bluuebunny/crossref_metadata_2025 huggingface dataset:
Trophic studies in a high-latitude fjord ecosystem — a comparison of stable isotope analyses (δ13C and δ15N) and trophic-level estimates from a mass-balance model
Authors: Nilsen Marianne , Pedersen Torstein , Nilssen Einar Magnus , Fredriksen Stein
Published: February 2009

Stable isotopes of δ13C and δ15N were used to examine food sources and trophic structure of 65 taxa, representing 19 ecological groups, in a high-latitude ecosystem. Discrimination was made between pelagic and benthic carbon sources, where feeding in most cases reflected the habitat. Trophic levels from these analyses, TLN, were compared with corresponding levels estimated by an Ecopath mass-balance model, TLE, constructed independently of the isotope data. The good correlation between the two methods (r2 = 0.72) supports the diet composition and the grouping of taxa into ecological groups in the model. However, when estimates diverged, this was often explained by the analyses of few taxa, taxa that were not the most representative for the group, or the analyses of specimens from a limited size range. Some assumed detrivores were assigned high TLN in favour of an abundant microbial community in the sediments. High TLN estimates for many invertebrate taxa, combined with relatively low TLN for fishes, suggest that parts of the benthic food web are decoupled from the classical food web.
Prevalence and recurrence of escaped farmed Atlantic salmon (Salmo salar) in eastern North American rivers
Authors: Morris Matthew R.J. , Fraser Dylan J. , Heggelin Anthony J. , Whoriskey Frederick G. , Carr Jonathan W. , O’Neil Shane F. , Hutchings Jeffrey A.
Published: February 2009

Knowledge of the prevalence of escaped farmed fishes in the wild is an essential first step to assessing the risk resulting from interactions between farmed and wild fishes. This is especially important in eastern North America, where Atlantic salmon ( Salmo salar ) aquaculture occurs near wild Atlantic salmon rivers and where many wild salmon populations are severely depressed. Here, we review the literature on the incidence of escaped farmed salmon in eastern North American rivers, for which there has been no comprehensive compilation to date. Escaped farmed salmon have been found in 54 of 62 (87%) rivers investigated within a 300 km radius of the aquaculture industry since 1984, including 11 rivers that contain endangered salmon populations. Averaged among all investigations, the proportional representation of farmed salmon among adults entering the rivers from the sea was 9.2% (range 0% to 100%). Where data were sufficient to examine temporal trends, farmed salmon proportions varied considerably over time, suggesting that escape events are episodic in nature. We conclude that escaped farmed salmon are sufficiently prevalent in eastern North American rivers to pose a potentially serious risk to the persistence of wild salmon populations, especially in those rivers that are adjacent to existing aquaculture sites.
Effect of pH and Dissolved Organic Carbon on the Toxicity of Copper to Larval Fathead Minnow (Pimephales promelas) in Natural Lake Waters of Low Alkalinity
Authors: Welsh P. G. , Skidmore J. F. , Spry D. J. , Dixon D. G. , Hodson P. V. , Hutchinson N. J. , Hickie B. E.
Published: February 2009

The impacts of pH and dissolved organic carbon (DOC) on the acute toxicity of Cu to larval fathead minnow (Pimephales promelas) were determined using natural soft water from two Precambrian Shield lakes in south-central Ontario. By artificially manipulating the pH and DOC levels of the water, we demonstrated that both acidification and the removal of DOC increased the toxicity of Cu. The 96-h Cu LC50s were determined over a pH range from 5.4 to 7.3 and a DOC concentration range from 0.2 to 16 mg∙L−1. The LC50s ranged from a low of 2 μg∙L−1(pH 5.6, DOC 0.2 mg∙L−1) to a high of 182 μg∙L−1(pH 6.9, DOC 15.6 mg∙L−1). A multiple regression model (log1096-h Cu LC50 = −0.308 + 0.192 pH + 0.136 (pH∙log10DOC)) was used to describe the relationship between Cu toxicity, pH, and DOC. The model was significant (p < 0.00001) and explained 93% of the variability in the toxicity data. These results suggest that current water quality objectives for Cu, and possibly for other metals, may not be sufficiently protective of aquatic life in soft, moderately acidic water containing low levels of DOC.
Seasonal Variation in the Diet of Harp Seals (Phoca groenlandica) from the Gulf of St. Lawrence and Western Hudson Strait
Authors: Beck Gregor Gilpin , Hammill Michael O. , Smith Thomas G.
Published: February 2009

Of 247 harp seal (Phoca groenlandica) stomachs collected between December 1988 and October 1990 from western Hudson Strait (autumn), the northern Gulf of St. Lawrence (December), the St. Lawrence estuary (winter and April), and the Magdalen Islands (March), 140 (57%) contained food. The Magdalen Islands sample contained significantly more empty stomachs (62%, n = 164) than those from all other locations. Both the unreconstructed mass of stomach contents and the proportion of fish and invertebrate prey within individual stomachs varied significantly with location and season. Harp seals obtained from the northern Gulf of St. Lawrence during their southward migration fed less intensively, and on a wider variety of both invertebrate and fish prey, notably Parathemisto libellula, Pandalus sp., sand lance (Ammodytes sp.), and Atlantic cod (Gadus morhua). Feeding was more intensive and specialized in Hudson Strait and the St. Lawrence estuary where capelin (Mallotus villosus) dominated in the diet. Capelin contributed 89 and 98% of gross energy in samples from Hudson Strait (1990) and the estuary (April). The number of capelin per stomach consumed by seals from the St. Lawrence estuary in April was high (169.4 ± 58.9, mean ± SD, n = 9). The mean estimated lengths of capelin and cod consumed were 132 and 140 mm.
Evaluation of Body Condition in the Northwest Atlantic Harp Seal (Phoca groenlandica)
Authors: Beck Gregor Gilpin , Smith Thomas G. , Hammill Michael O.
Published: February 2009

