bluuebunny/crossref_metadata_2025 huggingface dataset:
The outer membrane form of the mitochondrial protein Mcr1 follows a TOM‐independent membrane insertion pathway
Authors: Meineke Birthe , Engl Gertraud , Kemper Christian , Vasiljev-Neumeyer Andreja , Paulitschke Hanka , Rapaport Doron
Published: February 2008

The yeast gene MCR1 encodes two isoforms of the mitochondrial NADH‐cytochrome b5 reductase. One form is embedded in the outer membrane whereas the other is located in the intermembrane space (IMS). In the present work we investigated the biogenesis of the outer membrane form. We demonstrate that while the IMS form crosses the outer membrane via the translocase of the outer mitochondrial membrane (TOM) complex, the other form is integrated into the outer membrane by a process that does not require any of the known import components at the outer membrane. Thus, the import pathways of the two forms diverge in a stage before the encounter with the TOM complex and their mechanism of biogenesis represents a unique example how to achieve dual localization within one organelle.
Chronic effects of a high-fat diet enriched with virgin olive oil and a low-fat diet enriched with α-linolenic acid on postprandial endothelial function in healthy men
Authors: Fuentes F. , López-Miranda J. , Pérez-Martínez P. , Jiménez Y. , Marín C. , Gómez P. , Fernández J. M. , Caballero J. , Delgado-Lista J. , Pérez-Jiménez F.
Published: February 2008

Traditional cardiovascular risk factors are associated with endothelial dysfunction. The vascular endothelium plays a key role in local vascular tone regulation and can be modulated by dietary fat. We propose to determine the chronic effect of three diets with different fat compositions on postprandial endothelial function and inflammatory biomarkers. Twenty healthy men followed three 4-week diets in a randomised cross-over design: a Western diet, rich in saturated fat (22 % SFA, 12 % MUFA and 0·4 % α-linolenic acid (ALA), all fractions are % of energy); a Mediterranean diet, rich in MUFA ( < 10 % SFA, 24 % MUFA and 0·4 % ALA); a low-fat diet enriched in ALA ( < 10 % SFA, 12 % MUFA and 2 % ALA). At the end of each dietary period all subjects underwent a postprandial study. Plasma concentrations of lipid parameters, soluble intercellular cell-adhesion molecule-1, soluble vascular cell-adhesion molecule-1 (sVCAM-1), nitrates and nitrites (NOx) and endothelial function studied by laser Doppler were examined at 0, 2, 4, 6 and 8 h. The endothelium-dependent vasodilatory response was greater 4 h after the ingestion of the MUFA-rich diet than after the SFA or ALA low-fat diets (P = 0·031). The 4 h postprandial plasma sVCAM-1 levels were lower after the MUFA meals than after the ALA low-fat diet (P = 0·043). The bioavailability of NOx was higher following the MUFA diet than after the SFA and ALA low-fat diets (P = 0·027). We found no differences in the other parameters measured. Chronic ingestion of a Mediterranean diet avoids the postprandial deterioration of endothelial function associated with Westernised diets in healthy individuals.
Socio-economic, behavioural and environmental factors predicted body weights and household food insecurity scores in the Early Childhood Longitudinal Study-Kindergarten
Authors: Bhargava Alok , Jolliffe Dean , Howard Larry L.
Published: February 2008

Recent increases in obesity prevalence among children in developed countries are of policy concern. While significant positive associations between households' food insecurity status and body weights have been reported for adults, it is known from the energy physiology literature that energy requirements depend on BMR, anthropometric measures and physical activity. It is therefore important to model the bi-directional relationships between body weights and households' food insecurity scores especially for children that have evolving nutrient and energy requirements. The present paper estimated dynamic random effects models for children's body weights and BMI, and households' food insecurity scores using longitudinal data on 7635 children in the USA enrolled in 1st, 3rd and 5th grades (1999–2003) of the Early Childhood Longitudinal Study-Kindergarten. The main findings were, first, physical exercise and numbers of siblings were significantly (P < 0·05) negatively associated with body weights, while households' food insecurity score was not a significant predictor. Moreover, children's body weights were significantly lower in households with higher parental education and incomes; time spent watching television and in non-parental care were positively associated with weights. Second, models for households' food insecurity scores showed that poverty and respondents' poor emotional and physical health significantly increased food insecurity. Moreover, households with children who were taller and heavier for their ages faced significantly higher food insecurity levels. Overall, the results showed that household food insecurity was unlikely to exacerbate child obesity in the USA and it is important that children receive balanced school meals and perform higher physical activity.
Urinary isoflavonoid excretion is similar after consuming soya milk and miso soup in Japanese-American women
Authors: Maskarinec Gertraud , Watts Kirsten , Kagihara Jamie , Hebshi Sandra M. , Franke Adrian A.
Published: February 2008

