97 research outputs found
Oral history interview of 1988 YMCA Hall of Fame Inductee Rix Rogers
No full textThis is an oral history self interview of the 1988 YMCA Hall of fame Inductee, Rix G. Rogers. The audio lasts for around 34 minutes and was recorded on two sides of a cassette. The first side lasted around 32 minutes and the second side for around 3. The exact date the recording was made is not known, though it is thought to have been recorded in 1988 the year that he was inducted. On the tape Rix Rogers answers seven questions submitted by Mary Hedge, the director of Archives at the New York City YMCA.For more information on Rix G. Rogers, see https://springfield.as.atlas-sys.com/agents/people/749Digital technician who digitized file wrote, "Slightly noisy, but intelligible"
Deformation of landfill from measurements of shear wave velocity and damping - Discussion
Full text linkThe author presents a method for using in-situ seismic test results to estimate the short-term deformations of geomaterials. The effort to introduce rational algorithms for the evaluation of settlements of shallow foundations on the basis of measured physical quantities is noteworthy, considering that current geotechnical design, especially on small-scale projects, is often based on empirical correlations between
settlements and penetration test results that rarely reflect the actual site conditions. In this context the development of simple procedures based on the results of relatively inexpensive in-situ tests including seismic tests is of paramount importance.
Nevertheless it is important to account properly for the physics of wave propagation when inferring material parameters from seismic test results. In this respect, the writers would like to make some observations related to the methods used to evaluate the shear wave velocity and material
damping ratio of the solid waste from surface wave measurements. This discussion is focused on and restricted to the aspects of the paper related to the use of surface wave methods to estimate the waste properties
Investigation of head repositioning accuracy as a measure of cervicocephalic kinaesthetic sensibility in patients with chronic neck pain
No full textThe majority of people can expect to experience neck pain in their lifetime and some will go on to
develop prolonged or repetitive episodes of neck pain or related symptoms. These persistent complaints
have become a major cause of disability around the world.
Although chronic ‘mechanical’ neck pain can be defined in clinical terms, the underlying pathology
remains unclear. Research has failed to demonstrate a consistent relationship between the presence of
neck pain and pathology such as degenerative changes. As such, there has been an increasing interest
in altered neuro-muscular-articular function in the pathogenesis of neck pain. Over the last 17 years, the
role of cervical proprioceptive (mechanoreceptive) dysfunction in the perpetuation of chronic neck pain
has received increasing attention from researchers and clinicians. This is commonly referred to as
cervicocephalic kinaesthetic sensibility (KS).
Cervicocephalic KS has generally been studied utilising head repositioning accuracy (HRA) tasks. At
the beginning of this study only seven reports had been published in the area. Following review of this
literature, several focused areas of interest were apparent for further study - 1) comparison of KS in
various patient subgroups (e.g., insidious onset vs ‘whiplash’); 2) development of more sophisticated
methods of measuring head movement and repositioning errors; 3) establishing the characteristics of the
tests such as method agreement and reliability; 4) comparison of the discriminative value of repositioning
tasks to both subjective ‘straight ahead’ (SSA) and to non-neutral set points within the cervical range of
motion (non-straight ahead or nSA).
Investigation 1 used a laser pointer method to study head repositioning errors in patients with chronic
neck pain of insidious onset. The results suggested that these patients with chronic neck pain show little
evidence of impaired cervicocephalic KS, when measured as HRA-SSA. The study also served to
highlight several difficulties with the laser pointer method of measurement and the relatively poor
knowledge of HRA in healthy subjects. Most previous studies used the mean of 10 repetitions for the
measurement but more recent studies utilised fewer repetitions. Although the laser pointer method is
simple, inexpensive and easy to use, the method involves a degree of experimenter bias and inaccuracy.
It also does not lend itself to concurrent evaluation of variables such as range of motion and speed of
head movement.
Investigations 2 & 3 focused on the development of the testing method and the introduction of the
Zebris CMS 70P ultrasound system for the recording of HRA-SSA, namely; method agreement between a
5 and 10 repetition measuring protocol; method agreement between the laser pointer and Zebris system;
the intra/inter-examiner reliability of measurement methods.
