HYDROLOGIC EVALUATION OF RESIDENTIAL RAIN GARDENS USING A STORMWATER RUNOFF SIMULATOR

Engineered bioretention cells with underdrains have shown water quality and hydrologic benefits for abating urban stormwater problems. Less is known about the hydrologic performance of residential rain gardens that rely on in situ soil infiltration as the primary mechanism of volume control. Eleven residential rain gardens in Lincoln, Nebraska, were evaluated using a variable-rate stormwater runoff simulator. A volume-based water quality volume (WQV) design storm of 3.0 cm was applied to each rain garden as an SCS Type II runoff hydrograph until the system began overflowing to test the rain gardens for surface and subsurface storage capacity, drawdown rate, ponding depth, and overflow characteristics. Every rain garden tested drained in 30 h or less, with six gardens draining in less than 1 h. Rain garden surface storage capacity was poor, retaining on average only 16% of the WQV. On average, the rain gardens studied could store and infiltrate only 40% of the WQV, with only two gardens able to store and infiltrate greater than 90% of the WQV. On average, 59% of the runoff was captured as subsurface storage. Results of this study indicate that these 2- to 4-year-old rain gardens are limited not by drain times and rates, which often met or exceeded common design recommendations, but rather by inadequate surface storage characteristics. Extrapolating measured surface storage volumes to hypothetical systems with evenly graded depths of 15.2 cm, a minimum local depth recommendation, resulted in only one garden with enough storage to contain the WQV. On average, the extrapolated storage held only 65% of the WQV. It was shown that subsurface storage can make up for a lack of surface storage; the systems studied herein had an average of 2.7 times more subsurface storage than surface storage as a percentage of inflow volume before overflow began

Prevalence and co-infection of Toxoplasma gondii and Neospora caninum in Apodemus sylvaticus in an area relatively free of cats

The protozoan parasite Toxoplasma gondii is prevalent worldwide and can infect a remarkably wide range of hosts despite felids being the only definitive host. As cats play a major role in transmission to secondary mammalian hosts, the interaction between cats and these hosts should be a major factor determining final prevalence in the secondary host. This study investigates the prevalence of T. gondii in a natural population of Apodemus sylvaticus collected from an area with low cat density (<2·5 cats/km2). A surprisingly high prevalence of 40·78% (95% CI: 34·07%–47·79%) was observed despite this. A comparable level of prevalence was observed in a previously published study using the same approaches where a prevalence of 59% (95% CI: 50·13%–67·87%) was observed in a natural population of Mus domesticus from an area with high cat density (>500 cats/km2). Detection of infected foetuses frompregnant dams in both populations suggests that congenital transmission may enable persistence of infection in the absence of cats. The prevalences of the related parasite, Neospora caninum were found to be low in both populations (A. sylvaticus: 3·39% (95% CI: 0·12%–6·66%); M. domesticus: 3·08% (95% CI: 0·11%–6·05%)). These results suggest that cat density may have a lower than expected effect on final prevalence in these ecosystems

Mobile Criminals, Immobile Crime: The Efficiency of Decentralized Crime Deterrence

In this paper we examine a class of local crimes that involve perfectly mobile criminals, and perfectly immobile criminal opportunities. We focus on local non-rival crime deterrence that is more efficient against criminals pursuing domestic crimes than criminals pursuing crimes elsewhere. In a standard case of sincerely delegated politicians and zero transfers to other districts, we show that centralized deterrence unambiguously dominates the decentralized deterrence. With strategic delegation and voluntary in-kind transfers, the tradeoff is exactly the opposite: Decentralization achieves the social optimum, whereas cooperative centralization overprovides for enforcement. This is robust to various cost-sharing modes. We also examine the effects of the growing interdependence of districts, stemming from criminals' increasing opportunities to strategically displace. Contrary to the supposition in Oates's decentralization theorem, increasing interdependence makes centralization less desirable