We evaluated body condition in 315 harp seals (Phoca groenlandica) obtained between 1988 and 1991. Total percent lipid of blubber did not vary between the five body sites and three depths sampled. In nine winter specimens, blubber, carcass, viscera, and skin contributed 89.5, 8.7, 0.9, and 0.9% of total body lipid. Pregnant females in winter had higher percent lipid in muscle than males, but no difference was observed in percent lipid in liver or blubber or in liver mass. Those females obtained 1 mo postpartum had the highest percent lipid in muscle and liver, the heaviest livers, but the lowest blubber lipid content. Sculp mass (skin with attached blubber) increased from autumn through late winter, with pregnant females having heavier sculps than males in winter. Both sculp and core mass varied on a seasonal and annual basis in males and females. Blubber was most variable dorsally between 40 and 70% of length, measured from the snout, and thickest at 50%, coincident with the position of maximum girth. Blubber thickness measured over the sternum was significantly less variable than at the 50% dorsal position. The direct measurements of body component masses may be necessary to detect subtle differences in body condition.
Multivariate Analysis of Covariance in Morphometric Studies of the Reproductive Cycle
Authors: García-Berthou Emili , Moreno-Amich Ramon
Published: February 2009

A new approach for analysing morphometric data of reproductive cycles is proposed, involving multivariate analysis of covariance of the directly measured variables (e.g., total weight and gonadal weight), with body length being the covariate. Multivariate, univariate, and between-group tests can be used progressively if significant differences have been found previously. Seasonal variation and other factors of interest can be described with predicted means of the model, adjusted for covariate, rendering the use of indices such as condition factor and gonadosomatic index unnecessary. A special design of multivariate analysis of covariance, with a pooled covariate by factor interaction, can be used to test the fundamental assumption of homogeneous slopes (parallelism hypothesis) in the standard multivariate analysis of covariance. Data for an Iberian brackish water cyprinodontid fish are used to demonstrate the proposed method.
Distinguishing between Different Populations of Harp Seal (Phoca groenlandica) by Chemometry of the Fatty Acid Profiles in the Jaw Bone
Authors: Grahl-Nielsen Otto , Mjaavatten Olav , Tvedt Einar
Published: February 2009

The relative amounts of various fatty acids of jawbone and eye lens were determined in harp seals (Phoca groenlandica) caught in the Greenland Sea and in the Barents Sea. The two tissues had distinctly different profiles. The fatty acid profile in the lens tissue changed with age. Principal component analysis of the data showed that the profiles in the jawbone were different in seals from the two populations, while the difference was much less prominent in the case of the eye lens. Using the jawbone profiles from the western and eastern seals as reference, it was shown that seven seals, caught in west coast seine nets during the large invasion of harp seals along the Norwegian coast in the winter of 1986–87, had come from the eastern population.
Maternal Transfer of Organochlorine Compounds in Salmonines to Their Eggs
Authors: Miller Michael A.
Published: February 2009

To investigate relationships between the concentrations of lipophilic organochlorine compounds in salmonine fish and their eggs and the role of lipids in maternal transfer of these compounds, muscle tissue and fertilized eggs from chinook salmon (Oncorhynchus tshawytscha) and lake trout (Salvelinus namaycush) were analyzed using gas chromatography. The concentrations of organochlorine compounds in the muscle tissue of the gravid fish were significantly correlated with the concentration of these compounds in the eggs (P < 0.01). Egg lipid concentrations were species specific, poorly correlated with muscle tissue lipid concentration, and did not appear to influence organochlorine compound transfer to the eggs. Total concentrations of PCBs and p,p′-DDE concentrations in chinook salmon eggs and total concentrations of PCBs, p,p′-DDE, and dieldrin in lake trout eggs were significantly correlated with the concentrations of these compounds in the muscle tissue of the gravid fish. Consequently, spatial differences or temporal changes in the concentrations of lipophilic compounds in chinook salmon or lake trout may significantly influence the concentrations of these compounds in their eggs.
Content of Total Organic Carbon in Finnish Lakes and Its Relationship to Catchment Characteristics
Authors: Kortelainen Pirkko
Published: February 2009