Based on the hypothesis that isoflavones are absorbed more efficiently from fermented than from non-fermented soya foods, we compared the urinary isoflavonoid excretion (UIE) after intake of miso soup or soya milk. We recruited twenty-one women with Japanese ancestry who consumed standardized soya portions containing 48 mg isoflavones. On day 1, half the women consumed soya milk, the other half started with miso soup. On day 3, the subjects ate the other soya food and on day 5, they repeated the first food. Each participant collected a spot urine sample before and an overnight urine sample after soya food intake. All urine samples were analysed for daidzein, genistein and equol using LC–MS and were expressed as nmol/mg creatinine. We applied mixed models to evaluate the difference in UIE by food while including the baseline values and covariates. Relative to baseline, both groups experienced significantly higher UIE after consuming any of the soya foods. We observed no significant difference in UIE when soya milk was compared to miso soup (P = 0·87) among all women or in the seven equol producers (P = 0·88). Repeated intake of the same food on different days showed high reproducibility within subjects. These preliminary results indicate similar UIE after consuming a fermented soya food (miso) as compared to a non-fermented soya food (soya milk). Therefore, recommendations favouring fermented soya foods are not justified as long as the intestinal microflora is capable of hydrolysing the isoflavone glucosides from non-fermented soya foods.
Temporal distribution and population structure of two congeneric species ofCucullanus(Nematoda: Cucullanidae) inOrthopristis ruberin Venezuela
Authors: Bashirullah A.K. , Diaz M.T.
Published: February 2008

The qualitative and quantitative parameters of temporal distribution ofCucullanus tripapillatusandCucullanus chrysophrydesin the intestine ofOrthopristis ruberin the Caribbean Sea on the north of Margarita Island, Venezuela were analysed. A total of 540 fish were collected at random from the catch of commercial trawlers during 1982–83 and 1992–93. Both species ofCucullanuswere found throughout the year; prevalence and mean intensity ofC. tripapillatuswere higher than that ofC. chrysophrydes. A significant difference was found in infection between the two years of sampling. Female worms were more abundant than male in both years. Both species exhibited pronounced prevalence and maturity in September and March of each year, indicating seasonality. The patterns of occurrence of the two species ofCucullanusinO. ruberdid not change in the 10-year interval but the host size and number of parasites declined, which may be due to over-exploitation of definitive fish hosts.
Interrogative suggestibility, compliance and false confessions among prisoners and their relationship with attention deficit hyperactivity disorder (ADHD) symptoms
Authors: Gudjonsson G. H. , Sigurdsson J. F. , Bragason O. O. , Newton A. K. , Einarsson E.
Published: February 2008

Background

Interrogative suggestibility and compliance are important psychological vulnerabilities during interrogation. The aim of the study was to investigate the relationship of suggestibility and compliance with childhood and current symptoms of attention deficit hyperactivity disorder (ADHD). Compliance has not been studied previously in relation to ADHD. A further aim was to investigate the relationship between ADHD and the reporting of having made a false confession to the police.

Method

The participants were 90 male prisoners, all of whom had completed the Gudjonsson Suggestibility and Compliance Scales (GSS and GCS) within 10 days of admission to the prison. Childhood ADHD symptoms were screened by the Wender Utah Rating Scale (WURS) and current adult symptoms by the DSM-IV Checklist criteria for ADHD.

Results

Half of the prisoners (50%) were found on screening to meet criteria for ADHD in childhood and, of those, over half (60%) were either fully symptomatic or in partial remission of their symptoms. ADHD symptoms were found to be significantly associated with compliance, but not with suggestibility. The relationship with compliance was stronger (effect size) in relation to current than childhood symptoms. The ADHD symptomatic groups were significantly more likely to claim that they had made a false confession to the police in the past.

Conclusions

The findings raise important questions about the potential vulnerability of adults with ADHD symptoms in terms of their ability to cope with interrogation.
An alternative technique for transfer of anomalous left coronary artery from the pulmonary trunk in children and adults using autogenous aortic and pulmonary arterial flaps
Authors: Chowdhury Ujjwal K. , Kothari Shyam S. , Patel Chetan D. , Mishra Anand K. , Jagia Priya , Subramaniam Ganapathy K. , Pradeep Kizakke K. , Govindappa Raghu M.
Published: February 2008

Background

Direct re-implantation of an anomalous left coronary artery into the aorta is the preferred surgical option for creating a dual coronary arterial system in patients in whom the anomalous artery originated from the pulmonary trunk. This technique, however, is applicable only when the anomalous artery arises from the right posterior pulmonary sinus. We report a new technique for re-implantation using combined autogenous aortic and pulmonary arterial flaps in situations when a direct connection was not possible.

Patients and methods

We have treated 4 patients, aged 3 months, 6 months, 18 months, and 27 years respectively, who presented with anomalous origin of the left coronary artery from the left posterior pulmonary sinus. We used our proposed technique for transfer because lack of coronary arterial length, diminished vessel elasticity, and extensive collaterals around the pulmonary sinuses prevented direct attachment.

Results

There was no early or late death. Postoperatively, all patients are in functional class I, with good biventricular function at a median follow-up of 74 months, with a range from 9 to 96 months. Postoperative coronary angiography in our 4th patient showed good arterial flow, without any distortion.

