On using content addressable memory for packet classification

Packet switched networks such as the Internet require packet classification at every hop in order to ap-ply services and security policies to traffic flows. The relentless increase in link speeds and traffic volume imposes astringent constraints on packet classification solutions. Ternary Content Addressable Memory (TCAM) devices are favored by most network component and equipment vendors due to the fast and de-terministic lookup performance afforded by their use of massive parallelism. While able to keep up with high speed links, TCAMs suffer from exorbitant power consumption, poor scalability to longer search keys and larger filter sets, and inefficient support of multiple matches. The research community has responded with algorithms that seek to meet the lookup rate constraint with greater efficiency through the use of com-modity Random Access Memory (RAM) technology. The most promising algorithms efficiently achieve high lookup rates by leveraging the statistical structure of real filter sets. Due to their dependence on filter set characteristics, it is difficult to provision processing and memory resources for implementations that support a wide variety of filter sets. We show how several algorithmic advances may be leveraged to im-prove the efficiency, scalability, incremental update and multiple match performance of CAM-based packet classification techniques without degrading the lookup performance. Our approach, Label Encoded Content Addressable Memory (LECAM), represents a hybrid technique that utilizes decomposition, label encoding, and a novel Content Addressable Memory (CAM) architecture. By reducing the number of implementation parameters, LECAM provides a vehicle to carry several of the recent algorithmic advances into practice. We provide a thorough overview of CAM technologies and packet classification algorithms, along with a detailed discussion of the scaling issues that arise with longer search keys and larger filter sets. We also provide a comparative analysis of LECAM and standard TCAM using a collection of real and synthetic filter sets of various sizes and compositions

Neutral proteases of human polymorphonuclear granulocytes: putative mediators of pulmonary damage.

Tissue proteolytic enzymes are currently believed to be critical to the pathogenesis of panacinar emphysema. Polymorphonuclear leukocytes (Polys) have several enzymes including elastase and cathepsin G in their azurophil granules. They have collagenase in their specific granules. We have found that this collagenase is doubly latent. It has the lysosomal type of latency that depends on the impermeability of the unit membrane that surrounds each specific granule. In addition it has a latency that is converted to activity by proteolytic enzymes. The cathepsin G of the azurophil granule is a potent activator of this latent collagenase once the collagenase is released from its membrane dependent latency. Thus latency of enzymes, the nature of the latency and accessibility of the latent enzymes to activating mechanisms must all be taken into account in any analysis of their contribution to pathogenesis of local lung disease. Equally important is that fact that polys are not a prominent cellular component of normal lung. Polys must be attracted to the lung by chemotactic peptides. These peptides must be released by the interaction of inflammatory stimuli, such as smoke particles, with complement components or they must be provided by other sources. The hypothesis that lung damage in panacinar emphysema is mediated by polys and their proteases is attractive and suggestive evidence supporting this is available. However, more evidence that takes into full account the cell biology of the proteases any poly turnover in the lung are needed to extend the hypothesis and to form a rational basis for therapeutic and prophylactic measures

Risky sexual behaviors and sexually transmitted diseases: a comparison study of cocaine-dependent individuals in treatment versus a community-matched sample

Cocaine users routinely engage in high-risk sexual behaviors that place them at an elevated risk of contracting HIV and other blood-borne infections. The purpose of the present study was to compare trading sex for drugs and/or money, having 10 or more sexual partners in 1 year, and sexually transmitted diseases (STDs) of cocaine-dependent individuals in treatment for their dependence across race and gender and against participants who live in their community. Cocaine-dependent individuals (n = 459) were identified through nine publicly and privately funded inpatient and outpatient chemical dependency treatment centers in the St. Louis area during 2001–2006. Community-based participants (n = 459) were matched to cocaine-dependent participants on age, ethnicity, gender, and zip code of residence. Mean age of the sample was 36 years old, 50% were Caucasians, 50% were African American, and 47% were male. Nearly half of cocaine-dependent participants in treatment had traded sex for drugs and/or money and over one-third had more than 10 sexual partners in 1 year with a risk concentrated among African Americans even after controlling for income and educational attainment. Participants recruited from the community with some exposure to cocaine reported similar rates of high risk sexual behaviors as the cocaine dependent subjects from treatment settings. It is important for clinicians to recognize that once released from treatment, cocaine-dependent individuals may be returning to high-risk environments where sexual risk behaviors are occurring in the context of cocaine use

