Information Assurance Technology Forecast 2008

A virtual roundtable (featuring panelists Steven Bellovin, Terry Benzel, Bob Blakely, Dorothy Denning, Whitfield Diffie, Jeremy Epstein, and Paulo Verissimo) discussing the next 15 years in computer security.     

Linear Chain Ferromagnetic Charge Transfer Compounds

Charge transfer complexes possessing a … DADA … structure with both the donor, D, and acceptor, A, being S = 1/2 radicals may exhibit cooperative magnetic phenomena. The complex [Fe(C₅Me₅)₂]⁺·[TCNQ]⁻· exhibits metamagnetic behavior. The similarly structured [TCNE]⁻· and [C₄(CN)₆]⁻· complexes are ferromagnets, whereas the [DDQ]⁻· salt is a paramagnet. The high temperature magnetic susceptibility obeys the Curie-Weiss expression with θ = + 30, + 30, and + 3 for the [TCNE]⁻·, [C₄(CN)₆]⁻·, and [TCNQ]⁻· salts, respectively. The ferromagnetic [TCNE]⁻· salt exhibits zero field Zeeman split ⁵⁷Fe Mossbauer spectra with an internal field of 425.6 kOe at 4.23 K. After reviewing the current papers discussing ferromagnetism in molecular (organic) compounds, a qualitative model consistent with the necessary bulk spin alignment required for a ferromagnet is presented.     

Development into blastocysts of bovine oocytes cryopreserved by ultra-rapid cooling

The objective of the research described was to devise an efficient procedure to cryopreserve in vitro-matured bovine oocytes, using in vitro fertilization (IVF) and development of resultant zygotes into blastocysts as criteria of oocyte survival. Oocytes at metaphase II were found to be extremely sensitive to chilling. Cooling them to O degrees C for as little as 5 sec significantly decreased their capability to cleave and develop further after IVF; after 80 sec at 0 degrees C, only approximately 10% of chilled oocytes developed into blastocysts. Oocytes were also adversely affected by brief exposures to 4 M and 5.5 M ethylene glycol (EG) solutions supplemented with sucrose; after being suspended in either of these EG solutions in plastic straws and plunged directly into liquid nitrogen (LN2), few of the oocytes were fertilized and developed. To "outrace" chilling injury, oocytes contained in < 1 microliter of EG solution were placed onto electron microscope grids and plunged directly into N2 slush or LN2. After such ultra-rapidly cooled oocytes were warmed, 30% of them cleaved after IVF, and half of these developed into blastocysts-- survival rates equivalent to those for oocytes that had been exposed to EG without any cooling. This method offers promise as a novel way to cryopreserve bovine oocytes.     

Temporary Tasks Assignment Resolved

Among all basic on-line load balancing problems, the only unresolved problem was load balancing of temporary tasks on unrelated machines. This open problem existed for almost a decade, see [12]. We resolve this problem by providing an inapproximability result. In addition, a newer open question is to identify the dependency of the competitive ratio on the durations of jobs in the case where durations are known. We resolve this problem by characterizing this dependency. Finally, we provide a PTAS for the off-line problem with a fixed number of machines and show a 2 -inapproximability result for the general case.     

Tracking myocardial motion from cine DENSE images using spatiotemporal phase unwrapping and temporal fitting

Displacement encoding with stimulated echoes (DENSE) encodes myocardial tissue displacement into the phase of the MR image. Cine DENSE allows for rapid quantification of myocardial displacement at multiple cardiac phases through the majority of the cardiac cycle. For practical sensitivities to motion, relatively high displacement encoding frequencies are used and phase wrapping typically occurs. In order to obtain absolute measures of displacement, a two-dimensional (2-D) quality-guided phase unwrapping algorithm was adapted to unwrap both spatially and temporally. Both a fully automated algorithm and a faster semi-automated algorithm are proposed. A method for computing the 2-D trajectories of discrete points in the myocardium as they move through the cardiac cycle is introduced. The error in individual displacement measurements is reduced by fitting a time series to sequential displacement measurements along each trajectory. This improvement is in turn reflected in strain maps, which are derived directly from the trajectories. These methods were validated both in vivo and on a rotating phantom. Further measurements were made to optimize the displacement encoding frequency and to estimate the baseline strain noise both on the phantom and in vivo. The fully automated phase unwrapping algorithm was successful for 767 out of 800 images (95.9%), and the semi-automated algorithm was successful for 786 out of 800 images (98.3%). The accuracy of the tracking algorithm for typical cardiac displacements on a rotating phantom is 0.24 +/- 0.15 mm. The optimal displacement encoding frequency is in the region of 0.1 cycles/mm, and, for 2 scans of 17-s duration, the strain noise after temporal fitting was estimated to be 2.5 +/- 3.0% at end-diastole, 3.1 +/- 3.1% at end-systole, and 5.3 +/- 5.0% in mid-diastole. The improvement in intra-myocardial strain measurements due to temporal fitting is apparent in strain histograms, and also in identifying regions of dysfunctional myocardium in studies of patients with infarcts.     

Psychosocial predictors of cigarette smoking among adolescents living in public housing developments

BACKGROUND: Adolescents residing in low-income public housing developments in inner-city regions may be particularly vulnerable to a variety of risk factors associated with cigarette smoking. OBJECTIVE: To elucidate the aetiology of cigarette smoking among adolescents living in public housing developments. DESIGN, SETTING, AND SUBJECTS: We examined predictors of smoking from four domains: background characteristics, social influences, behavioural control, and psychosocial characteristics using a sample of seventh graders (mean age 12.9 years) who reside in public housing developments in New York City (n = 624). The addresses of participants in a larger investigation of the aetiology and prevention of smoking were checked to determine if they lived in one of 335 public housing developments in New York City. All participants living in public housing developments were included in the current study. MAIN OUTCOME MEASURES: African-American and Hispanic students completed questionnaires about their cigarette use, social pressures to smoke, smoking attitudes, smoking knowledge, and smoking resistance skills. Students also provided information on demographic and behavioural control (such as church and school attendance). RESULTS: Logistic regression analyses indicated that social influences from friends and family members predicted smoking. Psychosocial characteristics such as advertising resistance skills, anti-smoking attitudes, and refusal skills lowered the odds of smoking. CONCLUSIONS: These findings suggest that smoking prevention approaches targeted at these young people should increase their awareness of social pressures to smoke, correct misperceptions about the prevalence of smoking among friends, and teach relevant psychosocial skills.