During autumn 1987, 987 randomly selected lakes throughout Finland were surveyed. Drainage lakes are most common (70%), followed by headwater lakes (17%). The lakes in the survey span most of the variation in humic matter concentration found in aquatic ecosystems (total organic carbon (TOC) = 0.5–47 (mg∙L−1, colour = 0–600 mg Pt∙L−1. The median TOC, colour, and chemical oxygen demand (CODMn) are 12 mg∙L−1, 100 mg Pt∙L−1, and 15 mg O2∙L−1, respectively. TOC is significantly related to other water quality parameters including the following: CODMn(r2 = 0.92), colour (r2 = 0.86), total iron (r2 = 0.69), total nitrogen (r2 = 0.53), and total phosphorus (r2 = 0.41). TOC and nutrient concentrations are low in northern Finland compared with southern and central regions. Multiple linear regression shows that the proportion of the catchment area covered by peatlands is the most important catchment variable determining TOC concentrations. In northern Finland, where catchment areas are less disturbed compared with southern regions, peatlands and latitude explain 63% of the variation in TOC. In the full set of lakes, latitude, catchment to lake area ratio, and the proportion of the catchment area covered by peatlands, upstream lakes, and fields explain 55% of the variation in TOC.
Species Replacements among Orconectes Crayfishes in Wisconsin Lakes: The Role of Predation by Fish
Authors: DiDonato Guy T. , Lodge David M.
Published: February 2009

To test the role of size- and species-selective predation by fishes in species replacements among congeneric crayfishes in northern Wisconsin lakes, we tethered the same three sizes of each of three species of Orconectes at six sites in the littoral zone of Trout Lake, Vilas County, Wise. Small crayfish (15–18 mm carapace length) were removed by fish at significantly higher rates than medium (23–25 mm) and large (33–35 mm) crayfish. Orconectes virilis was removed at significantly higher rates than O. propinquus and O. rusticus. These species-selection results suggest that predation by native fishes contributes to the previously documented replacement of the native crayfish O. virilis by the exotic crayfishes O. propinquus and O. rusticus. In combination with the observations of others that adult size of O. rusticus is typically larger than that of O. propinquus in northern Wisconsin lakes, our size-selection results suggest that fish predation may also hasten the ongoing replacement of O. propinquus by O. rusticus. Thus, fish predation is probably an important mechanism driving the replacement of O. virilis by O. propinquus and the replacement of both congeners by O. rusticus.
Decadal, Interannual, and Seasonal Variability in Enrichment Bioassays at Lake Tahoe, California–Nevada, USA
Authors: Goldman Charles R. , Jassby Alan D. , Hackley Scott H.
Published: February 2009

The response of Lake Tahoe water to macronutrient supplementation has been assayed with inorganic 14C uptake since the 1960s. On the decadal scale, a change in bioassay response to macronutrient enrichment took place around 1980, with a decrease in the frequency of N stimulation and an increase in the frequency of P stimulation. On the annual scale, an effect of spring mixing depth on the size of the bioassay response could be observed: stronger mixing events resulted in a more positive response. On the seasonal scale, the response magnitude was affected by stratification, but the significance of the response was independent of season. In a subset of the bioassays, in vivo fluorescence and chlorophyll a were measured in addition to inorganic 14C uptake; bioassay results were essentially the same, regardless of which of these three bioassay response indicators was used.
Estimating Migration Rates for Pacific Herring (Clupea pallasi) Using Tag-Recovery Data
Authors: Schweigert Jacob F. , Schwarz Carl J.
Published: February 2009

Tag-recovery data can be used to estimate migration rates among a set of strata provided that both tagging and recoveries occur on all the strata over a number of years. The model formulation described here is a simple matrix extension of a tag-recovery experiment where individual recaptures are replaced by a matrix of recoveries representing movement between release and recovery sites. Derived parameters of emigration, immigration, and overall net survival can also be estimated. The models are applied to estimate the migration of Pacific herring (Clupea pallasi) between spawning grounds in the Prince Rupert District and Central District of British Columbia. Effects of the violation of assumptions and aspects of the planning of capture–recapture experiments are also presented.
Predator Stomachs as Sampling Tools for Prey Distribution: Atlantic Cod (Gadus morhua) and Capelin (Mallotus villosus)
Authors: Fahrig Lenore , Lilly George R. , Miller Daniel S.
Published: February 2009

We demonstrate a direct relationship between the amount of prey (capelin, Mallotus villosus) in its predators' stomachs (Atlantic cod, Gadus morhua) and the biomass of the prey in the same localities. The relationship at a local scale implies that predator stomach contents can be used to estimate prey distribution. There is no evidence for either (1) a negative effect of local predator abundance on stomach contents (expected if local prey depletion and/or feeding interference occurs when predator density is high) or (2) a negative effect of the amount of other food in cod stomachs on the amount of capelin in the stomachs (expected if prey switching occurs). There is a negative effect of bottom depth on amount of capelin in cod stomachs as expected, since capelin are pelagic and cod are primarily bottom-dwelling, resulting in less vertical overlap between the species in deep water. This type of analysis may be useful in other predator–prey systems. Simultaneous stomach samples and independent biomass estimates of the prey are required, but once the model is built, it permits estimation of prey distribution in places and times when no direct survey of the prey can be done.
Safety factors and limit states analysis in geotechnical engineering
Authors: Meyerhof G. G.
Published: February 2009

This paper outlines the ultimate and serviceability limit states in geotechnical engineering analyses. The magnitude of customary total and suggested partial safety factors in earthworks, earth retaining structures, excavations, and foundations is discussed. On the basis of comparisons between these safety factors and using recommended load factors on various types of loading, including water pressures, common resistance factors on cohesion and friction of soils and performance factors can be established together with some additional modification factors for particular stability conditions. The serviceability limit states of foundations and structures are briefly discussed.
Effects of groundwater geochemistry on the permeability of grouted fractures
Authors: Gale J. E. , Reardon E. J.
Published: February 2009

