Nanotecnología y los enclaves del conocimiento en Latinoamérica

Mucho se ha escrito sobre la nanotecnología en los últimos años, sobre todo en lo relacionado a su revolucionario significado para la ciencia y sus aplicaciones que, según se argumenta, plantean la posibilidad de cambiar profundamente el mundo en que vivimos. No obstante, muy poco se ha escrito acerca de cómo la nanotecnología se incorpora al contexto de la economía del conocimiento y las fuerzas impulsoras detrás de esta dinámica. En el artículo, los autores analizan la intención del Banco Mundial de desarrollar las Iniciativas Científicas Milenio como Centros de Excelencia en Latinoamérica, con el objetivo de incrementar la competitividad y promover el crecimiento económico, que son entendidos por el Banco Mundial como prerrequisitos del desarrollo. De igual forma, se exponen las implicaciones del régimen de patentes que terminan modificando la trayectoria de esta tecnología revolucionaria

Information and communication technology in Cuba : the case of the Joven Club de Computación y Electrónica

v, 70 leaves : ill. ; 28 cm.Includes abstract.Includes bibliographical references (leaves 68-70).Appendices in Spanish.In 1987, Cuba initiated the Joven Club de Computación y Electrónica (JCCE) programme, a nation-wide installation of staff and computer equipment that grew to encompass all 169 Cuban municipalities with community centres for computer-related training. Despite the severe economic upheaval that followed the 1989-1991 disappearance of Cuba's major trade ties with the U.S.S.R., the JCCE project endured. As the economy gradually recovered with the rapid growth of tourism and foreign investment, so, too, did investment in the JCCE. In 2000, the organization had 172 community centres. In less than four years, that number would nearly double. Approximately one-thousand centres are planned to be in operation within the next two years (2004-2006). Cuba's foray into this field is intended to "informaticize" its society, enabling Cubans to partake in the global "knowledge economy" through the participation of workers in joint-venture operations and through the creation and export of software and other technology. Similar ICT efforts on a smaller scale and with varying barriers to access not present in the Cuban example have been established by her Latin American neighbours, but only Cuba has the mass level of literacy and education to make that access relevant. This paper examines the development of the JCCE initiative, identifies the context in which it is being carried out and explores the Cuban experience as a sustainable model for mass ICT development

The influence on unaided vision of age, pupil diameter and spherocylindrical refractive error

Background - The aim was to derive equations for the relationship between unaided vision and age, pupil diameter, iris colour and sphero-cylindrical refractive error. Methods - Data were collected from 663 healthy right eyes of white subjects aged 20 to 70 years. Subjective sphero-cylindrical refractive errors ranged from -6.8 to +9.4 D (mean spherical equivalent), -1.5 to +1.9 D (orthogonal component, J0) and -0.8 to 1.0 D (oblique component, J45). Cylinder axis orientation was orthogonal in 46 per cent of the eyes and oblique in 18 per cent. Unaided vision (-0.3 to +1.3 logMAR), pupil diameter (2.3 to 7.5 mm) and iris colour (67 per cent light/blue irides) was recorded. The sample included mostly females (60 per cent) and many contact lens wearers (42 per cent) and so the influences of these parameters were also investigated. Results - Decision tree analysis showed that sex, iris colour, contact lens wear and cylinder axis orientation did not influence the relationship between unaided vision and refractive error. New equations for the dependence of the minimum angle of resolution on age and pupil diameter arose from step backwards multiple linear regressions carried out separately on the myopes (2.91.scalar vector +0.51.pupil diameter -3.14 ) and hyperopes (1.55.scalar vector + 0.06.age – 3.45 ). Conclusion - The new equations may be useful in simulators designed for teaching purposes as they accounted for 81 per cent (for myopes) and 53 per cent (for hyperopes) of the variance in measured data. In comparison, previously published equations accounted for not more than 76 per cent (for myopes) and 24 per cent (for hyperopes) of the variance depending on whether they included pupil size. The new equations are, as far as is known to the authors, the first to include age. The age-related decline in accommodation is reflected in the equation for hyperopes

Graptolites from Silurian (Llandovery Series) sedimentary deposits attributed to a forearc setting, Co To Formation, Co To archipelago, northeast Vietnam

Newly collected graptolites from the Co To Formation, Co To archipelago, NE Vietnam, comprise assemblages indicative of two biostratigraphical levels within the lower Silurian, Llandovery Series, Telychian Stage: the co-occurrence of Spirograptus turriculatus and Torquigraptus proteus? suggests an interval most likely within the upper part of the Spirograptus turriculatus Biozone or 'Monograptus' crispus Biozone, whilst Oktavites spirally and Monoclimacis cf. suhgeinitzi identify the Oktavites spiralis Biozone. The graptolites provide important biostratigraphical evidence for the age of the upper part of the lower Co To Formation, biostratigraphical ties between the NE Vietnamese succession of the Bac Bo Region and graptolite assemblages of the Long Dai Formation in the Viet-Lao Region of central Vietnam, and include the new species Monograptus hanutlus sp. nov. co-occurring with S. turriculatus, which is perhaps an ancestral form to the later Telychian species Monograptus drepanoformis. We also report the lirst chitinozoans, including Belonechitina, from the Co To Formation

