Stellar mass functions of galaxies, disks and spheroids at z~0.1

We present the stellar mass functions (SMF) and mass densities of galaxies, and their spheroid and disk components in the local (z~0.1) universe over the range 8.9 <= log(M/M_solar) <= 12 from spheroid+disk decompositions and corresponding stellar masses of a sample of over 600,000 galaxies in the SDSS-DR7 spectroscopic sample. The galaxy SMF is well represented by a single Schechter function (M* = 11.116+/-0.011, alpha = -1.145+/-0.008), though with a hint of a steeper faint end slope. The corresponding stellar mass densities are (2.670+/-0.110), (1.687+/-0.063) and (0.910+/-0.029)x10^8 M_solar Mpc^-3 for galaxies, spheroids and disks respectively. We identify a crossover stellar mass of log(M/M_solar) = 10.3+/-0.030 at which the spheroid and disk SMFs are equal. Relative contributions of four distinct spheroid/disk dominated sub-populations to the overall galaxy SMF are also presented. The mean disk-to-spheroid stellar mass ratio shows a five fold disk dominance at the low mass end, decreasing monotonically with a corresponding increase in the spheroidal fraction till the two are equal at a galaxy stellar mass, log(M/M_solar)=10.479+/-0.013, the dominance of spheroids then grows with increasing stellar mass. The relative numbers of composite disk and spheroid dominated galaxies show peaks in their distributions, perhaps indicative of a preferred galaxy mass. Our characterization of the low redshift galaxy population provides stringent constraints for numerical simulations to reproduce.Comment: 30 pages, 18 figures, 5 tables (2 online), Accepted for publication in MNRA

The Development of an Inventory Control Procedure for Low Usage Maintenance Spare Parts

This analysis was made in an attempt to establish an inventory control procedure which would be applicable for low wage maintenance spare parts. Spare parts inventories are unique in industry since they are maintained as insurance stock to provide protection against the inability to procure a part readily when it is needed for a repair.· Due to this characteristic, the demand for these items is low and unpredictable; therefore, classical inventory models are not applicable. More sophisticated approaches have been developed to take these characteristics into account; however, these approaches require assumptions to be made which may not hold true when applying these concepts in everyday operations. In an effort to gain understanding of the inventory process a simulation model was developed to parallel the inventory cycle as it is operated on a daily basis. In order to develop a realistic simulation model the physical attributes of the system and their interactions were established and provisions were made for evaluating the effect of various control parameters on these characteristics. By simulating the inventory cycle over an extended period of time the model provided an opportunity to introduce various inventory control points at predetermined usage rates. Consequently, the effect of these various control points on the inventory level, reorder cycle, and stockout frequency could be studied at each level of annual usage selected. The classical total variable cost equation was used to convert the results of the simulation into information which takes into account the cost factors of the inventory cycle. Using the values obtained from the simulation an economic evaluation was made for each set of fixed attributes in order to determine the most economical control point for each level of annual usage and lead time range. As could be expected, many combinations of unit cost and stockout cost are possible for inclusion in the total variable cost equation; however, in keeping with the characteristics of the majority of items in these inventories, these costs were limited to five hundred dollars each. The data from the economic evaluations was consolidated and arranged in graphical form in order to use the data as a tool for decision making . By determining the expected annual usage, lead time, unit cost, and probably stockout cost, the user can quickly determine the max-min control point which is the most economical for that set of variables. In addition to the graphical representation, the logic represented in the graphs was incorporated into a computerized inventory control system where it has been used success fully for several months. Although this analysis does not represent an exacting scientific approach to this type of inventory problem, experience indicates that near optimization has been achieved through proper application of the procedure

Technical guide on documentation requirements for open market contract acquisitions of information resources

A guide is presented to assist requestors in formulating and submitting the required Complete Package for Information Resources (IR) acquisitions. Advance discussions with cognizant procurement personnel are strongly recommended for complex IR requirements or for those requestors new to the acquisition process. Open Market means the requirement either is not available on GSA Schedule Contract or exceeds the $300,000 threshold and/or the quantity Maximum Order Limitation of the GSA Schedule Contract. Only open market contract acquisitions (i.e., in excess of the$25,000 small purchase threshold), are addressed

The Dynamics of Galaxy Pairs in a Cosmological Setting

We use the Millennium Simulation, and an abundance-matching framework, to investigate the dynamical behaviour of galaxy pairs embedded in a cosmological context. Our main galaxy-pair sample, selected to have separations under 250 kpc/h, consists of over 1.3 million pairs at redshift z = 0, with stellar masses greater than 10^9 Msun, probing mass ratios down to 1:1000. We use dark matter halo membership and energy to classify our galaxy pairs. In terms of halo membership, central-satellite pairs tend to be in isolation (in relation to external more massive galaxies), are energetically- bound to each other, and are also weakly-bound to a neighbouring massive galaxy. Satellite-satellite pairs, instead, inhabit regions in close proximity to a more massive galaxy, are energetically-unbound, and are often bound to that neighbour. We find that 60% of our paired galaxies are bound to both their companion and to a third external object. Moreover, only 9% of our pairs resemble the kind of systems described by idealised binary merger simulations in complete isolation. In sum, we demonstrate the importance of properly connecting galaxy pairs to the rest of the Universe.Comment: 25 pages, 14 figures, accepted by MNRA

