Factors associated with youth gang membership in low and middle-income countries: a systematic review.

Youth gang membership is associated with delinquency, violent crime and trafficking – and gang members are themselves frequently the victims of these offences. Yet youth gangs can also provide a form of social capital, a sense of belonging and purpose to disenfranchised youth. This review identifies the factors associated with young people joining gangs, and the differences between gang-involved and non-gang-involved youth. Understanding these associations is essential to reduce the levels of gang membership and the incidence of related violence

Characterizing the scent and chemical composition of Panthera leo marking fluid using solid-phase microextraction and multidimensional gas chromatography–mass spectrometry-olfactometry

Lions (Panthera leo) use chemical signaling to indicate health, reproductive status, and territorial ownership. To date, no study has reported on both scent and composition of marking fluid (MF) from P. leo. The objectives of this study were to: 1) develop a novel method for simultaneous chemical and scent identification of lion MF in its totality (urine + MF), 2) identify characteristic odorants responsible for the overall scent of MF as perceived by human panelists, and 3) compare the existing library of known odorous compounds characterized as eliciting behaviors in animals in order to understand potential functionality in lion behavior. Solid-phase microextraction and simultaneous chemical-sensory analyses with multidimensional gas-chromatography-mass spectrometry-olfactometry improved separating, isolating, and identifying mixed (MF, urine) compounds versus solvent-based extraction and chemical analyses. 2,5-Dimethylpyrazine, 4-methylphenol, and 3-methylcyclopentanone were isolated and identified as the compounds responsible for the characteristic odor of lion MF. Twenty-eight volatile organic compounds (VOCs) emitted from MF were identified, adding a new list of compounds previously unidentified in lion urine. New chemicals were identified in nine compound groups: ketones, aldehydes, amines, alcohols, aromatics, sulfur-containing compounds, phenyls, phenols, and volatile fatty acids. Twenty-three VOCs are known semiochemicals that are implicated in attraction, reproduction, and alarm-signaling behaviors in other species

The Emergence of Somatotopic Maps of the Body in S1 in Rats: The Correspondence Between Functional and Anatomical Organization

Most of what we know about cortical map development and plasticity comes from studies in mice and rats, and for the somatosensory cortex, almost exclusively from the whisker-dominated posteromedial barrel fields. Whiskers are the main effector organs of mice and rats, and their representation in cortex and subcortical pathways is a highly derived feature of murine rodents. This specialized anatomical organization may therefore not be representative of somatosensory cortex in general, especially for species that utilize other body parts as their main effector organs, like the hands of primates. For these reasons, we examined the emergence of whole body maps in developing rats using electrophysiological recording techniques. In P5, P10, P15, P20 and adult rats, multiple recordings were made in the medial portion of S1 in each animal. Subsequently, these functional maps were related to anatomical parcellations of S1 based on a variety of histological stains. We found that at early postnatal ages (P5) medial S1 was composed almost exclusively of the representation of the vibrissae. At P10, other body part representations including the hindlimb and forelimb were present, although these were not topographically organized. By P15, a clear topographic organization began to emerge coincident with a reduction in receptive field size. By P20, body maps were adult-like. This study is the first to describe how topography of the body develops in S1 in any mammal. It indicates that anatomical parcellations and functional maps are initially incongruent but become tightly coupled by P15. Finally, because anatomical and functional specificity of developing barrel cortex appear

Representative traces of multi-unit activity in a P5 (A) and P15 (B) rat.

<p>A) Multi-unit activity in response to stimulation of both ipsilateral (left) and contralateral (right) vibrissae. Tic marks indicate the temporal pattern of stimulation. The inset box includes a depiction of S1 with the recording site indicated by an open circle (scale = 1 mm). B) Multi-unit activity in response to stimulation of toe 4 (left) and toe 5 (right) of the contralateral hindpaw. The receptive field for the neurons is indicated in gray on the schematic of the contralateral hindpaw. The inset box includes an illustration of S1 with the recording site marked by an open circle (scale = 1 mm).</p

List of Abbreviations.

<p>List of Abbreviations.</p

Receptive field progressions in P10 and P5 rats.

<p>A) Progressions of recording sites in S1 in a P10 rat (left) and corresponding receptive fields for neurons at those sites (right). In P10 rats, the topographic organization is imprecise. The receptive fields are very large and many receptive fields cover multiple body parts (i.e., sites 7–9). Vibrissae representations are found throughout S1 in inappropriate locations (i.e., sites 1, 2, 4 and 5). As recording sites progress from medial to lateral in the caudal portion of S1 (1–3) corresponding receptive fields were all on the ipsilateral vibrissae. Recording sites in the far medial location (4, 5), in what would be the hindpaw representation in the adult, had receptive fields on the ipsilateral or vibrissae. Recording sites in medial portions of S1 in what would normally be the forepaw representation (6–9) had receptive fields on the forepaw, split receptive fields on the upper body and vibrissae, bilateral vibrissae and face and vibrissae. B) Progressions of recording sites in S1 in a P5 rat (left) and corresponding receptive fields for neurons at those sites (right). In P5 rats there is no apparent topography. Receptive fields are large, and, when present on the limbs, encompass both hairy and glabrous portions of the paws. Receptive fields are also observed on both the contralateral and ipsilateral body parts. Vibrissae representations are prevalent and found throughout S1. As recording sites progress from medial to lateral in the caudal portion of S1 (1–3) corresponding receptive fields move from the contralateral vibrissae to the lateral trunk. Far medial recording sites (4–5) in what would normally be the hindpaw representation had receptive field on the vibrissae, and in one instance the dorsal and ventral hindpaw. More medial recording sites (6–8), in what would normally be the forepaw representation had receptive fields on the contralateral or bilateral vibrissae, and wrist and vibrissae. Compare this figure with the full map of the body illustrated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032322#pone-0032322-g001" target="_blank">Figure 1</a>. Conventions as in previous figures.</p