A numerical study of interactions and stellar bars

For several decades it has been known that stellar bars in disc galaxies can be triggered by interactions, or by internal processes such as dynamical instabilities. In this work, we explore the differences between these two mechanisms using numerical simulations. We perform two groups of simulations based on isolated galaxies, one group in which a bar develops naturally, and another group in which the bar could not develop in isolation. The rest of the simulations recreate 1:1 coplanar fly-by interactions computed with the impulse approximation. The orbits we use for the interactions represent the fly-bys in groups or clusters of different masses accordingly to the velocity of the encounter. In the analysis we focus on bars' amplitude, size, pattern speed and their rotation parameter, ${\cal R}=R_{CR}/R_{bar}$. The latter is used to define fast (${\cal R}1.4$). Compared with equivalent isolated galaxies we find that bars affected or triggered by interactions: (i) remain in the slow regime for longer; (ii) are more boxy in face-on views; (iii) they host kinematically hotter discs. Within this set of simulations we do not see strong differences between retrograde or prograde fly-bys. We also show that slow interactions can trigger bar formation.Comment: 12 pages, 7 figures. Accepted for publication in MNRA

Access to Barrier Perches Improves Behavior Repertoire in Broilers

Restriction of behavioral opportunities and uneven use of space are considerable welfare concerns in modern broiler production, particularly when birds are kept at high densities. We hypothesized that increased environmental complexity by provision of barrier perches would help address these issues by encouraging perching and enhancing use of the pen space across a range of stocking densities. 2,088 day-old broiler chicks were randomly assigned to one of the following barrier and density treatment combinations over four replications: simple barrier, complex barrier, or control (no barrier) and low (8 birds/m2), moderate (13 birds/m2), or high (18 birds/m2) density. Data were collected on focal birds via instantaneous scan sampling from 2 to 6 weeks of age. Mean estimates per pen for percent of observations seen performing each behavior, as well as percent of observations in the pen periphery vs. center, were quantified and submitted to an analysis of variance with week as the repeated measure. Barrier perches, density and age affected the behavioral time budget of broilers. Both simple and complex barrier perches effectively stimulated high perching rates. Aggression and disturbances were lower in both barrier treatments compared to controls (P<0.05). Increasing density to 18 birds/m2 compared to the lower densities suppressed activity levels, with lower foraging (P<0.005), decreased perching (P<0.0001) and increased sitting (P = 0.001) earlier in the rearing period. Disturbances also increased at higher densities (P<0.05). Use of the central pen area was higher in simple barrier pens compared to controls (P<0.001), while increasing density above 8 birds/m2 suppressed use of the central space (P<0.05). This work confirms some negative effects of increasing density and suggests that barrier perches have the potential to improve broiler welfare by encouraging activity (notably by providing accessible opportunities to perch), decreasing aggression and disturbances, and promoting more even distribution of birds throughout the pen space

Motivasi Dan Kemampuan Berpikir Tingkat Tinggi Siswa Setelah Pembelajaran Kimia Dengan Strategi Inkuiri Terbimbing

Motivasi dan Kemampuan Berpikir Tingkat Tinggi Siswa Setelah Pembelajaran Kimia Dengan Strategi Inkuiri Terbimbing. Tujuan penelitian ini adalah untuk mengetahui pengaruh strategi inkuiri terbimbing terhadap motivasi dan kemampuan berpikir tingkat tinggi siswa pada pembelajaran hi­drolisis. Penelitian eksperimen semu ini menggunakan pretest-postest control group design. Subjek pe­nelitian adalah dua kelas XI IPA dengan rerata kemampuan yang setara, yaitu kelas XI IPA 1 (kelas eks­positori) dan kelas XI IPA 3 (kelas inkuiri terbimbing) SMA Negeri 6 Malang tahun pelajaran 2013/2014. Ketiga instrumen pengukuran yaitu tes motivasi, tes kemampuan berpikir tingkat tinggi yang terdiri dari tes pemahaman konseptual dan algoritmik serta tes kemampuan logika deduktiv, telah diuji coba dan menun­jukkan bahwa ketiganya valid dan reliabel. Perbedaan hasil tes di kedua kelas dianalisis dengan uji MA­NOVA. Hasil penelitian menunjukkan bahwa motivasi belajar dan kemampuan berpikir tingkat tinggi, baik dalam bentuk pemahaman konseptual dan pemahaman algoritmik, maupun kemampuan logika de­duktif, dari siswa yang dibelajarkan dengan strategi inkuiri terbimbing adalah lebih tinggi dibanding siswa yang dibelajarkan dengan strategi ekspositori

