Simulation of the White Dwarf -- White Dwarf galactic background in the LISA data

LISA (Laser Interferometer Space Antenna) is a proposed space mission, which will use coherent laser beams exchanged between three remote spacecraft to detect and study low-frequency cosmic gravitational radiation. In the low-part of its frequency band, the LISA strain sensitivity will be dominated by the incoherent superposition of hundreds of millions of gravitational wave signals radiated by inspiraling white-dwarf binaries present in our own galaxy. In order to estimate the magnitude of the LISA response to this background, we have simulated a synthesized population that recently appeared in the literature. We find the amplitude of the galactic white-dwarf binary background in the LISA data to be modulated in time, reaching a minimum equal to about twice that of the LISA noise for a period of about two months around the time when the Sun-LISA direction is roughly oriented towards the Autumn equinox. Since the galactic white-dwarfs background will be observed by LISA not as a stationary but rather as a cyclostationary random process with a period of one year, we summarize the theory of cyclostationary random processes and present the corresponding generalized spectral method needed to characterize such process. We find that, by measuring the generalized spectral components of the white-dwarf background, LISA will be able to infer properties of the distribution of the white-dwarfs binary systems present in our Galaxy.Comment: 14 pages and 6 figures. Submitted to Classical and Quantum Gravity (Proceedings of GWDAW9

Sulphate-controlled Diversity of Subterranean Microbial Communities over Depth in Deep Groundwater with Opposing Gradients of Sulphate and Methane

The groundwater system in Olkiluoto, Finland, is stratified with a mixing layer at a depth of approximately 300m between sulphate-rich, methane-poor and sulphate-poor, methane-rich groundwaters. New sequence library data obtained by 454 pyrotag sequencing of the v4v6 16S rDNA region indicated that sulphate-reducing bacteria (SRB) dominated the mixing layer while SRB could not be detected in the deep sulphate-poor groundwater samples. With the indispensable support of the sequence data, it could be demonstrated that sulphate was the only component needed to trigger a very large community transition in deep sulphate-poor, methane-rich groundwater from a non-sulphate-reducing community comprising Hydrogenophaga, Pseudomonas, Thiobacillus, Fusibacter, and Lutibacter to a sulphate-reducing community with Desulfobacula, Desulfovibrio, Desufobulbaceae, Desulfobacterium, Desulfosporosinus, and Desulfotignum. Experiments with biofilms and planktonic microorganisms in flow cells under in situ conditions confirmed that adding sulphate to the sulphate-poor groundwater generated growth of cultivable SRB and detectable SRB-related sequences. It was also found that the 16S rDNA diversity of the biofilms was conserved over 103 d and that there was great similarity in diversity between the microorganisms in the biofilms and in the flowing groundwater. This work demonstrates that the presence/absence of only one geochemical parameter, i.e., sulphate, in the groundwater significantly influenced the diversity of the investigated subterranean microbial community

RECOGNITION OF TAXONOMICALLY SIGNIFICANT CLUSTERS NEAR THE SPECIES LEVEL, USING COMPUTATIONALLY INTENSE METHODS, WITH EXAMPLES FROM THE STEPHANODISCUS NIAGARAE COMPLEX (BACILLARIOPHYCEAE) 1

Since the early 1960s, numerical techniques have produced a wide variety of methods to suggest classifications of organisms based on quantitative measurements. A long-recognized shortcoming of these methods is that they will suggest classifications for any group of organisms and any set of measurements, whether or not the clusters in the suggested classification have any natural meaning or significance. Some progress has been made in assessing the reality of clusters determined by various methods. Data simulated to reflect known cluster structure have been used to test the accuracy of different methods, Various methods have been applied to the same data sets to compare how well they realize various desirable properties. Here we define a data-based model of randomness to represent what might be meant by “no natural basis for subdivision into clusters” and use it to compare an observed measure of cluster distinctness to the distribution of this measure predicted by this model of randomness. In this way, unwarranted subdivision can be statistically avoided, and significant subdivisions can be investigated with confidence. Our methods are illustrated with some examples from the Stephanodiscus niagarae Ehrenb. species complex. Significant differences in morphologic expression are identified in S. reimerii Theriot and Stoermer in Theriot, S. superiorensis Theriot and Stoermer and S. yellowstonensis Theriot and Stoermer. In addition, statistically significant clusters are identified in S. niagarae populations from different geographic locations and in members of the same population grown in different environments. These results suggest current criteria for resolving diatom taxa may not be sufficient to discern subtle differences that occur between real species.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65691/1/j.0022-3646.1997.01049.x.pd