Conclusions

The potential benefits of this modification of the trapdoor technique are excellent operative exposure, use of autogenous and viable tissue capable of further growth, avoidance of injury to the aortic and pulmonary valvar apparatus and production of obstruction within the right ventricular outflow tract, complete elimination of use of pericardium for augmentation of the neo-aortic tube, achievement of the anastomosis with correct angling and length, and the possibility of implantation in all patients, including adults, regardless of the distance from the aorta or the coronary arterial configuration.
The HI that Barked in the Night
Authors: Disney Mike
Published: February 2008

I discuss some of the interesting discoveries gradually emerging from the HIPASS HI survey. Why were so very few dark clouds and dark galaxies identified? Could that be partly due to optical misidentifications? In some cases yes. Will Arecibo overcome some of the deficiencies of HIPASS? I argue not because large telescopes are ill suited to blind surveys. I discuss the problem of Inchoate Galaxies which can be neither young nor old, and the constancy of HI column density found amongst all sources turning up in blind HI surveys. Could some of these unexpected phenomena be the result of Spin Temperature Freezeout? If so there is a lot more HI out there than we imagined.
The Detection of Dark Galaxies in Blind HI Surveys
Authors: Davies Jonathan I.
Published: February 2008

One explanation for the disparity between Cold Dark Matter predictions of galaxy numbers and observations could be that there are numerous dark galaxies in the Universe. These galaxies may still contain baryons, but no stars, and may be detectable in the 21cm line of atomic hydrogen. In this paper we describe a numerical model of the galaxy population and predict what might be found in blind 21cm surveys. We describe the detection of a dark galaxy candidate (VIRGOHI21) and discuss a model of its origin.
Constraints on Dark and Visible Mass in Galaxies from Strong Gravitational Lensing
Authors: Dye Simon , Warren Steve
Published: February 2008

We give a non-exhaustive review of the use of strong gravitational lensing in placing constraints on the quantity of dark and visible mass in galaxies. We discuss development of the methodology and summarise some recent results.
The mass distribution in Spiral galaxies
Authors: Salucci Paolo
Published: February 2008

In the past years a wealth of observations has allowed us to unravel the structural properties of the Dark and Luminous mass distribution in spirals. As result, it has been found that their rotation curves follow, out their virial radius, an Universal function (URC) made by two terms: one due to the gravitational potential of a Freeman stellar disk and the other due to that of a dark halo. The importance of the latter is found to decrease with galaxy mass. Individual objects reveal in detail that dark halos have a density core, whose size correlates with its central value. These properties will guide ΛCDM Cosmology to evolve to match the challenge that observations presently pose.
The ALFALFA Search for (Almost) Dark Galaxies across the HI Mass Function
Authors: Haynes Martha P.
Published: February 2008

The Arecibo Legacy Fast ALFA (ALFALFA) survey is a second generation blind extragalactic HI survey currently in progess which is exploiting Arecibo's superior sensitivity, angular resolution and digital technology to derive a census of the local HI universe over a cosmologically significant volume. As of the time of this meeting, some 4500 good quality extragalactic HI line sources have been identified in about 15% of the final survey area. ALFALFA is detecting HI masses as low as 106M⊙and as large as 1010.8M⊙with positional accuracies typically better than 20″, allowing immediate identification of the most probable optical counterparts. Only 3% of all extragalactic HI sources and less than 1% of detections withMH I> 109.5M⊙cannot be identified with a stellar component. Because ALFALFA is far from complete, the discussion here focuses on limitations of past surveys that ALFALFA will overcome because of its greater volume, sensitivity and reduced susceptibility to source confusion and on a sampling of illustrative preliminary results. First ALFALFA results already suggest, in agreement with previous studies, that there does not appear to be a cosmologically significant population of optically dark but HI rich galaxies. ALFALFA promises a wealthy dataset for the exploration of many issues in near-field cosmology and galaxy evolution studies, setting the stage for their extension to higher redshifts in the future with the Square Kilometer Array (SKA).
HI Clouds Detected Toward Virgo with the Arecibo Legacy Fast ALFA Survey
Authors: Kent Brian R.
Published: February 2008

The Arecibo Legacy Fast ALFA survey is in the process of yielding a complete HI dataset of the Virgo Cluster and its environs (Giovanelli et al. 2007, Kent et al., in preparation). Assuming a distance to Virgo of 16.7 Mpc, the minimum detectable HI mass by ALFALFA is of order 2 × 107 M⊙. A number of the HI detections appear to have interesting properties. Some appear associated with, but offset from, low surface brightness optical counterparts; others, at larger spatial offsets, may be tidally related to optical counterparts. Yet another class includes detections which are not identifiable with any optical counterparts. We present the ALFALFA results on these objects in the Virgo region, as well as followup aperture synthesis observations obtained with the VLA.
Where are the Stars in Dark Galaxies?
Authors: Rosenberg Jessica L. , Salzer John J. , Cannon John
Published: February 2008

Blind HI surveys provide a census of galaxies in the local universe that is unbiased by their optical properties. Even the Arecibo Dual-Beam Survey with a sample of only 265 galaxies discovered many low surface brightness galaxies and one galaxy with no obvious stellar component. Overall the galaxies in this survey display a diverse range of gas-to-stellar properties. The environment in which a galaxy resides is shown to be one of the factors responsible for this diversity, but it is not the only one. Clearly there are other factors affecting the complex processes responsible for the conversion of gas into stars rapidly in some galaxies, slowly in others, and rapidly in the center while slowly in the outskirts in still other galaxies. Nevertheless, even the inefficient star formation observed in a large fraction of the gas-rich galaxies appears to be a significant contributor to the overall star-formation rate density locally and therefore an important driver of galaxy evolution that must be understood. We focus on a discussion of the stellar and star formation properties in a 21 cm selected sample of galaxies because it is these measurements that contain the most information about the nature of star formation in galaxies.
Voids in the Local Volume: a Limit on Appearance of a Galaxy in a Dark Matter Halo
Authors: Tikhonov Anton V. , Klypin Anatoly A.
Published: February 2008