The Zebris system results suggested that the two methods of measurement agree sufficiently well for
the 5 repetition method to replace the 10 repetition method to obtain a mean HRA score and that both
could be used interchangeably. Further results suggested that the Zebris and laser pointer methods do
not agree sufficiently well to be used interchangeably. The test-retest reliability was comparable between
both methods suggesting that from this perspective, either could be used for measuring HRA-SSA. The
inter-rater test-retest reliability was comparable to the test-retest reliability suggesting that trained
examiners could be interchanged when carrying out repeated measurements.
Investigation 4, the final study in this thesis, investigated HRA with the Zebris system using the 5
repetition protocol in two groups of chronic neck pain patients; insidious onset and neck pain from a
‘whiplash’ injury. The results suggested that patients with chronic neck pain of both insidious onset and
from a ‘whiplash’ injury show little evidence of impaired cervicocephalic KS when measured using HRASSA
and nSA tests. These results conflict with previous studies
Despite numerous investigations over the last 17 years, a test that can be routinely applied in the
clinical setting for the purposes of diagnosis and treatment monitoring has not been established. Studies
to date suggest that an active HRA test to SSA/NHP that is established by the patient may have the
greatest discriminative value. Although HRA testing shows some promise in identifying deficits in
‘whiplash’ patients, it is unlikely that the KS tests identify specific subgroups of chronic neck pain patients.
There have been several contradictory studies which have shown considerable overlap between patient
and healthy groups. It is also unlikely that HRA tests represent a unique test of cervical proprioceptive
function (peripheral or central integration) and therefore provide a test exclusive to neck disorders
Blakistonia maryae Harrison & Rix & Harvey & Austin 2018, sp. n.
No full text<i>Blakistonia maryae</i>, sp. n. <p>(Fig. 17 A–L)</p> <p> <b> Type material. AUSTRALIA: <i>South Australia:</i></b> Holotype male, South Middleback Ranges, 33°14’S, 137°07’E, 6 June 1984, pitfall trap, B. Guerin (SAM NN20077). Paratype: 1 male, South Middleback Ranges, 33°14’S, 137°07’E, 6 June 1984, pitfall trap, B. Guerin (SAM NN20075).</p> <p> <b> Other material examined. AUSTRALIA: <i>South Australia:</i></b> 1 female, Scrubby Peak, Gawler Ranges, 33°03’23”S, 136°19’ 40°0”E, 17–26 September 2007, dug up, SEG/DEH Survey 587 (SAM NN26663 DNA); 1 female, Kolay Hut, Gawler Ranges, 32°33’24”S, 135°35’20”E, 11 November 2013, dug up from bank, M. Rix, S.E. Harrison (SAM NN29604 DNA); 1 female, Tumby Bay, Eyre Peninsula, 34°22’27”S, 136°05’18”E, 1 May 2013, dug from grassy verge, S.E. Harrison, M. Harrison (SAM NN29565 DNA); 1 juvenile, same data (NN29566 DNA); 1 male, same data except 5 June 1984 (SAM NN20071); 3 males, Kimba, Eyre Peninsula, 32°29’40.9”S, 135°21’52.0”E, 25–28 November, from pitfall trap, Eyre Peninsula Survey (SAM NN26633–5).</p> <p> <b>Diagnosis.</b> Males of <i>B. maryae</i> can be distinguished from those of <i>B. bella</i>, <i>B. pidax</i>, <i>B. tunstilli</i>, <i>B. emmottorum</i>, <i>B. gemmelli</i> and <i>B. aurea</i> by the absence of prolateral clasping spurs on tibia I (Fig. 17 G–I); from those of <i>B. plata</i>, <i>B. parva</i>, <i>B. birksi</i>, <i>B. olea</i>, <i>B. tariae</i>, <i>B. carnarvon</i>, and <i>B. raveni</i> by the square eye group (Fig. 17D); and from those of <i>B. newtoni</i> and <i>B. hortoni</i> by the field of spinules on the palpal tibia being relatively narrow and not in a rounded