Second fundamental form of the Prym map in the ramified case

In this paper we study the second fundamental form of the Prym map $P_{g,r}: R_{g,r} \rightarrow {\mathcal A}^{\delta}_{g-1+r}$ in the ramified case $r>0$. We give an expression of it in terms of the second fundamental form of the Torelli map of the covering curves. We use this expression to give an upper bound for the dimension of a germ of a totally geodesic submanifold, and hence of a Shimura subvariety of ${\mathcal A}^{\delta}_{g-1+r}$, contained in the Prym locus.Comment: To appear in Galois Covers, Grothendieck-Teichmueller Theory and Dessins d'Enfants - Interactions between Geometry, Topology, Number Theory and Algebra. Springer Proceedings in Mathematics & Statistics. arXiv admin note: text overlap with arXiv:1711.0342

DEMOGRAPHICS AND THE ECOLOGICAL ROLE OF THE CHANNEL CATFISH (ICTALURUS PUNCTATUS) IN COMMERCIALLY EXPLOITED AND UNEXPLOITED REACHES OF THE WABASH RIVER WITH IMPLICATIONS FOR THE FLATHEAD CATFISH (PYLODICTIS OLIVARIS)

Catfish are a major component of the Wabash River fish assemblage and are commercially fished below river kilometer (Rkm) 500. From Rkm 322 through 499 the commercial fishery is subjected only to Indiana fishing regulations. In this reach of river, there is a 254-mm minimum total length limit on both sport and commercially harvested catfish. Below RM 322, the Wabash River forms the state boundary of Indiana and Illinois. In this region of river there are two different length limits on commercially harvested catfish with Indiana having a 254-mm length limit and Illinois having a 381-mm length limit. There is no length limit on sport harvest of catfish by Illinois anglers; however, there is a 254-mm length limit on the Indiana sport fishers. The primary objective of this study was to assess the general population dynamics of the channel catfish (Ictalurus punctatus) under various sport and commercial fishing regulations and to determine the sources of energy for this species. To accomplish this, I sampled both fished (IN, IN & IL) and unfished (NON) treatment reaches of the Wabash River during fall 2001 through 2004 using three-phase alternating current (AC) electrofishing and cheese baited, 25-mm and 32-mm bar-mesh hoop nets. Of the 2,807 catfish collected, 91% were channel, 8% were flathead (Pylodictis olivaris) and 1% were blue catfish (I.furcatus). Length frequency distributions and mean age of fish differed across the three different gear types (P \u3c 0.02), with electrofishing sampling larger, older channel catfish. Densities estimated from catch per unit effort (CPUE) did not differ among treatment reaches (NON, IN, IN & IL) using hoop nets (25-mm: P \u3c 0.1, 32-mm: P = 0.4); however, electrofishing CPUE was greater in the unfished reach compared to the two commercially exploited reaches (P \u3c 0.001). Additionally, length frequency distributions and stock indices differed among treatment reaches (P = 0.017). As suggested by the high relative stock density of preferred length fish (RSD-P) values, more large catfish resided in the unfished reach than the fished reaches. Age structure also varied among reaches. More old fish were in the commercially unexploited treatment reach, leading to greater mean age (P \u3c 0.005). Ages derived from the articulating process of the pectoral spine agreed well with those determined from the sagittal otolith. Mortality estimated from the slope of the regression of age on Log10 frequency (catch curve) was greater for both gear types in the commercially exploited reaches than in the non exploited reach. Mean length at age 5 and condition of channel catfish was greater in the commercially exploited reaches than the unexploited reach. There was a positive relationship between channel catfish electrofishing CPUE and habitat quality as measured by the qualitative habitat assessment index (QHEI). Yield-per-recruit modeling of the commercially exploited river reaches predicted that at the current level of harvest the channel catfish fishery is sustainable; however, if both states adopted a 254-mm length limit and fishing mortality increased both growth and recruitment overfishing would likely occur even at fairly low levels of harvest (30% fishing mortality). Yield-per-recruit modeling of the flathead catfish population suggested this population was not sustainable at any of the length limits modeled. Based on stable isotope analysis of δ13C and δ15N, channel catfish did not differ in their trophic status among the treatment reaches, and the structures of the food webs among reaches were similar. These results provide additional support to the hypothesis that growth and condition are functions of density. The results of this study suggest that a harvest reserve in a large river acts similarly to marine reserves, in that density increases on the reserve lead to decreased growth and condition of individuals on the reserve

