bluuebunny/crossref_metadata_2025 huggingface dataset:
The density model of the Milky Way from the tangent-point measurements of the rotation curve
Authors: Golubov Oleksiy , Just Andreas
Published: March 2013

We use measurements of the rotation curve of the Milky Way by the tangent point method to reconstruct the density model of the Milky Way. The observed inner rotation curve is fitted by a theoretical density model, consisting of a Dehnen bulge, an exponential disc with a hole, and a flattened dark matter halo with a cored isothermal or NFW density profile. The density model is also set to be consistent with the local density constraints in the solar neighborhood.
Infrared observation of Mira variables and their galactic distribution
Authors: Miyanoshita Ryo , Omodaka Toshihiro , Handa Toshihiro , Kamezaki Tatsuya , Nakai Chihiro , Fujiwara Hiroshi
Published: March 2013

Since November 2003, we have monitored AGB candidates in infrared wavelengths with the Kagoshima 1m telescope. We present the latest results based on the data until June 2011. For each of 400 monitored AGB stars, we estimate the periods, amplitudes, and mean apparent magnitudes in K band. Based on the two color diagram we choose 259 objects as Miras. We use the period–luminosity relation to obtain distances to them. As results we show the 3 dimensional distribution of 259 Mira variables.
MAGMA-SMC: The Molecular Cloud Survey of the SMC
Authors: Muller Erik , Wong Tony , Hughes Annie , Ott Jürgen , Pineda Jorge L. ,   the MAGMA collaboration
Published: March 2013

We present a brief summary and description of the upcoming 12CO(1-0) Magellanic Mopra Assesment (MAGMA) SMC survey data release. The MAGMA-SMC survey has sampled 100% of the known CO in the SMC (at ∼33″ resolution; 12 pc at D = 60 kpc). Having explored 522 × 103 square parsecs throughout the SMC with 69 5′ × 5′ fields, to a sensitivity of ∼150 mK, we apply the cloudprops (Rosolowsky & Leroy 2006) cloud-search algorithm optimized for low S/N data, to detect more than 30 CO clouds with virial masses between 103–104 M⊙, mean radii ∼5 pc and 0.3–0.9 km s−1 velocity width. Typical brightness temperatures are ∼1 K Tmb. All detected molecular regions are associated with at least one 24 μm compact emission source. Smoothing rarely increases the total detected CO flux, implying the CO emission is typically confined to small spatial scales. As recent dust maps of the SMC imply extended H2 mass, the apparent compact nature of the CO population indicates some departures from the canonical Galactic XCO-factor in the low-metallicity and relatively un-evolved ISM of the SMC.
Different Evolutionary Stages in the Massive Star-forming Complex W3 Main
Authors: Wang Yuan , Beuther Henrik , Zhang Qizhou , Bik Arjan , Rodón Javier A. , Jiang Zhibo , Fallscheer Cassandra
Published: March 2013

We observed with the Submillimeter Array and IRAM 30 m telescope three high-mass star-forming regions in different evolutionary stages in the W3 high-mass star formation complex. These regions, i.e. W3 SMS1 (W3 IRS5), SMS2 (W3 IRS4) and SMS3, are located within the same large-scale environment, which allows us to study rotation and outflows as well as chemical properties in an evolutionary sense. While we find multiple mm continuum sources toward all regions, these three subregions exhibit different dynamical and chemical properties, which indicates that they are in different evolutionary stages. Even within each sub-region, massive cores of different ages are found, e.g. in SMS2, sub-sources from the most evolved UCHii region to potential starless cores exist within 30 000 AU (left panel, Fig. 1). Outflows and rotational structures are found in SMS1 and SMS2. Evidence for interactions between the molecular cloud and the HII regions is found in the 13CO channel maps (right panel, Fig. 1), which may indicate triggered star formation.
An Updated View of Giant Molecular Clouds, Gas Flows and Star Formation in M51 with PAWS
Authors: Meidt S. E. , Schinnerer E. , Hughes A. , Colombo D. , Pety J. , Garcia-Burillo S. , Leroy A. , Dobbs C. L. , Schuster K. F. , Kramer C. , Dumas G. , Thompson T.
Published: March 2013

We present an overview of the latest results from the PdBI Arcsecond Whirlpool Survey (PAWS, PI: E. Schinnerer), which has mapped CO(1-0) emission in the nearby grand-design spiral galaxy M51 at 40pc resolution. Our data are sensitive to GMCs above 105 M⊙, allowing the construction of the largest GMC catalog to date – containing over 1500 objects – using the CPROPS algorithm (Rosolowsky & Leroy 2006). In the inner disk of M51, the properties of the CO emission show significant variation that can be linked to the dynamical environment in which the molecular gas is located. We find that dynamically distinct regions host clouds with different properties and exhibit different GMC mass spectra, as well as distinct patterns of star formation. To understand how this sensitivity to environment emerges, we consider the role of pressure on GMC stabilization (including shear and star formation feedback-driven turbulence). We suggest that, in the presence of significant external pressure, streaming motions driven by the spiral arm can act to reduce the surface pressure on clouds. The resulting stabilization impacts the global pattern of star formation and can account for the observed non-monotonic radial dependence of the gas depletion time. Our findings have implications for the observed scatter in the standard GMC relations and extragalactic star formation laws.
Environmental effects on the atomic gas content of galaxies in the local universe
Authors: Li Cheng
Published: March 2013

