Showing papers by "University of Los Andes published in 2003"
TL;DR: In this article, the authors examined the effects of urban form and public transit supply on the commute mode choices and annual vehicle miles traveled (VMTs) of households living in 114 urban areas in 1990.
Abstract: We examine the effects of urban form and public transit supply on the commute mode choices and annual vehicle miles traveled (VMTs) of households living in 114 urban areas in 1990. The probability of driving to work is lower the higher are population centrality and rail miles supplied and the lower is road density. Population centrality, jobs-housing balance, city shape, and road density have a significant effect on annual household VMTs. Although individual elasticities are small absolute values (≤0.10), moving sample households from a city with the characteristics of Atlanta to a city with the characteristics of Boston reduces annual VMTs by 25%.
538 citations
TL;DR: The time line of the different milestones that were answering successively and logically the outstanding scientific questions identified by the Scientific Working Group in 1978 are presented and that influenced the development and industrial production of practical solutions for diagnosis of the infection and disease control.
Abstract: Chagas disease, named after Carlos Chagas who first described it in 1909, exists only on the American Continent. It is caused by a parasite, Trypanosoma cruzi, transmitted to humans by blood-sucking triatomine bugs and by blood transfusion. Chagas disease has two successive phases, acute and chronic. The acute phase lasts 6 to 8 weeks. After several years of starting the chronic phase, 20% to 35% of the infected individuals, depending on the geographical area will develop irreversible lesions of the autonomous nervous system in the heart, esophagus, colon and the peripheral nervous system. Data on the prevalence and distribution of Chagas disease improved in quality during the 1980's as a result of the demographically representative cross-sectional studies carried out in countries where accurate information was not available. A group of experts met in Brasilia in 1979 and devised standard protocols to carry out countrywide prevalence studies on human T. cruzi infection and triatomine house infestation. Thanks to a coordinated multi-country program in the Southern Cone countries the transmission of Chagas disease by vectors and by blood transfusion has been interrupted in Uruguay in1997, in Chile in 1999, and in 8 of the 12 endemic states of Brazil in 2000 and so the incidence of new infections by T. cruzi in the whole continent has decreased by 70%. Similar control multi-country initiatives have been launched in the Andean countries and in Central America and rapid progress has been recorded to ensure the interruption of the transmission of Chagas disease by 2005 as requested by a Resolution of the World Health Assembly approved in 1998. The cost-benefit analysis of the investments of the vector control program in Brazil indicate that there are savings of US$17 in medical care and disabilities for each dollar spent on prevention, showing that the program is a health investment with good return. Since the inception in 1979 of the Steering Committee on Chagas Disease of the Special Program for Research and Training in Tropical Diseases of the World Health Organization (TDR), the objective was set to promote and finance research aimed at the development of new methods and tools to control this disease. The well known research institutions in Latin America were the key elements of a world wide network of laboratories that received - on a competitive basis - financial support for projects in line with the priorities established. It is presented the time line of the different milestones that were answering successively and logically the outstanding scientific questions identified by the Scientific Working Group in 1978 and that influenced the development and industrial production of practical solutions for diagnosis of the infection and disease control.
409 citations
TL;DR: Age estimates based on Y-chromosome microsatellite diversity place the initial settlement of the American continent at approximately 14,000 years ago, in relative agreement with the age of well-established archaeological evidence.
Abstract: To scrutinize the male ancestry of extant Native American populations, we examined eight biallelic and six microsatellite polymorphisms from the nonrecombining portion of the Y chromosome, in 438 individuals from 24 Native American populations (1 Na Dene and 23 South Amerinds) and in 404 Mongolians. One of the biallelic markers typed is a recently identified mutation (M242) characterizing a novel founder Native American haplogroup. The distribution, relatedness, and diversity of Y lineages in Native Americans indicate a differentiated male ancestry for populations from North and South America, strongly supporting a diverse demographic history for populations from these areas. These data are consistent with the occurrence of two major male migrations from southern/central Siberia to the Americas (with the second migration being restricted to North America) and a shared ancestry in central Asia for some of the initial migrants to Europe and the Americas. The microsatellite diversity and distribution of a Y lineage specific to South America (Q-M19) indicates that certain Amerind populations have been isolated since the initial colonization of the region, suggesting an early onset for tribalization of Native Americans. Age estimates based on Y-chromosome microsatellite diversity place the initial settlement of the American continent at ∼14,000 years ago, in relative agreement with the age of well-established archaeological evidence.