A radiative transfer model for the spiral galaxy M33

We present the first radiative transfer (RT) model of a non-edge-on disk galaxy in which the large-scale geometry of stars and dust is self-consistently derived through fitting of multiwavelength imaging observations from the UV to the submm. To this end we used the axi-symmetric RT model of Popescu et al. and a new methodology for deriving geometrical parameters, and applied this to decode the{spectral energy distribution (SED) of M33. We successfully account for both the spatial and spectral energy distribution, with residuals typically within 7% in the profiles of surface brightness and within 8% in the spatially-integrated SED. We predict well the energy balance between absorption and re-emission by dust, with no need to invoke modified grain properties, and we find no submm emission that is in excess of our model predictions. We calculate that 80±8% of the dust heating is powered by the young stellar populations. We identify several morphological components in M33, a nuclear, an inner, a main and an outer disc, showing a monotonic trend in decreasing star-formation surface-density (ΣSFR) from the nuclear to the outer disc. In relation to surface density of stellar mass, the ΣSFR of these components define a steeper relation than the "main sequence" of star-forming galaxies, which we call a "structurally resolved main sequence". Either environmental or stellar feedback mechanisms could explain the slope of the newly defined sequence. We find the star-formation rate to be SFR=0.28+0.02−0.01M⊙yr−1

Human osteoblasts obtained from distinct periarticular sites demonstrate differences in biological function in vitro.

AIMS: Accumulated evidence indicates that local cell origins may ingrain differences in the phenotypic activity of human osteoblasts. We hypothesized that these differences may also exist in osteoblasts harvested from the same bone type at periarticular sites, including those adjacent to the fixation sites for total joint implant components. METHODS: Human osteoblasts were obtained from the acetabulum and femoral neck of seven patients undergoing total hip arthroplasty (THA) and from the femoral and tibial cuts of six patients undergoing total knee arthroplasty (TKA). Osteoblasts were extracted from the usually discarded bone via enzyme digestion, characterized by flow cytometry, and cultured to passage three before measurement of metabolic activity, collagen production, alkaline phosphatase (ALP) expression, and mineralization. RESULTS: Osteoblasts from the acetabulum showed lower proliferation (p = 0.034), cumulative collagen release (p < 0.001), and ALP expression (p = 0.009), and produced less mineral (p = 0.006) than those from the femoral neck. Osteoblasts from the tibia produced significantly less collagen (p = 0.021) and showed lower ALP expression than those from the distal femur. CONCLUSION: We have demonstrated for the first time an anatomical regional variation in the biological behaviours of osteoblasts on either side of the hip and knee joint. The lower osteoblast proliferation, matrix production, and mineralization from the acetabulum compared to those from the proximal femur may be reflected in differences in bone formation and implant fixation at these sites. Cite this article: Bone Joint Res 2021;10(9):611-618

Radio and Millimeter Monitoring of Sgr A*: Spectrum, Variability, and Constraints on the G2 Encounter

We report new observations with the Very Large Array, Atacama Large Millimeter Array, and Submillimeter Array at frequencies from 1.0 to 355 GHz of the Galactic Center black hole, Sagittarius A*. These observations were conducted between October 2012 and November 2014. While we see variability over the whole spectrum with an amplitude as large as a factor of 2 at millimeter wavelengths, we find no evidence for a change in the mean flux density or spectrum of Sgr A* that can be attributed to interaction with the G2 source. The absence of a bow shock at low frequencies is consistent with a cross-sectional area for G2 that is less than $2 \times 10^{29}$ cm$^2$. This result fits with several model predictions including a magnetically arrested cloud, a pressure-confined stellar wind, and a stellar photosphere of a binary merger. There is no evidence for enhanced accretion onto the black hole driving greater jet and/or accretion flow emission. Finally, we measure the millimeter wavelength spectral index of Sgr A* to be flat; combined with previous measurements, this suggests that there is no spectral break between 230 and 690 GHz. The emission region is thus likely in a transition between optically thick and thin at these frequencies and requires a mix of lepton distributions with varying temperatures consistent with stratification.Comment: Accepted for publication in Ap

Particulate matter exposure during pregnancy is associated with birth weight, but not gestational age, 1962-1992: a cohort study

<p>Abstract</p> <p>Background</p> <p>Exposure to air pollutants is suggested to adversely affect fetal growth, but the evidence remains inconsistent in relation to specific outcomes and exposure windows.</p> <p>Methods</p> <p>Using birth records from the two major maternity hospitals in Newcastle upon Tyne in northern England between 1961 and 1992, we constructed a database of all births to mothers resident within the city. Weekly black smoke exposure levels from routine data recorded at 20 air pollution monitoring stations were obtained and individual exposures were estimated via a two-stage modeling strategy, incorporating temporally and spatially varying covariates. Regression analyses, including 88,679 births, assessed potential associations between exposure to black smoke and birth weight, gestational age and birth weight standardized for gestational age and sex.</p> <p>Results</p> <p>Significant associations were seen between black smoke and both standardized and unstandardized birth weight, but not for gestational age when adjusted for potential confounders. Not all associations were linear. For an increase in whole pregnancy black smoke exposure, from the 1^st(7.4 μg/m³) to the 25^th(17.2 μg/m³), 50^th(33.8 μg/m³), 75^th(108.3 μg/m³), and 90^th(180.8 μg/m³) percentiles, the adjusted estimated decreases in birth weight were 33 g (SE 1.05), 62 g (1.63), 98 g (2.26) and 109 g (2.44) respectively. A significant interaction was observed between socio-economic deprivation and black smoke on both standardized and unstandardized birth weight with increasing effects of black smoke in reducing birth weight seen with increasing socio-economic disadvantage.</p> <p>Conclusions</p> <p>The findings of this study progress the hypothesis that the association between black smoke and birth weight may be mediated through intrauterine growth restriction. The associations between black smoke and birth weight were of the same order of magnitude as those reported for passive smoking. These findings add to the growing evidence of the harmful effects of air pollution on birth outcomes.</p