Modeling Large Whale Entanglement Injuries: An Experimental Analysis of the Influence of Tissue Compliance, Line Tension, and Draw-Length on Epidermal Abrasion Resistance

Two test systems were developed to evaluate the influence of draw-length and tissue compliance on entanglement-induced epidermal abrasion in humpback (Megaptera novaeangliae) and right whale (Eubalaena glacialis) tissue samples. Under straight pull abrasion tests an adult right whale fluke required 3.7 times the load and 15 times the draw-length of a right whale calf flipper to induce epidermal failure while a humpback fluke was intermediate between these extremes. Epidermal thickness did not appear to be the cause of this difference in abrasion resistance. Epidermal thickness averaged 8.0k0.2 mm for the calf flipper, 4.9k0.4 rnrn for the humpback fluke, and 5.1k0.1 mm for the right whale fluke. It is unknown whether the difference in abrasion resistance is a function of species (right vs. humpback whale), age (adult vs. calf), or body region (fluke vs. flipper). Repeated tests with different line materials (new and used float vs. sink) did not show a significant difference in the rate of epidermal abrasion. However, line diameter does appear to influence tissue abrasion rates. Thinner (6.4 mm diameter) lines cut substantially deeper than thicker (9.5 mm diameter) lines under similar loads and draw-lengths. Tests with the oscillatory abrasion system revealed that draw-lengths that exceed the tissue compliance limit resulted in substantially increased rates of tissue abrasion. Draw-lengths below the compliance limit did not penetrate the epidermis while those exceeding the compliance limit deeply cut into the underlying dermis. In actual entanglement situations, the relative draw-length to tissue compliance ratio may be the critical component that determines if the line will cut into the body or benignly press against the skin. Investigations into the potential for reducing line modulus to allow lines to stretch with flexure of the body and thus minimize sliding relative to the skin may be beneficial in reducing the mortality associated with entanglement injuries

Is this a pattern?

In the current climate, pattern is an often-misused buzzword. However, there is no clear definition of pattern-ness, perhaps because patterns do not lend themselves to prescriptive, formal definitions. The authors propose a set of characteristics that can be used as a test for pattern-ness. Each characteristic in their test describes an essential aspect of a design pattern. Recognizing these characteristics will help software designers understand, use, and write better patterns

A High Stellar Obliquity in the WASP-7 Exoplanetary System

We measure a tilt of 86+-6 deg between the sky projections of the rotation axis of the WASP-7 star, and the orbital axis of its close-in giant planet. This measurement is based on observations of the Rossiter-McLaughlin (RM) effect with the Planet Finder Spectrograph on the Magellan II telescope. The result conforms with the previously noted pattern among hot-Jupiter hosts, namely, that the hosts lacking thick convective envelopes have high obliquities. Because the planet's trajectory crosses a wide range of stellar latitudes, observations of the RM effect can in principle reveal the stellar differential rotation profile; however, with the present data the signal of differential rotation could not be detected. The host star is found to exhibit radial-velocity noise (``stellar jitter') with an amplitude of ~30m/s over a timescale of days.Comment: ApJ accepted, 9 pages, 9 figure

Obliquities of Hot Jupiter host stars: Evidence for tidal interactions and primordial misalignments

We provide evidence that the obliquities of stars with close-in giant planets were initially nearly random, and that the low obliquities that are often observed are a consequence of star-planet tidal interactions. The evidence is based on 14 new measurements of the Rossiter-McLaughlin effect (for the systems HAT-P-6, HAT-P-7, HAT-P-16, HAT-P-24, HAT-P-32, HAT-P-34, WASP-12, WASP-16, WASP-18, WASP-19, WASP-26, WASP-31, Gl 436, and Kepler-8), as well as a critical review of previous observations. The low-obliquity (well-aligned) systems are those for which the expected tidal timescale is short, and likewise the high-obliquity (misaligned and retrograde) systems are those for which the expected timescale is long. At face value, this finding indicates that the origin of hot Jupiters involves dynamical interactions like planet-planet interactions or the Kozai effect that tilt their orbits, rather than inspiraling due to interaction with a protoplanetary disk. We discuss the status of this hypothesis and the observations that are needed for a more definitive conclusion.Comment: Accepted for publication in ApJ; typos corrected, 2 broken references fixed, 26 pages, 25 figure

Discovery of a Galaxy Cluster in the Foreground of the Wide-Separation Quasar Pair UM425

We report the discovery of a cluster of galaxies in the field of UM425, a pair of quasars separated by 6.5arcsec. Based on this finding, we revisit the long-standing question of whether this quasar pair is a binary quasar or a wide-separation lens. Previous work has shown that both quasars are at z=1.465 and show broad absorption lines. No evidence for a lensing galaxy has been found between the quasars, but there were two hints of a foreground cluster: diffuse X-ray emission observed with Chandra, and an excess of faint galaxies observed with the Hubble Space Telescope. Here we show, via VLT spectroscopy, that there is a spike in the redshift histogram of galaxies at z=0.77. We estimate the chance of finding a random velocity structure of such significance to be about 5%, and thereby interpret the diffuse X-ray emission as originating from z=0.77, rather than the quasar redshift. The mass of the cluster, as estimated from either the velocity dispersion of the z=0.77 galaxies or the X-ray luminosity of the diffuse emission, would be consistent with the theoretical mass required for gravitational lensing. The positional offset between the X-ray centroid and the expected location of the mass centroid is about 40kpc, which is not too different from offsets observed in lower redshift clusters. However, UM425 would be an unusual gravitational lens, by virtue of the absence of a bright primary lensing galaxy. Unless the mass-to-light ratio of the galaxy is at least 80 times larger than usual, the lensing hypothesis requires that the galaxy group or cluster plays a uniquely important role in producing the observed deflections. Based on observations performed with the Very Large Telescope at the European Southern Observatory, Paranal, Chile.Comment: 12 pages, accepted by ApJ 2005, May 1