A granite core containing a natural fracture, oriented parallel to the core axis, was collected, prepared, and its permeability measured in a hydrostatic test cell at different confining pressures. After the permeability hysteresis had been removed by several cycles of increasing and decreasing confining pressure, grout was placed within the fracture plane and allowed to cure for 40 days. Distilled water was forced through the sample until a significant flow rate developed. The influent solution for the sample was changed twice during the study to examine the effects of differing concentrations of Ca(HCO3)2 solutions on calcite precipitation within the fracture plane. The interaction of the Ca(HCO3)2 solution with the grout material resulted in a decrease in the permeability of the fracture plane over several months. At the close of the experiments, the sample was removed from the hydrostatic cell and opened along the fracture plane. The fracture exhibited two discrete braided channelways each with an average width of 2 mm. Precipitated calcite formed a rind along the walls of the channelways averaging 0.25 mm in thickness. The quantity of calcite precipitate determined from physical measurements was in reasonable agreement with that calculated using reaction rate expressions for calcite precipitation. The results of this study suggest the possibility that strategically located geochemical material could induce a geochemical evolution of groundwater within poorly grouted fractures, so as to decrease the permeability of the fractured rock system. Keywords: fracture permeability, grouted fractures, geochemistry, laboratory experiments, calcite precipitation.
Frost heave prediction of chilled pipelines buried in unfrozen soils
Authors: Konrad J.-M. , Morgenstern N. R.
Published: February 2009

Frost heave is an important consideration in the design of buried chilled pipelines. A procedure for calculating the amount of heave under a chilled gas pipeline is presented based on a finite-difference formulation of the heat and mass transfer in saturated soils. The frost heave of the soil is characterized in terms of the segregation potential concept developed in earlier papers by the authors. Good agreement is found between the predictions of heave obtained with this procedure and that observed in long-term full-scale experiments at a test site in Calgary, Canada. Additional calculations are presented to explore the influence of pipeline temperature, pipe insulation, and ground temperature on frost heave of buried pipelines.
Hydraulic stabilization of earth structures
Authors: Mitchell Robert J. , Madsen James D. , Crawford T. Wayde
Published: February 2009

Hydraulic stabilization of soils using gravity drainage, pumped wells (dewatering), vacuum wells, and vacuum blankets has been applied with success in numerous field situations. References to the vacuum methods, however, are not abundant and the analytical developments with regard to these methods are limited. This paper provides methods for analytical evaluation of hydraulic stabilization and applies these methods to vacuum pretreatment of soft clay foundations and to temporary stabilization of slopes using vacuum wells. Both applications indicate that the vacuum methods are effective. Detailed analyses of various vacuum well placements and some discussion on the types of systems applicable to various problems are included in the paper. Other applications of the vacuum methods of hydraulic stabilization of soil masses are briefly discussed. Keywords: stabilization, slopes, foundations, vacuum wells, remedial measures.
Analgesic and Anti-Inflammatory Activities ofTorenia concolorLindley var.formosanaYamazaki and Betulin in Mice
Authors: Lin Ying-Chih , Cheng Hao-Yuan , Huang Tai-Hung , Huang Hsin-Wei , Lee Yi-Hsuan , Peng Wen-Huang
Published: February 2009

The present study was intended to examine the analgesic effect of the 70% methanol extract of Torenia concolor Lindley var. formosana Yamazaki (TCMeOH) and betulin using models of acetic acid-induced writhing response and formalin test. In addition, we investigated the anti-inflammatory effect of TCMeOHand betulin using model of λ-carrageenan-induced paw edema. We observed the activities of antioxidant enzymes (SOD, GPx and GR) in the liver and the levels of malondialdehyde (MDA) and nitric oxide (NO) in the edema paw. The results showed that TCMeOH(1.0 and 2.0 g/kg) and betulin (30 and 90 mg/kg), significantly inhibited the acetic acid-induced writhing response. TCMeOH(2.0 g/kg) and betulin (30 and 90 mg/kg) significantly inhibited formalin-induced licking time during both the early and late phases. TCMeOH(0.5, 1.0 and 2.0 g/kg) and betulin (30 and 90 mg/kg) also significantly decreased the paw edema at the 4th hour after λ-carrageenan injection. Furthermore, TCMeOHand betulin treatment also significantly increased the activities of SOD, GR and GPx in the liver while decreasing the level of MDA in the edema paw. Finally, betulin (30 and 90 mg/kg) also caused considerable reduction of NO level in the edema paw. Taken together, the present results indicated that TCMeOHand betulin possessed analgesic and anti-inflammatory effects. The anti-inflammatory mechanism of TCMeOHand betulin may be related to decreasing the levels of MDA and NO in the edema paw by increasing the activities of antioxidant enzymes in the liver.
Effects of Hedysari Polysaccharides on Regeneration and Function Recovery Following Peripheral Nerve Injury in Rats
Authors: Wei Shao-Yin , Zhang Pei-Xun , Han Na , Dang Yu , Zhang Hong-Bo , Zhang Dian-Ying , Fu Zhong-Guo , Jiang Bao-Guo
Published: February 2009

