Mixing Languages during Learning? Testing the One Subject—One Language Rule

In bilingual communities, mixing languages is avoided in formal schooling: even if two languages are used on a daily basis for teaching, only one language is used to teach each given academic subject. This tenet known as the one subject-one language rule avoids mixing languages in formal schooling because it may hinder learning. The aim of this study was to test the scientific ground of this assumption by investigating the consequences of acquiring new concepts using a method in which two languages are mixed as compared to a purely monolingual method. Native balanced bilingual speakers of Basque and Spanish—adults (Experiment 1) and children (Experiment 2)—learnt new concepts by associating two different features to novel objects. Half of the participants completed the learning process in a multilingual context (one feature was described in Basque and the other one in Spanish); while the other half completed the learning phase in a purely monolingual context (both features were described in Spanish). Different measures of learning were taken, as well as direct and indirect indicators of concept consolidation. We found no evidence in favor of the non-mixing method when comparing the results of two groups in either experiment, and thus failed to give scientific support for the educational premise of the one subject—one language rule.     

Distribution, Ecology and Population Dynamics of the American Burying Beetle [Nicrophorus Americanus Olivier (Coleoptera, Silphidae)] in South-central Nebraska, USA

The endangered American burying beetle, Nicrophorus americanus Olivier, was previously widespread throughout eastern North America. In the past century numbers of this beetle have drastically declined and currently remnant populations are known from only six states despite intensive surveying efforts conducted for the last nine years. Efforts aimed at discovering and managing remnant populations have been generally limited by a lack of knowledge concerning N. americanus biology. We used baited pitfall traps to define the range of the Gothenburg, Nebraska population of N. americanus. Using mark-recapture techniques, we estimate that the annual Gothenburg population consists of more than one thousand individuals, meeting the recovery plan criterion to become the third breeding population in the Midwest region. Beyond estimates of population size and range, we present novel data on seasonal and daily activity, sex ratio, age-grading and foraging distances. In 1995 and 1996, the Nebraska population was univoltine and female biased, with over-wintering mature beetles emerging in early June and teneral beetles emerging in August. Nocturnal activity was highest in the third and fourth hours following sunset but was not strongly correlated with temperature. During foraging, beetles travel up to six kilometers, but the majority of our recaptures occurred at distances of less than 0.5 km, suggesting that distances between traps be increased to ensure independence of sampling units. This information will allow future work on captive breeding, re-introduction and genetic studies.     

The Danish Registry for Plastic Surgery of the Breast: establishment of a nationwide registry for prospective follow-up,quality assessment,and investigation of breast surgery

Although numerous epidemiologic studies have examined the long-term safety of silicone breast implants during the past decade, there is a relative lack of surveillance data on short-term health effects and complications following cosmetic surgery of the breast. The Danish Registry for Plastic Surgery of the Breast, established in May of 1999, provides plastic surgeons with a nationwide system for the collection of preoperative, perioperative, and postoperative data on women undergoing breast implantation, breast reduction, or mastopexy. The purpose of the Registry is to examine short-term and, eventually, long-term local complications and possible health effects, and to contribute to an ongoing evaluation of surgical results and surveillance of the products. Furthermore, the Registry will allow the identification of new areas for research into cosmetic and reconstructive breast surgery. Women accepting registration in the Danish Registry for Plastic Surgery of the Breast complete a self-administered questionnaire focusing on medical history and demographic and behavioral factors. Preoperative blood samples are drawn for storage. Surgical data, postoperative results, and complications are registered following surgery and at postoperative visits. Currently, registration has been initiated at 24 private and public clinics, representing more than 80 percent of the plastic surgery clinics in Denmark. As of November of 2001, a total of 1472 women with breast implants and 560 women with breast reduction were included in the Registry. These figures are expected to increase annually by 1000 women undergoing breast implantation and 500 women undergoing breast reduction or mastopexy. The authors present their experience of establishing the first nationwide comprehensive clinical-epidemiologic database and biological bank for cosmetic and reconstructive surgery procedures.     

Leveraging flow mechanics to determine critical process and scaling parameters in a continuous viral inactivation reactor

A continuous viral inactivation (CVI) chamber has been designed to operate with acceptable residence time distribution (RTD) characteristics. However, altering the CVI's geometry and operation to accommodate the scale was not obvious. In this work, we elucidate the influence of Dean vortices and leverage the transition into the weak turbulent regime to establish relationships between input variables and process outputs. This study was targeted to understand and quantify the impact of viscosity, Dean number, internal diameter, and path length on the RTD. When the Dean number exceeds 70, radial mixing generated by the Dean vortices began to consistently alter the axial dispersive effects experienced by the pulse injection. Increasing to a Dean number of >100, the axial dispersive effects were dominated by the Dean vortices which allowed the calculation of the minimum and maximum residence time to be generated. This work provides a method to calculate operational solutions for a tubular incubation reactor in terms of path length, internal diameter, flow rate, and target minimum and maximum residence time specifications that assures both viral residence times while also establishing criteria to maximize product quality during continuous operation.     

Genome-Wide Analyses of Recombination Suggest That Giardia intestinalis Assemblages Represent Different Species

Giardia intestinalis is a major cause of waterborne enteric disease in humans. The species is divided into eight assemblages suggested to represent separate Giardia species based on host specificities and the genetic divergence of marker genes. We have investigated whether genome-wide recombination occurs between assemblages using the three available G. intestinalis genomes. First, the relative nonsynonymous substitution rates of the homologs were compared for 4,009 positional homologs. The vast majority of these comparisons indicate genetic isolation without interassemblage recombinations. Only a region of 6 kbp suggests genetic exchange between assemblages A and E, followed by gene conversion events. Second, recombination-detecting software fails to identify within-gene recombination between the different assemblages for most of the homologs. Our results indicate very low frequency of recombination between the syntenic core genes, suggesting that G. intestinalis assemblages are genetically isolated lineages and thus should be viewed as separated Giardia species.     