Why Buckling Stellar Bars Weaken in Disk Galaxies

Young stellar bars in disk galaxies experience a vertical buckling instability which terminates their growth and thickens them, resulting in a characteristic peanut/boxy shape when viewed edge on. Using N-body simulations of galactic disks embedded in live halos, we have analyzed the bar structure throughout this instability and found that the outer third of the bar dissolves completely while the inner part (within the vertical inner Lindblad resonance) becomes less oval. The bar acquires the frequently observed peanut/boxy-shaped isophotes. We also find that the bar buckling is responsible for a mass injection above the plane, which is subsequently trapped by specific 3-D families of periodic orbits of particular shapes explaining the observed isophotes, in line with previous work. Using a 3-D orbit analysis and surfaces of sections, we infer that the outer part of the bar is dissolved by a rapidly widening stochastic region around its corotation radius -- a process related to the bar growth. This leads to a dramatic decrease in the bar size, decrease in the overall bar strength and a mild increase in its pattern speed, but is not expected to lead to a complete bar dissolution. The buckling instability appears primarily responsible for shortening the secular diffusion timescale to a dynamical one when building the boxy isophotes. The sufficiently long timescale of described evolution, ~1 Gyr, can affect the observed bar fraction in local universe and at higher redshifts, both through reduced bar strength and the absence of dust offset lanes in the bar.Comment: 7 pages, 4 figures, ApJ Letters, in pres

Soil textural heterogeneity impacts bacterial but not fungal diversity

Soils harbour high levels of microbial diversity, underpinning their ability to provide key soil functions and ecosystem services. The extreme variety of soil microbial life is often explained by reference to the physical and chemical heterogeneity of the soil environment. However, detailed understanding of this link is still lacking, particularly as micro-scale studies are difficult to scale up to the soil profile or landscape level. To address this, we used soil samples collected from a wide range of temperate oceanic habitats (e.g. arable, grassland, coniferous and deciduous woodland, heathland; 335 sites in total) to evaluate the link between soil texture and microbial diversity. Soil particle size distribution was measured in each sample using laser granulometry (i.e. sand, silt, clay), while the diversity of bacterial and fungal communities were determined by metabarcoding with an Illumina MiSeq using16S and ITS1 taxonomy marker gene regions, respectively. Multifractal analysis of the soil particle size distribution was then used to describe the heterogeneity of the soil particle sizes. Overall, our results showed no impact of habitat type upon textural heterogeneity indicating that it is an aspect of soil quality resistant to management decisions. Using a structural equation modelling approach, we show that soil textural heterogeneity positively influences bacterial diversity but had little impact upon fungal diversity. We also find that textural composition impacts both bacterial and fungal composition, with many specific microbial taxa showing co-occurrence relationships with clay and fine-silt sized particles. Our results strongly indicate that soil textural heterogeneity influences microbial community diversity regardless of soil management practices and biophysical activities. The close linkages between different groups of soil organisms can obscure the mechanisms driving the development of biodiversity, however, it is clear that the soil physical environment has differential impacts on organisms with different life history strategies

Current Situation of Bacterial Infections and Antimicrobial Resistance Profiles in Pet Rabbits in Spain

Rabbits are the second most common specialty pet among households in Europe and the USA. However, research on antimicrobial resistance (AMR) in pet rabbits is very scarce. Therefore, scientific data on AMR in pet rabbits is urgently needed as a guide for veterinarian clinicians to optimize antibiotic use in rabbits for reducing the selection of antibiotic resistance. In addition, antimicrobial stewardship programs should be conducted to educate rabbit owners not to misuse antibiotics on their pets as it may put their own health at risk. This paper aims to provide an overview of the current state of AMR in rabbits attended to in veterinary clinics distributed in Spain to highlight the importance of addressing AMR under the One Health approach. Research on antimicrobial resistance (AMR) in pet rabbits is very scarce. The aim of this study was to provide an overview of the current state of AMR in rabbits attended to in veterinary clinics distributed in Spain. Records of 3596 microbiological results of clinical cases submitted from 2010 to 2021 were analyzed. Staphylococcus spp. (15.8%), Pseudomonas spp. (12.7%), Pasteurella spp. (10%), Bordetella spp. (9.6%) and Streptococcus spp. (6.8%) were the most frequently diagnosed agents. Enterobacteriaceae, principally Escherichia coli, Klebsiella pneumoniae and Enterobacter cloacae, accounted for about 18% of the cases and showed the highest proportion of multi-drug resistance (MDR) isolates, with 48%, 57.5% and 36% of MDR, respectively. Regarding the antimicrobial susceptibility testing for a number of antimicrobial categories/families, the largest proportion of isolates showing resistance to a median of five antimicrobial categories was observed in P. aeruginosa, Stenotrophomonas maltophilia and Burkolderia spp. In contrast, infections caused by Staphylococcus, Streptococcus spp. and Pasteurella multocida were highly sensitive to conventional antimicrobials authorized for veterinary use (categories D and C). The emergence of AMR major nosocomial opportunistic pathogens such as P. aeruginosa, S. maltophilia and K. pneumoniae in pet rabbits can represent a serious public health challenge. Consequently, collaboration between veterinarians and human health professionals is crucial in the fight against antimicrobial resistance, to optimize, rationalize and prudently use antimicrobial therapies in domestic animals and humans