It has been demonstrated that aqueous extract of Radix Hedysari Prescription and modified Radix Hedysari Prescription could improve the regeneration of injured peripheral nerve. Radix Hedysari is a main component in these two formulas. We hypothesized that Hedysari polysaccharides (HPS), a main active ingredient, could also enhance peripheral nerve regeneration after nerve injury in adult animals. In the present study, we examined the effects of HPS on sciatic nerve regeneration for 6 weeks following clamping in rats (administrated orally of 2 ml HPS liquid daily, 0.25 g/ml). The results showed that HPS was able to enhance sciatic function index (SFI) value, tibial function index (TFI) value, peroneal nerve function index (PFI) value, conduction velocity, and the number of regenerated myelinated nerve fibers, suggesting the potential clinical application of HPS for the treatment of peripheral nerve injury in humans.
In vivoAnti-Cancer Activity of KoreanAngelica Gigasand its Major Pyranocoumarin Decursin
Authors: Lee Hyo Jeong , Lee Hyo Jung , Lee Eun Ok , Lee Jae Ho , Lee Kuen Sung , Kim Kwan Hyun , Kim Sung-Hoon , Lü Junxuan
Published: February 2009

We have reported that a 10-herbal traditional formula containing Korean Angelica gigas Nakai (AGN) exerts potent anti-cancer efficacy and identified decursin and decursinol angelate (DA) from AGN as novel anti-androgens. Here, we determined whether AGN would exert in vivo anti-cancer activity and whether decursin or DA could account for its efficacy. The AGN ethanol extract was tested against the growth of mouse Lewis lung cancer (LLC) allograft in syngenic mice or human PC-3 and DU145 prostate cancer xenograft in immunodeficient mice. The pharmacokinetics of decursin and DA were determined. The AGN extract significantly inhibited LLC allograft growth (30 mg/kg) and PC-3 and DU145 xenograft growth (100 mg/kg) without affecting the body weight of the host mice. Biomarker analyses revealed decreased cell proliferation (Ki67, PCNA), decreased angiogenesis (VEGF, microvessel density) and increased apoptosis (TUNEL, cPARP) in treated tumors. Decursin and DA injected intraperitoneally were rapidly hydrolyzed to decursinol. Decursinol and decursin at 50 mg/kg inhibited LLC allograft growth to the same extent, comparable to 30 mg AGN/kg. Therefore the AGN extract possessed significant in vivo anti-cancer activity, but decursin and DA only contributed moderately to that activity, most likely through decursinol.
Compact and Anonymous Role-Based Authorization Chain
Authors: Yao Danfeng , Tamassia Roberto
Published: February 2009

We introduce a decentralized delegation model called anonymous role-based cascaded delegation. In this model, a delegator can issue authorizations on behalf of her role without revealing her identity. This type of delegation protects the sensitive membership information of a delegator and hides the internal structure of an organization. To provide an efficient storage and transmission mechanism for credentials used in anonymous role-based cascaded delegation, we present a new digital signature scheme that supports both signer anonymity and signature aggregation. Our scheme has compact role signatures that make it especially suitable for ubiquitous computing environments, where users may have mobile computing devices with narrow communication bandwidth and small storage units.
New Techniques for Private Stream Searching
Authors: Bethencourt John , Song Dawn , Waters Brent
Published: February 2009

A system for private stream searching, introduced by Ostrovsky and Skeith, allows a client to provide an untrusted server with an encrypted search query. The server uses the query on a stream of documents and returns the matching documents to the client while learning nothing about the nature of the query. We present a new scheme for conducting private keyword search on streaming data which requires
O
(
m
) server to client communication complexity to return the content of the matching documents, where
m
is an upper bound on the size of the documents. The required storage on the server conducting the search is also
O
(
m
). The previous best scheme for private stream searching was shown to have
O
(
m
log
m
) communication and storage complexity. Our solution employs a novel construction in which the user reconstructs the matching files by solving a system of linear equations. This allows the matching documents to be stored in a compact buffer rather than relying on redundancies to avoid collisions in the storage buffer as in previous work. This technique requires a small amount of metadata to be returned in addition to the documents; for this the original scheme of Ostrovsky and Skeith may be employed with
O
(
m
log
m
) communication and storage complexity. We also present an alternative method for returning the necessary metadata based on a unique encrypted Bloom filter construction. This method requires
O
(
m
log(
t
/
m
)) communication and storage complexity, where
t
is the number of documents in the stream. In this article we describe our scheme, prove it secure, analyze its asymptotic performance, and describe a number of extensions. We also provide an experimental analysis of its scalability in practice. Specifically, we consider its performance in the demanding scenario of providing a privacy preserving version of the Google News Alerts service.
Dynamic and Efficient Key Management for Access Hierarchies
Authors: Atallah Mikhail J. , Blanton Marina , Fazio Nelly , Frikken Keith B.
Published: February 2009

Hierarchies arise in the context of access control whenever the user population can be modeled as a set of partially ordered classes (represented as a directed graph). A user with access privileges for a class obtains access to objects stored at that class and all descendant classes in the hierarchy. The problem of key management for such hierarchies then consists of assigning a key to each class in the hierarchy so that keys for descendant classes can be obtained via efficient key derivation.

We propose a solution to this problem with the following properties: (1) the space complexity of the public information is the same as that of storing the hierarchy; (2) the private information at a class consists of a single key associated with that class; (3) updates (i.e., revocations and additions) are handledlocallyin the hierarchy; (4) the scheme is provably secure against collusion; and (5) each node can derive the key of any of its descendant with a number of symmetric-key operations bounded by the length of the path between the nodes. Whereas many previous schemes had some of these properties, ours is the first that satisfies all of them. The security of our scheme is based on pseudorandom functions, without reliance on the Random Oracle Model.

