4,373 research outputs found
Performance and evaluation of the Viking lander camera performance prediction program
A computer program is described for predicting the performance of the Viking lander cameras. The predictions are primarily concerned with two objectives: (1) the picture quality of a reference test chart (of which there are three on each lander) to aid in diagnosing camera performance; and (2) the picture quality of cones with surface properties of a natural terrain to aid in predicting favorable illumination and viewing geometries and operational camera commands. Predictions made with this program are verified by experimental data obtained with a Viking-like laboratory facsimile camera
A Review of the Impacts SMEs as Social Agents of Economic Liberations in Developing Economies
1/w hene.f/ts 1!1 o hooming .\ 1//~ sector can be seen in the creation of a sound industrial hm,· for an
emerging eumonn It rang!'~ .fi"om the prm·iswn of' employment, sources of subsistencl'. ,·,luiwble
distrthution of IIK0111es to its citi::ens. to deployment of domestic savings for investments. It ul.111 include.
bw not limited. to the increase in capital financial gains. important contribution to Cross I >omestic
Product (CIJI'i lwrnessing c1{ natil·e raw materials. curtailing rural-urban migration and efficient
uti!i::ation o(a nation·.\ resource. as can b~ seen in the case of Taiwan. South Korea, Singapore. <'t( These
are cowuries that were huilt on a d\'namic SML sector 1/owever. many less developed economies /w,·e not
bel'n a hie to jullt· utili::e the 111cmv henejits of this sl'ctor. perhaps due to ignorance. This revietr <'\llmined
the ntenlto which these .1ocial agems (S\1/~s) which hm·e libera!i::ed several economies oflhe d, l'e!opl'd
coumries. such as the { nitecl States. { nited 1\ ingdom. Wider Europe and the BRICS countrh ' 1 Bra:: if.
R11.11i11. India. ( 'llina wul So111h .lji-icaJ is being treated with levity within the developing econnlllll'.\. The
sttu!r howet'l.'r. focuses 011 the .)',\/Es operating within the Nigerian state. It employed in its ennrety !he
re1•ie1r ofsecondw:t· duta , 1171/findings revealed a plethora of issues. Of note was the facl that despite the
benefit~ of this l'ihrulll sector to the \'igerian economy. the government policies, infrastructures. finances
ammtgst others are not Jhl'omble for its gr01111t all(/ sustainability. The authors recommend that the
1\igerian gm·~mlll<'llt as well os gm·emme/11 of other developing economies must invest substamial!t·to the
growth. de,·elollllte/11 011(/ sustainohility of SM!~·s through the provision of essential inji·a.1tructures.
1111111111111 er. microfiiiWICI'. 1·ecurin• am/ adequate po!inji-cunework
MR diffusion changes in the perimeter of the lateral ventricles demonstrate periventricular injury in post-hemorrhagic hydrocephalus of prematurity
OBJECTIVES: Injury to the preterm lateral ventricular perimeter (LVP), which contains the neural stem cells responsible for brain development, may contribute to the neurological sequelae of intraventricular hemorrhage (IVH) and post-hemorrhagic hydrocephalus of prematurity (PHH). This study utilizes diffusion MRI (dMRI) to characterize the microstructural effects of IVH/PHH on the LVP and segmented frontal-occipital horn perimeters (FOHP).
STUDY DESIGN: Prospective study of 56 full-term infants, 72 very preterm infants without brain injury (VPT), 17 VPT infants with high-grade IVH without hydrocephalus (HG-IVH), and 13 VPT infants with PHH who underwent dMRI at term equivalent. LVP and FOHP dMRI measures and ventricular size-dMRI correlations were assessed.
RESULTS: In the LVP, PHH had consistently lower FA and higher MD and RD than FT and VPT (p\u3c.050). However, while PHH FA was lower, and PHH RD was higher than their respective HG-IVH measures (p\u3c.050), the MD and AD values did not differ. In the FOHP, PHH infants had lower FA and higher RD than FT and VPT (p\u3c.010), and a lower FA than the HG-IVH group (p\u3c.001). While the magnitude of AD in both the LVP and FOHP were consistently less in the PHH group on pairwise comparisons to the other groups, the differences were not significant (p\u3e.050). Ventricular size correlated negatively with FA, and positively with MD and RD (p\u3c.001) in both the LVP and FOHP. In the PHH group, FA was lower in the FOHP than in the LVP, which was contrary to the observed findings in the healthy infants (p\u3c.001). Nevertheless, there were no regional differences in AD, MD, and RD in the PHH group.
