Creating Ioffe-Pritchard micro-traps from permanent magnetic film with in-plane magnetization

We present designs for Ioffe-Pritchard type magnetic traps using planar patterns of hard magnetic material. Two samples with different pattern designs were produced by spark erosion of 40 $\mu$m thick FePt foil. The pattern on the first sample yields calculated axial and radial trap frequencies of 51 Hz and 6.8 kHz, respectively. For the second sample the calculated frequencies are 34 Hz and 11 kHz. The structures were used successfully as a magneto-optical trap for $^{87}$Rb and loaded as a magnetic trap. A third design, based on lithographically patterned 250 nm thick FePt film on a Si substrate, yields an array of 19 traps with calculated axial and radial trap frequencies of 1.5 kHz and 110 kHz, respectively.Comment: 8 pages, 5 figures Revised and accepted for EPJD, improved picture

Electron-Ion Recombination on Grains and Polycyclic Aromatic Hydrocarbons

With the high-resolution spectroscopy now available in the optical and satellite UV, it is possible to determine the neutral/ionized column density ratios for several different elements in a single cloud. Assuming ionization equilibrium for each element, one can make several independent determinations of the electron density. For the clouds for which such an analysis has been carried out, these different estimates disagree by large factors, suggesting that some process (or processes) besides photoionization and radiative recombination might play an important role in the ionization balance. One candidate process is collisions of ions with dust grains. Making use of recent work quantifying the abundances of polycyclic aromatic hydrocarbon molecules and other grains in the interstellar medium, as well as recent models for grain charging, we estimate the grain-assisted ion recombination rates for several astrophysically important elements. We find that these rates are comparable to the rates for radiative recombination for conditions typical of the cold neutral medium. Including grain-assisted ion recombination in the ionization equilibrium analysis leads to increased consistency in the various electron density estimates for the gas along the line of sight to 23 Orionis. However, not all of the discrepancies can be eliminated in this way; we speculate on some other processes that might play a role. We also note that grain-assisted recombination of H+ and He+ leads to significantly lower electron fractions than usually assumed for the cold neutral medium.Comment: LaTeX(12 pages, 8 figures, uses emulateapj5.sty, apjfonts.sty); submitted to ApJ; corrected typo

Delinquent Behavior of Dutch Rural Adolescents

This article compares Dutch rural and non-rural adolescents’ delinquent behavior and examines two social correlates of rural delinquency: communal social control and traditional rural culture. The analyses are based on cross-sectional data, containing 3,797 participants aged 13–18 (48.7% females). The analyses show that rural adolescents are only slightly less likely to engage in delinquent behavior. Furthermore, while rural adolescents are exposed more often to communal social control, this does not substantially reduce the likelihood that they engage in delinquent behavior. Concerning rural culture, marked differences appeared between rural and non-rural adolescents. First, alcohol use and the frequency of visiting pubs were more related to rural adolescents’ engagement in delinquent behavior. Second, the gender gap in delinquency is larger among rural adolescents: whereas rural boys did not differ significantly from non-rural boys, rural girls were significantly less likely to engage in delinquent behavior than non-rural girls. However, the magnitude of the effects of most indicators was rather low. To better account for the variety of rural spaces and cultures, it is recommended that future research into antisocial and criminal behavior of rural adolescents should adopt alternative measurements of rurality, instead of using an indicator of population density only

BMP signals and the transcriptional repressor BLIMP1 during germline segregation in the mammalian embryo

Molecular factors and tissue compartments involved in the foundation of the mammalian germline have been mainly described in the mouse so far. To find mechanisms applicable to mammals in general, we analyzed temporal and spatial expression patterns of the transcriptional repressor BLIMP1 (also known as PRDM1) and the signaling molecules BMP2 and BMP4 in perigastrulation and early neurulation embryos of the rabbit using whole-mount in situ hybridization and high-resolution light microscopy. Both BMP2 and BMP4 are expressed in annular domains at the boundary of the embryonic disc, which—in contrast to the situation in the mouse—partly belong to intraembryonic tissues. While BMP2 expression begins at (pregastrulation) stage 1 in the hypoblast, BMP4 expression commences—distinctly delayed compared to the mouse—diffusely at (pregastrulation) stage 2; from stage 3 onwards, BMP4 is expressed peripherally in hypoblast and epiblast and in the mesoderm at the posterior pole of the embryonic disc. BLIMP1 expression begins throughout the hypoblast at stage 1 and emerges in single primordial germ cell (PGC) precursors in the posterior epiblast at stage 2 and then in single mesoderm cells at positions identical to those identified by PGC-specific antibodies. These expression patterns suggest that function and chronology of factors involved in germline segregation are similar in mouse and rabbit, but higher temporal and spatial resolution offered by the rabbit demonstrates a variable role of bone morphogenetic proteins and makes “blimping” a candidate case for lateral inhibition without the need for an allantoic germ cell niche

