Cx. quiquefasciatus in the second. The artificial repositories, low tanks and other repositories had the highest number of mosquito focuses in the municipality. The Cx quinquefasciatus preferred the artificial depositories, whereas the A. aegypti preferred the low tanks. Most of the positive depositories were colonized by only one species (92.7% of the total). 7.3% corresponded to mixed focuses. It was found that Cx. quinqufasciatus and A. aegypti were the most associated species.
Assuntos
Aedes , Animais , Cuba , Culex , Comportamento de Retorno ao Território Vital , Densidade Demográfica , Saúde da População UrbanaRESUMO
After damming the Colorado River the freshwater flow was reduced to 1% of its virgin flow to the Upper Gulf of California (UGC). The ecological effects need to be properly documented. The UGC is the nursery area for Litopenaeus stylirostris, the most profitable fishery in the zone. In order to know the relative abundance of L. stylirostris postlarval stage we conducted a sampled survey every 14 days in 1993, 1994 and 1997, plus an intensive sampling during a complete tide cycle in July 1995 and 1996. We did 10 min trawls each hour during the flood tide. Relative abundance of postlarvae was higher (p < 0.05) in those years when freshwater flow reached the UGC.
Assuntos
Água Doce , Penaeidae/fisiologia , Animais , California , México , Densidade DemográficaRESUMO
Background: the computer program WHONET generates a common database to analyze local or general antimicrobial resistance of bacteria. A surveillance of agents causing urinary tract infections in Chile has been performed using this program. Aim: to report the results after 12 months of urinary tract infection agent surveillance. Material and methods: since november, 1997, a surveillance of in vitro antimicrobial resistance, using agar diffusion techniques, has been performed in 20 to 40 bacterial strains per month, isolated from 11 hospitals in the country. Results have been analyzed using WHONET program. Results: in first 12 months, 3144 strains, 1625 coming from outpatients, have been studied. Seventy four percent of isolated strains were E. coli, 19 percent were other enterobacteria, 4.1 percent were non fermenting bacilli and 2.1 percent were Gram (+) cocci. Sixty five percent of E coli strains were resistant to ampicillin, 11 percent to cefazolin, 2.5 percent to cefuroxime, 19 percent to ceftriaxone, 9 percent to ceftazidime, 4.2 percent to gentamicin 1.3 percent to amikacin, 5.6 percent to ciprofloxacin, 8.4 percent to grepafloxacin, 4.3 percent to nitrofurantoin and 43 percent to trimeproprim/sulphamethoxazole. Eighty two percent of other enterobacteria strains were resistant to ampicillin, 45.5 percent to cefazolin, 33.5 percent to cefuroxime, 26.6 percent to ceftriaxone, 21.5 percent to ceftazidime, 30.3 percent to gentamicin 17.2 percent to amikacin, 21 percent to ciprofloxacin, 16.3 percent to grepafloxacin, 48.2 percent to nitrofurantoin and 44.6 percent to trimeproprim/sulphamethoxazole. There were differences in betalactamic resistance among hospitals. Conclusions: noteworthy is the high resistance rates to third generation cephalosporins, evidenced when the new cutoff values for E coli and klebsiella spp are used. This national surveillance provides updated information on antimicrobial resistance of agents causing urinary tract infections
Assuntos
Humanos , Masculino , Feminino , Adolescente , Pré-Escolar , Lactente , Adulto , Pessoa de Meia-Idade , Infecções Urinárias/tratamento farmacológico , Resistência Microbiana a Medicamentos , Infecções Urinárias/etiologia , Ceftriaxona/farmacologia , Resistência a Ampicilina , Fatores Etários , Enterobacteriaceae/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Ampicilina/farmacologia , Hospitais PúblicosRESUMO
Subacute sclerosing panencephalitis is an infrequent central nervous system viral disease and is a late manifestation of persistent infection by a mutant form of measles virus. Since it affects mainly children and teenagers, the diagnosis in older ages is difficult. Its main clinical symptoms are cognitive impairment, behavioral disturbances and myoclonia. We report two males, aged 21 and 22 years old, presenting with the disease with atypical manifestations. One had a catatonic syndrome and the other, amaurosis. The recognition of the different presentation forms of the disease, endemic in developing countries, allows an earlier diagnosis and a more efficient treatment, when available.
Assuntos
Panencefalite Esclerosante Subaguda/diagnóstico , Adulto , Idade de Início , Humanos , Masculino , Fatores de TempoRESUMO
Proportional abundance of the four most common mosquito species was determined in six types of breeding places located in Plaza de la Revolución municipality, City of Havana from 1993-1996. Culex quinquifasciatus exhibited values over 0.60 except in tyres and larval traps in 1993 and 1994 whereas Aedes mediovittatus showed similar values in low tanks and artificial reservoirs in 1994 (0.43 and 0.56 respectively). It was also observed that this species prefers larval traps. Aedes aegypti and Culex migripaplpus had the lowest abundance values (0.01). These results allowed us to state that there is a sort of shared use by these species of those reservoirs where they breed and that Culex quinquefasciatus is the predominant one.