Current explanation of the overabundance of dark matter subhalos in the Local Group (LG) indicates that there maybe a limit on mass of a halo, which can host a galaxy. This idea can be tested using voids in the distribution of galaxies: at some level small voids should not contain any (even dwarf) galaxies. We use observational samples complete to MB = −12 with distances less than 8 Mpc to construct the void function (VF): the distribution of sizes of voids empty of any galaxies. There are ~ 30 voids with sizes ranging from 1 to 5 Mpc. We then study the distribution of dark matter halos in very high resolution simulations of the LCDM model. The theoretical VF matches the observations remarkably well only if we use halos with circular velocities larger than 45 ± 10 km/s. This agrees with the Local Group predictions. There are smaller halos in the voids, but they should not produce any luminous matter. Small voids look quite similar to their giant cousins: the density has a minimum at the center of a void and it increases as we get closer to the border. Small nonluminous halos inside the void form a web of tiny filaments. Thus, both the Local Group data and the nearby voids indicate that isolated halos below 45 ± 10 km/s must not host galaxies and that small (few Mpc) voids are truly dark.
QSO Strong Gravitational Lensing and the Detection of Dark Halos
Authors: Macciò Andrea V.
Published: February 2008

We present recent results concerning the possibility to detect dark satellites around galaxies using QSO strong gravitational lensing. Combining high resolution hydrodynamical simulations of galaxy formation and analytic studies we show that current QSO observations data do not present any evidence for the existence of such satellites. The amount of substructures predicted by CDM within a galaxy size dark matter halo is too low to explain the observed anomalies in the QSO images flux ratio.

Nevertheless the fluxes of QSO multiple images can be used to constrain the CDM power spectrum on small scales and test different dark matter candidates. We show that a warm dark matter scenario, with an insufficiently massive particle, fails to reproduce the observational data. Our results suggest a lower limit of few keV (~ 10) for the mass of warm dark matter candidates in the form of a sterile neutrino, in good agreement with previous results coming from Lyman-α forest and Cosmic Microwave Background analysis.
Mapping the Distribution of Luminous and Dark Matter in Strong Lensing Galaxies
Authors: Ferreras Ignacio , Saha Prasenjit , Williams Liliya L. R. , Burles Scott
Published: February 2008

We present the distribution of luminous and dark matter in a set of strong lensing (early-type) galaxies. By combining two independent techniques – stellar population synthesis and gravitational lensing – we can compare the baryonic and dark matter content in these galaxies within the regions that can be probed using the images of the lensed background source. Two samples were studied, extracted from the CASTLES and SLACS surveys. The former probes a wider range of redshifts and allows us to explore the mass distribution out to ~ 5Re. The high resolution optical images of the latter (using HST/ACS) are used to show a pixellated map of the ratio between total and baryonic matter. We find dark matter to be absent in the cores of these galaxies, with an increasing contribution at projected radii R ≳ Re. The slopes are roughly compatible with an isothermal slope (better interpreted as an adiabatically contracted NFW profile), but a large scatter in the slope exists among galaxies. There is a trend suggesting most massive galaxies have a higher content of dark matter in the regions probed by this analysis.
Tidal Debris Posing as Dark Galaxies
Authors: Duc Pierre–Alain , Bournaud Frédéric , Brinks Elias
Published: February 2008

Debris sent into the intergalactic medium during tidal collisions has received much attention as it can tell us about several fundamental properties of galaxies, in particular their missing mass, both in the form of cosmological Dark Matter and so-called Lost Baryons.

High velocity encounters, which are common in clusters of galaxies, are able to produce faint tidal debris that may appear as star–less, free floating HI clouds. These may be mistaken for Dark Galaxies, a putative class of gaseous, dark matter (DM) dominated, objects which for some reason never managed to form stars. VirgoHI21, in the Virgo Cluster, is by far the most spectacular and most discussed Dark Galaxy candidate so far detected in HI surveys. We show here that it is most likely made out of material expelled 750 Myr ago from the nearby spiral galaxy NGC 4254 during its fly–by at about 1000 km s−1by a massive intruder. Our numerical model of the collision is able to reproduce the main characteristics of the system: in particular the absence of stars, and its prominent velocity gradient. Originally attributed to the gas being in rotation within a massive dark matter halo, we find it instead to be consistent with a combination of simple streaming motion plus projection effects (Duc & Bournaud, 2007).

Based on our multi-wavelength and numerical studies of galaxy collisions, we discuss several ways to identify a tidal origin in a Dark Galaxy candidate such as optical and millimetre–wave observations to reveal a high metallicity and CO lines, and more importantly, kinematics indicating the absence of a prominent Dark Matter halo. We illustrate the method using another HI system in Virgo, VCC 2062, which is most likely a Tidal Dwarf Galaxy (Ducet al., 2007).

