Poole-Frenkel Effect and Phonon-Assisted Tunneling in GaAs Nanowires

We present electronic transport measurements of GaAs nanowires grown by catalyst-free metal-organic chemical vapor deposition. Despite the nanowires being doped with a relatively high concentration of substitutional impurities, we find them inordinately resistive. By measuring sufficiently high aspect-ratio nanowires individually in situ, we decouple the role of the contacts and show that this semi-insulating electrical behavior is the result of trap-mediated carrier transport. We observe Poole-Frenkel transport that crosses over to phonon-assisted tunneling at higher fields, with a tunneling time found to depend predominantly on fundamental physical constants as predicted by theory. By using in situ electron beam irradiation of individual nanowires we probe the nanowire electronic transport when free carriers are made available, thus revealing the nature of the contacts

Issues Complicating Rights of Spouses, Parents, and Children to Sue For Wrongful Death

There are two types of wrongful death statutes, the personal representative type, and the beneficiary type. With the personal representative type, the action is brought by the personal representative of the deceased on behalf of all persons statutorily eligible to benefit from the action. In the beneficiary type of statute, the statutorily authorized beneficiaries are joined together and bring the action in their own names. Irrespective of the type of statute, the statutes seem to name clearly the persons who are acceptable beneficiaries. These beneficiaries, at a minimum, include spouses, parents and children. The difficult issues arise when the plaintiff does not exactly fall within the statutory defined class of acceptable beneficiaries (e.g. common law spouses, or illegitimate children). The balance of this paper discusses spouses, parents and children as acceptable beneficiaries within the outer limits of the context of wrongful death statutes

Uninsured Motorist Insurance Now Covers Punitive Award - Hutchinson v. J.C. Penny Casualty Insurance Company

A split of authority exists among the few states which have decided the issue In jurisdictions permitting recovery of punitive damages, uninsured motorist coverage is intended to place the insurer in the shoes of the uninsured tortfeasor. Since the insurer stands in the shoes of the tortfeasor, and since punitive damages could be covered if the tortfeasor had his own insurance, it is illogical to deny the victim punitive damages simply because the tortfeasor is uninsured. Other jurisdictions believe that punitive damages should not be awarded since that award would not operate to punish the tortfeasor and would therefore violate public policy. In Hutchinson v. J.C Penney Casualty Insurance Company, the Ohio Supreme Court held that such recovery is permissible and does not violate public policy

Use of Highway Culverts, Box Bridges, and Caves by Winter-Roosting Bats in Mississippi

White-nose Syndrome (WNS) has caused declines in bat populations in many areas of North America. To understand bat use and fungus presence in caves and culverts in Mississippi, I recorded bat species and abundance in these sites, roosting site characteristics, and incidence of WNS in selected caves and culverts used by bats. Sixteen caves and 214 culverts were surveyed from November-March 2010-2015. Five bat species were detected, and tricolor bats (Perimyotis subflavus) and southeastern myotis (Myotis austroriparius) were most abundant. Over five years, 3,789 roosting bats were recorded in caves and 16,812 were detected in culverts. I found significant relationships between bat numbers in culverts and microclimate conditions, dimensions, and proximity to public lands (P \u3c 0.03). This study can help biologists with prioritization of protection and monitoring of culvert and cave roost sites and provide a greater understanding WNS incidence in these sites

Fish growth responses to a changing environment: effects of aquatic nuisance species and environmental conditons in a shallow, eutrophic lake

Growth rates of fish may vary in response to changing environmental conditions and presence of aquatic nuisance species (ANS). Two ANS, common carp and zebra mussels, are present in Clear Lake, Iowa, and may affect growth rates of fish along with other environmental factors. We (1) documented annual growth rates of four fish species in their first year of life and at maturity in Clear Lake, (2) examined relationships of growth with environmental factors, and (3) compared contemporary growth to previous studies. Age-0 black bullhead, common carp, walleye and yellow bass showed a significant, positive relationship with common carp commercial harvest in the previous year and annual number of degree days where water was above 5oC. Chlorophyll a concentration showed a positive relationship with age-0 growth of common carp and yellow bass. Age-0 black bullhead growth was positively related with zooplankton concentration and common carp and yellow bass were negatively related. We saw no significant relationships between environmental variables and annual growth at length-at-maturity. Black bullheads grew similarly in 1955 and this study, but showed slower growth in 1999. Common carp were growing substantially faster in 1952 than in 1999 and the present. Walleye mean length-at-age data collected in this study was similar to the mean length-at-age data recorded in the two historical studies. In the 1940\u27s, yellow bass were growing substantially faster than in the 1960\u27s and currently. Our results demonstrate that growth of all four species has changed over time, that growth varies in response to environmental factors and ANS, and that continued management of common carp by removal may result in faster growth early in the life cycle of several fish species in Clear Lake

Effizienzerhöhung in der Kultivierung von Mikroalgen – Prozessoptimierung und Bioreaktorentwicklung