Genesis of Neuronal and Glial Progenitors in the Cerebellar Cortex of Peripuberal and Adult Rabbits

Adult neurogenesis in mammals is restricted to some brain regions, in contrast with other vertebrates in which the genesis of new neurons is more widespread in different areas of the nervous system. In the mammalian cerebellum, neurogenesis is thought to be limited to the early postnatal period, coinciding with end of the granule cell genesis and disappearance of the external granule cell layer (EGL). We recently showed that in the rabbit cerebellum the EGL is replaced by a proliferative layer called ‘subpial layer’ (SPL) which persists beyond puberty on the cerebellar surface. Here we investigated what happens in the cerebellar cortex of peripuberal rabbits by using endogenous and exogenously-administered cell proliferation antigens in association with a cohort of typical markers for neurogenesis. We show that cortical cell progenitors extensively continue to be generated herein. Surprisingly, this neurogenic process continues to a lesser extent in the adult, even in the absence of a proliferative SPL. We describe two populations of newly generated cells, involving neuronal cells and multipolar, glia-like cells. The genesis of neuronal precursors is restricted to the molecular layer, giving rise to cells immunoreactive for GABA, and for the transcription factor Pax2, a marker for GABAergic cerebellar interneuronal precursors of neuroepithelial origin that ascend through the white matter during early postnatal development. The multipolar cells are Map5+, contain Olig2 and Sox2 transcription factors, and are detectable in all cerebellar layers. Some dividing Sox2+ cells are Bergmann glia cells. All the cortical newly generated cells are independent from the SPL and from granule cell genesis, the latter ending before puberty. This study reveals that adult cerebellar neurogenesis can exist in some mammals. Since rabbits have a longer lifespan than rodents, the protracted neurogenesis within its cerebellar parenchyma could be a suitable model for studying adult nervous tissue permissiveness in mammals

Besides Purkinje cells and granule neurons: an appraisal of the cell biology of the interneurons of the cerebellar cortex

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Development of a Real-Time PCR for Identification of Brachyspira Species in Human Colonic Biopsies

Background: Brachyspira species are fastidious anaerobic microorganisms, that infect the colon of various animals. The genus contains both important pathogens of livestock as well as commensals. Two species are known to infect humans: B. aalborgi and B. pilosicoli. There is some evidence suggesting that the veterinary pathogenic B. pilosicoli is a potential zoonotic agent, however, since diagnosis in humans is based on histopathology of colon biopsies, species identification is not routinely performed in human materials. Methods: The study population comprised 57 patients with microscopic evidence of Brachyspira infection and 26 patients with no histopathological evidence of Brachyspira infection. Concomitant faecal samples were available from three infected patients. Based on publically available 16S rDNA gene sequences of all Brachyspira species, species-specific primer sets were designed. DNA was extracted and tested by real-time PCR and 16S rDNA was sequenced. Results: Sensitivity and specificity for identification of Brachyspira species in colon biopsies was 100% and 87.7% respectively. Sequencing revealed B. pilosicoli in 15.4% of patients, B. aalborgi in 76.9% and a third species, tentatively named ‘‘Brachyspira hominis’’, in 26.2%. Ten patients (12.3%) had a double and two (3.1%) a triple infection. The presence of Brachyspira pilosicoli was significantly associated with inflammatory changes in the colon-biopsy (p = 0.028). Conclusions: This newly designed PCR allows for sub-differentiation of Brachyspira species in patient material and thus allows large-scaled surveillance studies to elucidate the pathogenicity of human Brachyspira infections. One-third of affected patients appeared to be infected with a novel species