crescent shape (Fig. 17J, L). Females of <i>B. maryae</i> can be distinguished from those of <i>B. wingellina</i> and <i>B. nullarborensis</i> by having a square or slightly subquadrate eye group (Fig. 18D); from those of <i>B. bassi</i> and <i>B. mainae</i> by the combined absence of fine golden hairs on the carapace (Fig. 18A) and the absence of dark brown on the book lungs (in contrast to a paler abdomen) (Fig. 18C); from those of <i>B. birksi</i> by abdominal chevrons being dark golden-brown, with abdomen golden-brown between chevrons (as opposed to chevrons that are dark brown to almost black, with abdomen dark brown between chevrons (Fig. 18A); and from those of <i>B. aurea</i> by the absence of cuspules on the labium (Fig. 18F).</p> <p> All life stages of <i>B. maryae</i> can also be distinguished from those of other species with sequence data by the following nucleotide substitutions (<i>n</i> = 4 specimens): C(276), G(354); and by the following unique motifs: GAA(482–484).</p> <p> <b>Description.</b> <i>Holotype male</i> (SAM NN20077). Small idiopid spider (total length 9.4). <i>Colour</i> (in ethanol; Fig. 17 A–C): Carapace, legs and pedipalp pale golden orange-brown, with darker lines on caput, radiating backwards from fovea, and around edges of carapace (Fig. 17A, G–L); sternum, labium and maxillae very similar colour; chelicerae darker red-brown (Fig. 17E, F); abdomen orange golden-brown with pattern of <i>ca.</i> seven mottled, indistinct chevrons, all divided (Fig. 17A, C).</p> <p> <i>Cephalothorax</i>: Carapace 4.8 long, 3.7 wide, 3.2 high, 1.3 times longer than wide; oval (Fig. 17A), caput low, ocular area raised (Fig. 17C); cuticle smooth, with pits outward from fovea and both sides of caput; fovea straight; carapace very sparsely setose, concentrated and forming fringe around edge of carapace; line of setae between fovea and eye group absent, however, few setae on lateral sides of eye area; median clump of thickened setae on clypeus (Fig. 17D). Length of median clypeus less than 1.0; anterior margin slightly convex. Eye group 0.7 wide, 0.7 long, 0.2 of carapace width; anterior eye row strongly procurved, PLE–PLE /ALE–ALE ratio 1.1; posterior eye row straight to very slightly procurved; AME only slightly smaller than ALE and separated by about the diameter of AME; ALE and PLE separated by about twice the diameter of ALE; PME pale, less than half size of AME and about half size of PLE, and separated from PLE by just less than its own diameter (Fig. 17D). Labium with five cuspules near anterior margin (Fig. 17F). Sternum 2.5 long, 2.1 wide, evenly setose (Fig. 17E). Maxillae with 12 (left) and 21 (right) cuspules (Fig. 17E, F).</p> <p> <i>Legs</i>: setose and diffusely spinose; tarsi I, II ventrally flattened; metatarsi and distal tarsi I, II weakly scopulate (Fig. 17 G–I). Paired tarsal claws: leg I p6 (6 large) r6 (6 large); leg II p8 (3 large, 5 small), r8 (3 large, 5 small); leg III p7 (3 large, 4 small), r5 (3 large, 2 small); leg IV p9 (9 large), r7 (3 large, 4 small).</p> <p> <i>Spination</i>: Tibia I with single prolateral macroseta (Fig. 17 G–I). All legs without clear demarcation between lanceolate setae and smaller spine-like setae.</p> <p> <i>Leg and pedipalp measurements</i>: Length of legs IV> I> II> III. Leg I: femur 4.5, patella 2.1, tibia 3.4, metatarsus 3.1, tarsus 1.6, total = 15.3. Leg II: femur 4.4, patella 2.0, tibia 3.3, metatarsus 2.2, tarsus 2.1, total = 14.0. Leg III: femur 3.1, patella 1.6, tibia 2.6, metatarsus 3.2, tarsus 2.3, total = 12.3. Leg IV (right): femur 4.7, patella 2.6, tibia 4.5, metatarsus 4.5, tarsus 2.6, total = 18.4. Pedipalp: femur 2.5, patella 1.2, tibia 2.2, tarsus 1.2, total = 7.2.