Effects of galaxy environment on its cold gas content are studied in detail using different date sets and statistics. These include measuring the clustering of galaxies as a function of their Hi mass fraction, quantifying the depletion of Hi gas content of cluster galaxies as a function of cluster-centric radius, and comparing the dependence of environmental density on galaxy star formation rate with the dependence on Hi gas mass fraction. Results from these studies are all consistent with a picture in which ram-pressure stripping may play an important role in removing atomic gas from the outer disks of low mass satellite galaxies.
Probing the black hole - bulge relationship at high redshift with CO molecular lines
Authors: Wu Xue-Bing
Published: March 2013

It has been suggested that the CO line width (FWHM(CO)) is a surrogate for the bulge velocity dispersion (σ) of the host galaxies of high-redshift quasars, and the black hole – bulge (M−σ) relation obtained with this assumption departs significantly from the M−σ relation in the local universe. Based on an investigation of the correlation between the CO line width and the bulge velocity dispersion using a sample of 33 nearby Seyfert galaxies, we find that the formula adopted in previous studies, σ=FWHM(CO)/2.35, is generally not a good approximation. By involving the galactic inclination angle i as an additional parameter, we obtain a tight correlation between the inclination-corrected CO line width and the bulge velocity dispersion, namely, FWHM(CO)/sin i=−67.16±80.18+(3.62±0.68)σ. Using this new relation, we can better estimate the bulge velocity dispersion from the CO line width if the galactic inclination is known. We apply this new relation to nine high-redshift quasars with CO line detections and find that they are consistent with the local M−σ relation if their inclination angles are around 15°. The possible smaller inclinations of the high-redshift quasars are preferred because of their relatively greater likelihood of detection, and are also consistent with their relatively smaller CO line widths compared to the submillimeter galaxies (SMGs) at high redshift having a similar total amount of molecular gas.
The roles of atomic and molecular gas on the redshift evolution of star formation and metallicity in galaxy formation models
Authors: Fu Jian , Kauffmann Guinevere
Published: March 2013

We study the redshift evolution of neutral and molecular gas in the interstellar medium with the results from semi-analytic models of galaxy formation and evolution, which track the cold gas related physical processes in radially resolved galaxy disks. Two kinds of prescriptions are adopted to describe the conversion between molecular and neutral gas in the ISM: one is related to the gas surface density and gas metallicity based on the model results by Krumholz, Mckee & Tumlinson; the other is related the pressure of ISM. We try four types of star formation laws in the models to study the effect of the molecular gas component and the star formation time scale on the model results, and find that the H2 dependent star formation rate with constant star formation efficiency is the preferred star formation law. We run the models based on both Millennium and Millennium II Simulation haloes, and the model parameters are adjusted to fit the observations at z = 0 from THINGS/HERACLES and ALFALFA/COLD GASS. We give predictions for the redshift evolution of cosmic star formation density, H2 to HI cosmic ratios, gas to star mass ratios and gas metallicity vs stellar mass relation. Based on the model results, we find that: (i) the difference in the H2 to HI ratio at z > 3 between the two H2 fraction prescriptions can help future observations to test which prescription is better; (ii) a constant redshift independent star formation time scale will postpone the star formation processes at high redshift and cause obvious redshift evolution for the relation between gas metallicity and stellar mass in galaxies at z < 3.
A Herschel Spectroscopic Survey of Warm Molecular Gas in Local Infrared Luminous Galaxies
Authors: Lu N. , Zhao Y. , Xu C. K. , Gao Y. ,   the GOALS FTS Team
Published: March 2013

We describe an on-going 194-671 μm spectroscopic survey of a flux-limited sample of 125 local luminous infrared galaxies (LIRGs) with Herschel SPIRE Fourier Transform Spectrometer (FTS). The survey targets primarily the CO spectral line energy distribution (SLED), from J = 4-3 up to J = 13-12, to probe dense and warm molecular gas that should play an intimate role in star formation and/or active galactic nuclear activities in these galaxies. The program is about 75% finished. At S/N > 5, besides the CO lines, we also detected [N ii] 205 μm and [C i] 370 μm (3P2 − 3P1) lines in every target observed. In about half of the observed targets, we also detected [C i] 609 μm (3P1 – 3P0).
A Herschel Survey of the [N ii] 205 μm Emission in Local Infrared Luminous Galaxies
Authors: Zhao Yinghe , Lu Nanyao , Xu C. Kevin , Gao Yu ,   GOALS FTS Team
Published: March 2013

The [N ii] line is a major coolant in ionized interstellar medium, and is expected to be a good star formation rate indicator. Here we present a statistical study of [N ii] line emission for a large sample of local luminous infrared galaxies (LIRGs) using Herschel SPIRE FTS data (Lu et al. 2012; Zhao et al. 2012, in preparation). For our sample of galaxies, the [N ii] to the total infrared luminosity ratio (L[Nii]/LIR) varies from ∼ 10−5 to ∼ 10−4. We investigate the correlation between L[Nii] and LIR, as well as the dependence of L[Nii]/LIR on LIR, infrared colors (f60/f100) and the OIII 88 μm to [N ii] luminosity ratio. We find that L[Nii] strongly, and almost linearly correlates with LIR for star-forming galaxies, namely log LIR = (4.23 ± 0.33) + (0.99 ± 0.05) log L[NII] (see Fig. 1). The scatter in this relation is mainly due to the variation of hardness, and/or high ionization parameter, of the background UV field.
The Herschel view on the dust properties of the Large Magellanic Cloud
Authors: Galliano Frédéric
Published: March 2013