Smoking cessation is associated with lower rates of mood/anxiety and alcohol use disorders

BACKGROUND: The psychological outcomes that accompany smoking cessation are not yet conclusive but positive outcomes could help to persuade quitting. METHOD: We use data from the longitudinal National Epidemiological Study of Alcohol and Related Conditions. Logistic regression was used to examine associations between cigarette smoking reduction and Wave 2 status of addiction/mental health disorder among daily smokers at Wave 1, stratified by status of the diagnosis of interest at Wave 1. We adjusted for differences in baseline covariates between smokers with different levels of smoking reduction between Wave 1 and Wave 2 using propensity score regression adjustment. RESULTS: After adjusting for propensity scores and other mental health/addiction comorbidities at Wave 2, among daily smokers who had current or lifetime history diagnosis of the outcome of interest at Wave 1, quitting by Wave 2 predicted a decreased risk of mood/anxiety disorder (aOR 0.6, 95% CI 0.4, 0.9) and alcohol disorder (aOR 0.7, 95% CI 0.5, 0.99) at Wave 2. Among daily smokers with no lifetime history diagnosis of the outcome of interest at Wave 1, quitting smoking by Wave 2 predicted a decreased risk of drug use disorder at Wave 2 aOR 0.3, 95% CI 0.1, 0.9). CONCLUSIONS: There is no support in our data for the concern that smoking cessation would result in smokers’ increased risk of some mental disorders. To the contrary, our data suggest that smoking cessation is associated with risk reduction for mood/anxiety or alcohol use disorder, even among smokers who have had a pre-existing disorder

Cytokinesis in bloodstream stage Trypanosoma brucei requires a family of katanins and spastin

Microtubule severing enzymes regulate microtubule dynamics in a wide range of organisms and are implicated in important cell cycle processes such as mitotic spindle assembly and disassembly, chromosome movement and cytokinesis. Here we explore the function of several microtubule severing enzyme homologues, the katanins (KAT80, KAT60a, KAT60b and KAT60c), spastin (SPA) and fidgetin (FID) in the bloodstream stage of the African trypanosome parasite, Trypanosoma brucei. The trypanosome cytoskeleton is microtubule based and remains assembled throughout the cell cycle, necessitating its remodelling during cytokinesis. Using RNA interference to deplete individual proteins, we show that the trypanosome katanin and spastin homologues are non-redundant and essential for bloodstream form proliferation. Further, cell cycle analysis revealed that these proteins play essential but discrete roles in cytokinesis. The KAT60 proteins each appear to be important during the early stages of cytokinesis, while downregulation of KAT80 specifically inhibited furrow ingression and SPA depletion prevented completion of abscission. In contrast, RNA interference of FID did not result in any discernible effects. We propose that the stable microtubule cytoskeleton of T. brucei necessitates the coordinated action of a family of katanins and spastin to bring about the cytoskeletal remodelling necessary to complete cell divisio

Infant head growth in male siblings of children with and without autism spectrum disorders

Previous research has indicated that children with autism exhibit accelerated head growth (HG) in infancy, although the timing of acceleration varies between studies. We examined infant HG trajectory as a candidate autism endophenotype by studying sibling pairs. We retrospectively obtained serial head orbitofrontal circumference measurements of: a) 48 sibling pairs in which one (n = 28) or both (n = 20) sibs were affected by an autism spectrum disorder (ASD); and b) 85 control male sibling pairs. Rate of HG of ASD subjects was slightly accelerated compared to controls, but the magnitude of difference was below the limit of reliability of standard measurement methods. Sibling intra class correlation for rate of HG was highly statistically significant; the magnitude was significantly stronger among autism-affected families (ICC = .63) than among controls (ICC = .26), p < .01. Infant HG trajectory appears familial—possibly endophenotypic—but was not a reliable marker of autism risk among siblings of ASD probands in this sample