</p> <p> <i>Pedipalp</i>: Femur dorsally spinose; patella with thickened ventral setae; tibia short and swollen, RTA very short, pointed, with clump of setae and covered in short, dense spinules and for just over half of distance between base of apophysis and distal tibia, becoming more sparse towards distal tibia; long, erect setae on ventral tibia; bulb uniform, globular; embolus simple, slender, tapering, tip slightly twisted, only slightly longer than bulb; cymbium covered in rows of short spinules, becoming longer closer to distal edge (Fig. 17 J–L).</p> <p> <i>Abdomen</i>: Setose, oval, dorsal sigilla not evident; 4.6 long, 2.7 wide (Fig. 17A).</p> <p> <i>Variation (n=6):</i> Carapace 3.0–4.8 long, 2.5–2.7 wide, 5-6 labial cuspules.</p> <p> <i>Female</i> (SAM NN29565). Medium-sized idiopid spider (total length 18.5).</p> <p> <i>Colour (in ethanol</i>; Fig. 18 A–C): Carapace medium golden-brown, slightly darker around fovea and lateral margins of caput; sternum lighter golden-brown, darker towards anterior and lateral margins; labium and maxillae same golden-brown as margins of sternum, chelicerae dark brown (Fig. 18E, F); abdomen grey-brown with 6 mottled chevrons of uniform width spaced over length of abdomen, anterior-most chevron divided by pale medial patch (Fig. 18A, C); legs and pedipalps medium golden-brown (Fig. 18G, H).</p> <p> <i>Cephalothorax</i>: Carapace 8.2 long, 6.3 wide, 5.9 high, 1.3 times longer than wide; oval (Fig. 18A); caput moderately raised, ocular area very slightly raised (Fig. 18C); cuticle uniformly smooth; fovea procurved; two parallel rows of large setae from fovea to eye group, with smaller setae located laterally to these rows; smaller fine setae also scattered across carapace, concentrated and forming fringe around lateral margins; median clump of thickened setae on clypeus (Fig. 18D). Length of median clypeus less than 1.0; anterior margin slightly convex. Eye group 1.4 wide, 0.9 long, 0.2 of carapace width; anterior eye row strongly procurved, PLE–PLE/ALE–ALE ratio 1.0; posterior eye row straight; AME <i>ca</i>. two-thirds the size of ALE and separated by less than diameter of AME; ALE and PLE separated by about diameter of AME; PLE and PME contiguous, oval (Fig. 18D). Labium without cuspules (Fig. 18F). Sternum 4.3 long, 3.5 wide, moderately setose with setae becoming denser and longer around margins; 3 pairs of sigilla, anterior-most pair at lateral margins, middle pair at half length, posterior pair slightly less than twice their width from edge (Fig. 18E). Maxillae with 22 (left) and 32 (right) cuspules (Fig. 18E, F).</p> <p> <i>Legs</i>: moderately setose and diffusely spinose, leg III more heavily setose; distinct upright setae on metatarsi and of tibiae I, II; femora I, II, and pedipalp laterally bowed; tarsi and metatarsi I, II, and palpal tarsus heavily scopulate (Fig. 18G, H). Paired tarsal claws: p1 (1 large) r2 (2 large); leg II p3 (2 large, 1 small), r1 (large); right leg III r2 (1 large, 1 small), r2 (2 small); right leg IV p0, r4 (1 large, 4 small). Pedipalp claw with 2 large teeth.</p> <p> <i>Spination</i>: Leg I: tibia p1, r5; metatarsus p4, r7; tarsus p3, r8. Leg II: tibia p4, r5; metatarsus II p4, r5; tarsus II p2, r4. Right leg III: patella p7; metatarsus III p6, r10; tarsus with 11 short spines ventrally. Right leg tibia IV: p8, r3; tarsus with <i>ca</i>. 23 short spines ventrally. Pedipalp: tibia p8, r5; tarsus p3, r3.</p> <p> <i>Leg and pedipalp measurements</i>: Length of legs IV> II> I> III. Leg I: femur 3.7, patella 2.7, tibia 2.4, metatarsus 2.0, tarsus 1.7, total = 12.5. Leg II: femur 4.2, patella 2.9, tibia 2.7, metatarsus 2.0, tarsus 1.8, total = 13.6. Leg III (right): femur 3.4, patella 2.5, tibia 2.1, metatarsus 1.5, tarsus 1.5, total = 11.8. Leg IV (right): femur 5.2, patella 3.7, tibia 4.6, metatarsus 3.8, tarsus 4.1, total = 21.4. Pedipalp: femur 3.6, patella 2.3, tibia 2.2, tarsus 2.8, total = 10.9.