I summarize a recent study scrutinizing the various sources of uncertainties in estimating the dust mass of a galaxy. These effects are demonstrated on the Herschel observations of the Large Magellanic Cloud.
The Origin of Unidentified Infrared Emission Features in Galaxies
Authors: Kwok Sun
Published: March 2013

The family of unidentified infrared emission features, consisting of discrete and plateau features in the mid-infrared, are now observed in distant galaxies. A significant fraction of the total energy output of some infrared galaxies is emitted in these features. Comparisons of these features with those observed in the circumstellar and interstellar media suggest that these organic species are synthesized and ejected by evolved stars. Models of possible chemical structures of the carrier of these features are discussed.
GOODS-Herschel: Dust attenuation up to z∼4
Authors: Pannella M. , Elbaz D. , Daddi E.
Published: March 2013

We quantitatively explore in a unbiased way the evolution of dust attenuation up to z ≈ 4 as a function of galaxy properties. We have used one of the deepest datasets available at present, in the GOODS-N field, to select a star forming galaxy sample and robustly measure galaxy redshifts, star formation rates, stellar masses and UV restframe properties. Our main results can be summarized as follows: i) we confirm that galaxy stellar mass is a main driver of UV dust attenuation in star forming galaxies: more massive galaxies are more dust attenuated than less massive ones; ii) strikingly, we find that the correlation does not evolve with redshift: the amount of dust attenuation is the same at all cosmic epochs for a fixed stellar mass; iii) this finding explains why and how the SFR–AUV relation evolves with redshift: the same amount of star formation is less attenuated at higher redshift because it is hosted in less massive galaxies; iv) combining our finding with results from line emission surveys, we confirm that line reddening is larger than continuum reddening, at least up to z ≈ 1.5; v) given the redshift evolution of the mass-metallicity relation, we predict that star forming galaxies at a fixed metal content are more attenuated at high redshift. Finally, we explored the correlation between UV dust attenuation and the spectral slope: vi) the correlation is evolving with redshift with star forming galaxies at lower redshift having redder spectra than higher redshift ones for the same amount of dust attenuation.
Resolved Schmidt-Kennicutt Relation for Star Forming Regions in the Galaxy and Magellanic Clouds
Authors: Chen C.-H. R. , Indebetouw R. , Muller E. , Messineo M. , Menten K. M. ,   the SAGE-SMC Team
Published: March 2013

The relationship between star formation rate (SFR) and the gas surface density (Σgas) is one of the most critical links between star formation and galaxy evolution. The observed SFR- Σgas relation, the “Schmidt-Kennicutt (S-K) law”, is tight when properties are averaged over kpc, but breaks down at the scale of giant molecular clouds (GMCs). To understand the physics governing the variations at GMC scales and the tight correlation at kpc scales, spatially and temporally resolved data covering a wide range of linear scale are needed. We have used the Spitzer surveys of the Large Magellanic Cloud and Magellanic Bridge to identify massive young stellar objects (YSOs), estimate “instantaneous” SFRs, and compare them to the S-K relation. These instantaneous SFRs are further compared to that estimated from integrated Hα and 24 μm luminosities to examine how SFRs vary on 10 Myr timescales. We have also used SINFONI near-IR integral field spectra of two Galactic mini-starbursts W31 and W43 to determine their underlying massive stellar content, estimate the SFRs, and compare to the S-K relation. To investigate evironmental effects on star formation, we have used complete YSO samples in the LMC and the Bridge to estimate global star formation efficiencies (SFE) in these two systems.
Star formation laws in extreme starbursts
Authors: García-Burillo S. , Usero A. , Alonso-Herrero A.
Published: March 2013

The observational study of star formation laws is paramount to disentangling the physical processes at work on local and global scales in galaxies. To this aim we have expanded the sample of extreme starbursts, represented by local LIRGs and ULIRGs, with high-quality data obtained in the 1-0 line of HCN. The analysis of the new data shows that the star formation efficiency of the dense molecular gas, derived from the FIR/HCN luminosity ratio, is a factor 3-4 higher in extreme starbursts compared to normal galaxies. We find a duality in the Kennicutt-Schmidt laws that is enhanced if we account for the different conversion factor for HCN (αHCN) in extreme starbursts and correct for the unobscured star formation rate in normal galaxies. We find that it is possible to fit the observed differences in the FIR/HCN ratios between normal galaxies and LIRGs/ULIRGs with a common constant star formation rate per free-fall time (SFRff) if we assume that HCN densities are ∼1–2 orders of magnitude higher in LIRGs/ULIRGs, and provided that SFRff∼0.005-0.01 and/or if αHCN is a factor of a few lower than our favored values.
Probing the star–formation modes in merging galaxies
Authors: Duc P.-A. , Belles P.-E. , Brinks E. , Bournaud F.
Published: March 2013

Merging systems at low redshift provide the unique opportunity to study the processes related to star formation in a variety of environments that presumably resemble those seen at higher redshifts. Previous studies of distant starbursting galaxies suggest that stars are born in turbulent gas, with a higher efficiency than in MW-like spirals. We have investigated in detail the turbulent-driven regime of star-formation in nearby colliding galaxies combining high resolution VLA B array Hi maps and UV GALEX observations. With these data, we could check predictions of our state-of-the-art simulations of mergers, such as the global sharp increase of the fraction of dense gas, as traced by the SFR, with respect to the diffuse gas traced by Hi during the merging stage, following the increased velocity dispersion of the gas. We present here initial results obtained studying the SFR-Hi relation at 4.5 kpc resolution. We determined SFR/Hi mass ratios that are higher in the external regions of mergers than in the outskirts of isolated spirals, though both environments are Hi dominated. SFR/Hi increases towards the central regions following the decrease of the atomic gas fraction and possibly the increased star–formation efficiency. These results need to be checked with a larger sample of systems and on smaller spatial scales. This is the goal of the on-going Chaotic THINGS project that ultimately will allow us to determine why starbursting galaxies deviate from the Kennicutt-Schmidt relation between SFR density and gas surface density.
Anatomy of Starbursts in Extragalactic Giant HII Regions: M51 Case Study
Authors: Evans Jessica Marie , Chu You-Hua
Published: March 2013