Come for the looks, stay for the personality? A mixed methods investigation of reacquisition and owner recommendation of Bulldogs, French Bulldogs and Pugs

Brachycephalic breeds are proliferating internationally, with dramatic rises in popularity juxtaposed with common and severe breed-related health problems. Physical appearance is as a dominant factor attracting owners to brachycephalic breeds; however, whether these owners will choose their current breed for future ownership and develop 'breed-loyalty' in the face of health problems is not yet known. The aims of this study were (1) to quantify levels of, and explore factors associated with, brachycephalic dog owners' intentions to: (i) reacquire and/or (ii) recommend their current breed to potential first-time dog owners, and (2) to use qualitative methods to explore why brachycephalic dog owners would or would not recommend their current breed. This large mixed methods study reports on 2168 owners of brachycephalic breeds (Pugs: n = 789; French Bulldog: n = 741; Bulldogs: n = 638). Owners were highly likely to want to own their breed again in the future (93.0%) and recommend their breed to other owners (65.5%). Statistical modelling identified that first-time ownership and increased strength of the dog-owner relationship increased the likelihood of reacquisi-tion and/or recommendation. In contrast, an increased number of health problems, positive perception of their dog's health compared with the rest of their breed, and dog behaviour being worse than expected decreased the likelihood of reacquisition and/or recommendation. Thematic analyses constructed three themes describing why owners recommend their breed: positive behavioural attributes for a companion dog, breed suited to a sedentary lifestyle with limited space, and suitability for households with children. Five themes described why owners recommended against their breed: high prevalence of health problems, expense of ownership, ethical and welfare issues associated with breeding brachycephalic dogs, negative effects upon owner lifestyle and negative behavioural attributes. Understanding how breed-loyalty develops, and whether it can be attenuated, will be key to controlling the current population boom in brachycephalic breeds in the long-term

Evidence for the η_b(1S) Meson in Radiative Υ(2S) Decay

We have performed a search for the η_b(1S) meson in the radiative decay of the Υ(2S) resonance using a sample of 91.6 × 10^6 Υ(2S) events recorded with the BABAR detector at the PEP-II B factory at the SLAC National Accelerator Laboratory. We observe a peak in the photon energy spectrum at E_γ = 609.3^(+4.6)_(-4.5)(stat)±1.9(syst) MeV, corresponding to an η_b(1S) mass of 9394.2^(+4.8)_(-4.9)(stat) ± 2.0(syst) MeV/c^2. The branching fraction for the decay Υ(2S) → γη_b(1S) is determined to be [3.9 ± 1.1(stat)^(+1.1)_(-0.9)(syst)] × 10^(-4). We find the ratio of branching fractions B[Υ(2S) → γη_b(1S)]/B[Υ(3S) → γη_b(1S)]= 0.82 ± 0.24(stat)^(+0.20)_(-0.19)(syst)

Measurement of the quasi-elastic axial vector mass in neutrino-oxygen interactions

The weak nucleon axial-vector form factor for quasi-elastic interactions is determined using neutrino interaction data from the K2K Scintillating Fiber detector in the neutrino beam at KEK. More than 12,000 events are analyzed, of which half are charged-current quasi-elastic interactions nu-mu n to mu- p occurring primarily in oxygen nuclei. We use a relativistic Fermi gas model for oxygen and assume the form factor is approximately a dipole with one parameter, the axial vector mass M_A, and fit to the shape of the distribution of the square of the momentum transfer from the nucleon to the nucleus. Our best fit result for M_A = 1.20 \pm 0.12 GeV. Furthermore, this analysis includes updated vector form factors from recent electron scattering experiments and a discussion of the effects of the nucleon momentum on the shape of the fitted distributions.Comment: 14 pages, 10 figures, 6 table