Another substantial contribution of this work is that we are able to lower the key derivation time at the expense of modestly increasing the public storage associated with the hierarchy. Insertion of additional, so-called shortcut, edges, allows to lower the key derivation to a small constant number of steps for graphs that are total orders and trees by increasing the total number of edges by a small asymptotic factor such asO(log*n) for ann-node hierarchy. For more general access hierarchies of dimensiond, we use a technique that consists of adding dummy nodes and dimension reduction. The key derivation work for such graphs is then linear indand the increase in the number of edges is by the factorO(logd − 1n) compared to the one-dimensional case.

Finally, by making simple modifications to our scheme, we show how to handle extensions proposed by Crampton [2003] of the standard hierarchies to “limited depth” and reverse inheritance.
Run-Time Enforcement of Nonsafety Policies
Authors: Ligatti Jay , Bauer Lujo , Walker David
Published: February 2009

A common mechanism for ensuring that software behaves securely is to monitor programs at run time and check that they dynamically adhere to constraints specified by a security policy. Whenever a program monitor detects that untrusted software is attempting to execute a dangerous action, it takes remedial steps to ensure that only safe code actually gets executed.

This article improves our understanding of the space of policies enforceable by monitoring the run-time behaviors of programs. We begin by building a formal framework for analyzing policy enforcement: we precisely define policies, monitors, and enforcement. This framework allows us to prove that monitors enforce an interesting set of policies that we call the infinite renewal properties. We show how to construct a program monitor that provably enforces any reasonable infinite renewal property. We also show that the set of infinite renewal properties includes some nonsafety policies, that is, that monitors can enforce some nonsafety (including some purely liveness) policies. Finally, we demonstrate concrete examples of nonsafety policies enforceable by practical run-time monitors.
Risks to the public
Authors: Neumann Peter G.
Published: February 2009

Edited by Peter G. Neumann (Risks Forum Moderator and Chairman of the ACM Committee on Computers and Public Policy), plus personal contributions by others, as indicated. Opinions expressed are individual rather than organizational, and all of the usual disclaimers apply. We address problems relating to software, hardware, people, and other circumstances relevant to computer systems. To economize on space, we include pointers to items in the online Risks Forum: (R i j) denotes RISKS vol i number j. Cited RISKS items generally identify contributors and sources, together with URLs. Official RISKS archives are available at www.risks.org (which redirects to Newcastle and gets you nice html formatting and a search engine courtesy of Lindsay Marshall; http://catless.ncl.ac.uk/Risks/i.j.html gets you (R i j)) and at ftp://www.sri.com/risks .
Metrics to study symptoms of bad software designs
Authors: Chahal Kuljit Kaur , Singh Hardeep
Published: February 2009

Design of a software product largely influences its quality. Good design is one of the pre-requisites of a high quality product. Me-trics are usually used to assess the quality of software designs. The metrics for object oriented design focus on design characteristics, such as abstraction, coupling, cohesion, inheritance, polymorphism and encapsulation and are applied at attribute, method, class, pack-age, file and systems levels. Design metrics help the software de-signers to understand the problem areas in a design and to develop prediction models. A number of studies have modeled relation-ships between object oriented metrics and reusability, defects and faults, maintainability, and effort, and cost savings. So design me-trics can give an early indication of goodness of design and thus of the software product developed using that design. If designers know symptoms of bad design then it is helpful for them to avoid the bad design. In this paper, we have explored some of the symp-toms of bad design and studied metric relationships which high-light these symptoms.
Application of support vector machine to predict fault prone classes
Authors: Singh Yogesh , Kaur Arvinder , Malhotra Ruchika
Published: February 2009

Empirical validation of software metrics to predict quality using machine learning methods is important to ensure their practical relevance in the software organizations. It would also be interesting to know the relationship between object-oriented metrics and fault proneness. In this paper, we build a Support Vector Machine (SVM) model to find the relation-ship between object-oriented metrics given by Chidamber and Kemerer and fault proneness. The proposed model is empirically evaluated using open source software. The performance of the SVM method was evaluated by Receiver Operating Characteristic (ROC) analysis. Based on these results, it is reasonable to claim that such models could help for planning and performing testing by focusing resources on fault- prone parts of the design and code. Thus, the study shows that SVM method may also be used in constructing software quality models. However, similar types of studies are required to be carried out in order to establish the acceptability of the model.
State model extraction of a software component by observing its behavior
Authors: Suman Rajiv Ranjan , Mall Rajib
Published: February 2009

We propose a novel black-box approach to reverse engineer the state model of a software component. We assume that in different states of a component, different subsets of its services are supported and state of a component may change due to invocation of its services. Therefore, we construct the state model of a component by tracking the changes (if any) to its supported services that occur after accessing its services. Case study carried out by us shows that our approach can generate the state model with sufficient accuracy and completeness for simple components.
A local roughness measure for 3D meshes and its application to visual masking
Authors: Lavoué Guillaume
Published: February 2009