</p> <p> <i>Abdomen</i>: Setose, oval, three pairs of non-sclerotised, irregular dorsal sigilla on anterior three chevrons; 10.3 long, 6.8 wide (Fig. 18A).</p> <p> <i>Genitalia</i>: Spermathecae paired, simple, unbranched, stout and outward facing, with lobe of epigyne ca. same width as stalk, covered in opaque mottled brown nodules, becoming more concentrated towards distal spermathecae (Fig. 18I).</p> <p> <i>Variation (n=3):</i> Carapace 6.7–10.3 long, 6.2–7.7 wide, no labial cuspules. Spination: Leg I: tibia p1–3, r4–6; metatarsus r3–4, r5–7; tarsus p2–3, r3–8. Leg II: tibia p1–4, r5–7: metatarsus p4 r5–7; tarsus p2–3, tarsus r4–11. Leg III: patella p5–7, tibia p0–2, r0–1; tarsus with 11–17 short spines ventrally. Leg IV: tibia p0–1, r0–1; metatarsus p6–11, r2–4; tarsus with 20–28 spines ventrally. Pedipalp: tibia p2–9, r4–7; tarsus p3–5, r3–4.</p> <p> <b>Etymology.</b> This species is named in honour of the senior author’s mother, Mary Harrison, for her invaluable assistance on numerous collecting trips.</p> <p> <b>Distribution.</b> <i>Blakistonia maryae</i> is found on the Eyre Peninsula, and is known from Tumby Bay, the Middleback Ranges, Kimba, and two localities in the Gawler Ranges (Fig. 32).</p> <p> <b>Remarks.</b> The burrow lid of <i>B</i>. <i>maryae</i> is D-shaped and slightly indented (Fig. 2 H–K). The rim of the burrow is usually lined with twigs and small leaves (Fig. 2 H–K), which although common in other idiopid genera such as <i>Idiosoma</i> and <i>Gaius</i>, has not been previously documented in <i>Blakistonia</i>. These twigs are used as ‘feeling lines’ to increase the area of foraging (Main 1962). Twig-lining was not observed in the specimen from Kolay Hut, Gawler Ranges (Fig. 2K), however, it is likely that the absence of twig-lining was a result of the burrow being built on an unconsolidated bank, with erosion and no leaf litter available. We have tentatively linked the females from Tumby Bay and Gawler Ranges with the males from Kimba and Mount Crawford, due to their distributions on the Eyre Peninsula, and no conflicting differences in other morphological features, such as eye group shape.</p>Published as part of <i>Harrison, Sophie E., Rix, Michael G., Harvey, Mark S. & Austin, Andrew D., 2018, Systematics of the Australian spiny trapdoor spiders of the genus Blakistonia Hogg (Araneae: Idiopidae), pp. 1-76 in Zootaxa 4518 (1)</i> on pages 45-49, DOI: 10.11646/zootaxa.4518.1.1, <a href="http://zenodo.org/record/2609500">http://zenodo.org/record/2609500</a>
The Fourth Annual YMCA Hall of Fame Induction ceremony (June 22, 1988)
No full textThis is a video of the Fourth Annual YMCA Hall of Fame Induction ceremony that took place on June 22, 1988. Harold T. Friermood, H. Harper Glezen, Rix G. Rogers, and Walter F. Worrill were inducted. The video is around 17 minutes long. The ceremony takes place at the 1988 YMCA General Assembly. There is a brief introduction given by Peter Post and Frank Falcone, the President of Springfield College. The inductees give a brief acceptance speech. All except for Glezen where able to attend.Digital technician who digitized file wrote, "Difficult tape that took several attempts to get an encode. Begins in black and fades up to stills and then video in dark gymnasium, so the contrast is low. Opening pictures has wavy lines in the picture and no audio other than noise. Visible head switching at bottom of screen. Audio is on both channels but difficult to understand due to gym echo. Ends in black."