Now, whereas tidal debris should not contain any dark matter from the halo of their parent galaxies, it may exhibit missing mass in the form of dark baryons, unaccounted for by classical observations, as recently found in the collisional ring of NGC 5291 (Bournaudet al., 2007) and probably in the TDG VCC 2062. These “Lost Baryons” must originally have been located in the disks of their parent galaxies.
Numerical Simulation of the Dwarf Companions of Giant Galaxies
Authors: Nelson A. H. , Williams P. R.
Published: February 2008

We report simulations of the formation of a giant disc galaxy from cosmological initial conditions. Two sets of initial conditions are used, initially smooth density for both gas and stars, representing the Warm dark Matter scenario, and an initially fluctuating density representing the standard spectrum for the Cold dark Matter scenario. For the WDM initial conditions, the galaxy has a population of long lived dwarf satellites at z = 0, with orbits close to a plane coincident with that of the giant galaxy disc. The detailed properties of these dwarfs mimic closely the observed properties of Local Group dwarfs with respect to mass, and kinematics. However they do not have individual dark matter halos, but orbit in the nearly spherical dark matter halo of the giant galaxy. The reason for this is that the initial population of dwarf dark matter haloes, which form during the initial collapse phase, all merge into the halo of the giant galaxy within a few to several Gyears, while the long lived dwarfs form as a secondary population by gravitational collapse of high angular momentum gas in the outer reaches of the giants proto-galactic disc. Due to their late formation and their more distant orbits, they survive until the present epoch as individual dwarf galaxies at radii 20-50kpc from the giants centre. For CDM initial conditions there are many more dwarf satellites at z = 0, some of which form early on as gas condensations in DM sub-halos, and survive with these individual DM halos till z = 0 due to their being sufficiently well bound to avoid merging with the main galaxy. However even in this case some second generation satellites form as initially gas only objects, just as for the smooth initial conditions of WDM.
Delayed Galaxies
Authors: Struck Curtis , Hancock Mark , Smith Beverly J. , Appleton Phillip N. , Charmandaris Vassilis , Giroux Mark
Published: February 2008

We can define Delayed Galaxies as a class of rare galaxies that maintained the bulk of their gas for most of the age of the universe following the initial formation of their disks, with little or no star formation. Invisible galaxies and Malin 1 type low-surface-brightness galaxies qualify as class members. Rare examples among interacting galaxies show that collisions can restart the stalled evolution of such galaxies, and suggest that other members of the Delayed class can be found among interacting systems with vigorous current star formation.
Probe of Dark Galaxies via Disturbed/Lopsided Isolated Galaxies
Authors: Karachentsev Igor D. , Karachentseva Valentina E. , Huchtmeier Walter K. , Makarov Dmitry I. , Kaisin Serafim S.
Published: February 2008

Searching for lopsided/interacting objects among 1500 isolated galaxies yields only eight strongly disturbed galaxies which may be explained as a result of their interaction with massive dark objects. We present results of spectral and photometric observations of these galaxies performed with the 6-m telescope that lead to significant restriction on cosmic abundance of dark galaxies.
Star Formation in Massive Low Surface Brightness Galaxies
Authors: O'Neil K.
Published: February 2008

Massive low surface brightness galaxies have disk central surface brightnesses at least one magnitude fainter than the night sky, but total magnitudes and masses that show they are among the largest galaxies known. Like all low surface brightness (LSB) galaxies, massive LSB galaxies are often in the midst of star formation yet their stellar light has remained diffuse, raising the question of how star formation is proceeding within these galaxies. We have undertaken a multi-wavelength study to clarify the structural parameters and stellar and gas content of these enigmatic systems. The results of these studies, which include HI, CO, optical, near UV, and far UV images of the galaxies will provide the most in depth study done to date of how, when, and where star formation proceeds within this unique subset of the galaxy population.
Linking Clustering Properties and the Evolution of Low Surface Brightness Galaxies
Authors: Bomans Dominik J. , Rosenbaum S. Dominik
Published: February 2008

The reasons for the presence of two branches of galaxy evolution, one producing high surface brightness disks and one creating low surface brightness disks, is still unknown. Possible are the imprint of the properties of the dark matter halo, as well as evolutionary effects. In this paper we present an analysis of the clustering properties of LSB and HSB galaxies using the Sloan Digital Sky Survey. We show that LSB galaxies reside in regions of lower galaxy density than HSB galaxies on all scales between 0.8 and 8 Mpc, from scales of galaxy pairs to filaments of the Large Scale Structure. This implies a probable scenario of LSB galaxies preferentially forming as a result of local peaks in the large-scale valleys of the primordial density distribution.
Star Formation in Damped Lyman α Selected Galaxies
Authors: Christensen Lise
Published: February 2008

I present results from an ongoing survey to study galaxies associated with damped Lyman-α (DLA) systems at redshifts z>2. Integral field spectroscopy is used to search for Lyα emission line objects at the wavelengths where the emission from the quasars have been absorbed by the DLAs. The DLA galaxy candidates detected in this survey are found at distances of 10–20 kpc from the quasar line of sight, implying that galaxies are surrounded by neutral hydrogen at large distances. If we assume that the distribution of neutral gas is exponential, the scale length of the neutral gas is ~6 kpc, similar to large disk galaxies in the local Universe. The emission line luminosities imply smaller star formation rates compared to other high redshift galaxies found in luminosity selected samples.
Mass Modelling of dwarf Spheroidal Galaxies
Authors: Klimentowski Jarosław , Łokas Ewa L. , Kazantzidis Stelios , Prada Francisco , Mayer Lucio , Mamon Gary A.
Published: February 2008