3D models are subject to a wide variety of processing operations such as compression, simplification or watermarking, which may introduce some geometric artifacts on the shape. The main issue is to maximize the compression/simplification ratio or the watermark strength while minimizing these visual degradations. However few algorithms exploit the human visual system to
hide
these degradations, while perceptual attributes could be quite relevant for this task. Particularly, the
masking effect
defines the fact that one visual pattern can hide the visibility of another. In this context we introduce an algorithm for estimating the
roughness
of a 3D mesh, as a local measure of geometric noise on the surface. Indeed, a textured (or
rough
) region is able to hide geometric distortions much better than a smooth one. Our measure is based on curvature analysis on local windows of the mesh and is independent of the resolution/connectivity of the object. The accuracy and the robustness of our measure, together with its relevance regarding visual masking have been demonstrated through extensive comparisons with state-of-the-art and subjective experiment. Two applications are also presented, in which the roughness is used to lead (and improve) respectively compression and watermarking algorithms.
The complexity of online memory checking
Authors: Naor Moni , Rothblum Guy N.
Published: February 2009

We consider the problem of storing a large file on a remote and unreliable server. To verify that the file has not been corrupted, a user could store a small private (randomized) “fingerprint” on his own computer. This is the setting for the well-studied authentication problem in cryptography, and the required fingerprint size is well understood. We study the problem of sublinear authentication: suppose the user would like to encode and store the file in a way that allows him to verify that it has not been corrupted, but without reading the entire file. If the user only wants to readqbits of the file, how large does the sizesof the private fingerprint need to be? We define this problem formally, and show a tight lower bound on the relationship betweensandqwhen the adversary is not computationally bounded, namely:s×q= Ω(n), wherenis the file size. This is an easier case of the online memory checking problem, introduced by Blum et al. [1991], and hence the same (tight) lower bound applies also to that problem.

It was previously shown that, when the adversary is computationally bounded, under the assumption that one-way functions exist, it is possible to construct much better online memory checkers. The same is also true for sublinear authentication schemes. We show that the existence of one-way functions is also a necessary condition: even slightly breaking thes×q= Ω(n) lower bound in a computational setting implies the existence of one-way functions.
Evolvability
Authors: Valiant Leslie G.
Published: February 2009

Living organisms function in accordance with complex mechanisms that operate in different ways depending on conditions. Darwin's theory of evolution suggests that such mechanisms evolved through variation guided by natural selection. However, there has existed no theory that would explain quantitatively which mechanisms can so evolve in realistic population sizes within realistic time periods, and which are too complex. In this article, we suggest such a theory. We treat Darwinian evolution as a form of computational learning from examples in which the course of learning is influenced only by the aggregate fitness of the hypotheses on the examples, and not otherwise by specific examples. We formulate a notion of evolvability that distinguishes function classes that are evolvable with polynomially bounded resources from those that are not. We show that in a single stage of evolution monotone Boolean conjunctions and disjunctions are evolvable over the uniform distribution, while Boolean parity functions are not. We suggest that the mechanism that underlies biological evolution overall is “evolvable target pursuit”, which consists of a series of evolutionary stages, each one inexorably pursuing an evolvable target in the technical sense suggested above, each such target being rendered evolvable by the serendipitous combination of the environment and the outcomes of previous evolutionary stages.
Engineered glucagon-like peptide-1-producing hepatocytes lower plasma glucose levels in mice
Authors: Riedel Michael J. , Lee Corinna Wai Kwan , Kieffer Timothy J.
Published: February 2009

Glucagon-like peptide (GLP)-1 is an incretin hormone with well-characterized antidiabetic properties, including glucose-dependent stimulation of insulin secretion and enhancement of β-cell mass. GLP-1 agonists have recently been developed and are now in clinical use for the treatment of type 2 diabetes. Rapid degradation of GLP-1 by enzymes including dipeptidyl-peptidase (DPP)-IV and neutral endopeptidase (NEP) 24.11, along with renal clearance, contribute to a short biological half-life, necessitating frequent injections to maintain therapeutic efficacy. Gene therapy may represent a promising alternative approach for achieving long-term increases in endogenous release of GLP-1. We have developed a novel strategy for glucose-regulated production of GLP-1 in hepatocytes by expressing a DPP-IV-resistant GLP-1 peptide in hepatocytes under control of the liver-type pyruvate kinase promoter. Adenoviral delivery of this construct to hepatocytes in vitro resulted in production and secretion of bioactive GLP-1 as measured by a luciferase-based bioassay developed to detect the NH2-terminally modified GLP-1 peptide engineered for this study. Transplantation of encapsulated hepatocytes into CD-1 mice resulted in an increase in plasma GLP-1 levels that was accompanied by a significant reduction in fasting plasma glucose levels. The results from this study demonstrate that a gene therapy approach designed to induce GLP-1 production in hepatocytes may represent a novel strategy for long-term secretion of bioactive GLP-1 for the treatment of type 2 diabetes.
Enhancement of aldosterone-induced catecholamine production by bone morphogenetic protein-4 through activating Rho and SAPK/JNK pathway in adrenomedullar cells
Authors: Goto Junko , Otsuka Fumio , Yamashita Misuzu , Suzuki Jiro , Otani Hiroyuki , Takahashi Hiroko , Miyoshi Tomoko , Mimura Yukari , Ogura Toshio , Makino Hirofumi
Published: February 2009