Carcinoma Primario Intraóseo y quiste odontogénico: tres casos clínicos y revisión de la Literatura

Introducción: Los Carcinomas Intraóseos Primarios Odontogénicos (PIOC) son un raro grupo de tumores malignos con unos estrictos criterios diagnósticos clínicos y anatomo-patológicos. Las diferentes clasificaciones sugeridas para estos tumores y el escaso número de casos descritos en la literatura hacen difícil conocer con exactitud cuantos son los casos reales publicados hasta el día de hoy. Material y métodos: presentamos tres nuevos casos de PIOC originados a partir de una lesión quística previa que fueron tratados en nuestro centro. Dos en región posterior mandibular que es el lugar de más frecuente aparición, y un tercero en maxilar superior. Explicamos el tipo de cirugía llevado a cabo en cada caso y la reconstrucción estético-funcional utilizada que son dos injertos osteomiocutáneos de peroné y un injerto de hueso de cresta iliaca con posterior colocación de implantes. Se discute la clasificación, el diagnóstico clinico-radiológico, el tratamiento y su supervivencia. Resultados: en los tres casos se pudo constatar en la anatomía patológica un epitelio celular bien diferenciado acompañando a células carcinomatosas afectando al hueso exclusivamente sin afectación de la mucosa oral circundante ni de tejidos vecinos a la lesión así como ausencia de patología tumoral en otra zona del organismo. Uno de los pacientes falleció por recidiva cervical masiva precoz mientras que los otros dos están libres de enfermedad en la actualidad después de 10 años en uno de ellos y 15 meses en el otro. Conclusiones: es muy importante el análisis anatomo-patológico de todas las lesiones de características quísticas a nivel maxilar por el riesgo de coexistir con células carcinomatosas. El tratamiento de estos tumores debe ser la práctica de una cirugía agresiva y, en algunos casos, asociados a radio y/o quimioterapia post intervención.Introduction: The Odontogenic Primary Intraosseous Carcinoma (PIOC) are a rare group of malignant tumours with strict clinic and anatomy pathological diagnosis criteria. The different classification suggested for these tumours and the small amount of cases described in literature makes it hard to know exactly how many of the cases published until now are real. Material and methods: We present three new cases of PIOC originated from a previous cystic lesion that where treated in our Hospital. Two of them in the posterior jaw region where is more frequent, and the third in the upper jaw. We explain the procedure we used in each case and the aesthetic-functional reconstruction used witches are two fibula osseomiocutaneous free flaps and a bone graft of iliac crest and further placing of implants. The classification, the clinical and radiological diagnosis, the treatment and its survival are discussed. Results: in all three cases we were able to see in the anatomy pathological study an epithelial, exclusively without surrounding oral mucosa affectation or tissues near the lesion as well as the lack of tumorous pathology in other parts of the body. One of the patients died because of premature massive cervical recidiva while the other two patients are currently free form illness, for ten years one of them and fifteen months the other. Conclusions: the anatomy pathological study of all of the lesions of cystic characteristics at jaw level is very important because of the risk of coexisting with carcinomatous cells. The treatment of these tumours consists in practising aggressive surgery and, in some cases, radio and/or chemotherapy post intervention

Decoupled richness of generalist anaerobes and sulphate-reducing bacteria is driven bypHacross land uses in temperate soils