We study the origin and properties of unbound stars in the kinematic samples of dwarf spheroidal galaxies. For this purpose we have run a high resolution N-body simulation of a two-component dwarf galaxy orbiting in a Milky Way potential. We create mock kinematic data sets by observing the dwarf in different directions. When the dwarf is observed along the tidal tails the kinematic samples are strongly contaminated by unbound stars from the tails. However, most of the unbound stars can be removed by the method of interloper rejection proposed by den Hartog & Katgert. We model the velocity dispersion profiles of the cleaned-up kinematic samples using solutions of the Jeans equation. We show that even for such a strongly stripped dwarf the Jeans analysis, when applied to cleaned samples, allows us to reproduce the mass and mass-to-light ratio of the dwarf with accuracy typically better than 25%.
Evolution of Dwarf Galaxies in the Centaurus A Group
Authors: Makarova L. , Makarov D.
Published: February 2008

We consider the star formation properties of dwarf galaxies in the Cen A group observed within our HST/ACS projects number 9771 and 10235. We model color-magnitude diagrams of the galaxies under consideration and measure star formation rate and metallicity dependence on time. We study the environmental dependence of the galaxy evolution and probable origin of the dwarf galaxies in the group.
Morphology and Environment of Dwarf Galaxies in the Local Universe
Authors: Ann H. B.
Published: February 2008

Analysis of dwarf galaxies in the local universe shows that dwarf irregular galaxies are its dominant populations and the majority of dwarf elliptical galaxies are likely to be located in the overdense regions, However, a significant fraction of blue dwarf ellipticals (dEblue) and peculiar dwarf ellipticals (dEpec are found to be located in the under-dense regions.
The True Surface Mass density of Cold Dark Matter Halos
Authors: Holopainen Janne , Zackrisson E. , Knebe A. , Nurmi P. , Heinämaki P. , Gill S. , Flynn C. , Reihm T.
Published: February 2008

The cold dark matter (CDM) scenario generically predicts the existence of triaxial dark matter halos which contain notable amounts of substructure. However, analytical halo models with smooth, spherically symmetric density profiles are routinely adopted in the modelling of light propagation effects through such objects. In this paper, we report the biases introduced by this procedure by comparing the surface mass densities of actual N-body halos against the widely used analytical model suggested by Navarro, Frenk and White (1996) (NFW). We conduct our analysis in the redshift range of 0.0 − 1.5.

In cluster sized halos, we find that triaxiality can cause scatter in the surface mass density of the halos up to σ+= +60% and σ−= −70%, where the 1-σ limits are relative to the analytical NFW model given value. Subhalos can increase this scatter to σ+= +70% and σ−= −80%. In galaxy sized halos, the triaxial scatter can be as high as σ+= +80% and σ−= −70%, and with subhalos the values can change to σ+= +40% and σ−= −80%.

We have developed an analytical model for the surface mass density scatter as a function of distance to the halo centre, halo redshift and halo mass. The analytical description enables one to investigate the reliability of results obtained with simplified halo models. Additionally, it provides the means to add simulated surface density scatter to analytical density profiles. We have tested our model on the calculation of microlensing optical depths for MACHOs in CDM halos.
Warps in Galactic Disks
Authors: Józsa Gyula I.G. , Kenn Franz , Klein Ulrich , Oosterloo Thomas A.
Published: February 2008

We have embarked on a detailed study of the kinematical and morphological structure of HI disks of warped galaxies, which are parametrised by means of kinematic modelling of spectroscopic observations. We present current results and compare them to predictions of theories for warp formation and -maintenance.
Deciphering Quasar Millilensing – How to Distinguish Between Dark and Luminous Lenses
Authors: Lietzen Heidi , Flynn Chris , Zackrisson Erik , Nurmi Pasi
Published: February 2008

Dwarf-galaxy sized dark matter halos may be detectable when a bright background source is gravitationally lensed on scales of milliarcseconds. Such effects can be caused by dark galaxies as well as luminous ones. Here we discuss conditions for detecting a luminous lensing object through direct imaging, via measurements of the point spread function (PSF) to subtract the quasar from the image, revealing the quasar host galaxy and any luminous lens. The technique applies to both types of millilensing effect, i.e. magnification and image splitting. We show that luminous dwarf-galaxy lenses should be detectable with this method up to redshifts z~0.2.
Dark Matter Problem in the Local Supercluster
Authors: Makarov Dmitry , Karachentsev Igor
Published: February 2008

The Local Supercluster is an ideal laboratory to study distribution of luminous and dark matter in the nearby Universe. The 1100 small groups have been selected using algorithm based on assumption that a total energy of physical pair of galaxies must be negative. The properties of the groups have been considered.
On the Probability for Sub-Halo Detection through Quasar Image Splitting
Authors: Riehm T. , Zackrisson E. , Wiik K. , Möller O.
Published: February 2008

Dark galaxies may in principle be detectable through strong-lensing image splitting of quasars on small angular scales (milliarcseconds or below). Here, we estimate the overall probabilities for such detections under the assumption that the quasars can be treated as point sources. Due to the very low probabilities derived, we conclude that it is currently not feasable to use this strategy to put the CDM predictions for the dark galaxy population to the test.
Tidal Influences on Cluster Dwarf Evolution
Authors: Smith R. , Davies J. I. , Nelson A.
Published: February 2008