Here we investigated the effects of mineralocorticoid in the regulation of catecholamine biosynthesis using rat pheochromocytoma PC12 cells. Expression of mineralocorticoid receptor (MR) was confirmed in undifferentiated PC12 cells. Aldosterone stimulated dopamine production by PC12 cells without any increase in cAMP activity. Aldosterone-induced dopamine accumulation was enhanced in accordance with the increase in the rate-limiting enzyme tyrosine hydroxylase (TH). Blocking MR with eplerenone suppressed aldosterone-induced increases of TH mRNA and dopamine production. A glucocorticoid receptor (GR) antagonist, RU-486, attenuated dexamethasone- but not aldosterone-induced TH expression. Cycloheximide reduced both aldosterone- and dexamethasone-induced TH mRNA. A SAPK/JNK inhibitor, SP600125, suppressed aldosterone-induced TH mRNA expression; however, the aldosterone-induced TH expression was not affected by inhibition of ERK1/2, p38-MAPK, Rho-kinase, PI 3-kinase, and PKC. It was of note that cotreatment with eplerenone and SP600125 restored aldosterone-induced TH mRNA expression to basal levels. To investigate the involvement of bone morphogenetic protein (BMP) actions in aldosterone-induced catecholamine production, we examined the effects of BMP-4 and BMP-7, which are expressed in the adrenal medulla, on catecholamine biosynthesis. BMP-4 preferentially enhanced aldosterone-induced TH mRNA and dopamine production, although BMP-4 alone did not affect TH expression. The BMP-4 enhancement of aldosterone-induced TH expression was not observed in cells treated with eplerenone. BMP-4 did not affect MR expression of PC12 cells; however, it did enhance aldosterone-induced SAPK/JNK phosphorylation. Inhibition of SAPK/JNK or Rho suppressed BMP-4 enhancement of aldosterone-induced TH expression. Collectively, our findings demonstrate that aldosterone stimulates catecholamine biosynthesis in adrenomedullar cells via MR through genomic action and partly through nongenomic action by Rho-SAPK/JNK signaling, the latter of which is facilitated by BMP-4. A functional link between MR actions and endogenous BMP may be involved in the catecholamine production.
Modulation of BKCaChannel Gating by Endogenous Signaling Molecules
Authors: Hou Shangwei , Heinemann Stefan H. , Hoshi Toshinori
Published: February 2009

Large-conductance Ca2+- and voltage-activated K+(BKCa, MaxiK, or Slo1) channels are expressed in almost every tissue in our body and participate in many critical functions such as neuronal excitability, vascular tone regulation, and neurotransmitter release. The functional versatility of BKCachannels owes in part to the availability of a spectacularly wide array of biological modulators of the channel function. In this review, we focus on modulation of BKCachannels by small endogenous molecules, emphasizing their molecular mechanisms. The mechanistic information available from studies on the small naturally occurring modulators is expected to contribute to our understanding of the physiological and pathophysiological roles of BKCachannels.
Higher‐Order Splitting Method for Elastic Wave Propagation
Authors: Geiser Jürgen
Published: February 2009

Motivated by seismological problems, we have studied a fourth‐order split scheme for the elastic wave equation. We split in the spatial directions and obtain locally one‐dimensional systems to be solved. We have analyzed the new scheme and obtained results showing consistency and stability. We have used the split scheme to solve problems in two and three dimensions. We have also looked at the influence of singular forcing terms on the convergence properties of the scheme.
Trastuzumab Reverses Letrozole Resistance and Amplifies the Sensitivity of Breast Cancer Cells to Estrogen
Authors: Sabnis Gauri , Schayowitz Adam , Goloubeva Olga , Macedo Luciana , Brodie Angela
Published: February 2009

In this study, we investigated adaptive mechanisms associated with aromatase inhibitor (AI) resistance in breast cancer cells and show that sensitivity to AIs can be extended through dual inhibition of estrogen receptor (ER) and human epidermal receptor-2 (Her-2) signaling. We used human ER-positive breast cancer cells stably transfected with the aromatase gene (MCF-7Ca). These cells grow as tumors in nude mice and are inhibited by AIs. Despite continued treatment, tumors eventually become insensitive to AI letrozole. The cells isolated from these long-term letrozole-treated tumors (LTLT-Ca) were found to have decreased ERα levels. Our results suggest that LTLT-Ca cells survive estrogen deprivation by activation of Her-2/mitogen-activated protein kinase (MAPK) pathway. Here, we show that trastuzumab (antibody against Her-2; IC50 = 0.4 mg/mL) was very effective in restoring the ERα levels and sensitivity of LTLT-Ca cells to endocrine therapy by down-regulation of Her-2/MAPK pathway and up-regulation of ERα. In contrast, trastuzumab was ineffective in the parental hormone-responsive MCF-7Ca cells (IC50 = 4.28 mg/mL) and xenografts. By blocking Her-2, trastuzumab also up-regulates ERα and aromatase expression and hypersensitized MCF-7Ca cells to E2. We show that trastuzumab is beneficial in hormone-refractory cells and xenografts by restoring ER, implicating Her-2 as a negative regulator of ERα. In xenograft studies, the combination of trastuzumab plus letrozole is equally effective in inhibiting growth of MCF-7Ca tumors as letrozole alone. However, on the acquisition of resistance and increased Her-2 expression, the combination of letrozole plus trastuzumab provided superior benefit over letrozole or trastuzumab alone. [Cancer Res 2009;69(4):1416–28]