Mapping galaxy encounters in numerical simulations: The spatial extent of induced star formation

We employ a suite of 75 simulations of galaxies in idealised major mergers (stellar mass ratio ~2.5:1), with a wide range of orbital parameters, to investigate the spatial extent of interaction-induced star formation. Although the total star formation in galaxy encounters is generally elevated relative to isolated galaxies, we find that this elevation is a combination of intense enhancements within the central kpc and moderately suppressed activity at large galacto-centric radii. The radial dependence of the star formation enhancement is stronger in the less massive galaxy than in the primary, and is also more pronounced in mergers of more closely aligned disc spin orientations. Conversely, these trends are almost entirely independent of the encounter's impact parameter and orbital eccentricity. Our predictions of the radial dependence of triggered star formation, and specifically the suppression of star formation beyond kph-scales, will be testable with the next generation of integral-field spectroscopic surveys.Comment: 12 pages, 8 figures, accepted by MNRA

Intracranial fusarium fungal abscess in an immunocompetent patient: case report and review of the literature.

Introduction Fusarium spp is an omnipresent fungal species that may lead to fatal infections in immunocompromised populations. Spontaneous intracranial infection by Fusarium spp in immunocompetent individuals is exceedingly rare. Case Report An immunocompetent 33-year-old Hispanic woman presented with persistent headaches and was found to have a contrast-enhancing mass in the left petrous apex and prepontine cistern. She underwent a subsequent craniotomy for biopsy and partial resection that revealed a Fusarium abscess. She had a left transient partial oculomotor palsy following the operation that resolved over the next few weeks. She was treated with long-term intravenous antifungal therapy and remained at her neurologic baseline 18 months following the intervention. Discussion To our knowledge, this is the first reported case of Fusarium spp brain abscess in an immunocompetent patient. Treatment options include surgical intervention and various antifungal medications. Conclusion This case demonstrates the rare potential of intracranial Fusarium infection in the immunocompetent host, as well as its successful treatment with surgical aspiration and antifungal therapy

Bulge mass is king: The dominant role of the bulge in determining the fraction of passive galaxies in the Sloan Digital Sky Survey

We investigate the origin of galaxy bimodality by quantifying the relative role of intrinsic and environmental drivers to the cessation (or `quenching') of star formation in over half a million local Sloan Digital Sky Survey (SDSS) galaxies. Our sample contains a wide variety of galaxies at z=0.02-0.2, with stellar masses of 8 < log(M*/M_sun) < 12, spanning the entire morphological range from pure disks to spheroids, and over four orders of magnitude in local galaxy density and halo mass. We utilise published star formation rates and add to this recent GIM2D photometric and stellar mass bulge + disk decompositions from our group. We find that the passive fraction of galaxies increases steeply with stellar mass, halo mass, and bulge mass, with a less steep dependence on local galaxy density and bulge-to-total stellar mass ratio (B/T). At fixed internal properties, we find that central and satellite galaxies have different passive fraction relationships. For centrals, we conclude that there is less variation in the passive fraction at a fixed bulge mass, than for any other variable, including total stellar mass, halo mass, and B/T. This implies that the quenching mechanism must be most tightly coupled to the bulge. We argue that radio-mode AGN feedback offers the most plausible explanation of the observed trends.Comment: Accepted to MNRAS. 32 pages, 27 figures. [This version is virtually identical to v1

Star Formation in a Stellar Mass Selected Sample of Galaxies to z=3 from the GOODS NICMOS Survey (GNS)

We present a study of the star-forming properties of a stellar mass-selected sample of galaxies in the GOODS NICMOS Survey (GNS), based on deep Hubble Space Telescope imaging of the GOODS North and South fields. Using a stellar mass selected sample, combined with HST/ACS and Spitzer data to measure both UV and infrared derived star formation rates (SFR), we investigate the star forming properties of a complete sample of ~1300 galaxies down to log M*=9.5 at redshifts 1.5<z<3. Eight percent of the sample is made up of massive galaxies with M*>10^11 Msun. We derive optical colours, dust extinctions, and ultraviolet and infrared SFR to determine how the star formation rate changes as a function of both stellar mass and time. Our results show that SFR increases at higher stellar mass such that massive galaxies nearly double their stellar mass from star formation alone over the redshift range studied, but the average value of SFR for a given stellar mass remains constant over this 2 Gyr period. Furthermore, we find no strong evolution in the SFR for our sample as a function of mass over our redshift range of interest, in particular we do not find a decline in the SFR among massive galaxies, as is seen at z < 1. The most massive galaxies in our sample (log M*>11) have high average SFRs with values, SFR(UV,corr) = 103+/-75 Msun/yr, yet exhibit red rest-frame (U-B) colours at all redshifts. We conclude that the majority of these red high-redshift massive galaxies are red due to dust extinction. We find that A(2800) increases with stellar mass, and show that between 45% and 85% of massive galaxies harbour dusty star formation. These results show that even just a few Gyr after the first galaxies appear, there are strong relations between the global physical properties of galaxies, driven by stellar mass or another underlying feature of galaxies strongly related to the stellar mass.Comment: 18 pages, 10 figures, accepted for publication in MNRA