Kaskaskia College

A thin viscous accretion disc around a Kerr black hole, which is warped due to the Lense-Thirring (LT) effect, was shown to cause the spin axis of the black hole to precess and align with the outer disc. We calculate the total LT torque acting on the black hole, and compute the alignment and precession time-scales for both persistent and transient accretors. In our analysis, we consider the contribution of the inner disc, as it can stay misaligned with the black hole spin for a reasonable range of parameter values. We find that the alignment time-scale increases with a decrease in the Kerr parameter below a critical Kerr parameter value, contrary to earlier predictions. Besides, the time-scales are generally longer for transience than the time-scales calculated for persistent accretion. From our analysis of the transient case, we find that the black hole in the low mass X-ray binary (LMXB) 4U 1543-47 could be misaligned, whereas that in the LMXB XTE J1550-564 has aligned itself with the outer disc. The age of the LMXB H 1743-322 is estimated assuming a misaligned disc. We also find that the black hole in a typical Galactic LMXB can take a significantly longer time to align than what was estimated in the past. This may have an important implication on the measurement of black hole spin using the continuum X-ray spectral fitting method.

Abstract Communities of organisms are shaped by a complex suite of positive and negative species interactions. Ecological phenomena like biological invasions typically evoke notions of negative effects on native communities. Yet, negative effects within specific food‐web components can also have positive feedbacks that manifest elsewhere within the food web. We designed an experiment to evaluate the direct and indirect effects of invasive bighead carp (Hypophthalmichthys nobilis: Cyprinidae) on planktonic and benthic invertebrates and the growth and survival of juvenile bluegill sunfish (Lepomis macrochirus: Centrarchidae). Our experiment indicated that the presence of bighead carp indirectly facilitated bluegill growth and survival. The underlying processes driving predator–predator facilitation stemmed from a combination of indirect interactions occurring through invertebrates in planktonic and vegetated habitats. Individual bluegill consumed more cladocerans and predatory macroinvertebrates in the presence of bighead carp. The presence of bighead carp appears to have indirectly influenced interactions among cladocerans, invertebrate predators, and bluegill. Understanding the cumulative direct and indirect effects of bigheaded carp on aquatic ecosystems requires the documentation of both negative and positive effects. Although one taxon benefitted from the presence of an invader, our findings demonstrate that this response occurred because bigheaded carp caused imbalances within the food web. We urge that future studies consider a priori how positive and negative interspecific interactions shape the structure of food webs.

Abstract Muskellunge Esox masquinongy are broadly distributed across the northern United States and southern Canada. Intraspecific genetic variation suggests the existence of divergent stocks related to residence in major river drainages. Populations and stocks have likely adapted to specific environmental conditions associated with geographic location, especially latitude and the associated thermal regime. In this study, we examined differences in survival and growth among stocks of juvenile Muskellunge stocked into lakes throughout Illinois. Muskellunge from the Ohio River drainage stock, the upper Mississippi River drainage stock, and the current mixed Illinois broodstock were used for comparisons. Stocking mortality was related to temperature and was greatest for Illinois and Ohio River drainage fish that were stocked during the early fall. Mississippi River drainage fish experienced high mortality over the first summer after stocking, resulting in the lowest abundance during the second fall poststocking. In addition to low catch rates, Muskellunge from the Mississippi River drainage were significantly smaller than fish from the Illinois and Ohio River drainage stocks by the second fall. Populations from similar latitudes and climate (Illinois and Ohio) performed the best in terms of survival and growth and should be utilized in future stockings. Received October 7, 2016; accepted March 15, 2017 Published online May 4, 2017

