Potential operational multi-satellite sensor mapping of snow cover in maritime sub-polar regions

Scottish snow cover as an example of a maritime sub-polar region has two principal problems for an operational monitoring programme: the often ephemeral nature of the snow cover, and the loss of direct access to snow imagery due to clouds. At present only the NOAA AVHRR series provides images with the required temporal and spatial resolutions. Based on the availability of data from the Dundee satellite data receiving station a range of NOAA-12, -14 and -15 day and night passes were collected and processed. Three snow cover products were produced from the NOAA AVHRR/2 data: snow area based on channel 134 ISODATA classifications, percentage snow cover based on multi-temporal Normalized Difference Vegetation Index (NDVI), and daily maximum snow surface temperature maps using split-window combinations of thermal channels. Noted improvements were evident in the accuracy and resolution of snow cover classifications based on provisional testing of AVHRR/3 data. Maximum snow surface temperature maps indicated a potential for mapping areas of snow melt. The principal limitation in the operational snow cover mapping with AVHRR, however, remains the loss of temporal resolution due to cloud cover.     

Evaluating the Vulnerability of Network Traffic Using Joint Security and Routing Analysis

Joint analysis of security and routing protocols in wireless networks reveals vulnerabilities of secure network traffic that remain undetected when security and routing protocols are analyzed independently. We formulate a class of continuous metrics to evaluate the vulnerability of network traffic as a function of security and routing protocols used in wireless networks. We develop two complementary vulnerability definitions using set theoretic and circuit theoretic interpretations of the security of network traffic, allowing a network analyst or an adversary to determine weaknesses in the secure network. We formalize node capture attacks using the vulnerability metric as a nonlinear integer programming minimization problem and propose the GNAVE algorithm, a Greedy Node capture Approximation using Vulnerability Evaluation. We discuss the availability of security parameters to the adversary and show that unknown parameters can be estimated using probabilistic analysis. We demonstrate vulnerability evaluation using the proposed metrics and node capture attacks using the GNAVE algorithm through detailed examples and simulation.     

Engineered human carboxypeptidase B enzymes that hydrolyse hippuryl-L- glutamic acid: reversed-polarity mutants

Variants of human pancreatic carboxypeptidase B (HCPB), with specificity for hydrolysis of C-terminal glutamic acid and aspartic acid, were prepared by site-directed mutagenesis of the human gene and expressed in the periplasm of Escherichia coli. By changing residues in the lining of the S1' pocket of the enzyme, it was possible to reverse the substrate specificity to give variants able to hydrolyse prior to C- terminal acidic amino acid residues instead of the normal C-terminal basic residues. This was achieved by mutating Asp253 at the base of the S1' specificity pocket, which normally interacts with the basic side- chain of the substrate, to either Lys or Arg. The resulting enzymes had the desired reversed polarity and enzyme activity was improved significantly with further mutations at residue 251. The [G251T,D253K]HCPB double mutant was 100 times more active against hippuryl-L-glutamic acid (hipp-Glu) as substrate than was the single mutant, [D253K]HCPB. Triple mutants, containing additional changes at Ala248, had improved activity against hipp-Glu substrate when position 251 was Asn. These reversed-polarity mutants of a human enzyme have the potential to be used in antibody-directed enzyme prodrug therapy of cancer.      

An analysis of group versus individual child health supervision

This study compares the effectiveness of group health supervision (three or four families counseled simultaneously) with traditional visits in conveying knowledge of child health and development, increasing perceived maternal support, and mitigating maternal depression. Subjects were recruited from a predominantly white, middle-class, suburban/rural pediatric practice. Twenty-five families were allocated to group health supervision and 25 to individual visits. A questionnaire covering knowledge of child health and development (CHDQ), the Maternal Social Support Index (MSSI), and the Center for Epidemiologic Studies Depression Scale (CESD) were administered to both groups before their 2-month and after their 10-month visits. A subset of these charts was reviewed for problem visits between 2 and 6 months. As compared with families having traditional visits, families who received the group intervention did at least as well in acquiring knowledge of child care and development and, although not statistically significant, tended to recover from postpartum depression faster and deal better with minor illnesses. The investigators found group child health supervision to be a pleasant and effective method of health care delivery.