Reproductive Demographics and Early Life History of the Shovelnose Sturgeon (SCAPHIRHYNCHUS PLATORYNCHUS)

Due to the collapse of the historic caviar fisheries in the Volga River and Caspian Sea, the demand on domestically produced caviar has increased. To supply the increased demand, the harvest of the shovelnose sturgeon Scaphirhynchus latorynchus has increased. Because caviar fisheries preferentially harvest females, information regardingthe sexual demographics of these populations is essential for effective fisheries management. To date, knowledge regarding the sex ratios and reproductive development of the shovelnose sturgeon population in the Middle Mississippi River is lacking. In Chapter 1, I describe this problem in detail and in subsequent chapters I explain how I addressed this problem using a combination of field and laboratory techniques. The shovelnose sturgeon and other acipenserids have no known sexually dimorphic traits, making field identification of sex difficult. Thus, in Chapter 2, I developed a non-surgical method for the determination of sex of shovelnose sturgeon. Ultrasound imaging was used to determine the sex of shovelnose sturgeon (n=51). Overall, ultrasound imaging provided an effective method for determining sex, with 86% correct identification of all individuals examined. Ultrasound was ineffective at determining the sex of post spawn females, with 60% being incorrectly identified as males. This method would allow managers to quickly identify sex in the field so that the sex ratio of the shovelnose sturgeon populations could be tracked and population dynamics can be modeled. Understanding of the sequence of gonadal development allows for the determination of spawning stock size in a given year. This information is currently lacking for the shovelnose sturgeon. To address this, I developed a guide for shovelnose sturgeon reproductive development in Chapter 3. Shovelnose sturgeon were sampled seasonally from the Middle Mississippi River to account for all stages of reproductivedevelopment. I found that stages of gonadal development of the shovelnose sturgeon were both grossly and histologically similar to those of other sturgeon species. This sample allowed me to estimate the sex ratio in the population using an unbiased approach. The shovelnose sturgeon population in the MMR did not differ from 1: 1. The shovelnose sturgeon has been extirpated from several portions of its historic range. Conservation aquaculture can be used to reestablish shovelnose sturgeon populations to these regions. This requires detailed information about early life history which is currently unavailable. In Chapter 4, I described the stages of development of embryonic and larval shovelnose sturgeon to resolve this issue, giving culturists the ability to track the development of their spawn using proper development as an indicator of success. Additionally, otoliths provide little use in determining hatch date in the acipenserids. Using this information, managers will be able to determine hatch date using stage of development and river temperature

Use of Ultrasound Imaging to Determine Sex of Shovelnose Sturgeon

During November 2002, 51 shovelnose sturgeon Scaphirhynchus platorynchus were sexed by ultrasound imaging using a portable ultrasonograph. We identified males with 96% accuracy (N = 25) and females with 80% accuracy (N = 25); one hermaphroditic individual was misidentified as a male. Overall, ultrasound imaging was 86% accurate. Sex in postspawned females was difficult to determine, 60% being misidentified as males (N = 5). Ultrasonography is an effective noninvasive method for sex determination that can be applied to other species of Acipenseriformes. Modern portable equipment expands its utility to field studies

Declining Recruitment and Growth of Shovelnose Sturgeon in the Middle Mississippi River: Implications for Conservation

To determine how populations of shovelnose sturgeon Scaphirhynchus platorynchus are changing and may respond to poor environmental conditions, current commercial harvest of black-egg (sexually mature) females, and incidental mortality of males, we require annual information about sex-specific age structure as it relates to the recruitment of new cohorts. We sampled shovelnose sturgeon by use of gill nets (5-cm bar mesh) monthly during 2002-2006 in the Middle Mississippi River between Cairo, Illinois, and St. Louis, Missouri. We compared patterns of size and age structure over time and projected age structure and population size into the future. Sex ratio in 2005-2006 was 1.14:1.00 (416 males and 363 females; P = 0.06), deviating from the 1:1 ratio that occurred in 2002-2003. Annual mortality increased from 37% in 2002-2003 to 44% by 2005-2006. Female shovelnose sturgeon were larger than males. Across years, the population shifted toward longer, older fish, and growth in length declined. Recruitment declined through time (29% per year). If these trends continue and if immigration from nonharvested populations is limited, population density may decline by an order of magnitude within one decade. Under current conditions, resilience to harvest and environmental perturbations is probably limited