Correlated X-ray/ultraviolet/optical variability in the very low mass AGN NGC 4395
Full text linkWe report the results of a 1-yr Swift X-ray/ultraviolet (UV)/optical programme monitoring the dwarf Seyfert nucleus in NGC4395 in 2008-2009. The UV/optical flux from the nucleus was found to vary dramatically over the monitoring period, with a similar pattern of variation in each of the observed UV/optical bands (spanning 1900-5500 Å). In particular, the luminosity of NGC4395 in the 1900 Å band changed by more than a factor of 8 over the monitoring period. The fractional variability was smaller in the UV/optical bands than that seen in the X-rays, with the X-ray/optical ratio increasing with increasing flux. Pseudo-instantaneous flux measurements in the X-ray and each UV/optical band were well correlated, with cross-correlation coefficients of ≥0.7, significant at 99.9per cent confidence. Archival Swift observations from 2006 sample the intra-day X-ray/optical variability on NGC4395. These archival data show a very strong correlation between the X-ray and b bands, with a cross-correlation coefficient of 0.84 (significant at >99per cent confidence). The peak in the cross-correlation function is marginally resolved and asymmetric, suggesting that X-rays lead the b band, but by ≤1h. In response to recent (2011 August) very high X-ray flux levels from NGC4395 we triggered Swift target of opportunity observations, which sample the intra-hour X-ray/UV variability. These observations indicate, albeit with large uncertainties, a lag of the 1900 Å band behind the X-ray flux of ∼400s. The tight correlation between the X-ray and UV/optical lightcurves, together with the constraints we place on the lag time-scale, is consistent with the UV/optical variability of NGC4395 being primarily due to reprocessing of X-ray photons by the accretion disc
Testing the evolutionary link between submillimetre galaxies and quasars: CO observations of QSOs at z~2
Full text linkWe have used the IRAM Plateau de Bure millimetre interferometer and the UKIRT 1–5 μm Imager Spectrometer (UIST) to test the connection between the major phases of spheroid growth and nuclear accretion by mapping CO emission in nine submillimetre-detected QSOs at z= 1.7–2.6 with black hole (BH) masses derived from near-infrared spectroscopy. When combined with one QSO obtained from the literature, we present sensitive CO(3–2) or CO(2–1) observations of 10 submillimetre-detected QSOs selected at the epoch of peak activity in both QSOs and submillimetre (submm) galaxies (SMGs). CO is detected in 5/6 very optically luminous (MB∼−28) submm-detected QSOs with BH masses MBH≃ 109–1010 M⊙, confirming the presence of large gas reservoirs of Mgas≃ 3.4 × 1010 M⊙. Our BH masses and dynamical mass constraints on the host spheroids suggest, at face value, that these optically luminous QSOs at z= 2 lie about an order of magnitude above the local BH–spheroid relation, MBH/Msph, although this result is dependent on the size and inclination of the CO-emitting region. However, we find that their BH masses are ∼30 times too large and their surface density is ∼300 times too small to be related to typical SMGs in an evolutionary sequence. Conversely, we measure weaker CO emission in four fainter (MB∼−25) submm-detected QSOs with properties, BH masses (MBH≃ 5 × 108 M⊙), and surface densities similar to SMGs. These QSOs appear to lie near the local MBH/Msph relation, making them plausible ‘transition objects’ in the proposed evolutionary sequence linking QSOs to the formation of massive young galaxies and BHs at high redshift. We show that SMGs have a higher incidence of bimodal CO line profiles than seen in our QSO sample, which we interpret as an effect of their relative inclinations, with the QSOs seen more face-on. Finally, we find that the gas masses of the four fainter submm-detected QSOs imply that their star formation episodes could be sustained for ∼10 Myr, and are consistent with representing a phase in the formation of massive galaxies which overlaps a preceding SMG starburst phase, before subsequently evolving into a population of present-day massive ellipticals
The star formation rate of the Universe atz≈ 6 from the Hubble ultra-Deep Field