Legacy microsite effect on the survival of bitterbrush outplantings after prescribed fire: capitalizing on spatial variability to improve restoration

Restoration of shrubs in arid and semi‐arid rangelands is hampered by low success rates. Planting shrub seedlings is a method used to improve success in these rangelands; however, it is expensive and labor intensive. The efficiency of shrub restoration could be improved by identifying microsites where shrub survival is greater. Bitterbrush (Purshia tridentata Pursh DC) is an important shrub to wildlife that has declined because of conifer encroachment, excessive defoliation, wildfires, and low recruitment. We investigated planting bitterbrush seedlings in western juniper (Juniperus occidentalis ssp. occidentalis Hook) encroached shrublands after prescribed fire was used to control trees. Bitterbrush seedlings were planted in under (canopy) and between (interspace) former juniper canopies at five blocks and evaluated for three growing seasons. Bitterbrush survival was greater than 50% in the former canopy, but only 5% in the interspace microsite by the third growing season. Growth of bitterbrush was also greater in the former canopy compared with the interspace, potentially due to markedly less perennial vegetation in this microsite. Exotic annual grasses and annual forbs became prevalent in the former canopy in the second and third growing season, suggesting that soil resource availability was greater in this microsite. These results suggest that restoration success will vary by specific locations within a burned landscape and that this variability can be used to improve restoration efficiency. In this situation, bitterbrush restoration can be improved by planting seedlings in former canopy compared with interspace microsites.     

Quantitative phosphoproteome analysis of lysophosphatidic acid induced chemotaxis applying dual-step (18)O labeling coupled with immobilized metal-ion affinity chromatography

Reversible protein phosphorylation is a central cellular regulatory mechanism in modulating protein activity and propagating signals within cellular pathways and networks. Development of more effective methods for the simultaneous identification of phosphorylation sites and quantification of temporal changes in protein phosphorylation could provide important insights into molecular signaling mechanisms in various cellular processes. Here we present an integrated quantitative phosphoproteomics approach and its application for comparative analysis of Cos-7 cells in response to lysophosphatidic acid (LPA) gradient stimulation. The approach combines trypsin-catalyzed (16)O/ (18)O labeling plus (16)O/ (18)O-methanol esterification for quantitation, a macro-immobilized metal-ion affinity chromatography trap for phosphopeptide enrichment, and LC-MS/MS analysis. LC separation and MS/MS are followed by neutral loss-dependent MS/MS/MS for phosphopeptide identification using a linear ion trap (LTQ)-FT mass spectrometer. A variety of phosphorylated proteins were identified and quantified including receptors, kinases, proteins associated with small GTPases, and cytoskeleton proteins. A number of hypothetical proteins were also identified as differentially expressed followed by LPA stimulation, and we have shown evidence of pseudopodia subcellular localization of one of these candidate proteins. These results demonstrate the efficiency of this quantitative phosphoproteomics approach and its application for rapid discovery of phosphorylation events associated with LPA gradient sensing and cell chemotaxis.     

Whole genome sequencing of a natural recombinant Toxoplasma gondii strain reveals chromosome sorting and local allelic variants

Background  

Toxoplasma gondii is a zoonotic parasite of global importance. In common with many protozoan parasites it has the capacity for sexual recombination, but current evidence suggests this is rarely employed. The global population structure is dominated by a small number of clonal genotypes, which exhibit biallelic variation and limited intralineage divergence. Little is known of the genotypes present in Africa despite the importance of AIDS-associated toxoplasmosis.     

A common cortical substrate activated by horizontal and vertical sound movement in the human brain

Perception of movement in acoustic space depends on comparison of the sound waveforms reaching the two ears (binaural cues) as well as spectrotemporal analysis of the waveform at each ear (monaural cues). The relative importance of these two cues is different for perception of vertical or horizontal motion, with spectrotemporal analysis likely to be more important for perceiving vertical shifts. In humans, functional imaging studies have shown that sound movement in the horizontal plane activates brain areas distinct from the primary auditory cortex, in parietal and frontal lobes and in the planum temporale. However, no previous work has examined activations for vertical sound movement. It is therefore difficult to generalize previous imaging studies, based on horizontal movement only, to multidimensional auditory space perception. Using externalized virtual-space sounds in a functional magnetic resonance imaging (fMRI) paradigm to investigate this, we compared vertical and horizontal shifts in sound location. A common bilateral network of brain areas was activated in response to both horizontal and vertical sound movement. This included the planum temporale, superior parietal cortex, and premotor cortex. Sounds perceived laterally in virtual space were associated with contralateral activation of the auditory cortex. These results demonstrate that sound movement in vertical and horizontal dimensions engages a common processing network in the human cerebral cortex and show that multidimensional spatial properties of sounds are processed at this level.     

Gene mapping in the wild with SNPs: guidelines and future directions

One of the biggest challenges facing evolutionary biologists is to identify and understand loci that explain fitness variation in natural populations. This review describes how genetic (linkage) mapping with single nucleotide polymorphism (SNP) markers can lead to great progress in this area. Strategies for SNP discovery and SNP genotyping are described and an overview of how to model SNP genotype information in mapping studies is presented. Finally, the opportunity afforded by new generation sequencing and typing technologies to map fitness genes by genome-wide association studies is discussed.