Mit dem in dieser Arbeit vorgestellten Photobioreaktor sollen die Nachteile der klassischen Photobioreaktortypen umgangen und eine Möglichkeit der ökonomischen Produktion von Mikroalgenbiomasse geschaffen werden. Durch die Zick-Zack-Struktur der Oberfläche des hier behandelten Horizontalreaktors soll die Lichtenergie auf moderate Level verdünnt werden, so dass die Mikroalgen keinen inhibierenden Strahlungsintensitäten ausgesetzt sind und die Energie effizient umsetzen können. Zur Validierung dieser Behauptung wurde eine Simulation der Energieeinträge auf der Oberfläche des Zick-Zack-Reaktors durchgeführt. Als Vergleich wurde eine Simulation einer Freiland-Kultivierung in einem Plattenreaktor herangezogen, die mit empirisch bestimmten Daten belegt wurde. Die Basis für diese Simulationen bildeten in Labor-Reaktoren ermittelte Zeitkonstanten des Chlorophyllgehalts der Mikroalgen in Abhängigkeit der Photonenflussdichte sowie eine Regression des Absorptionskoeffizienten bei adaptierten Lichtintensitäten und Chlorophyllanteilen. Neben der Lichtverteilung im Photobioreaktor ist der Stofftransport, genauer die CO2-Versorgung und O2-Abreicherung, ein wichtiger Faktor zur Produktivitätssteigerung. Zur Auslegung der Begasung des Reaktors wurden zunächst empirisch volumetrische Stoffübergangskoeffizienten der im Reaktor integrierten Oberflächenbegasung ermittelt und der Stofftransport in einer CFD-Simulation modelliert. Ausgehend von diesen Erkenntnissen wurden Membrankontaktoren über fundierte Transportgleichungen ausgelegt und in das System integriert

Experimental demonstration of the microscopic origin of circular dichroism in two-dimensional metamaterials

Optical activity and circular dichroism are fascinating physical phenomena originating from the interaction of light with chiral molecules or other nano objects lacking mirror symmetries in three-dimensional (3D) space. While chiral optical properties are weak in most of naturally occurring materials, they can be engineered and significantly enhanced in synthetic optical media known as chiral metamaterials, where the spatial symmetry of their building blocks is broken on a nanoscale. Although originally discovered in 3D structures, circular dichroism can also emerge in a two-dimensional (2D) metasurface. The origin of the resulting circular dichroism is rather subtle, and is related to non-radiative (Ohmic) dissipation of the constituent metamolecules. Because such dissipation occurs on a nanoscale, this effect has never been experimentally probed and visualized. Using a suite of recently developed nanoscale-measurement tools, we establish that the circular dichroism in a nanostructured metasurface occurs due to handedness-dependent Ohmic heating.ope

Fish growth changes over time in a Midwestern USA lake

Growth of Walleye Sander vitreus, Yellow Bass Morone mississippiensis, Common Carp Cyprinus carpio, and Black Bullhead Ameiurus melas was assessed in Clear Lake, Iowa, USA, over several decades and in relation to environmental variables. Growth of Common Carp was positively correlated with phytoplankton concentration. Recent Black Bullhead growth was faster than in the 1950s and 1990s, which may be a consequence of their recent decline in abundance. Growth of Common Carp and Yellow Bass was faster in the 1940s than in more recent time periods. Relative to their entire range, Common Carp first year growth was below average whereas length at later ages was above average. Walleye relative growth showed a similar pattern. The large changes in growth over several decades suggest that as the Clear Lake ecosystem continues to change, growth rates of its important fish species are also likely to continue changing

Dredging activity and associated sound have negligible effects on adult Atlantic sturgeon migration to spawning habitat in a large coastal river

Dredging is considered a major threat/impedance to anadromous fish migrating to spawning habitat. Due to the perceived threat caused by dredging, environmental windows that restrict dredge operations are enforced within many rivers along the east coast. However, it is generally unknown how anadromous fish react to encountering an active dredge during spawning migrations. Atlantic sturgeon (ATS) are an endangered, anadromous species along the Atlantic slope of North America. To determine if and how an active dredge may affect ATS spawning migration, a Vemco Positioning System array was deployed around an active hydraulic-cutterhead dredge that adult ATS must traverse to reach spawning habitat in the James River, VA. Telemetry data showed that all ATS that entered the study area survived. ATS that migrated upstream during dredge operations (N = 103) traversed the dredge area and continued upstream to spawning habitat. Many ATS made multiple trips through the study area during dredge operations. There was no noticeable difference in swim behavior regardless of whether the dredge was absent or working within the study area. We suggest that dredging in the lower James River does not create a barrier for adult ATS migrating to spawning habitat or cause adults to significantly modify swim behavior. This is the first study to utilize fine-scale telemetry data to describe how an organism moves in relation to an active dredge. This methodology could be used to describe dredge-sturgeon interactions on different life stages and in other locations and could be expanded to other aquatic organisms of concern