Extragalactic giant HII regions (EGHRs) are sites of active, concentrated star formation, and thus provide excellent labs to analyze the starburst phenomenon. Although they have been known for a long time, ground-based observations cannot resolve the physical structures and stellar content of EGHRs. The high resolution and sensitivity of Hubble Space Telescope (HST) are ideal for detailed studies of EGHRs. We have searched the Hubble Legacy Archives (HLA) and found 17 nearby galaxies, within ∼15 Mpc, with Hα and continuum images; to determine the best methods for analyzing these data, we perform an in-depth analysis of the EGHRs in M51. M51 is a face-on spiral galaxy ∼8.4 Mpc away, with well-resolved multi-wavelength observations in the HLA. We sample the 25 most luminous HII regions in M51, many of which are bonafide EGHRs with an H-alpha luminosity > 1039 ergs s−1. We use the Hα image to study the distribution and physical structure of the gas in each HII region and determine its Hα luminosity and required ionizing flux. We use the continuum images to determine whether super stellar clusters (SSCs) are found in these HII regions, and use photometric measurements to determine the mass and age spread of the resolved stellar population. These are then compared with the interstellar structures. The results help us provide the groundwork for studying EGHRs in multiple galaxies and elucidate the starburst phenomenon by investigating questions such as: What role does environment play in the formation of EGHRs? How do EGHRs evolve? How does star formation proceed in an EGHR?
Feedback and Outflows
Authors: Murray Norman
Published: March 2013

The low stellar and gas mass fractions, low galaxy-wide star formation rates (relative to galactic dynamical times) and observations of rapid outflows from galaxies, all suggest that stars and active galactic nuclei violently alter the state of the interstellar and even inter-halo gas in galaxies. I argue that the low galaxy wide star formation rates are not the result of turbulent suppression of star formation on small scale, but rather the result of a balance between dynamical pressure and the force (or rate of momentum deposition) provided by stellar feedback, either in the form of radiation pressure or by supernovae. Galaxy scale winds can also be driven by feedback, either from stars or active galactic nuclei, although the exact mechanisms involved are still not well determined.
Measuring AGN Feedback Parameters From Seyfert Galaxy Outflows
Authors: Müller-Sánchez F. , Malkan M. , Hicks E. K. S. , Davies R. I.
Published: March 2013

We present results of an on-going program to measure AGN feedback in Seyfert galaxies using integral-field spectroscopy and adaptive optics at Keck Observatory and VLT. Our integral-field observations are revealing AGN-driven outflows of ionized gas in Seyfert galaxies. By resolving the inner 10–40 parsecs, we are successfully modeling them as biconical structures, in which the ionized gas first accelerates and then decelerates. The model parameters provide crucial information on the orientation, geometry and kinematics of the outflows, which is used to estimate mechanical feedback from the AGN: mass and kinetic energy transferred to the interstellar medium. Mass outflow rates can be 102–104 times greater than accretion rates, but in some cases, they are comparable to the estimated inflow rates to the central 10–25 pc, suggesting that the outflows may remove a considerable amount of the infalling gas before it reaches the accretion disk. In half of the AGN measured so far, the kinetic energy of the outflows appears sufficient to provide the eagerly-sought AGN feedback invoked to explain fundamental galaxy properties such as the MBH − σ* relation (0.5–5 Lbol). The other AGN, which lack powerful outflows, also have weaker and more compact radio jets.
Do AGN suppress star formation in disc-dominated galaxies?
Authors: Husemann B. , Walcher J. , Wisotzki L. , Gerssen J. , Jahnke K. , Sánchez S. F. , Wild V.
Published: March 2013

We present preliminary results of our integral field spectroscopy (IFS) observations to test whether AGN can suppress star formation in disc-dominated galaxies. We find a lower specific star formation rate and a different radial Hα profile for AGN than in the control sample.
Ethics and international law: integrating the global justice project(s)
Authors: Ratner Steven
Published: March 2013

Academic discourse on global justice is at an all-time high. Within ethics and international law, scholars are undertaking new inquiries into age-old questions of building a just world order. Ethics – within political and moral philosophy – poses fundamental questions about responsibilities at the global level and produces a tightly reasoned set of frameworks regarding world order. International law, with its focus on legal norms and institutional arrangements, provides a path, as well as illuminates the obstacles, to implementing theories of the right or of the good. Yet despite the complementarity of these two projects, neither is drawing what it should from the other. The result is ethical scholarship that often avoids, or even misinterprets, the law; and law that marginalizes ethics even as it recognizes the importance of justice. The cost of this avoidance is a set of missed opportunities for both fields. This article seeks to help transform the limited dialogue between philosophers and international lawyers into a meaningful collaboration. Through a critical stocktaking of the contributions of the two disciplines, examining where they do and do not engage with the other, it offers an appraisal of the causes and costs of separation and an argument for an interdisciplinary approach.
Formen der Arbeitszufriedenheit
Authors: Ziegler René , Schlett Christian
Published: March 2013