Maturation and Reproduction of Shovelnose Sturgeon in the Middle Mississippi River

Shovelnose sturgeon Scaphirhynchus platorynchus in the middle Mississippi River provide one of the last commercially viable sturgeon fisheries in the world, yet their maturation and reproduction have not been linked. During 2005 and 2006, we sampled adult and age-0 shovelnose sturgeon to link age at maturation, the timing and periodicity of spawning, age-0 sturgeon production, and the resulting age-0 growth rates. Age at maturity was later than previous estimates, the minimum age of first maturation being 8 years for males and 9 years for females. Total egg count was slightly lower than previously reported (mean = 29,573 per female; SE = 2,472). Males and females typically spawned every 2 and 3 years, respectively. Peaks in mature fish coincided with rising river stages and water temperatures at which shovelnose sturgeon probably spawn. Peaks in spent adults followed. Age-0 shovelnose sturgeon occurred during June and July 2005 and May and June 2006, confirming successful spawning. Age-0 sturgeon grew between 0.69 and 1.69 mm total length/d; four distinct weekly cohorts occurred each year. During fall 2006, females contained ripe eggs, males were milting, and a single age-0 sturgeon (total length = 55 mm) was captured, suggesting that shovelnose sturgeon spawn during fall as well as spring. Management must consider the protracted nature of spawning within seasons as well as differences in spawning activity between seasons

DNA Methylation Differs in Bluegill Among Temperate, Anthropogenically Warmed, and Tropical Lakes

Epigenetic mechanisms can alter gene expression and phenotypes in organisms responding to environmental changes. Within environmental parameters, temperature changes are notably the most pervasive abiotic factor for ectotherms, directly affecting organismal survival and fitness. The goal of this study was to investigate the scale of DNA methylation in populations of a cosmopolitan freshwater species occupying disparate thermal regimes. DNA methylation levels were compared among bluegill sunfish (Lepomis macrochirus) populations from an ambient temperature, temperate lake (Lake Mattoon), a nearby power plant-cooling lake (Lake Coffeen), and a tropical lake (Lake Lucchetti). We used epiRADseq to screen levels of DNA methylation at 105,811 loci among fish. We found levels of total DNA methylation increased among specimens as water temperature of lakes increased from the ambient temperature, temperate lake to the tropical lake. We identified loci with statistically significant differences in the frequency of DNA methylation among individuals between lakes: 654 loci between Lake Mattoon and Lake Lucchetti fish and 373 loci between Lake Coffeen and Lake Lucchetti fish. Considering that a previous study on the same power plant-cooling reservoirs showed a shorter lifespan, decrease in growth performance, and the populations skewed towards younger fish, this study observed DNA methylation pattern may be an important mechanism contributing to the observed phenotypic variations in bluegill from a anthropogenically-warmed lake compared to an ambient temperature lake. Our study suggests that epigenetic regulation of phenotypic plasticity in aquatic organisms may be a critical factor in understanding the organismal response to environmental stress

Behavioral profiling of multiple pairs of rats selectively bred for high and low alcohol intake using the MCSF test