226 citations
TL;DR: The study showed that the TOC content of the pre-treated solution could be removed up to 68% by an aerobic biological treatment as well as co-digested with municipal wastewater (TOC removal up to 82%), with similar operating retention times to a municipal wastewater plant (12-24 h).
188 citations
TL;DR: In this paper, the socio-pragmatic phenomenon of academic conflict (AC) is addressed from a cross-cultural and diachronic perspective, and is examined by combining a quantitative approach and a qualitative discoursal analysis of its salient rhetorical features in a corpus of Spanish, French and English medical articles published between 1930 and 1995.
177 citations
TL;DR: In this paper, pyrolysis of coffee bean husks in presence of phosphoric acid (chemical activities) was used to obtain activated carbons (Acs) with high surface area and pore volume.
170 citations
TL;DR: The authors have proposed 2 alternative hypotheses and consider that T. rangeli could have had clonal evolution or have been subjected to speciation processes, leading to better understanding of the epidemiology and interactions with this parasite's vertebrate hosts and triatomine vectors.
Abstract: Trypanosoma rangeli, a parasite generally considered non-pathogenic for man, is the second species of human trypanosome to be reported from the New World. The geographical distribution of T. rangeli often overlaps with that of T. cruzi, the same vertebrate and invertebrate hosts being infected. Their differentiation thus becomes of real, practical importance, particularly as they share approximately half the antigenic determinants recognized by the humoral response. Little is known about the life cycle of T. rangeli in the vertebrate host, although thousands of human and wild animal infections have been reported. Recent studies have revealed 2 major phylogenetic lineages in T. rangeli having different characteristics, thus leading to better understanding of the epidemiology and interactions with this parasite's vertebrate hosts and triatomine vectors. Based on further genetic characterization analysis, the authors have proposed 2 alternative hypotheses and consider that T. rangeli could have had clonal evolution or have been subjected to speciation processes.
158 citations
TL;DR: This paper proposes a new delayed ACK scheme in which the delay coefficient varies with the sequence number of the TCP packet, and shows that the ACK thinning allows to increase TCP throughput substantially more than previous improvement methods.
Abstract: We study in this paper TCP performance over a static multihop network that uses IEEE 802.11 protocol for access. For such networks it has been shown in [6] that TCP performance is mainly determined by the hidden terminal effects (and not by drop probabilities at buffers) which limits the number of packets that can be transmitted simultaneously in the network. We propose new approaches for improving the performance based on thinning the ACK streams that competes over the same radio resources as the TCP packets. In particular, we propose a new delayed ACK scheme in which the delay coefficient varies with the sequence number of the TCP packet. Through simulations we show that the ACK thinning allows to increase TCP throughput substantially more than previous improvement methods.
144 citations
TL;DR: Evidence of a constant rate of succession during the first 12 years is found, contradicting the generally accepted hypothesis in the succession literature of a continous slow down up to the climax and raising doubts about the conservationist value of this management strategy.
Abstract: Vegetation restoration during old-field succession was studied in an alpine Andean ecosystem (paramo). 123 plots with different fallow times (1 to 12 years) and 8 plots under natural vegetation were sampled. The results indicate that secondary succession in the paramo, like in other extreme environments, can be interpreted as an autosuccession: there are mainly changes in species relative abundance and little floristic relay (i.e. species turnover). Only a few herbaceous species, mostly introduced (e.g. Rumex acetosella), act as strict pioneers and strongly dominate the early stages. Then, they undergo a progressive decline, while native forbs (e.g. Lupinus meridanus) and grasses (e.g. Vulpia myuros) have their peak abundance in intermediate stages. The characteristic paramo life forms, sclerophilous shrubs (e.g. Baccharis prunifolia, Hypericum laricifolium) and giant rosettes (e.g. Espeletia schultzii), appear very early and gradually increase in abundance during succession, becoming dominant in the late stages and showing a dual behaviour, both as ruderal and stress tolerant species. The 1st axis of a Detrended Correspondence Analysis arranges the sites according to their fallow time. The 2nd and 3rd axes, associated with diverging pathways of regeneration, are correlated with topographic factors and physio-chemical soil characteristics. Hence, structural divergence between plots increases along succession as community composition starts to reflect the conditions of each site. We found evidence of a constant rate of succession during the first 12 years, contradicting the generally accepted hypothesis in the succession literature of a continous slow down up to the climax. Regeneration of vegetation physiognomy is relatively fast, questioning the prevailing idea of slow restoration in alpine ecosystems. However, 12 years of fallow are insufficient to attain the species richness of the natural paramo. Under the current trend of fallow length reduction observed in traditional potato cultivation in the Andes, our results raise doubts about the conservationist value of this management strategy.
