Resurrection of an East African House Bat Species, Scotophilus altilis (Chiroptera: Vespertilionidae)

Several house bat specimens superficially resembling the white-bellied house bat Scotophilus leucogaster (Cretzschmar, 1830), were recently captured in southwestern Ethiopia and southern South Sudan. These S. cf. leucogaster differed from typical S. leucogaster by their slightly smaller size and ventral coloration, conforming instead with the original description of S. altilis Allen, 1914. Scotophilus altilis is an overlooked taxon known from the Blue Nile region in Sudan that is currently considered a junior synonym of S. leucogaster. Phylogenetic analysis of mitochondrial cytochrome b gene (cytb) sequences revealed S. cf. leucogaster as a sister clade to S. leucogaster with a genetic distance of ca. 10%. Comparative specimens of questionable S. nigritellus de Winton, 1899 from northwestern Ethiopia and a wing biopsy sample of another S. cf. leucogaster from western Kenya also fell within this clade. Sequence data from two nuclear markers (zfy and fgb7) corroborated the distinction of S. cf. leucogaster from S. leucogaster. Likewise, morphometric analysis of cranial data largely supported this distinction, as well as taxonomic affiliation with S. altilis based on comparison with the only available paratype specimen. The position of this paratype specimen within the new Scotophilus clade, inferred from analysis of a short fragment of cytb, confirmed its taxonomic identity. Based on the presented evidence, the overlooked East African taxon S. altilis should be resurrected as a full species within the genus Scotophilus

The Fossil Phase in the Life of a Galaxy Group

We investigate the origin and evolution of fossil groups in a concordance LCDM cosmological simulation. We consider haloes with masses between (1-5)\times10^{13} \hMsun and study the physical mechanisms that lead to the formation of the large gap in magnitude between the brightest and the second most bright group member, which is typical for these fossil systems. Fossil groups are found to have high dark matter concentrations, which we can relate to their early formation time. The large magnitude-gaps arise after the groups have build up half of their final mass, due to merging of massive group members. We show that the existence of fossil systems is primarily driven by the relatively early infall of massive satellites, and that we do not find a strong environmental dependence for these systems. In addition, we find tentative evidence for fossil group satellites falling in on orbits with typically lower angular momentum, which might lead to a more efficient merger onto the host. We find a population of groups at higher redshifts that go through a ``fossil phase'': a stage where they show a large magnitude-gap, which is terminated by renewed infall from their environment.Comment: 9 pages and 8 figures, submitted to MNRA

Pseudocontact shifts and paramagnetic susceptibility in semiempirical and quantum chemistry theories

Pseudocontact shifts are traditionally described as a function of the anisotropy of the paramagnetic susceptibility tensor, according to the semiempirical theory mainly developed by Kurland and McGarvey (R.J. Kurland and B.R. McGarvey, J. Magn. Reson. 2, 286 (1970)). The paramagnetic susceptibility tensor is required to be symmetric. Applying point-dipole approximation to the quantum chemistry theory of hyperfine shift, pseudocontact shifts are found to scale with a non-symmetric tensor that differs by a factor g/ge from the paramagnetic susceptibility tensor derived within the semiempirical framework. We analyze the foundations of the Kurland-McGarvey pseudocontact shift expression and recall that it is inherently based on the Russell-Saunders (LS) coupling approximation for the spin-orbit coupling. We show that the difference between the semiempirical and quantum chemistry pseudocontact shift expressions arises directly from the different treatment of the orbital contribution to the hyperfine coupling

The Effect of Bicarbonate Administration via Continuous Venovenous Hemofiltration on Acid-Base Parameters in Ventilated Patients

Background. Acute kidney injury (AKI) and metabolic acidosis are common in the intensive care unit. The effect of bicarbonate administration on acid-base parameters is unclear in those receiving continuous venovenous hemofiltration (CVVH) and mechanical ventilatory support. Methods. Metabolic and ventilatory parameters were prospectively examined in 19 ventilated subjects for up to 96 hours following CVVH initiation for AKI at an academic tertiary care center. Mixed linear regression modeling was performed to measure changes in pH, partial pressure of carbon dioxide (pCO2), serum bicarbonate, and base excess over time. Results. During the 96-hour study period, pCO2 levels remained stable overall (initial pCO2 42.0 ± 14.6 versus end-study pCO2 43.8 ± 16.1 mmHg; P=0.13 for interaction with time), for those with initial pCO2 ≤40 mmHg (31.3 ± 5.7 versus 35.0 ± 4.8; P=0.06) and for those with initial pCO2 >40 mmHg (52.7 ± 12.8 versus 53.4 ± 19.2; P=0.57). pCO2 decreased during the immediate hours following CVVH initiation (42.0 ± 14.6 versus 37.3 ± 12.6 mmHg), though this change was nonsignificant (P=0.052). Conclusions. We did not detect a significant increase in pCO2 in response to the administration of bicarbonate via CVVH in a ventilated population. Additional studies of larger populations are needed to confirm this finding

Molecular Screening for Terahertz Detection with Machine-Learning-Based Methods

The molecular requirements are explored for achieving efficient signal up-conversion in a recently developed technique for terahertz (THz) detection based on molecular optomechanics. We discuss which molecular and spectroscopic properties are most important for predicting efficient THz detection and outline a computational approach based on quantum-chemistry and machine-learning methods for calculating these properties. We validate this approach by bulk and surface-enhanced Raman scattering and infrared absorption measurements. We develop a virtual screening methodology performed on databases of millions of commercially available compounds. Quantum-chemistry calculations for about 3000 compounds are complemented by machine-learning methods to predict applicability of 93 000 organic molecules for detection. Training is performed on vibrational spectroscopic properties based on absorption and Raman scattering intensities. Our top molecules have conversion intensity two orders of magnitude higher than an average molecule from the database. We also discuss how other properties like molecular shape and self-assembling properties influence the detection efficiency. We identify molecular moieties whose presence in the molecules indicates high activity for THz detection and show an example where a simple modification of a frequently used self-assembling compound can enhance activity 85-fold. The capabilities of our screening method are demonstrated on narrow-band and broadband detection examples, and its possible applications in surface-enhanced spectroscopy are also discussed

Structure of the RBM7-ZCCHC8 core of the NEXT complex reveals connections to splicing factors

The eukaryotic RNA exosome participates extensively in RNA processing and degradation. In human cells, three accessory factors (RBM7, ZCCHC8 and hMTR4) interact to form the nuclear exosome targeting (NEXT) complex, which directs a subset of non-coding RNAs for exosomal degradation. Here we elucidate how RBM7 is incorporated in the NEXT complex. We identify a proline-rich segment of ZCCHC8 as the interaction site for the RNA-recognition motif (RRM) of RBM7 and present the crystal structure of the corresponding complex at 2.0 resolution. On the basis of the structure, we identify a proline-rich segment within the splicing factor SAP145 with strong similarity to ZCCHC8. We show that this segment of SAP145 not only binds the RRM region of another splicing factor SAP49 but also the RRM of RBM7. These dual interactions of RBM7 with the exosome and the spliceosome suggest a model whereby NEXT might recruit the exosome to degrade intronic RNAs