Genetic aspects of alcoholism have been modeled using rats selectively bred for extremes of alcohol preference and voluntary alcohol intake. These lines show similar alcohol drinking phenotypes but have different genetic and environmental backgrounds and may therefore display diverse behavioral traits as seen in human alcoholics. The multivariate concentric square field™ (MCSF) test is designed to provoke exploration and behaviors associated with risk assessment, risk taking and shelter seeking in a novel environment. The aim was to use the MCSF to characterize behavioral profiles in rat lines from selective breeding programs in the United States (P/NP, HAD1/LAD1, HAD2/LAD2), Italy (sP/sNP) and Finland (AA/ANA). The open field and elevated plus maze tests were used as reference tests. There were substantial differences within some of the pairs of selectively bred rat lines as well as between all alcohol-preferring rats. The most pronounced differences within the pairs of lines were between AA and ANA rats and between sP and sNP rats followed by intermediate differences between P and NP rats and minor differences comparing HAD and LAD rats. Among all preferring lines, P, HAD1 and HAD2 rats shared similar behavioral profiles, while AA and sP rats were quite different from each other and the others. No single trait appeared to form a common 'pathway' associated with a high alcohol drinking phenotype among all of the alcohol-preferring lines of rats. The marked behavioral differences found in the different alcohol-preferring lines may mimic the heterogeneity observed among human alcoholic subtypes

Gear-Specific Population Demographics of Channel Catfish in a Large Midwestern River

Various gear types have been used to sample populations of channel catfish Ictalurus punctatus in lotic systems. However, these gears produce different population characteristics (i.e., recruitment, growth, and mortality). We compared the population demographics of channel catfish in the Wabash River, Indiana, sampled with baited 25- and 32-mm-bar mesh hoop nets and three-phase alternating current (AC) electrofishing. Based on catch per unit effort, the relative abundance of channel catfish sampled with 32-mm hoop nets was lower than that of fish sampled with 25-mm hoop nets and AC electrofishing. Each gear type also resulted in a different length frequency, mean length increasing progressively in sampling with 25-mm hoop nets, 32-mm hoop nets, and AC electrofishing. Similarly, age-frequency distributions differed among gears. The 25-mm hoop nets biased the age structure toward younger individuals (mean age = 2.5), whereas both 32-mm hoop nets (mean age = 4.0) and AC electrofishing (mean age = 5.8) included older fish. Catch-curve analysis generated different mortality rates for the three gear types, the mortality rate being highest (50%) in fish sampled with 25-mm hoop nets. Gear-specific size and age structures led to differences in von Bertalanffy statistics among the 25-mm hoop nets and AC electrofishing, while the results for 32-mm hoop nets were uninterpretable. Because the different gears led to conflicting parameter estimates, management practices based on sampling with single gears may be contradictory. Given the differences in gear selectivity, biologists need to approach management cautiously until calibration to the true size and age structure is conducted

A randomized comparison of a sirolimus-eluting stent with a standard stent for coronary revascularization

BACKGROUND: The need for repeated treatment of restenosis of a treated vessel remains the main limitation of percutaneous coronary revascularization. Because sirolimus (rapamycin) inhibits the proliferation of lymphocytes and smooth-muscle cells, we compared a sirolimus-eluting stent with a standard uncoated stent in patients with angina pectoris. METHODS: We performed a randomized, double-blind trial to compare the two types of stents for revascularization of single, primary lesions in native coronary arteries. The trial included 238 patients at 19 medical centers. The primary end point was in-stent late luminal loss (the difference between the minimal luminal diameter immediately after the procedure and the diameter at six months). Secondary end points included the percentage of in-stent stenosis of the luminal diameter and the rate of restenosis (luminal narrowing of 50 percent or more). We also analyzed a composite clinical end point consisting of death, myocardial infarction, and percutaneous or surgical revascularization at 1, 6, and 12 months. RESULTS: At six months, the degree of neointimal proliferation, manifested as the mean (+/-SD) late luminal loss, was significantly lower in the sirolimus-stent group (-0.01+/-0.33 mm) than in the standard-stent group (0.80+/-0.53 mm, P<0.001). None of the patients in the sirolimus-stent group, as compared with 26.6 percent of those in the standard-stent group, had restenosis of 50 percent or more of the luminal diameter (P<0.001). There were no episodes of stent thrombosis. During a follow-up period of up to one year, the overall rate of major cardiac events was 5.8 percent in the sirolimus-stent group and 28.8 percent in the standard-stent group (P<0.001). The difference was due entirely to a higher rate of revascularization of the target vessel in the standard-stent group. CONCLUSIONS: As compared with a standard coronary stent, a sirolimus-eluting stent shows considerable promise for the prevention of neointimal proliferation, restenosis, and associated clinical events