143 citations
TL;DR: The total-etch adhesives evaluated produced higher bond strengths to normal and caries-affected dentine than self-etching systems, and the DIAGNOdent laser fluorescence and Knoop microhardness measurements of the substrates did not permit high correlations with resin-dentine bond strengths in carie's affected dentine.
139 citations
TL;DR: In this paper, the authors studied the problem of aggregating population in a bounded domain of R d, d > 1 with homogeneous boundary conditions of the Neumann type, and showed that the aggregating mechanism induced by Φ(u) allows the survival of a species in danger of extinction.
Abstract: In this paper we study the equation u t = Δ(Φ(u) - λf(u) + λu t ) + f(u) in a bounded domain of R d , d > 1 with homogeneous boundary conditions of the Neumann type, as a model of aggregating population with a migration rate determined by Φ, and total birth and mortality rates characterized by f. We will show that the aggregating mechanism induced by Φ(u) allows the survival of a species in danger of extinction. Numerical simulations suggest that the solutions stabilize asymptotically in time to a not necessarily homogeneous stationary solution. This is shown to be the case for a particular version of the function Φ(u).
TL;DR: This paper examined the stability of the general foreign language classroom anxiety construct across English and French students, who were majoring simultaneously in these two languages, participated in the study, and found that the scale exhibited high reliability but moderate construct validity.
Abstract: The present study examined the stability of the general foreign language classroom anxiety construct across English and French. Preservice teachers from two western universities in Venezuela, who were majoring simultaneously in these two foreign languages, participated in the study. The students represented a variety of levels within each language. They completed two Spanish versions (one for each language) of the Foreign Language Classroom Anxiety Scale (FLCAS; Horwitz, Horwitz, & Cope, 1986). Separate analyses were performed on the full sample and on a restricted sample that included only those students who were at the same level in both languages. The results supported the indirect findings reported by Saito, Horwitz, and Garza (1999) while providing direct evidence suggesting the stability of the construct across English and French. Evidence obtained for overall, within-institution, and within-level comparisons. Furthermore, analysis of psychometric technical aspects of the FLCAS indicated that the scale exhibited high reliability but moderate construct validity.
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TL;DR: In this paper, a macroscopic muscle with sensing and actuating capabilities was used as an actuator and a sensor in an electrochemo-mechanical triple layer actuator.
Abstract: The variation of the consumed electric energy by an electrochemo-mechanical triple layer actuator (polypyrrole film/non-conducting and adhesive film/polypyrrole film) can be used as sensor of the physical or chemical variables controlling the electrochemical reaction. Amongst others, the electrolyte concentration and the temperature of cell can be sensed. A physical variable that not participates in the electrochemical reaction, as the trailed weight by the triple layer during a bent can also be determined. The electric energy consumed during a constant movement of the triple layer changes linearly as a function of these variables. So, this artificial muscle works as an actuator and sensor simultaneously. This macroscopic muscle with sensing and actuating capabilities only require two wires connecting equipment and the device.
TL;DR: In this article, the expected behavior of the time-dependent FUV field for random positions in the local ISM was determined using McKee & Williams' distribution of birthrates for OB associations in the Galaxy.
