Constructing and verifying a robust Mix Net using CSP

A Mix Net is a cryptographic protocol that unlinks the correspondence between its inputs and its outputs. In this paper, we formally analyse a Mix Net using the process algebra CSP and its associated model checker FDR. The protocol that we verify removes the reliance on a Web Bulletin Board: rather than communicating via a Web Bulletin Board, the protocol allows the mix servers to communicate directly, exchanging signed messages and maintaining their own records of the messages they have received. Mix Net analyses in the literature are invariably focused on safety properties; important liveness properties, such as deadlock freedom, are wholly neglected. This is an unhappy omission, however, since a Mix Net that produces no results is of little use. In contrast, we verify here that the Mix Net is guaranteed to terminate, with each honest mix server outputting the decrypted vector of plaintexts alongside a chain proving that each re-encryption/permutation and partial decryption operation was performed correctly, under the assumption that there is an honest majority of them acting according to the protocol.     

Requirements for Autonomous Underwater Vehicles (AUVs) for scientific data collection in the Laurentian Great Lakes: A questionnaire survey

Using mobile environmental monitoring can aid in gathering ecological data to meet fish community goals in the Great Lakes. One such approach is the use of large Autonomous Underwater Vehicles (AUVs) to gather data, or the potential use of AUV swarms, where multiple small AUVs work together with each having different data-gathering capabilities. To understand data needs that could be collected by mobile sensor networks to inform decision making, we surveyed Great Lakes professionals involved directly and indirectly in such decision making. Basic data that respondents chose as most important to collect were water temperature, dissolved oxygen, chlorophyll a, turbidity, and blue-green “algae”, which seems to align with variables affecting fish directly or indirectly (through identification of harmful algal blooms). Specialized data chosen as most important were mapping of habitat characteristics, sonar of groupings of fish, and images/video. The time of year to collect all data was chosen as all seasons by the majority of respondents, the frequency most chosen was once a season for mapping of habitat characteristics, once a week for sonar detection of groupings of fish, and once per day for images/video and water temperature. Results were very similar when respondents were asked where data should be collected in the Great Lakes (i.e., tributaries, nearshore areas, etc.) except respondents indicated that images/video should be collected most in fish spawning habitats. Understanding data important to inform decisions of resource professionals will help guide the design of mobile and stationary sensor networks in the Great Lakes.     

Turnover of cholesterol and dipalmitoyl phosphatidylcholine in surfactant of adult rat lung

In order to compare the turnover of two major surfactant components, [1α,2α(n)-³H]cholesterol and [methyl ¹⁴ C choline] dipalmitoyl phosphatidylcholine (DPPC) were introduced as lamellar bodiesvia the trachea into lightly anesthetized rats which were then allowed to recover. The radiotracers were assumed to have entered the alveolar surfactant pool and to have subsequently recycled in part into the lamellar bodies of alveolar type II cells. For DPPC, the specific activityvs. time curves of tubular myelin rich (alv-1) and tubular myelin poor (alv-2) alveolar lavage fractions were similar, and there was a plausible precursor-product relationship between lamellar bodies and either (or both) of these compartments. In contrast, however, the specific activities of alv-1 and alv-2 for cholesterol were quite different, allowing us to reject the hypothesis of a precursor-product relationship between classical lamellar bodies and alv-2. The estimated turover time for DPPC in alv-1 was 240 or 206 min, depending on which subfraction of lamellar bodies one takes to be the precursor. For cholesterol it was 583 or 624 min. These longer turnover times for cholesterol should lead to a greater than twofold increase in the relative concentration of cholesterol in the putative product compartment. Such an increase was not found. We interpret this as reflecting either noncompartmental behavior of the alveolar surfactant pool, or multiple pools of lamellar bodies with different turnover times. We conclude that two major components of pulmonary surfactant, cholesterol and DPPC, are handled differently, and that for at least one of these substances, the widely accepted scenario of a compartmental precursor-product relationship between lamellar bodies and alveolar surfactant must be rejected.     

Effect of Glass Additions on the Indentation-Strength Behavior of Alumina

The effect of small calcium aluminosilicate (CAS) glass additions on the microstructure and flaw tolerance of alumina ceramics is investigated, and the results compared to a high-purity alumina. The high-purity alumina specimens were dense with microstructures consisting of a uniform grain size distribution and equiaxed grain morphology. Additions of only 1 wt% glass phase resulted in a bimodal grain size distribution containing large, elongated grains within a fine-grain matrix. Indentation-strength tests indicated enhanced flaw tolerance with the bimodal microstructure, even though both materials had nominally the same average grain size. The strength of unindented specimens was also observed to decrease with glass additions. Observations of crack paths show a greater propensity for bridging in the glass-containing alumina due to the presence of coarse, elongated grains and perhaps a lower grain boundary toughness. However, crack extension occurs transgranularly when the size of the coarsest grains becomes too large. This suggests that an optimum in flaw tolerance will be achieved with an elongated grain morphology and intermediate grain size.     