Clustering gene expression data with a penalized graph-based metric

<p>Abstract</p> <p>Background</p> <p>The search for cluster structure in microarray datasets is a base problem for the so-called "-omic sciences". A difficult problem in clustering is how to handle data with a manifold structure, i.e. data that is not shaped in the form of compact clouds of points, forming arbitrary shapes or paths embedded in a high-dimensional space, as could be the case of some gene expression datasets.</p> <p>Results</p> <p>In this work we introduce the Penalized k-Nearest-Neighbor-Graph (PKNNG) based metric, a new tool for evaluating distances in such cases. The new metric can be used in combination with most clustering algorithms. The PKNNG metric is based on a two-step procedure: first it constructs the k-Nearest-Neighbor-Graph of the dataset of interest using a low k-value and then it adds edges with a highly penalized weight for connecting the subgraphs produced by the first step. We discuss several possible schemes for connecting the different sub-graphs as well as penalization functions. We show clustering results on several public gene expression datasets and simulated artificial problems to evaluate the behavior of the new metric.</p> <p>Conclusions</p> <p>In all cases the PKNNG metric shows promising clustering results. The use of the PKNNG metric can improve the performance of commonly used pairwise-distance based clustering methods, to the level of more advanced algorithms. A great advantage of the new procedure is that researchers do not need to learn a new method, they can simply compute distances with the PKNNG metric and then, for example, use hierarchical clustering to produce an accurate and highly interpretable dendrogram of their high-dimensional data.</p

Elicitation of Neutralizing Antibodies Directed against CD4-Induced Epitope(s) Using a CD4 Mimetic Cross-Linked to a HIV-1 Envelope Glycoprotein

The identification of HIV-1 envelope glycoprotein (Env) structures that can generate broadly neutralizing antibodies (BNAbs) is pivotal to the development of a successful vaccine against HIV-1 aimed at eliciting effective humoral immune responses. To that end, the production of novel Env structure(s) that might induce BNAbs by presentation of conserved epitopes, which are otherwise occluded, is critical. Here, we focus on a structure that stabilizes Env in a conformation representative of its primary (CD4) receptor-bound state, thereby exposing highly conserved “CD4 induced” (CD4i) epitope(s) known to be important for co-receptor binding and subsequent virus infection. A CD4-mimetic miniprotein, miniCD4 (M64U1-SH), was produced and covalently complexed to recombinant, trimeric gp140 envelope glycoprotein (gp140) using site-specific disulfide linkages. The resulting gp140-miniCD4 (gp140-S-S-M64U1) complex was recognized by CD4i antibodies and the HIV-1 co-receptor, CCR5. The gp140-miniCD4 complex elicited the highest titers of CD4i binding antibodies as well as enhanced neutralizing antibodies against Tier 1 viruses as compared to gp140 protein alone following immunization of rabbits. Neutralization against HIV-27312/V434M and additional serum mapping confirm the specific elicitation of antibodies directed to the CD4i epitope(s). These results demonstrate the utility of structure-based approach in improving immunogenic response against specific region, such as the CD4i epitope(s) here, and its potential role in vaccine application

HYDROLOGIC EVALUATION OF RESIDENTIAL RAIN GARDENS USING A STORMWATER RUNOFF SIMULATOR

Engineered bioretention cells with underdrains have shown water quality and hydrologic benefits for abating urban stormwater problems. Less is known about the hydrologic performance of residential rain gardens that rely on in situ soil infiltration as the primary mechanism of volume control. Eleven residential rain gardens in Lincoln, Nebraska, were evaluated using a variable-rate stormwater runoff simulator. A volume-based water quality volume (WQV) design storm of 3.0 cm was applied to each rain garden as an SCS Type II runoff hydrograph until the system began overflowing to test the rain gardens for surface and subsurface storage capacity, drawdown rate, ponding depth, and overflow characteristics. Every rain garden tested drained in 30 h or less, with six gardens draining in less than 1 h. Rain garden surface storage capacity was poor, retaining on average only 16% of the WQV. On average, the rain gardens studied could store and infiltrate only 40% of the WQV, with only two gardens able to store and infiltrate greater than 90% of the WQV. On average, 59% of the runoff was captured as subsurface storage. Results of this study indicate that these 2- to 4-year-old rain gardens are limited not by drain times and rates, which often met or exceeded common design recommendations, but rather by inadequate surface storage characteristics. Extrapolating measured surface storage volumes to hypothetical systems with evenly graded depths of 15.2 cm, a minimum local depth recommendation, resulted in only one garden with enough storage to contain the WQV. On average, the extrapolated storage held only 65% of the WQV. It was shown that subsurface storage can make up for a lack of surface storage; the systems studied herein had an average of 2.7 times more subsurface storage than surface storage as a percentage of inflow volume before overflow began