Abstract: Far Ultraviolet (FUV, 6 eV< h� <13.6 eV) radiation has been recognized as the main source of heating of the neutral interstellar gas, and, as a consequence, it determines whether the thermal balance of the neutral gas results in cold (T � 50 − 100K) clouds (CNM), warm (T � 10 4 K) clouds (WNM), or a combination of the two. High FUV fields convert the neutral gas to WNM, while low fields result in CNM. The knowledge of how these fractions depend on the FUV sources (i.e. the star formation rate, the IMF, and the size distribution of associations) is a basic step in building any detailed model of the large scale behavior of the ISM and the mutual relation between the ISM and the star formation rate in a galaxy. The sources of FUV radiation are the short-lived massive stars that generally originate in associations that form in Giant Molecular Clouds present in the galactic disk. Using McKee & Williams’ (1997) distribution of birthrates for OB associations in the Galaxy, we determine the expected behavior of the time-dependent FUV field for random positions in the local ISM. The FUV field is calculated in two bands (912 − 1100 u and 912 − 2070 u and at the wavelength 1400 u In terms of U−17 � U=(10 −17 erg cm −3 u −1 ), where U is the energy density of the radiation field in some band, we find (mean, median) values at the solar circle of U−17 =(15.7, 7.4) and (14.2, 7.2) for the [912-1100 u and [912-2070 u bands, respectively. At 1400 u we find (mean, median) values of U−17 =(14.4, 7.5). Our median value for the [912-2070 u band is G0 = 1:6 times Habing’s (1968) value for the radiation field at the solar circle in this band, and quite close to Draine’s (1976) value, G0 = 1:7. Both the latter values are based on observations of sources of FUV radiation in the solar neighborhood, so all three values are close to observed values. Due to attenuation by dust, only associations within about 500 pc contribute significantly to the energy density at a given point. Large angle scattering produces a diffuse field that is about 10% of the field produced by the sum of direct and small angle (< 5 o ) scattering from discrete sources (the associations), as observed. At a point exposed to the median radiation field, the brightest association typically produces about 20% of the total energy density. At a
TL;DR: Data from the first occultations by Pluto since 1988 are reported and it is found that, during the intervening 14 years, there seems to have been a doubling of the atmospheric pressure, a probable seasonal effect on Pluto.
Abstract: Pluto's tenuous nitrogen atmosphere was first detected by the imprint left on the light curve of a star that was occulted by the planet in 1985 (ref. 1), and studied more extensively during a second occultation event in 1988 (refs 2-6). These events are, however, quite rare and Pluto's atmosphere remains poorly understood, as in particular the planet has not yet been visited by a spacecraft. Here we report data from the first occultations by Pluto since 1988. We find that, during the intervening 14 years, there seems to have been a doubling of the atmospheric pressure, a probable seasonal effect on Pluto.
TL;DR: It is relevant that the type species of Minyobates resulted as the sister group of the genus Dendrobates, and that species of Mannophryne and Nephelobates formed monophyletic clades, corroborating the validity of these genera.
TL;DR: In this article, the authors developed an evaluation method that combines qualitative evidence with quantitative survey data analyzed with propensity score methods, on matched samples, to study the impact of a participatory community driven Social Fund on preference targeting, collective action, and community decision making.
Abstract: This paper develops an evaluation method that combines qualitative evidence with quantitative survey data analyzed with propensity score methods, on matched samples, to study the impact of a participatory community driven Social Fund on preference targeting, collective action, and community decision making. The data are from a case-study of five pairs of communities in Jamaica where one community in the pair has received funds from the Jamaica Social Investment Fund while the other has not, but has been picked to match the funded community in its social and economic characteristics. The qualitative data reveal that the social fund process is elite-driven and decision making tends to be dominated by a small group of motivated individuals. However, by the end of the project there is broad based satisfaction with the outcome. The quantitative data from 500 households mirror these findings by showing that ex-ante the social fund does not address the expressed needs of the majority of individuals in the majority of communities. By the end of the construction process, however, 80 per cent of the community expresses satisfaction with the outcome. An analysis of the determinants of participation demonstrates that better educated and better networked individuals dominate the process. Propensity score analysis reveals that JSIF has had a causal impact on improvements in trust and the capacity for collective action, but these gains are greater for elites within the community. Both JSIF and non-JSIF communities are more likely now to make decisions that affect their lives which is indicative of a broad based effort to promote participatory development in the country, but JSIF communities do not show higher levels of community driven decisions than non-JSIF communities. The evidence in this paper sheds light on the complex ways in which community driven development works inside communities, a process that is deeply imbedded within Jamaicas socio-cultural and political context.
TL;DR: A rapid serologic test for diagnosis of T. cruzi infection using recombinant proteins in an immunochromatographic assay that uses one device per sample, does not require refrigeration nor a laboratory structure or specialized skills to be performed, accepts different types of samples and may be stored for long periods of time for result checking and documentation.
TL;DR: The white rot fungus Trametes elegans was used for direct treatment of spent blackliquor from pulping processes with the aim to degrade solubilized lignin which is the primary organic by-product from the chemical digestion of lignocellulosic raw materials.
TL;DR: A general account of international relations studies (IR) in Latin America through an examination of IR thinking in the region, an inventory of IR theory courses in seven Latin American countries (Argentina, Brazil, Chile, Colombia, Costa Rica, Mexico, and Trinidad and Tobago) is given in this paper.
