26 research outputs found
Retratos de Chaurand y de Semo. El Financiero, sección Cultura "Clicks a la distancia"
No full textReferencias bibliográficas:Elogio de luz, Semo fotógrafo, 1894-1981 Memoria del cuerpo, Semo BalletNota sobre los libros Elogio de luz, de Susana Chaurand editato por Cemex, y Semo fotógrafo, 1894-1981 editado por Conaculta-INAH/ Filmoteca, UNAM, Artención, con una recopilación de la investigadora Emma Cecilia García Krinsky. Ambos publicados en el 2002
The regulation of the mammalian circadian system by the inner retina
No full textEThOS - Electronic Theses Online ServiceGBUnited Kingdo
Developmental dynamics of cone photoreceptors in the eel
No full textBackground: Many fish alter their expressed visual pigments during development. The number of retinal opsins expressed and their type is normally related to the environment in which they live. Eels are known to change the expression of their rod opsins as they mature, but might they also change the expression of their cone opsins?Results: The Rh2 and Sws2 opsin sequences from the European Eel were isolated, sequenced and expressed in vitro for an accurate measurement of their lambda(max) values. In situ hybridisation revealed that glass eels express only rh2 opsin in their cone photoreceptors, while larger yellow eels continue to express rh2 opsin in the majority of their cones, but also have <5% of cones which express sws2 opsin. Silver eels showed the same expression pattern as the larger yellow eels. This observation was confirmed by qPCR (quantitative polymerase chain reaction).Conclusions: Larger yellow and silver European eels express two different cone opsins, rh2 and sws2. This work demonstrates that only the Rh2 cone opsin is present in younger fish (smaller yellow and glass), the sws2 opsin being expressed additionally only by older fish and only in <5% of cone cells
Fotografía y Ciencia. Num. 14 Año 5 (2002) primavera-verano. Alquimia. Sistema Nacional de Fototecas
No full text- Fotografía y Ciencia: una relación apenas asomada - Notas sobre el origen y práctica de la fotografía científica en México, por Ignacio Gutiérrez Ruvalcaba - La fotografía en el registro de la agricultura mexicana del Porfiriato, por Teresa Rojas Rabiela - La fotografía en la historia de la biología en México, por Consuelo Cuevas Cardona - Astrofotografía en el México del siglo XIX, por Marco Arturo Moreno Corral - Flora mexicana, por Mariano Muciño y Martín de Sessé - Algunas aplicaciones de la fotografía, por Luis G. León - Donaciones al Sistema Nacional de Fototecas - El toque de un estilo: la fotografía de SEMO, por Heladio Vera Trejo - Voces y silencios. Museo del Palacio de Bellas Artes, por Rebeca Monroy Nasr - Cosmes de Cossío, un precursor del fotorreportaje, por Arturo Aguilar Ochoa - El Manual para la gestión de fondos y colecciones fotográficas, por Juan Carlos Valdez Marín
A role for the ciliary marginal zone in the melanopsin-dependent intrinsic pupillary light reflex.
No full textMaintenance of pupillary constriction in light-adapted rodents has traditionally been thought to involve a reflex between retina, brain and iris, with recent work identifying the melanopsin-expressing intrinsically photosensitive retinal ganglion cells (ipRGCs) as the major conduits for retinal input to the brain. There is also a less well-understood phenomenon whereby the iris of some mammals, including mice, will constrict to light when either the eye, or the iris itself is physically isolated from the brain. The intrinsic pupillary light reflex (iPLR) is the term given to pupil constriction in the absence of retinal input to the brain. Here, using an intraocular axotomy approach, we show that the iPLR in conscious mice spans a dynamic range over 3 log units of irradiance. This iPLR response is absent in melanopsin knockout (MKO) mice and can be significantly inhibited by atropine. Immunohistochemistry for cfos and melanopsin, in combination with light exposure revealed a population of small ipRGCs in the retinal ciliary marginal zone (CMZ), which remain responsive to light in axotomised mice. We report that damage to the CMZ in a novel in vitro preparation removes a significant component of the iPLR response, while a detailed immunohistochemical analysis of the CMZ in wildtype mice revealed a melanopsin-rich plexus, which was consistently most intense in nasal retina. There were clear examples of melanopsin-positive, direct retino-ciliary projections, which appear to emanate from Brn3b negative, M1 type ipRGCs. These cells are clustered along the melanopsin-rich plexus nasally and may channel ipRGC signals from retina into the iris via ciliary body. Comparison between wildtype and MKO mice reveals that the ciliary body is also weakly stained for melanopsin. Our results show that the full extent of iPLR in mice requires cholinergic neurotransmission and intact signalling at the CMZ / ciliary body. This response may be mediated to some extent by ipRGCs, which send direct projections from the retina into ciliary body. In addition to the melanopsin-mediated iris sphincter constriction suggested by others, we propose a new mechanism, which may involve constriction of the ciliary body and ipRGC-mediated relaxation of the iris dilator muscle