Full text linkWe determine the abundance of i′-band dropouts in the recently released HST/ACS Hubble Ultra-Deep Field (UDF). Because the majority of these sources are likely to be z≈ 6 galaxies whose flux decrement between the F775W i′-band and F850LP z′-band arises from Lyman-α absorption, the number of detected candidates provides a valuable upper limit to the unextincted star formation rate at this redshift. We demonstrate that the increased depth of UDF enables us to reach an 8 σ limiting magnitude of z′AB= 28.5 (equivalent to 1.5 h−270 M⊙ yr−1 at z= 6.1, or 0.1 L⋆UV for the z≈ 3U-drop population), permitting us to address earlier ambiguities arising from the unobserved form of the luminosity function. We identify 54 galaxies (and only one star) at z′AB 1.3 over the deepest 11-arcmin2 portion of the UDF. The characteristic luminosity (L⋆) is consistent with values observed at z≈ 3. The faint end slope (α) is less well constrained, but is consistent with only modest evolution. The main change appears to be in the number density (Φ*). Specifically, and regardless of possible contamination from cool stars and lower-redshift sources, the UDF data support our previous result that the star formation rate at z≈ 6 was approximately six times less than at z≈ 3. This declining comoving star formation rate [0.005 h70 M⊙ yr−1 Mpc−3 at z≈ 6 at LUV > 0.1 L⋆ for a Salpeter initial mass function (IMF)] poses an interesting challenge for models which suggest that LUV > 0.1 L⋆ star-forming galaxies at z≃ 6 reionized the Universe. The short-fall in ionizing photons might be alleviated by galaxies fainter than our limit, or a radically different IMF. Alternatively, the bulk of reionization might have occurred at z≫ 6
Heat transfer effects during cold dense gas dispersion
Full text linkFinal report.November 1983.Includes bibliographical references.CER83-84-GA-DEN-RNM3.GRI-83-0082.Wind tunnel concentration data were obtained for continuous area releases of isothermal, cold N2, cold CO2 and cold CH4 clouds. Wind tunnel results were compared to field test results and to a computer model simulation. Heat transfer and humidity effects on model concentration distributions were significant for methane plumes when surface Richardson numbers, Rix, were large (i.e. low wind speed and high boiloff rates conditions). At field scales heat transfer and humidity still play a role in the dispersion of methane spill cases, but plume dilution and lift off are not as exaggerated as for the-model cases.For Gas Research Institute, Contract No. 5014-352-0203
Environment and self-regulation in galaxy formation
Full text linkThe environment is known to affect the formation and evolution of galaxies considerably best visible through the well-known morphology–density relationship. It is less clear, though, whether the environment is equally important at a given galaxy morphology. In this paper, we study the effect of environment on the evolution of early-type galaxies as imprinted in the fossil record by analysing the stellar population properties of 3360 galaxies morphologically selected by visual inspection from the Sloan Digital Sky Survey in a narrow redshift range ( 0.05 ≤z≤ 0.06 ). The morphological selection algorithm is critical, as it does not bias against recent star formation. We find that the distribution of ages is bimodal with a strong peak at old ages and a secondary peak at young ages around ∼2.5 Gyr containing about 10 per cent of the objects. This is an analogue to 'red sequence' and 'blue cloud' identified in galaxy populations usually containing both early- and late-type galaxies. The fraction of the young, rejuvenated galaxies increases with both decreasing galaxy mass and decreasing environmental density up to about 45 per cent, which implies that the impact of environment increases with decreasing galaxy mass. The rejuvenated galaxies have lower α/Fe ratios than the average and most of them show signs of ongoing star formation through their emission line spectra. All objects that host active galactic nuclei in their centres without star formation are part of the red sequence population. We confirm and statistically strengthen earlier results that luminosity weighted ages, metallicities and α/Fe element ratios of the red sequence population correlate well with velocity dispersion and galaxy mass. Most interestingly, however, these scaling relations are not sensitive to environmental densities and are only driven by galaxy mass. We infer that early-type galaxy formation has undergone a phase transition a few billion years ago around z∼ 0.2 . A self-regulated formation phase without environmental dependence has recently been superseded by a rejuvenation phase, in which the environment plays a decisive role possibly through galaxy mergers and interactions
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