Das Arbeitszufriedenheitsmodell von Bruggemann (1974) unterscheidet verschiedene Formen der Arbeits(un‐)zufriedenheit (AZ-Formen). In zwei Studien (N = 309 Universitätsbeschäftigte; N = 275 Krankenpflegekräfte) wurden die Validität der Methode der Selbstzuordnung zu einer der AZ-Formen (stabilisierte Zufriedenheit, progressive Zufriedenheit, resignative Zufriedenheit, konstruktive Unzufriedenheit, fixierte Unzufriedenheit) sowie Unterschiede zwischen den AZ-Formen bezüglich der Valenz der Arbeit, der arbeitsbezogenen Ambivalenz, der dispositionalen Affektivität und der Arbeitssituation überprüft. Modellkonforme Unterschiede zwischen den AZ-Formen hinsichtlich der Arbeitszufriedenheit und des Ausmaßes an Resignation ( Baillod & Semmer, 1994 ) belegen die Validität der Selbstzuordnungsmethode. Außerdem unterschieden sich die AZ-Formen hinsichtlich verschiedener Indikatoren der Valenz der Arbeit (positive versus negative Bewertungen, Emotionen und Kognitionen) und der arbeitsbezogenen Ambivalenz hypothesenkonform. Schließlich sprechen Befunde zur dispositionalen positiven versus negativen Affektivität und der Arbeitssituation für den Einfluss dieser Faktoren auf das Ergebnis des im Modell postulierten Soll-Ist-Vergleichs. Wir diskutieren die Implikationen dieser Ergebnisse für die Forschung zum Arbeitszufriedenheitsmodell von Bruggemann (1974) .
Plasma membrane—endoplasmic reticulum contact sites regulate phosphatidylcholine synthesis
Authors: Tavassoli Shabnam , Chao Jesse T , Young Barry P , Cox Ruud C , Prinz William A , de Kroon Anton I P M , Loewen Christopher J R
Published: March 2013

Synthesis of phospholipids, sterols and sphingolipids is thought to occur at contact sites between the endoplasmic reticulum (ER) and other organelles because many lipid‐synthesizing enzymes are enriched in these contacts. In only a few cases have the enzymes been localized to contacts in vivo and in no instances have the contacts been demonstrated to be required for enzyme function. Here, we show that plasma membrane (PM)—ER contact sites in yeast are required for phosphatidylcholine synthesis and regulate the activity of the phosphatidylethanolamine N‐methyltransferase enzyme, Opi3. Opi3 activity requires Osh3, which localizes to PM–ER contacts where it might facilitate in trans catalysis by Opi3. Thus, membrane contact sites provide a structural mechanism to regulate lipid synthesis.
Heat-shock factor 1 both positively and negatively affects cellular clonogenic growth depending on p53 status
Authors: Nguyen Chau H. , Lang Benjamin J. , Chai Ryan C. C. , Vieusseux Jessica L. , Kouspou Michelle M. , Price John T.
Published: March 2013

HSF1 (heat-shock factor 1) is the master regulator of the heat-shock response; however, it is also activated by cancer-associated stresses and supports cellular transformation and cancer progression. We examined the role of HSF1 in relation to cancer cell clonogenicity, an important attribute of cancer cells. Ectopic expression or HSF1 knockdown demonstrated that HSF1 positively regulated cancer cell clonogenic growth. Furthermore, knockdown of mutant p53 indicated that HSF1 actions were mediated via a mutant p53-dependent mechanism. To examine this relationship more specifically, we ectopically co-expressed mutant p53R273H and HSF1 in the human mammary epithelial cell line MCF10A. Surprisingly, within this cellular context, HSF1 inhibited clonogenicity. However, upon specific knockdown of endogenous wild-type p53, leaving mutant p53R273H expression intact, HSF1 was observed to greatly enhance clonogenic growth of the cells, indicating that HSF1 suppressed clonogenicity via wild-type p53. To confirm this we ectopically expressed HSF1 in non-transformed and H-RasV12-transformed MCF10A cells. As expected, HSF1 significantly reduced clonogenicity, altering wild-type p53 target gene expression levels consistent with a role of HSF1 increasing wild-type p53 activity. In support of this finding, knockdown of wild-type p53 negated the inhibitory effects of HSF1 expression. We thus show that HSF1 can affect clonogenic growth in a p53 context-dependent manner, and can act via both mutant and wild-type p53 to bring about divergent effects upon clonogenicity. These findings have important implications for our understanding of HSF1's divergent roles in cancer cell growth and survival as well as its disparate effect on mutant and wild-type p53.
A model of the large-scale organization of chromatin
Authors: Barbieri Mariano , Chotalia Mita , Fraser James , Lavitas Liron-Mark , Dostie Josée , Pombo Ana , Nicodemi Mario
Published: March 2013

In the cell nucleus, chromosomes have a complex spatial organization, spanning several length scales, which serves vital functional purposes. It is unknown, however, how their three-dimensional architecture is orchestrated. In the present article, we review the application of a model based on classical polymer physics, the strings and binders switch model, to explain the molecular mechanisms of chromatin self-organization. We explore the scenario where chromatin architecture is shaped and regulated by the interactions of chromosomes with diffusing DNA-binding factors via thermodynamics mechanisms and compare it with available experimental data.
Topological features in stretching of proteins
Authors: Cieplak Marek , Sikora Mateusz
Published: March 2013