Sulphate‐reducing bacteria (SRB) represent a key biological component of the global sulphur (S) cycle and are common in soils, where they reduce SO42− to H2S during the anaerobic degradation of soil organic matter. The factors that regulate their distribution in soil, however, remain poorly understood. We sought to determine the ecological patterns of SRB richness within a nationwide 16S metabarcoding dataset. Across 436 sites belonging to seven contrasting temperate land uses (e.g., arable, grasslands, woodlands, heathland and bog), SRB richness was relatively low across land uses but greatest in grasslands and lowest in woodlands and peat‐rich soils. There was a shift in dominant SRB taxa from Desulfosporosinus and Desulfobulbus in arable and grassland land uses to Desulfobacca in heathland and bog sites. In contrast, richness of other generalist anaerobic bacterial taxa found in our dataset (e.g., Clostridium, Geobacter and Pelobacter) followed a known trend of declining richness linked to land‐use productivity. Overall, the richness of SRBs and anaerobes had strong positive correlations with pH and sulphate concentration and strong negative relationships with elevation, soil organic matter, total carbon and carbon‐to‐nitrogen ratio. It is likely that these results reflect the driving influence of pH and competition for optimal electron acceptors with generalist anaerobic bacteria on SRB richness

Amphiphilic Gemini Pyridinium-mediated incorporation of Zn(II)meso-tetrakis(4-carboxyphenyl)porphyrin into water-soluble gold nanoparticles for photodynamic therapy

Zn-containing porphyrins are intensely investigated for their ability to form reactive oxygen species and thereby being potent photosensitizers for use in photodynamic therapy (PDT). Some of the drawbacks of the PDT approach, such as unspecific distribution, could be addressed by means of photosensitizer drug delivery systems. In this work, we synthesize and characterize new water-soluble gold nanoparticles (GNP) stabilized by a mixture of a polyethyleneglycol-containing thiol (to improve water solubility) and a new amphiphilic gemini-type pyridinium salt, which also acts as promotor of the incorporation of the anionic photosensitizer Na-ZnTCPP into the GNP. The obtained GNP have sizes between 7 and 10 nm, as observed by Transmission Electron Microscopy. The incorporation of the photosensitizer caused an increase in the hydrodynamic size, detected by Dynamic Light Scattering, as well as a shift in the Surface Plasmon Resonance peak on the GNP UV–vis absorption spectra. The presence of the photosensitizer in the GNP was corroborated using Fluorescence Spectroscopy. The amount of Na-ZnTCPP was found to be 327 molecules per GNP. The porphyrin-containing Na-ZnTCPP-1·GNP showed good enhanced ability to produce singlet oxygen, compared to free Na-ZnTCPP. Their cytotoxicity and phototoxicity were investigated in vitro using two different human breast cell lines, one of tumoral origin (SKBR-3) and another of normal epithelium origin (MCF-10A). SKBR-3 cells showed higher sensitivity to Na-ZnTCCP and Na-ZnTCPP-1·GNP in dark conditions. After irradiation, no significant differences were observed between both cell lines except for 1 μM Na-ZnTCCP-1·GNP where SKBR-3 cells were also more sensitive

Polycomb Controls Gliogenesis by Regulating the Transient Expression of the Gcm/Glide Fate Determinant

The Gcm/Glide transcription factor is transiently expressed and required in the Drosophila nervous system. Threshold Gcm/Glide levels control the glial versus neuronal fate choice, and its perdurance triggers excessive gliogenesis, showing that its tight and dynamic regulation ensures the proper balance between neurons and glia. Here, we present a genetic screen for potential gcm/glide interactors and identify genes encoding chromatin factors of the Trithorax and of the Polycomb groups. These proteins maintain the heritable epigenetic state, among others, of HOX genes throughout development, but their regulatory role on transiently expressed genes remains elusive. Here we show that Polycomb negatively affects Gcm/Glide autoregulation, a positive feedback loop that allows timely accumulation of Gcm/Glide threshold levels. Such temporal fine-tuning of gene expression tightly controls gliogenesis. This work performed at the levels of individual cells reveals an undescribed mode of Polycomb action in the modulation of transiently expressed fate determinants and hence in the acquisition of specific cell identity in the nervous system. © 2012 Popkova et al.Fondation pour la Recherche Médicale and by Centre Européen de Recherche en Biologie et en Médecine; Association pour la Recherche sur le Cancer; Institut National de la Santé et de la Recherche Médicale; Centre National de la Recherche Scientifique; Université de Strasbourg; Hôpital de Strasbourg; Institut National du Cancer; the Agence Nationale de la Recherche; Alma Mater Studiorum; Università di Bologna; European Research Council (ERC-2008-AdG No 232947); Institut National de la Santé et de la Recherche Médicale; Centre National de la Recherche Scientifique; European Network of Excellence EpiGeneSys; Fundacion Mutua Madrileña (FMM-2006) and Ministerio de Ciencia y Tecnología (BFU-2008-5404)Peer Reviewe