Eventual Contact Research Articles

Incorporating lag effects in register-based age-of-onset distributions in schizophrenia

Epidemiological studies often use age-of-first-admission from psychiatric case registers to estimate age-of-onset in schizophrenia. Retrospective, interview-based methods have shown that there is a delay between onset of symptoms and eventual contact with psychiatric services, and that this delay can vary both among individuals and at different ages. This delay or lag can confound the interpretation of first admission data such as age-of-onset. To evaluate the potential impact of this factor, we constructed a flexible mathematical model which integrates age-at-first-admission with estimates of this lag, which were derived from interview-based studies and clinical judgement. We applied this model to age-of-first-admission data for 4218 patients with ICD8/9 schizophrenia drawn from a state-wide psychiatric register. Both the raw age-of-first-admission distribution curve and the transformed data (‘estimated age-of-onset’) reinforce previous findings that (a) there is a wide range of age-of-onset and (b) the shapes of the curves differ between the sexes. Inspection of the mathematically derived distribution supports the proposition that (a) transformation for a lag effect produces a lower onset age and (b) including a variable length of lag produces a change in shape of the distribution. We propose that the mathematical transformation of age-of-first-admission data may have heuristic value, but requires further empirical data on which to base the assumptions of the model.

Analysis of Ambient Concentrations of Organic Vapors with a Passive Sampler

Volatile organic compounds can contribute to the failure of electronic equipment in both switching offices and data centers. They can also be useful indicators of ventilation needs. Only within the past decade have ambient concentrations of volatile organics been measured routinely. In standard sampling approach, a pump is used to pull a known volume of air through an adsorbent. This study examines a sampling procedure that does not use a pump, but instead depends on molecular diffusion for eventual contact between the vapor phase compounds and the charcoal sorbent (passive sampling). The technique is both simpler and less expensive than active sampling with a pump. This method has been validated for low-level sampling over extended time intervals. This study demonstrates that collected amounts vary linearly with airborne concentrations for sampling intervals in excess of four weeks: even after eight weeks of sampling at typical ambient concentrations, the amount of material collected does not approach th...

Ethological Differences and the Probability of Introgressive Hybridization Between Two Species of the Ninespine Stickleback, Pungitius Pungitius and Pungitius Platygaster, in Eurasia

Two closely related allopatric species of the ninespine stickleback occur in Eurasia. One, Pungitius pungitius, is widespread within the arctic basin and the other, P. platygaster, ranges in the southern regions (Pontearal-Caspian province). The ranges of both species were affected in recent years by human activities and there now appears to be a strong likelihood that their ranges will come to overlap in the near future. The differences in reproductive behavior among species of the Gasterosteidae plays a leading role in the formation of interspecific barriers (WOOTTON, 1976). In anticipation of the eventual contact of the two forms, I conducted experiments to investigate the question: Does the prolonged adaptation of these forms to different ecological conditions result in sterility of hybrids or not? Some preference tests were made between sexual partners in aquaria under laboratory conditions. The methods I used (following FOSTER, 1977) increased the likelihood of free choice of conspecific or sexual partners. Females of both forms approximately equally chose to spawn with males of their own and the unfamiliar species. Some females of both species showed preference for males of P. pungitius, which used more striking and demonstrative postures in the nuptial dance. The main differences in the spawning behavior of the two forms actually amount to differences in the elements of twisting and leading, and to the faster completion of spawning in P. platygaster. It seems, that these differences are of only slight importance and, in case of sympatry of the two forms in the wild, probably would not prevent hybridization. Interspecific group crosses of P. pungitius x P. platygaster in controlled natural conditions (ponds) confirmed my assumption that hybrid populations would be viable. F1 and F2 hybrids and backcrosses were fertile and viable, and hybrid-pond populations were self-reproductive and increased their numbers during the two years that I observed them. There is an interesting peculiarity in the spawning of hybrid males. Instead of building their nests on stems of plants, like males of either pure-species form, they build their nests under rocks on the substrate, like the males of Gasterosteus aculeatus. In summary, the results of my experiments have led me to conclude that, in case of contact between the two species in the wild (Irtyshriver, West Siberia), it is highly probable that substantial amounts of introgressive hybridization will occur.

Histocompatibility in the Cheilostome Bryozoan "Thalamoporella californica"

Histocompatibility in the Cheilostome Bryozoan "Thalamoporella californica"

Histocompatibility in the Cheilostome Bryozoan Thalamoporella californica

Histocompatibility in the Cheilostome Bryozoan Thalamoporella californica

Making Edentulous Impressions

Making edentulous impressions involves the intimacy of contact between the tissue surface of the denture and the residual structures of the alveolar and bearing areas, the form of the denture base to internal structures of the oral cavity, and the eventual contact of each denture base through an articulating surface. All steps in denture construction deserve equal consideration.