In the present article, we highlight the diversity of mechanical clamps, some of them topological in nature, that have been found by making surveys of mechanostability of approximately 18000 proteins within structure-based models. The existence of superstable proteins (with the characteristic unfolding force in the region of 1000 pN) is predicted.
LFM‐CW signal generator based on hybrid DDS‐PLL structure
Authors: Zhao Z.Y. , Li X.Y. , Chang W.G.
Published: March 2013

A new method of predistortion to improve the qualities of the wideband LFM‐CW signal generated by a hybrid DDS‐PLL generator is introduced. The purpose of the predistortion is to reduce the phase error in the output without any increasing of the complexity. A circuit is designed and realised to generate wideband LFM‐CW. With the predistortion, the maximum phase error is depressed to be less than 5°, and the PLSR of the compression with Hamming weighting is improved to be better than −37dB.
Miniature multi‐band monopole antenna using spiral ring resonators for radiation pattern characteristics improvement
Authors: Wan Y.‐T. , Yu D. , Zhang F.‐S. , Zhang F.
Published: March 2013

A compact coplanar waveguide (CPW)‐fed multi‐band monopole antenna loaded with spiral ring resonators is presented. The proposed antenna consists of two spiral ring strips which are printed on the different sides of the substrate and connected through a via‐hole. The size of the miniaturised antenna is only about 27.5 × 20 × 1 mm3. The proposed antenna can excite multi‐resonant modes close to the 2.5/3.5/5.5 GHz bands to meet the specifications of the worldwide interoperability for microwave access (WiMAX) system. By introducing the spiral ring structure, very good radiation pattern characteristics can be obtained. With a figure‐of‐eight pattern in the E‐plane and omnidirectional pattern in the H‐plane, measured peak gains are about 2.0/2.23/2.58 dBi at the 2.5/3.5/5.5 GHz operating bands, respectively.
GPU‐accelerated time‐domain marching‐on‐in‐degree solution
Authors: Shi Y. , Jin J. M.
Published: March 2013

A marching‐on‐in‐degree (MOD) method accelerated by graphics processing units has been developed to solve the time‐domain electric‐field integral equation for the analysis of transient electromagnetic scattering problems. With the use of weighted Laguerre polynomials as entire‐domain temporal basis functions and the Galerkin temporal testing procedure, the MOD algorithm overcomes the late‐time instability. Two matrix‐division schemes are proposed and an asynchronous approach based on streams in CUDA is adopted to accelerate the TDEFIE‐MOD algorithm. Numerical results reveal that the computational efficiency of the proposed algorithm is greatly enhanced.
MEMS‐based piezoelectric BAW resonator based on out‐of‐plane degenerate mode for micro angular detector
Authors: Cheng Y.X. , Zhang W.P. , Guan R. , Zhang G. , Xu Z.X. , Chen W.Y.
Published: March 2013

A novel microelectromechanical piezoelectric concentrated‐mass bulk acoustic wave (BAW) resonator based on out‐of‐plane degenerate mode is proposed for detecting micro angles. A PZT resonator with a concentrated‐mass is designed to enhance the driving and sensing efficiency. The device combines the bulk acoustic wave drive/sense with a rocking concentrated mass to increase the resonant frequency, the signal quality and the resolution of the sensor. A 10 × 10 mm device has been fabricated and assembled by the microelectromechanical system process and the traditional mechanical process. The test results measured by the impedance analyser in air show that the resonant frequency and the quality factor of this device are about 174 kHz and 110, respectively. Moreover, the frequency split is only about 200Hz without any tuning methods.
High‐breakdown voltage and low on‐resistance AlGaN/GaN on Si MOS‐HEMTs employing an extended TaN gate on HfO2 gate insulator
Authors: Seok O. , Ahn W. , Han M.‐K. , Ha M.‐W.
Published: March 2013

Proposed is a new extended gate towards a source in AlGaN/GaN metal‐oxide‐semiconductor–high‐electron‐mobility transistors (MOS‐HEMTs) in order to increase breakdown voltage and reduce on‐resistance. The TaN gate was isolated from the source by a 15 nm‐thick RF‐sputtered HfO2 gate insulator. A high breakdown voltage of 1410 V was measured as a result of the successfully blocked gate leakage current and surface passivation by the HfO2 gate insulator. The extended gate towards the source was an effective method to improve the on‐resistance and drain current density by eliminating the gate‐source space. The proposed device with the extended gate exhibited low specific on‐resistance of 2.28 mΩ·cm2 while that of the MOS‐HEMT with the conventional structure was 2.91 mΩ·cm2. Also, maximum drain current density at the VGS of 2 V was increased from 332 to 420 mA/mm by the proposed extended TaN gate.
Adaptive controller for the double‐sided linear switched reluctance motor based on the nonlinear inductance modelling
Authors: Pan J.F. , Zou Yu , Cao Guangzhong
Published: March 2013

A linear switched reluctance motor (LSRM) is an attractive candidate for high‐precision position control applications in industry. Compared to its single‐sided counterpart, a double‐sided LSRM (DLSRM) has a more propulsion force to mass ratio and normal force can be counteracted from serially connected excitation windings and a symmetric machine structure. In this study, a nonlinear inductance modelling method is proposed by introducing a K factor that reflects both current and position effect on inductance. Considering uncertainties and disturbances from the DLSRM‐based motion system, this study implements online parameter estimation with adaptive control strategy to detect system parameter variations and regulate control parameters in real time. Experimental results demonstrate that the proposed control method is capable of position tracking with the desired performance and adaptive to operational changes either under command signal variations or external disturbances. These results prove the effectiveness of the proposed control method for high‐precision position control of the DLSRM.
Comment on ‘Analytical equivalence between substrate‐integrated waveguide and rectangular waveguide’
Authors: Tork Ladani Faezeh , Jam Shahrokh , Safian Reza
Published: March 2013