CTQ 414: A New Gravitational Lens

We report the discovery and ground based observations of the new gravitational lens CTQ 414. The source quasar lies at a redshift of z = 1.29 with a B magnitude of 17.6. Ground based optical imaging reveals two point sources separated by 1.2 arcsec with a magnitude difference of roughly 1 mag. Subtraction of two stellar point spread functions from images obtained in subarcsecond seeing consistently leaves behind a faint, residual object. Fits for two point sources plus an extended object places the fainter object collinear with the two brighter components. Subsequent HST/NICMOS observations have confirmed the identification of the fainter object as the lensing galaxy. VLA observations at 8.46 GHz reveal that all components of the lensing system are radio quiet down to the 0.2 mJy flux level.Comment: Latex, 18 pages including 2 ps figures; accepted for publication in A

CTQ 839: Candidate for the Smallest Projected Separation Binary Quasar

We report the discovery of the new double quasar CTQ 839. This B = 18.3, radio quiet quasar pair is separated by 2.1" in BRIH filters with magnitude differences of delta m_B = 2.5, delta m_R = delta m_I = 1.9, and delta m_H = 2.3. Spectral observations reveal both components to be z = 2.24 quasars, with relative redshifts that agree at the 100 km/s level, but exhibit pronounced differences in the equivalent widths of related emission features, as well as an enhancement of blue continuum flux in the brighter component longward of the Ly alpha emission feature. In general, similar redshift double quasars can be the result of a physical binary pair, or a single quasar multiply imaged by gravitational lensing. Empirical PSF subtraction of R and H band images of CTQ 839 reveal no indication of a lensing galaxy, and place a detection limit of R = 22.5 and H = 17.4 for a third component in the system. For an Einstein-de Sitter cosmology and SIS model, the R band detection limit constrains the characteristics of any lensing galaxy to z_lens >= 1 with a corresponding luminosity of L >~ 5 L_*, while an analysis based on the redshift probability distribution for the lensing galaxy argues against the existence of a z_lens >~ 1 lens at the 2 sigma level. A similar analysis for a Lambda dominated cosmology, however, does not significantly constrain the existence of any lensing galaxy. The broadband flux differences, spectral dissimilarities, and failure to detect a lensing galaxy make the lensing hypothesis for CTQ 839 unlikely. The similar redshifts of the two components would then argue for a physical quasar binary. At a projected separation of 8.3/h kpc (Omega_matter = 1), CTQ 839 would be the smallest projected separation binary quasar currently known.Comment: Latex, 23 pages including 5 ps figures; accepted for publication in A

ACUTE DESTRUCTION BY HUMORAL ANTIBODY OF RAT SKIN GRAFTED TO MICE : THE ROLE OF COMPLEMENT AND POLYMORPHONUCLEAR LEUKOCYTES

A study has been made of the roles played by complement and polymorphonuclear leukocytes (PMN) in the acute destruction of xenografts of rat skin that follows injection of their hosts with antisera specifically reactive with graft antigens. The rat skin was grafted onto mice whose immune responses were suppressed by removal of the thymus and a brief course of treatment with rabbit antimouse lymphocyte serum. At about 2 wk after grafting the mice were injected intravenously or intraperitoneally with mouse antirat serum (MARS). This time interval was chosen because it avoided the complications that might be associated with either the process of healing in or with incipient rejection. Signs of graft damage were evident as early as 10 min after the injection of MARS, and in most animals so injected the grafts were completely destroyed within 24–48 h. The role of complement (C) in this acute destructive process is indicated by the results of three lines of experimentation. (a) Non-C-fixing antibodies or antibody fragments failed to cause damage to the grafts. Indeed, both chicken antirat serum and F(ab')2 fragments from rabbit antirat serum completely protected the grafts against the effects of MARS that was administered 24 h later. (b) When mice were depleted of hemolytic C by treatment with cobra venom factor or heat-aggregated gamma globulin, the damage caused by MARS was greatly reduced or completely inhibited. (c) In mice with a genetically determined absence of C5 much greater quantities of MARS were required to cause graft damage; the tempo of the destructive process was consistently slower; and a greater number of grafts recovered from the initial inflammatory process than was the case for animals with an intact complement system. The participation of PMN in serum-mediated destruction of grafts was initially suggested by the results of microscope examination of fixed tissues. The essential role of these cells in the process is indicated by the failure of MARS to cause tissue damage in mice whose circulating PMN have been reduced to very low levels by treatment with nitrogen mustard or more specifically with an anti-PMN serum. The absence of tissue damage when circulating PMN are reduced but C levels are normal suggests that C-mediated cytolysis is unimportant in graft destruction and that the role of C lies in its ability to generate chemotactic factors. The latter may then attract the PMN that provide mediators of tissue damage