A new intermediate mass protostar in the Cepheus A HW2 region

We present the discovery of the first molecular hot core associated with an intermediate mass protostar in the CepA HW2 region. The hot condensation was detected from single dish and interferometric observations of several high excitation rotational lines (from 100 to 880K above the ground state) of SO2 in the ground vibrational state and of HC3N in the vibrationally excited states v7=1 and v7=2. The kinetic temperature derived from both molecules is 160K. The high-angular resolution observations (1.25'' x 0.99'') of the SO2 J=28(7,21)-29(6,24) line (488K above the ground state) show that the hot gas is concentrated in a compact condensation with a size of 0.6''(430AU), located 0.4'' (300AU) east from the radio-jet HW2. The total SO2 column density in the hot condensation is 10E18cm-2, with a H2 column density ranging from 10E23 to 6 x 10E24cm-2. The H2 density and the SO2 fractional abundance must be larger than 10E7cm-3 and 2 x 10E-7 respectively. The most likely alternatives for the nature of the hot and very dense condensation are discussed. From the large column densities of hot gas, the detection of the HC3N vibrationally excited lines and the large SO2 abundance, we favor the interpretation of a hot core heated by an intermediate mass protostar of 10E3 Lo. This indicates that the CepA HW2 region contains a cluster of very young stars

ArlCDE form the archaeal switch complex

Cells require a sensory system and a motility structure to achieve directed movement. Bacteria and archaea both possess rotating filamentous motility structures that work in concert with the sensory chemotaxis system. This allows microorganisms to move along chemical gradients. The central response regulator protein CheY can bind to the motor of the motility structure, the flagellum in bacteria and the archaellum in archaea. Both motility structures have a fundamentally different protein composition and structural organization. Yet, both systems receive input from the chemotaxis system. We applied a fluorescent microscopy approach in the model euryarchaeon Haloferax volcanii, and shed light on the sequence order in which signals are transferred from the chemotaxis system to the archaellum. Our findings indicate that the euryarchaeal specific ArlCDE are part of the archaellum motor and that they directly receive input from the chemotaxis system via the adaptor protein CheF. Hence, ArlCDE are an important feature of the archaellum of euryarchaea, are essential for signal transduction during chemotaxis and represent the archaeal switch complex

Insights into the Carbon chemistry of Mon R2

Aiming to learn about the chemistry of the dense PDR around the ultracompact (UC) HII region in Mon R2, we have observed a series of mm-wavelength transitions of C3H2 and C2H. In addition, we have traced the distribution of other molecules, such as H13CO+, SiO, HCO, and HC3N. These data, together with the reactive ions recently detected, have been considered to determine the physical conditions and to model the PDR chemistry. We then identified two kind of molecules. The first group, formed by the reactive ions (CO+, HOC+) and small hydrocarbons (C2H, C3H2), traces the surface layers of the PDR and is presumably exposed to a high UV field (hence we called it as "high UV", or HUV). HUV species is expected to dominate for visual absorptions 2 < Av < 5 mag. A second group (less exposed to the UV field, and hence called "low UV", or LUV) includes HCO and SiO, and is mainly present at the edges of the PDR (Av > 5 mag). While the abundances of the HUV molecules can be explained by gas phase models, this is not the case for the studied LUV ones. Although some efficient gas-phase reactions might be lacking, grain chemistry sounds like a probable mechanism able to explain the observed enhancement of HCO and SiO. Within this scenario, the interaction of UV photons with grains produces an important effect on the molecular gas chemistry and constitutes the first evidence of an ionization front created by the UC HII region carving its host molecular cloud. The physical conditions and kinematics of the gas layer which surrounds the UC HII region were derived from the HUV molecules. Molecular hydrogen densities > 4 10^6 cm^(-3) are required to reproduce the observations. Such high densities suggest that the HII region could be pressure-confined by the surrounding high density molecular gas.Comment: 32 pages, 8 figures. Accepted by Astrophysical Journa

p-wave Holographic Superconductors and five-dimensional gauged Supergravity

We explore five-dimensional ${\cal N}=4$ $SU(2)\times U(1)$ and ${\cal N}=8$ SO(6) gauged supergravities as frameworks for condensed matter applications. These theories contain charged (dilatonic) black holes and 2-forms which have non-trivial quantum numbers with respect to U(1) subgroups of SO(6). A question of interest is whether they also contain black holes with two-form hair with the required asymptotic to give rise to holographic superconductivity. We first consider the ${\cal N}=4$ case, which contains a complex two-form potential $A_{\mu\nu}$ which has U(1) charge $\pm 1$. We find that a slight generalization, where the two-form potential has an arbitrary charge $q$, leads to a five-dimensional model that exhibits second-order superconducting transitions of p-wave type where the role of order parameter is played by $A_{\mu\nu}$, provided $q \gtrsim 5.6$. We identify the operator that condenses in the dual CFT, which is closely related to ${\cal N}=4$ Super Yang-Mills theory with chemical potentials. Similar phase transitions between R-charged black holes and black holes with 2-form hair are found in a generalized version of the ${\cal N}=8$ gauged supergravity Lagrangian where the two-forms have charge $q\gtrsim 1.8$.Comment: 35 pages, 14 figure

Nanoencapsulation for Probiotic Delivery

Gut microbiota dynamically participate in diverse physiological activities with direct impact on the host's health. A range of factors associated with the highly complex intestinal flora ecosystem poses challenges in regulating the homeostasis of microbiota. The consumption of live probiotic bacteria, in principle, can address these challenges and confer health benefits. In this context, one of the major problems is ensuring the survival of probiotic cells when faced with physical and chemical assaults during their intake and subsequent gastrointestinal passage to the gut. Advances in the field have focused on improving conventional encapsulation techniques in the microscale to achieve high cell viability, gastric and temperature resistance, and longer shelf lives. However, these microencapsulation approaches are known to have limitations with possible difficulties in clinical translation. In this Perspective, we present a brief overview of the current progress of different probiotic encapsulation methods and highlight the contemporary and emerging single-cell encapsulation strategies using nanocoatings for individual probiotic cells. Finally, we discuss the relative advantages of various nanoencapsulation approaches and the future trend toward developing coated probiotics with advanced features and health benefits