Abstract Permafrost dynamics play an important role in high‐latitude peatland carbon balance and are key to understanding the future response of soil carbon stocks. Permafrost aggradation can control the magnitude of the carbon feedback in peatlands through effects on peat properties. We compiled peatland plant macrofossil records for the northern permafrost zone (515 cores from 280 sites) and classified samples by vegetation type and environmental class (fen, bog, tundra and boreal permafrost, and thawed permafrost). We examined differences in peat properties (bulk density, carbon (C), nitrogen (N) and organic matter content, and C/N ratio) and C accumulation rates among vegetation types and environmental classes. Consequences of permafrost aggradation differed between boreal and tundra biomes, including differences in vegetation composition, C/N ratios, and N content. The vegetation composition of tundra permafrost peatlands was similar to permafrost‐free fens, while boreal permafrost peatlands more closely resembled permafrost‐free bogs. Nitrogen content in boreal permafrost and thawed permafrost peatlands was significantly lower than in permafrost‐free bogs despite similar vegetation types (0.9% versus 1.5% N). Median long‐term C accumulation rates were higher in fens (23 g C m−2 yr−1) than in permafrost‐free bogs (18 g C m−2 yr−1) and were lowest in boreal permafrost peatlands (14 g C m−2 yr−1). The plant macrofossil record demonstrated transitions from fens to bogs to permafrost peatlands, bogs to fens, permafrost aggradation within fens, and permafrost thaw and reaggradation. Using data synthesis, we have identified predominant peatland successional pathways, changes in vegetation type, peat properties, and C accumulation rates associated with permafrost aggradation.

The present experiment was conducted to evaluate the effect of α-tocopherol as an antioxidant for avoiding the side effects of incorporation of cottonseed meal (CSM) in the diet of the Nile tilapia as a replacer of fish meal (FM). Twodiets were prepared; the first one contained fish meal and was considered as a control, in the second diet, FM was completely replaced by CSM. The second diet was divided into ten parts, the first one is a control and the other 9 diets were enriched with increased levels of vitamin E (1, 5, 10, 15, 20, 25, 30, 35 and 40 times of gossypol in CSM). Each diet was offered in three aquaria (3 replicates for each diet) and each aquarium was stocked with 25 fish (2.0-2.1g). Results are summarized in the following:- The highest average body weight (9.91 g) was recorded for the control group fed on thebasal diet (contained FM) and the lowest BW (5.66 g) was obtained for fish fed the dietD2 in which FM was completely replaced by CSM without vitamin E. Incorporation ofvitamin E in the experimental diet significantly improved the BW. Similar trend wasobserved for the other growth performance parameters body length (BL), weight gain(WG) and specific growth rate (SGR).- The best feed conversion ratio (FCR) was recorded for fish group fed on the diets D1and D3 which significantly differed from values recorded for the other treatments. Theworst FCR was recorded in fish group fed on the diet D2 in which FM was completelyreplaced by CSM without addition of vitamin E. Incorporation of vitamin E in theexperimental diets improved FCR specially fish group fed on the diet D3.- Protein content of the whole fish body ranged between 41.33 to 50.97% and thedifferences were significant. Fat content of fish fed the diet D2 significantly higherthan those obtained for fish fed the other groups. Compared to the two control dietsD1 and D2 all vitamin levels in the experimental diets increased ash content of thefish whole body and the graded levels of vitamin E in the diets significantly alteredthe ash content of tilapia fish.- The highest values for hematocrite (Ht) and haemoglobin (Hb) were obtained forfish fed on the control diet (D1). Incorporation of vitamin E in the experimentaldiets at increasing levels significantly affected Hb and Ht. Compared to thecontrol group (Diet1) aspartate transaminase (AST) and alanine transaminase(ALT) levels significantly increased fish groups fed on the other experimentaldiets.

ABSTRACT Full-time and part-time psychology faculty at 100 publicly-supported community colleges in 4 midwestern states were surveyed to determine their use of computer-assisted instruction (CAI). Attitudes about CAI and faculty access and availability of computers for classroom and personal use were also determined. Of the respondents, 97% had computers either in their office or at home. Overall, 60% reported using CAI, which included 69% of full-time and 51% of part-time instructors. The dominant teaching methods utilized were lecture and discussion with computers as the 7th most prevalent teaching technique.

Kaweski, Susan M.D. the Plastic Surgery Educational Foundation DATA Committee Author Information