Using N-Body/Treecode, SPH simulations, including a self regulating Star Formation-feedback model, the influence of cluster tidal forces on infalling dwarf irregulars is investigated. Results suggest that an encounter with the cluster potential can disrupt a rotating disk causing morphological transformation of the gaseous component, resulting in an enhancement of star formation rates (SFRs) of up to an order of magnitude.
The Chemical Enrichment of the Diffuse Gas in the Outer Galaxy and the Abundance Gradient of the Milky Way
Authors: Song Limin , Tripp Todd M. , Bowen David V. , Sembach Kenneth R.
Published: February 2008

Using data from HST/STIS (Hubble Space Telescope / Space Telescope Imaging Spectrograph) and FUSE (Far Ultraviolet Spectroscopic Explorer) toward two QSOs, H1821+643 and HS0624+6907, we find that the overall metallicity of the Galactic “Outer Arm” is Z=0.3−0.5 Z⊙ with underabundant nitrogen and little depletion by dust. The results are consistent with those based on H II region measurements in the outer galaxy and provide additional constrains on models of the Galactic abundance gradient and Milky Way (MW) chemical evolution. The lower metallicity observed in the outer galaxy is consistent with abundance patterns observed in higher redshift damped Lyα absorbers (DLAs) extrapolated to z=0. The slow metallicity evolution of DLAs could be due to the larger cross sections of the outer regions of galaxies combined with the observed metallicity gradients.
The ALFA Zone of Avoidance Survey: Results from the Precursor Observations
Authors: Springob C. M. , Henning P. A. , Catinella B. , Day F. , Minchin R. , Momjian E. , Koribalski B. , Masters K. L. , Muller E. , Pantoja C. , Putman M. , Rosenberg J. L. , Schneider S. , Staveley-Smith L.
Published: February 2008

The Arecibo L-band Feed Array Zone of Avoidance Survey (ALFA ZOA) will map 1350-1800 deg2 at low Galactic latitude, providing HI spectra for galaxies in regions of the sky where our knowledge of local large scale structure remains incomplete, owing to obscuration from dust and high stellar confusion near the Galactic plane. Because of these effects, a substantial fraction of the galaxies detected in the survey will have no optical or infrared counterparts. However, near infrared follow up observations of ALFA ZOA sources found in regions of lowest obscuration could reveal whether some of these sources could be objects in which little or no star formation has taken place (“dark galaxies”). We present here the results of ALFA ZOA precursor observations on two patches of sky totaling 140 deg2 (near l = 40°, and l = 192°). We have measured HI parameters for detections from these observations, and cross-correlated with the NASA/IPAC Extragalactic Database (NED). A significant fraction of the objects have never been detected at any wavelength. For those galaxies that have been previously detected, a significant fraction have no previously known redshift, and no previous HI detection.
ALFALFA in the Leo Region: Looking for Missing Satellites in HI
Authors: Stierwalt Sabrina
Published: February 2008

The location of two nearby galaxy groups within ~20 Mpc in the Leo region allows for a detailed study of low-mass galaxies. A catalog of HI line detections in Leo (9h36m < α < 11h36m, +8° < δ < +16°) has been made from the blind HI survey ALFALFA. More sensitive single-pixel Arecibo observations targeted Leo dwarf candidates noted optically by Karachentsev et al. 2004 (K04) to determine group members and allow for a comparison of HI and optically-selected samples. This presentation highlights the differences between the two samples and the significant contribution blind HI surveys can make to the missing satellites problem.
The Northern HIPASS Optical/IR Catalogue (NOIRCAT)
Authors: Wong O. Ivy , Webster Rachel L. , Waugh Meryl , Kilborn Virginia A. , Staveley-Smith Lister
Published: February 2008

We present the Northern HIPASS Optical/Infrared Catalogue (NOIRCAT), an optical/near-infrared counterpart catalogue for the Northern HIPASS catalogue (NHICAT). Of the 1002 sources in NHICAT, 655 (66%) have optical counterparts with matching optical velocities. A further 87 sources have optical counterparts with matching velocities from previous radio emission line surveys. Assuming a dark galaxy to be an isolated HI source with no detectable stars, no candidate dark galaxies have been confirmed.
The MareNostrum Galaxy Formation Simulation Project
Authors: Yepes G. , Martinez-Vaquero L. , Khalatyan A. , Gottlöber S. , Hoeft M. , Teyssier R.
Published: February 2008

The goal of this unprecedented large scale numerical project is to run state-of-the-art cosmological simulations of galaxy formation with two different numerical techniques: the particle based code GADGET-2 and the Eulerian AMR code RAMSES, starting from the same initial conditions. Both codes are fully parallel with MPI and can make efficient use of thousands of processors of the Marenostrum Supercomputer in Barcelona, where these two numerical experiments are being run.
Constrained Simulations of the Local Universe
Authors: Yepes G. , Martinez-Vaquero L. , Hoffman Y. , Gottlöber S. , Klypin A.
Published: February 2008