Cellular and Genomic Properties of Haloferax gibbonsii LR2-5, the Host of Euryarchaeal Virus HFTV1

Hypersaline environments are the source of many viruses infecting different species of halophilic euryarchaea. Information on infection mechanisms of archaeal viruses is scarce, due to the lack of genetically accessible virus-host models. Recently, a new archaeal siphovirus, Haloferax tailed virus 1 (HFTV1), was isolated together with its host belonging to the genus Haloferax, but it is not infectious on the widely used model euryarcheon Haloferax volcanii. To gain more insight into the biology of HFTV1 host strain LR2-5, we studied characteristics that might play a role in its virus susceptibility: growth-dependent motility, surface layer, filamentous surface structures, and cell shape. Its genome sequence showed that LR2-5 is a new strain of Haloferax gibbonsii. LR2-5 lacks obvious viral defense systems, such as CRISPR-Cas, and the composition of its cell surface is different from Hfx. volcanii, which might explain the different viral host range. This work provides first deep insights into the relationship between the host of halovirus HFTV1 and other members of the genus Haloferax. Given the close relationship to the genetically accessible Hfx. volcanii, LR2-5 has high potential as a new model for virus-host studies in euryarchaea

Monitoring the Large Proper Motions of Radio Sources in the Orion BN/KL Region

We present absolute astrometry of four radio sources in the Becklin-Neugebauer/Kleinman-Low (BN/KL) region, derived from archival data (taken in 1991, 1995, and 2000) as well as from new observations (taken in 2006). All data consist of 3.6 cm continuum emission and were taken with the Very Large Array in its highest angular resolution A configuration. We confirm the large proper motions of the BN object, the radio source I (GMR I) and the radio counterpart of the infrared source n (Orion-n), with values from 15 to 26 km/s. The three sources are receding from a point between them from where they seem to have been ejected about 500 years ago, probably via the disintegration of a multiple stellar system. We present simulations of very compact stellar groups that provide a plausible dynamical scenario for the observations. The radio source Orion-n appeared as a double in the first three epochs, but as single in 2006. We discuss this morphological change. The fourth source in the region, GMR D, shows no statistically significant proper motions. We also present new, accurate relative astrometry between BN and radio source I that restrict possible dynamical scenarios for the region. During the 2006 observations, the radio source GMR A, located about 1' to the NW of the BN/KL region, exhibited an increase in its flux density of a factor of ~3.5 over a timescale of one hour. This rapid variability at cm wavelengths is similar to that previously found during a flare at millimeter wavelengths that took place in 2003.Comment: Accepted for publication in Ap

M5 spikes and operators in the HVZ membrane theory

In this note we study some aspects of the so-called dual ABJM theory introduced by Hanany, Vegh & Zaffaroni. We analyze the spectrum of chiral operators, and compare it with the spectrum of functions on the mesonic moduli space M=C^2\times C^2/Z_k, finding expected agreement for the coherent branch. A somewhat mysterious extra branch of dimension N^2 opens up at the orbifold fixed point. We also study BPS solutions which represent M2/M5 intersections. The mesonic moduli space suggests that there should be two versions of this spike: one where the M5 lives in the orbifolded C^2 and another where it lives in the unorbifolded one. While expectedly the first class turns out to be like the ABJM spike, the latter class looks like a collection of stacks of M5 branes with fuzzy S^3 profiles. This shows hints of the appearance of the global SO(4) at the non-abelian level which is otherwise not present in the bosonic potential. We also study the matching of SUGRA modes with operators in the coherent branch of the moduli space. As a byproduct, we present some formulae for the laplacian in conical CY_4 of the form C^n\times CY_{4-n}.Comment: 22 pages, 1 figure. Published version with corrected typos

Vibrationally excited HC3N in NGC 4418

We investigate the molecular gas properties of the deeply obscured luminous infrared galaxy NGC 4418. We address the excitation of the complex molecule HC3N to determine whether its unusually luminous emission is related to the nature of the buried nuclear source. We use IRAM 30m and JCMT observations of rotational and vibrational lines of HC3N to model the excitation of the molecule by means of rotational diagrams. We report the first confirmed extragalactic detection of vibrational lines of HC3N. We detect 6 different rotational transitions ranging from J=10-9 to J=30-29 in the ground vibrational state and obtain a tentative detection of the J=38-37 line. We also detect 7 rotational transitions of the vibrationally excited states v6 and v7, with angular momenta ranging from J=10-9 to 28-27. The energies of the upper states of the observed transitions range from 20 to 850 K. In the optically thin regime, we find that the rotational transitions of the vibrational ground state can be fitted for two temperatures, 30 K and 260 K, while the vibrationally excited levels can be fitted for a rotational temperature of 90 K and a vibrational temperature of 500 K. In the inner 300 pc of NGC 4418, we estimate a high HC3N abundance, of the order of 10^-7. The excitation of the HC3N molecule responds strongly to the intense radiation field and the presence of warm, dense gas and dust at the center of NGC 4418. The intense HC3N line emission is a result of both high abundances and excitation. The properties of the HC3N emitting gas are similar to those found for hot cores in Sgr B2, which implies that the nucleus (< 300 pc) of NGC 4418 is reminiscent of a hot core. The potential presence of a compact, hot component (T=500 K) is also discussed