CONCLUSION: HG-IVH and PHH results in aberrant LVP/FOHP microstructure, with prominent abnormalities among the PHH group, most notably in the FOHP. Larger ventricular size was associated with greater magnitude of abnormality. LVP/FOHP dMRI measures may provide valuable biomarkers for future studies directed at improving the management and neurological outcomes of IVH/PHH
Direct contributions of dry forests to nutrition: a review
Globally, micronutrient deficiencies are more prevalent than calorie and protein deficiencies. In order to address global micronutrient deficiencies, increasing attention is being paid to the nutritional quality of people’s diets. While conventional agriculture is key for ensuring adequate calories, dietary quality depends on the consumption of a diverse range of micronutrient rich foods. Many wild foods are rich in micronutrients, particularly fruits, vegetables, and animal source food. As a result there has been increasing interest in the value of wild foods to meeting nutritional requirements.
We review literature on the consumption of wild foods in dry forest areas to assess the current state of knowledge as to how dry forests may contribute to nutrition. We focus on papers that quantify consumption of wild forest foods. Although there is a great deal of literature that lends weight to the notion that dry forests are important for food security and nutrition, we find surprisingly little evidence of direct contributions to diets. Of 2514 articles identified by our search, only four quantify the consumption of wild foods from dry forests, and only one of these puts this consumption in the context of the entire diet. There is a need for research on the nutritional importance of dry forest foods which combines methodologies from nutrition science with an understanding and appreciation of the ecological, social, cultural and economic context
Production of cold bromine atoms at zero mean velocity by photodissociation
The production of a translationally cold (T < 1 K) sample of bromine atoms with estimated densities of up to 108 cm−3 using photodissociation is presented. A molecular beam of Br2 seeded in Kr is photodissociated into Br + Br* fragments, and the velocity distribution of the atomic fragments is determined using (2 + 1) REMPI and velocity map ion imaging. By recording images with varying delay times between the dissociation and probe lasers, we investigate the length of time after dissociation for which atoms remain in the laser focus, and determine the velocity spread of those atoms. By careful selection of the photolysis energy, it is found that a fraction of the atoms can be detected for delay times in excess of 100 μs. These are atoms for which the fragment recoil velocity vector is directly opposed and equal in magnitude to the parent beam velocity leading to a resultant lab frame velocity of approximately zero. The FWHM velocity spreads of detected atoms along the beam axis after 100 μs are less than 5 ms−1, corresponding to temperatures in the milliKelvin range, opening the possibility that this technique could be utilized as a slow Br atom source
Multi-Instrument Observations of an MSTID over Arecibo Observatory
The Penn State All-Sky Imager (PSASI) at Arecibo Observatory provides planar horizontal context to the vertical ionospheric profiles obtained by the Incoherent Seatter Radar (TSR). Electric field measurements from the Communication/Navigation Outage Forecast System (C/NOFS) satellite are mapped down geomagnetic field lines to the height of the airglow layer; allowing multi-instrument studies of field-aligned irregularities with radar, imager, and satellite. A Medium-Scale Traveling Ionospheric Disturbance (MSTID) was observed during such a conjunction near the December solstice of 2009
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Comparison of free tropospheric western Pacific air mass classification schemes for the PEM-West A experiment
During September/October 1991, NASA's Global Tropospheric Experiment (GTE) conducted an airborne field measurement program (PEM-West A) in the troposphere over the western Pacific Ocean. In this paper we describe and use the relative abundance of the combustion products C2H2 and CO to classify air masses encountered during PEM-West A based on the degree that these tracers were processed by the combined effects of photochemical reactions and dynamical mixing (termed the degree of atmospheric processing). A large number of trace compounds (e.g., C2H6, C3H8, C6H6, NOy, and O3) are found to be well correlated with the degree of atmospheric processing that is reflected by changes in the ratio of C2H2/CO over the range of values from ∼0.3 to 2.0 (parts per trillion volume) C2H2/ (parts per billion volume) CO. This C2H2/CO-based classification scheme is compared to model simulations and to two independent classification schemes based on air mass back-trajectory analyses and lidar profiles of O3 and aerosols. In general, these schemes agree well, and in combination they suggest that the functional dependence that other observed species exhibit with respect to the C2H2/CO atmospheric processing scale can be used to study the origin, sources, and sinks of trace species and to derive several important findings. First, the degree of atmospheric processing is found to be dominated by dilution associated with atmospheric mixing, which is found to primarily occur through the vertical mixing of relatively recent emissions of surface layer trace species. Photochemical reactions play their major role by influencing the background concentrations of trace species that are entrained during the mixing (i.e., dilution) process. Second, a significant noncontinental source(s) of NO (and NOx) in the free troposphere is evident. In particular, the enhanced NO mixing ratios that were observed in convected air masses are attributed to either emissions from lightning or the rapid recycling of NOy compounds. Third, nonsoluble trace species emitted in the continental boundary layer, such as CO and hydrocarbons, are vertically transported to the upper troposphere as efficiently as they are to the midtroposphere. In addition, the mixing ratios of CO and hydrocarbons in the upper troposphere over the western Pacific may reflect a significant contribution from northern hemisphere land areas other than Asia. Finally, we believe that these results can be valuable for the quantitative evaluation of the vertical transport processes that are usually parameterized in models. Copyright 1996 by the American Geophysical Union
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