We have studied the formation of the Local Universe using constrained cosmological simulations. To this end we use the observed local mass and velocity distributions to generate the initial density field. A variety of N-body simulations with different box sizes and resolutions have been done so far. The largest structures, such as Coma, Virgo and the Local Supercluster are reproduced with high accuracy. We have also been able to obtain a representation of the Local Group with unprecedented accuracy and resolution. From these simulations we are studying in detail the dynamics of the dark matter in our neighborhood. The next step will be to include baryons and study in detail the galaxy formation in our local universe.
Cloud forming potential of secondary organic aerosol under near atmospheric conditions
Authors: Duplissy J. , Gysel M. , Alfarra M. R. , Dommen J. , Metzger A. , Prevot A. S. H. , Weingartner E. , Laaksonen A. , Raatikainen T. , Good N. , Turner S. F. , McFiggans G. , Baltensperger U.
Published: February 2008

Cloud droplets form by nucleation on atmospheric aerosol particles. Populations of such particles invariably contain organic material, a major source of which is thought to be condensation of photo‐oxidation products of biogenic volatile organic compounds (VOCs). We demonstrate that smog chamber studies of the formation of such biogenic secondary organic aerosol (SOA) formed during photo‐oxidation must be conducted at near atmospheric concentrations to yield atmospherically representative particle composition, hygroscopicity and cloud‐forming potential. Under these conditions, the hygroscopicity measured at 95% relative humidity can be used reliably to predict the CCN activity of the SOA particles by assuming droplet surface tension of pure water. We also show that the supersaturation required to activate a given size of particle decreases with age.
Effects of the 2006 El Niño on tropospheric composition as revealed by data from the Tropospheric Emission Spectrometer (TES)
Authors: Logan Jennifer A. , Megretskaia Inna , Nassar Ray , Murray Lee T. , Zhang Lin , Bowman Kevin W. , Worden Helen M. , Luo Ming
Published: February 2008

The Tropospheric Emission Spectrometer (TES) is unique in providing multi‐year coincident tropospheric profiles of CO, O3 and H2O. TES data show large differences in these gases over Indonesia and the eastern Indian Ocean in October–December 2006 relative to 2005. In 2006, O3 was higher by 15–30 ppb (30–75%) while CO was higher by >80 ppb in October and November, and by ∼25 ppb in December. These differences were caused by high fire emissions from Indonesia in 2006 associated with the lowest rainfall since 1997, reduced convection during the moderate El Niño, and reduced photochemical loss because of lower H2O. The persistence of the O3 difference into December is consistent with higher NOx emissions from lightning in 2006. TES CO and O3 enhancements in 2006 were larger than those observed during the weak El Niño of 2004.
Interplanetary conditions leading to superintense geomagnetic storms (Dst ≤ −250 nT) during solar cycle 23
Authors: Echer E. , Gonzalez W. D. , Tsurutani B. T.
Published: February 2008

The interplanetary causes of superintense geomagnetic storms (superstorms, Dst ≤ −250 nT) that occurred during solar cycle 23 are studied. Eleven superstorms occurred during the cycle, five close to solar maximum (2000–2001) and six in the post‐maximum/declining phase (2003–2004). About 1/3 of the superstorms were caused by magnetic clouds (MCs), 1/3 by a combination of sheath and MC fields, and 1/3 by sheath fields alone. The interplanetary parameter best correlated with peak Dst was the time‐ integrated Ey during the storm main phase (in contrast with peak Bs and/or peak Ey for less intense geomagnetic storms). The range of peak Dst for these storms was −263 to −422 nT. The storm main phase durations had a range of 3–33 h. We conclude from this study that: (1) only MCs and/or interplanetary sheaths had fields intense enough and with long enough durations to cause superstorms; (2) superstorms occurred only in the maximum and declining phases; (3) the total energy transferred from the solar wind to the magnetosphere is best correlated with the time‐integrated solar wind Ey parameter.
Carbon monoxide pollution from cities and urban areas observed by the Terra/MOPITT mission
Authors: Clerbaux Cathy , Edwards David P. , Deeter Merritt , Emmons Louisa , Lamarque Jean‐François , Tie Xue Xi , Massie Steve T. , Gille John
Published: February 2008

Carbon monoxide (CO) is a key species for tracking pollution plumes. The Measurement Of Pollution in The Troposphere (MOPITT) mission onboard the Terra satellite has already provided 7.5 years of CO atmospheric concentration measurements around the globe. Limited sensitivity to the boundary layer is well known to be a weakness of nadir looking thermal infrared sounders. This paper investigates the possibility of using the MOPITT surface measurements to detect CO emitted by cities and urban centers. By selecting the data and averaging them over long time periods, we demonstrate that the CO pollution arising from the large cities and urban areas can be distinguished from the background transported pollution. The more favorable observations are obtained during daytime and at locations where the thermal contrast (temperature gradient) between the surface and lower atmosphere is significant.
Defining the frequency of near‐shore tropical cyclone activity in the eastern North Pacific from historical surface observations (1921–2005)
Authors: Englehart Phil J. , Lewis Michael D. , Douglas Arthur V.
Published: February 2008

Due in part to limited historical observations, the long‐term variability of tropical cyclone (TC) activity in the eastern North Pacific has received little research attention. This paper outlines features of a long‐term (1921–2005) data set of TC frequency defined in a manner consistent with the quality and availability of historical surface observations. Simple analyses of the data set point to nonrandom behavior in the TC series and suggest that long period variability is an important component of TC activity.