The authors discuss a recently proposed analytical method for calculation of equivalent width of substrate integrated waveguide. Modifications are made to calculate the final analytical formula more accurately.
Design of compact planar crossover using Sierpinski carpet microstrip patch
Authors: Henin Bassem , Abbosh Amin
Published: March 2013

The design of a planar four‐port microstrip crossover is presented. The design starts by using a half‐wavelength square patch and two sets of orthogonal feeding lines. Based on the cavity theory, operation of the patch crossover is analysed. Full‐wave simulations and measurements are used to support the analysis. By etching the patch as a Sierpinski carpet, resonant frequency can be lowered significantly, and this property can be employed to reduce the size of the conventional patch crossover. It is shown that the size of the crossover can be reduced by 23% with even a better performance when a second‐order Sierpinski carpet microstrip patch is used. Full‐wave simulations and measurements are used to validate the proposed design method. The measured data show less than 1 dB insertion loss, more than 10 dB return loss, more than 17 dB isolation and about 0.1 ns group delay deviation across 10% fractional bandwidth centred at 2.4 GHz.
Design of miniaturised band‐notch ultra‐wideband monopole‐slot antenna by modified half‐mode substrate‐integrated waveguide
Authors: Ali‐Akbari Elnaz , Azarmanesh Mohammad‐Naghi , Soltani Saber
Published: March 2013

In this study, a compact ultra‐wideband (UWB) two‐layer printed microstrip line monopole‐slot antenna with triple band‐rejection characteristics is investigated. The proposed antenna consists of a planar UWB monopole‐slot antenna with a size of 40 × 47 × 1.016 mm3 and a modified half‐mode substrate‐integrated waveguide (M‐HMSIW) cavity with folded defected ground structure slot. The antenna is fabricated using two‐layer printed circuit board process. To generate band‐notched characteristics, M‐HMSIW cavity in the bottom layer of the antenna are utilised. By tuning the dimension of M‐HMSIW, triple notched bands with sharp rejection can be achieved at WiMAX band (3.3–3.69 GHz), along with a major part of the C‐band (3.7–4.2 GHz), lower wireless local area network (WLAN) band (5.15–5.35 GHz), and upper WLAN band (5.725–5.825 GHz). The simulated and measured impedance matching, radiation patterns and gain results of antenna are investigated. The results of the fabricated antenna show that this antenna is a good candidate for various UWB applications.
Improved reactance domain unitary propagator algorithms for electronically steerable parasitic array radiator antennas
Authors: Akkar Salem , Harabi Ferid , Gharsallah Ali
Published: March 2013

In this study, the authors propose four algorithms for directions of arrival (DoAs) estimation of multiple incoming narrowband plane waves onto electronically steerable parasitic array radiator antennas. The constraints on the proposed algorithms are the same as those imposed onto the classic subspace methods allowing superior high‐resolution and localisation capabilities even for correlated sources scenarios but with more reduced computations load and processing time than existing schemes. We also demonstrate that estimating the propagator operator through both introduced real‐valued orthogonal decompositions techniques not only yields to a faster DoAs estimation with a reduced computational complexity, but also it improves the robustness of the developed algorithms to noise as compared with the classic propagator algorithm. The Cramér–Rao bound on the variance of the estimated DoAs by the proposed algorithms is analysed. The achieved performance by the developed methods is studied and compared with conventional antenna arrays. The simulation results confirm that high‐resolution DoAs estimation can be achieved with the developed algorithms and prove the validity of the proposed approach.
Nonequilibrium molecular dynamics simulation of pressure-driven water transport through modified CNT membranes
Authors: Wang Luying , Dumont Randall S. , Dickson James M.
Published: March 2013

Nonequilibrium molecular dynamics (NEMD) simulations are presented to investigate the effect of water-membrane interactions on the transport properties of pressure-driven water flow passing through carbon nanotube (CNT) membranes. The CNT membrane is modified with different physical properties to alter the van der Waals interactions or the electrostatic interactions between water molecules and the CNT membranes. The unmodified and modified CNT membranes are models of simplified nanofiltration (NF) membranes at operating conditions consistent with real NF systems. All NEMD simulations are run with constant pressure difference (8.0 MPa) temperature (300 K), constant pore size (0.643 nm radius for CNT (12, 12)), and membrane thickness (6.0 nm). The water flow rate, density, and velocity (in flow direction) distributions are obtained by analyzing the NEMD simulation results to compare transport through the modified and unmodified CNT membranes. The pressure-driven water flow through CNT membranes is from 11 to 21 times faster than predicted by the Navier-Stokes equations. For water passing through the modified membrane with stronger van der Waals or electrostatic interactions, the fast flow is reduced giving lower flow rates and velocities. These investigations show the effect of water-CNT membrane interactions on water transport under NF operating conditions. This work can help provide and improve the understanding of how these membrane characteristics affect membrane performance for real NF processes.
Electrostatic free energy for a confined nanoscale object in a fluid
Authors: Krishnan Madhavi
Published: March 2013