Systemic Induction of Terpenoid Aldehydes in Cotton Pigment Glands by Feeding of Larval Spodoptera exigua

Pigment glands in cotton contain terpenoid aldehydes that are toxic and deterrent to feeding of several generalist lepidopteran insects. We hypothesized that previously observed systemically induced feeding deterrence may be associated with pigment glands. We conducted experiments to determine the dynamics and chemical nature of inducible feeding deterrents in leaves of cotton, Gossypium hirsutum L, to larvae of the beet armyworm, Spodoptera exigua. Production and/or filling of pigment glands was influenced by physiological age of Deltapine 90 cotton plants. In undamaged plants, successively formed leaves contained more pigment glands, up to the seventh or eighth true-leaf developmental stage. Feeding choice tests conducted one or seven days after initial feeding damage revealed that third instars of S. exigua consumed more of the two youngest leaves from control cotton plants than from plants whose two oldest leaves had been fed on previously for 24 hr by S. exigua. The preference for leaves from control plants was significant one day after initial damage and highly significant seven days after damage. Consumption of mature foliage (leaf immediately above initially damaged leaves) from control plants and damaged plants did not differ. More pigment glands were counted on the youngest leaf of damaged plants than on the youngest leaf of control plants one day after initial damage. HPLC analysis revealed greater amounts of hemigossypolone, heliocides 1 and 2 (H₁ and H₂), and total terpenoid aldehydes per gland in young foliage of damaged plants than control plants one day after initial injury. By seven days after initial injury, greater quantities of hemigossypolone and all heliocides except H₄ were detected in young foliage from damaged plants compared to control plants. Concentrations of H₁ per gland in young leaves from damaged plants increased the most of all terpenoid aldehydes measured (3.4× the amount found in leaves from control plants). Mature leaves from damaged plants did not contain more terpenoid aldehydes than mature leaves from control plants. We suggest that systemically induced feeding deterrence to S. exigua in young leaves of glanded cotton was due to increased amounts of terpenoid aldehydes in pigment glands.     

Display of {beta}-lactamase on the Escherichia coli surface: outer membrane phenotypes conferred by Lpp'-OmpA'-{beta}-lactamase fusions

Bacterial cell-surface exposure of foreign peptides and solubleproteins has been achieved recently by employing a fusion proteinmethodology. An Lpp'–OmpA(46–159)–Bla fusionprotein has been shown previously to display the normally periplasmicenzyme ß-lactamase (Bla) on the cell surface of theGram-negative bacterium Escherichia coli. Here, we have investigatedthe role of the OmpA domain of the tripartite fusion proteinin the surface display of the passenger domain (Bla) and havecharacterized the effects of the fusion proteins on the integrityand permeability of the outer membrane. We show that in additionto OmpA(46–159), a second OmpA segment, consisting ofamino acids 46–66, can also mediate the display of Blaon the cell surface. Other OmpA domains of various lengths (aminoacids 46–84, 46–109, 46–128, 46–141and 46–145) either anchored the Bla domain on the periplasmicface of the outer membrane or caused a major disruption of theouter membrane, allowing the penetration of antibodies intothe cell. Detergent and antibiotic sensitivity and periplasmicleakage assays showed that changes in the permeability of theouter membrane are an unavoidable consequence of displayinga large periplasmic protein on the surface of E.coli. This isthe first systematic report on the effects that cell surfaceengineering may have on the integrity and permeability propertiesof bacterial outer membranes.     

Exploratory Data Analysis With Categorical Variables: An Improved Rank-by-Feature Framework and a Case Study

Multidimensional data sets often include categorical information. When most dimensions have categorical information, clustering the data set as a whole can reveal interesting patterns in the data set. However, the categorical information is often more useful as a way to partition the data set: gene expression data for healthy versus diseased samples or stock performance for common, preferred, or convertible shares. We present novel ways to utilize categorical information in exploratory data analysis by enhancing the rank-by-feature framework. First, we present ranking criteria for categorical variables and ways to improve the score overview. Second, we present a novel way to utilize the categorical information together with clustering algorithms. Users can partition the data set according to categorical information vertically or horizontally, and the clustering result for each partition can serve as new categorical information. We report the results of a longitudinal case study with a biomedical research team, including insights gained and potential future work.     

Mental well-being and quality-of-life benefits of inclusion in nature for adults with disabilities and their caregivers

Abstract

The benefits of green space and nature experiences are increasingly being recognised and translated into public health policy and practice. Alongside this trend, inclusion of all people into parks and nature has been an important area of parks and recreation practice. Nature inclusion for those with disabilities, youth, seniors and immigrants has become a focus of Alberta in Western Canada. This study was designed to examine the influence of two such government supported nature interventions, including day trips and a more extensive weekend or week-long nature experience, on mental well-being outcomes. It is a mixed methods pilot study (N = 37) with baseline and post-intervention measures of quality of life using the standard Quality of Life Inventory (QOLI) alongside other qualitative accounts. Quantitative findings, while not statistically significant, show a positive trend towards improved depression markers, greater health satisfaction, improved social relationships (in particular, love and friendship), as well as satisfaction with a sense of community and experiences of helping. In addition to comments within the QOLI, qualitative data were elicited through reflective writing during the nature interventions. Three dominant qualitative themes of inclusive nature experiences were found: ‘Sensory Activation’, ‘Reimagined Social Relations’ and ‘Reinvented Self’.     

From dysfunctional to destitute: the governance of regional economic development in Newfoundland and Labrador

On 22 May 2012, the federal government announced that it was discontinuing the funding for all regional economic development (RED) organizations in Atlantic Canada, including the regional economic development boards (REDBs) in Newfoundland and Labrador (NL). Shortly after the federal announcement the provincial government in NL also withdrew its financial support, which led to the demise of the REDBs across the province. In this paper, we critically explore the governance of RED in NL and examine the REDB approach and its subsequent demise using Stoker’s five propositions of governance. While the REDBs were conceived as a fundamentally ‘new regional economic development approach’, they were never granted the level of autonomy, support, and resources that was envisioned in this new approach. However, we argue that the demise of the REDBs has shifted the governance of RED from dysfunctional to destitute. These changes are also situated within a ‘retreat from rural’ policy agenda and devolved responsibilities to local levels of government across Canada and in NL.