Abstract: This article offers a general account of international relations studies (IR) in Latin America through an examination of IR thinking in the region, an inventory of IR theory courses in seven Latin American countries (Argentina, Brazil, Chile, Colombia, Costa Rica, Mexico, and Trinidad and Tobago), and an analysis of journal articles selected from five specialized IR journals in Latin America. Although considerable U.S. influence upon the ways in which IR is approached in Latin America is made apparent through this narrative, the specific context in which IR studies have evolved in the region has substantially altered the content of U.S. IR discourse. Therefore, the article concludes with a discussion of the possible contributions of Latin American IR to Anglo-American perspectives in the field.
TL;DR: The data suggest that selection for enhanced jumping performance is relaxed in larger anoles and support the notion that no scaling model seems to be able to comprehensively predict changes in function with size across species; rather, natural selection seems to drive changes in the scaling relationships of some key variables such as force output or acceleration capacity.
Abstract: Scaling models predict how functional variables change as animals grow or increase in size evolutionarily. However, few experimental studies have found support for the predictions of these models. Here, we use a force plate to investigate the scaling of functional variables associated with jumping within (for three species) and across adults of 12 species of Anolis lizards. Both ontogenetically (with the exception of Anolis carolinensis) and across the 12 species examined, limb dimensions increased geometrically, making Anolis lizards an ideal study system to test the predictions of geometric scaling models. However, both the ontogenetic and interspecific scaling of functional variables deviated in several aspects from model predictions. Unexpectedly, the scaling of functional variables such as acceleration differed for different species. Whereas acceleration capacity increases with hindlimb length for A. carolinensis, no relationship was detected for the other two species. Interspecifically, the inclusion of two large species in our analysis appears to drive the absence of a correlation between acceleration capacity and hindlimb length across species. These data suggest that selection for enhanced jumping performance is relaxed in larger anoles and support the notion that no scaling model seems to be able to comprehensively predict changes in function with size across species; rather, natural selection seems to drive changes in the scaling relationships of some key variables such as force output or acceleration capacity.
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TL;DR: In this article, the authors provide an overview of the levels of minimum wages in Latin America and their true impact on the distribution of wages using both numerical measures and kernel density plots.
Abstract: This paper first provides an overview of the levels of minimum wages in Latin America and their true impact on the distribution of wages using both numerical measures and kernel density plots. It identifies numeraire' effects higher in the wage distribution and lighthouse' or reference effects in the unregulated or informal' sector. The final section then employs panel employment data from Colombia, a country where minimum wages seem high and very binding, to quantify the effects of an increase on wages and employment. The evidence suggests that in the Latin American context, the minimum wage has impacts beyond those usually contemplated in the advanced country literature.
TL;DR: In this paper, the semiconducting compound Cu{sub 2}SnSe{sub 3} has been investigated by means of X-ray powder diffraction and its structure has been refined by the Rietveld method.
TL;DR: To examine the presence of intestinal protozoan and helminth infections and their association with clinical signs and symptoms in children in Trujillo, Venezuela.
Abstract: OBJECTIVES To examine the presence of intestinal protozoan and helminth infections and their association with clinical signs and symptoms in children in Trujillo, Venezuela. METHODS Conventional microscopic methods (thick-smear, saline and iodine solutions) were used to identify parasites in stool samples of 301 children attending day care centres. A subgroup of 45 children was evaluated clinically and parasitologically five times during a 1-month period using conventional methods and the Kinyoun acid-fast stain for Cryptosporidium identification. RESULTS The point prevalence of protozoan infections was 21% for Giardia duodenalis, 1.0% for Entamoeba histolytica/dispar, 4% for Entamoeba coli, 16% for Blastocystis hominis, and 89% for Cryptosporidium parvum. Prevalence of helminth infection was 11% for Ascaris lumbricoides, 10% for Trichuris trichiura, 0.3% for Strongyloides stercoralis, and 1.3% for Hymenolepis nana. Over a 1-month time frame, new infections were observed at a rate of 11% for G. duodenalis, 4% for E. histolytica/dispar, 7% for A. lumbricoides, 11% for T. trichiura, 0% for S. stercoralis, and 2% for H. nana. Intestinal symptoms (diarrhoea, vomiting, gas, stomach pain, and loss of appetite) were associated with presence of one or more of C. parvum or B. hominis organisms in stool samples. CONCLUSIONS Intestinal parasitic infections contribute significantly to the enteric disease burden experienced by this group of children. The organisms most strongly implicated by this study are common and difficult-to-treat protozoan pathogens.