We present numerical calculations of electrostatic free energies, based on the nonlinear Poisson-Boltzmann (PB) equation, for the case of an isolated spherical nano-object in an aqueous suspension, interacting with charged bounding walls. We focus on systems with a low concentration of monovalent ions (≲10−4 M), where the range of electrostatic interactions is long (∼30 nm) and comparable to the system and object dimensions (∼100 nm). Locally tailoring the geometry of the boundaries creates a modulation in the object-wall interaction, which for appropriately chosen system dimensions can be strong enough to result in stable spatial trapping of a nanoscale entity. A detailed view of the underlying mechanism of the trap shows that the physics depends predominantly on counterion entropy and the depth of the potential well is effectively independent of the object's dielectric function; we further note an appreciable trap depth even for an uncharged object in the fluid. These calculations not only provide a quantitative framework for understanding geometry-driven electrostatic effects at the nanoscale, but will also aid in identifying contributions from phenomena beyond mean field PB electrostatics, e.g., Casimir and other fluctuation-driven forces.
Killing-Yano tensors in spaces admitting a hypersurface orthogonal Killing vector
Authors: Garfinkle David , Glass E. N.
Published: March 2013

Methods are presented for finding Killing-Yano tensors, conformal Killing-Yano tensors, and conformal Killing vectors in spacetimes with a hypersurface orthogonal Killing vector. These methods are similar to a method developed by the authors for finding Killing tensors. In all cases one decomposes both the tensor and the equation it satisfies into pieces along the Killing vector and pieces orthogonal to the Killing vector. Solving the separate equations that result from this decomposition requires less computing than integrating the original equation. In each case, examples are given to illustrate the method.
Multidimensional direct free energy perturbation
Authors: Boulougouris Georgios C.
Published: March 2013

In this work we propose a multidimensional free energy perturbation scheme that allows the evaluation of the free energy difference between a state sampled based on importance sampling and almost any state that can be constructed by the reduction of the number of molecules in the system and the change of either the interaction energy or the thermodynamic state variable (e.g., the temperature) of the system. We show that via this approach it is possible to evaluate any thermodynamic property included but not limited to free energy, chemical potential, and pressure, along a series of isotherms from a single molecular simulation.
Optical Tamm states in hetero-structures with highly dispersive planar plasmonic metamaterials
Authors: Lu Hai , Li Yunhui , Feng Tuanhui , Wang Shaohua , Xue Chunhua , Kang Xiubao , Du Guiqiang , Jiang Haitao , Chen Hong
Published: March 2013

Optical Tamm states (OTSs) in hetero-structures consisting of highly dispersive planar plasmonic metamaterials and truncated photonic crystal (PC) are investigated numerically. Compared to conventional OTSs in metal-PC structures, the reflectance of tunneling mode can be reduced from −10.2 dB to −32.0 dB, with an optimized Q-factor up to 17 times higher simultaneously. Further study on electromagnetic (EM) field distribution confirms that EM waves are highly localized at some special points. The confinement along the propagating direction provided by OTSs and the in-plane localization originated from the planar plasmonic metamaterials give rise to the three-dimensional enhancement of sub-wavelength EM localization corporately. As the advantages above are not at a cost of extra device volume, this structure is promising to be applied in highly sensitive dielectric sensing, nonlinear optical devices, and so on.
Point defects introduced by InN alloying into InxGa1−xN probed using a monoenergetic positron beam
Authors: Uedono A. , Tsutsui T. , Watanabe T. , Kimura S. , Zhang Y. , Lozac'h M. , Sang L. W. , Ishibashi S. , Sumiya M.
Published: March 2013

Native defects in InxGa1−xN (x = 0.06-0.14) grown by metal organic chemical vapor deposition were studied using a monoenergetic positron beam. Measurements of Doppler broadening spectra of the annihilation radiation as a function of incident positron energy for InxGa1−xN showed that vacancy-type defects were introduced with increasing InN composition, and the major defect species was identified as complexes between a cation vacancy and a nitrogen vacancy. The concentration of the divacancy, however, was found to be suppressed by Mg doping. The momentum distribution of electrons at the InxGa1−xN/GaN interface was close to that in defect-free GaN or InxGa1−xN, which was attributed to localization of positrons at the interface due to the built-in electric field, and to suppression of positron trapping by vacancy-type defects. We have also shown that the diffusion property of positrons is sensitive to an electric field near the InxGa1−xN/GaN interface.
Ab initio study on magnetic anisotropy change of SrCoxTixFe12−2xO19
Authors: Feng Min , Shao Bin , Wu Jian , Zuo Xu
Published: March 2013

The magnetic anisotropy change of Co-Ti substituted Sr-M hexaferrite has been investigated by using general gradient approximation (GGA) with on-site coulomb repulsion added (GGA + U) and force theorem method. The calculated dependence of magnetic anisotropy energy on angles of SrFe12O19 fits very well with theoretical description, and anisotropy constant K1 agrees well with experimental value. The impact of occupancy of Co2+ and Ti4+ on magnetic anisotropy in SrCo2Ti2Fe8O19 has been studied. The results show that Co2+ in 4f2 site and Ti4+ in 12 k site both contribute to the reduction of uniaxial magnetic anisotropy, and as Co2+ and Ti4+ in their first preference of substitution site, magnetic anisotropy of SrCo2Ti2Fe8O19 is weak, which would facilitate the formation of conical magnetic structure to induce electric polarization. As substitution rate x increases from 0 to 3, the magnetic anisotropy of SrCoxTixFe12−2xO19 is found to change from uniaxial to planar.