Impact of age and retinal degeneration on the light input to circadian brain structures
No full textAging causes anatomical and functional changes in visual and circadian systems. In wild type mice rods, cones, and photosensitive retinal ganglion cells (pRGCs) decline with age. In rd/rd cl mice, the early loss of rods and cones is followed by protracted transneuronal loss of inner retinal neurons as well as the pRGCs. Here we use Fos induction to study the light input pathway to the suprachiasmatic nuclei (SCN), the intergeniculate leaflets (IGL) and ventral lateral geniculate nuclei (vLGN) of old (∼700 days) and young (∼150 days) wild type and rd/rd cl mice. Cholera toxin tracing was used in parallel to study the anatomy of this pathway. We find that aging rather than retinal degeneration is a more important factor in reducing light input to the SCN, causing both a reduction in Fos expression and retinal afferents. Furthermore, we show light-induced Fos within the vLGN and IGL is predominantly subserved by rods and cones, and once again aging reduces the amplitude of this response
Are Transaction Logs Useful? A Ten-Year Study
No full textIntroduction
Transaction log analysis has long been a staple in academic libraries. Recently, for example, authors have reported on transaction logs and their use in identifying access point use, re-engineering the online public access catalog (OPAC), improving search retrieval, utilizing flip charts at terminals, and employing log data for general personnel management. There are still questions left unanswered, however, about the usefulness of transaction log analysis in marshalling personnel resources. One is whether the logs have predictive value over a span of time, and another is whether any useful trends can be discerned from the logs\u27 data. To answer these questions, transaction log totals, i.e., author, title, subject, keyword, and total searches, were collected spring and fall 1998 and spring 1999 semesters for statistical analysis. The researcher contrasted and correlated this data generated at Southeast Missouri State University (SEMO), a mid-sized, regional university with an enrollment of 8,869 undergraduate and graduate students, with comparable data collected ten years ago at SEMO and with data reported by Neal Kaske at the University of Alabama
Uptake of HIV and syphilis testing of pregnant women and their male partners in a programme for prevention of mother-to-child HIV transmission in Uganda.
No full textOBJECTIVE: To describe uptake of HIV and syphilis testing in a prevention of mother-to-child HIV transmission programme in Uganda. METHODS: Analysis of data from routine HIV and syphilis testing at Entebbe Hospital antenatal services. RESULTS: A total of 20,738 women attended antenatal services. Exactly 62.8% of women, but only 1.8% of their male partners, accepted testing for HIV; 82.2% of women, but only 1.1% of their male partners accepted syphilis testing. Partners of women with positive HIV results were more likely to come for subsequent testing. Of 200 couples whose partners accepted HIV-testing within 30 days of one another, 19 (9.5%) were HIV-discordant, representing 65.5% of couples with at least one partner HIV-positive. HIV prevalence was 12.6% for women and 10.8% for men; syphilis prevalence was 4.0% for women and 6.2% for men. CONCLUSION: Uptake of HIV and syphilis testing was fairly good among pregnant women attending antenatal clinics at Entebbe Hospital, but very low among their male partners. The level of HIV-discordant couples was high. These clinics should be made more couples-friendly to identify both HIV-positive men for treatment and discordant couples for HIV prevention
El toque de un estilo: la fotografía de SEMO. Alquimia. Sistema Nacional de Fototecas: Fotografía y Ciencia. Num. 14 Año 5 (2002) primavera-verano
No full textSingle-sex schools and science engagement
No full textThis paper considers whether single-sex schooling affects gendered patterns in the uptake of science courses in year 11 and the development of science-related career paths. In particular, the author is interested in exploring gender differences surrounding the life and physical sciences. The author explores these issues using data from the Longitudinal Surveys of Australian Youth. Differences in the uptake of life and physical science subjects by males and females occur across all schools. In girls-only schools girls are more likely to undertake physical science subjects than their female counterparts in co-educational schools, but there is no difference when it comes to planning a physical science career. On the other hand, boys in boys-only schools are no more likely to take up life science subjects than their male counterparts in co-educational schools, but they are more likely to plan life science careers