TL;DR: In this paper, a bipartite division of the modes of a Gaussian state is considered, where a given mode on one side is entangled with only one corresponding mode of the other.
Abstract: We address the decomposition of a multimode pure Gaussian state with respect to a bipartite division of the modes. For any such division the state can always be expressed as a product state involving entangled two-mode squeezed states and single-mode local states at each side. The character of entanglement of the state can therefore be understood modewise; that is, a given mode on one side is entangled with only one corresponding mode of the other, and therefore the total bipartite entanglement is the sum of the modewise entanglement. This decomposition is generally not applicable to all mixed Gaussian states. However, the result can be extended to a special family of ``isotropic'' states, characterized by a phase space covariance matrix with a completely degenerate symplectic spectrum.
TL;DR: In this paper, a large sample of firms during 1995-2001 and examine the determinants of foreign indebtedness and the effects on firm performance of holding dollar debt amid real depreciations (i.e., the so-called "balance sheet effect") is examined.
TL;DR: The trypanosoma cruzi hexokinase gene has been cloned, sequenced, and expressed as an active enzyme in Escherichia coli as discussed by the authors, which contains an N-terminal peroxisome-targeting signal (PTS-2) and has a calculated basic isoelectric point (pI = 9.67).
TL;DR: The stirring intensity has a complex effect on the catastrophic inversion of emulsions in the direction of change from abnormal to normal morphology at both low and high stirring energy.
Abstract: The stirring intensity has a complex effect on the catastrophic inversion of emulsions in the direction of change from abnormal to normal morphology At both low and high stirring energy, the inversion takes place early, after a low amount of the internal phase is added and through the occurrence of a multiple emulsion At some intermediate stirring energy, the inversion appears to be delayed and it takes place without the occurrence of multiple emulsions
TL;DR: The variation in the amino acid neurotransmitter contents during mouse parietal cortex development, from embryonic day 13 until young adulthood, between postnatal day 21 (P21) and P30, suggests a neuroprotective action of taurine against excitotoxicity.
Abstract: This study documents the variation in the amino acid neurotransmitter contents during mouse parietal cortex development, from embryonic day 13 (E13) until young adulthood, between postnatal day 21 (P21) and P30. Taurine, an inhibitory neurotransmitter and neuromodulator, is the most abundant neurotransmitter in the developing neocortex, whereas, at the adult stage, glutamate is the more prominent neurotransmitter playing an excitatory role, and GABA is the major inhibitory neurotransmitter. During the proliferative stage of neurogenesis in the mouse cerebral cortex, between E13 and E17, relatively high levels of glutamate, aspartate, taurine and glycine were detected, consistent with a possible trophic influence of these neurotransmitters during cortical development prior to synaptogenesis. Between E17 and E19, a significant decline in the contents of these neurotransmitters was observed, consistent with earlier reports of cell death in the ventricular and subventricular zones during this stage of development. During the perinatal period, a progressive increment in glutamate level was seen between E21 and P5, and then the values remained constant until the second postnatal week. Glutamate also decreased by about 25% between P11 and P15, on the other hand, aspartate diminished by about 20% between P7 and P9. These results were consistent with previous reports of histogenetic cell death during the first 2 postnatal weeks in mouse neocortex. GABA increased from the embryonic period until young adulthood, in contrast, the glycine content decreased; thus, in the adult parietal cortex, the GABA content was about 2.6-fold higher than that of glycine. During the first postnatal week, the concentrations of glutamate and GABA showed significant increments between P0 and P5, while those of aspartate and glycine remained constant. During this period, amino acids are predominantly excitatory and the cerebral cortex is vulnerable to epileptiform activity; the significant increment in taurine content between P0 and P3 suggests a neuroprotective action of taurine against excitotoxicity. At P15, coinciding with the period of maximum cortical synaptogenesis, significant increments in GABA and glycine contents were observed which could be related to the maturation of inhibitory synaptic transmission. At the young adult stage, there was a rise in the levels of both excitatory neurotransmitters, glutamate and aspartate, and a significant reduction in the contents of all three inhibitory neurotransmitters, GABA, glycine and taurine.
TL;DR: In this paper, the flow characteristics of aqueous foams were studied in a thin flow channel and a round pipe instrumented for pressure gradient and flow rate measurements, and an overall correlation for the friction factor as a function of Reynolds number which applies to both channel and pipe was derived.