Perceptions and understanding of research situations as a function of consent form characteristics and experimenter instructions

Two studies examined how research methodology affected participant behaviors. Study 1 tested (a) consent form perspective (1st, 2nd, or 3rd person) and (b) information on participants’ right to sue upon perceptions of coercion, ability to recall consent information, and performance on experimental tasks. Unexpectedly, participants who received instructions without the right to sue information had significantly better recall of their research rights. Study 2 manipulated (a) consent form complexity (presence or absence of jargon) and (b) the detail of verbal instructions (simple, elaborate); participants who received a consent form with simpler language spent more time on a difficult task, and participants in the elaborate instruction condition recalled more details. Together, these studies suggest (a) explaining the right to sue may actually be counterproductive; (b) providing a more detailed explanation may help participants remember procedural details; and (c) using jargon may decrease task performance

Exploiting the Oral Microbiome to Prevent Tooth Decay: Has Evolution Already Provided the Best Tools?

To compete in the relatively exposed oral cavity, resident microbes must avoid being replaced by newcomers. This selective constraint, coupled with pressure on the host to cultivate a beneficial microbiome, has rendered a commensal oral microbiota that displays colonization resistance, protecting the human host from invasive species, including pathogens. Rapid increases in carbohydrate consumption have disrupted the evolved homeostasis between the oral microbiota and dental health, reflected by the high prevalence of dental caries. Development of novel modalities to prevent caries has been the subject of a breadth of research. This mini review provides highlights of these endeavors and discusses the rationale and pitfalls behind the major avenues of approach. Despite efficacy, fluoride and other broad-spectrum interventions are unlikely to further reduce the incidence of dental caries. The most promising methodologies in development are those that exploit the exclusive nature of the healthy oral microbiome. Probiotics derived from the dental plaque of healthy individuals sharply antagonize cariogenic species, such as Streptococcus mutans. Meanwhile, targeted antimicrobials allow for the killing of specific pathogens, allowing reestablishment of a healthy microbiome, presumably with its protective effects. The oral microbiota manufactures a massive array of small molecules, some of which are correlated with health and are likely to antagonize pathogens. The prohibitive cost associated with sufficiently rigorous clinical trials, and the status of dental caries as a non-life-threatening condition will likely continue to impede the advancement of new therapeutics to market. Nevertheless, there is room for optimism, as it appears evolution may have already provided the best tools

Sexually transmitted infections (STI) in men who have sex with men (MSM)

The impact of increasingly efficient antiretroviral therapy (ART) on survival and general well-being has contributed to a "business as usual" attitude to sex among men who have sex with men (MSM). There has been a recent marked increase of sexually transmitted infections (STI) including syphilis, LGV and Hepatits C among MSM. STIs located in the oral cavity or rectum are asymptomatic in over 80% and 50%, respectively and these sites must be seen as important reservoirs. On the other hand severe proctitis may be mistreated as inflammatory bowel disease without adequate medical history and testing. Due to the reappearance of syphilis, all genital ulcers, non-itching exanthema and severe disease symptoms (e.g. fever, fatigue, lymphadenopathy, hepato-splenomegaly, increased liver enzymes, neurological and ophthalmologic symptoms without other explanations) should lead to testing for syphilis. There is a marked association between STIs and HIV. Syphilis, LGV and Hepatits C are strongly overrepresented in HIV positive MSM, while gonorrhoea, LGV and syphilis increase the HIV susceptibility. Syphilis leads to increased viral load in HIV positive. The major risk factors for Hepatitis B are number of sex partners and receptive anal intercourse. High grade Human Papilloma Virus (HPV) anal lesions can progress to cancer. There is a 30 fold increase risk for anal cancer among MSM, a risk that is doubled in HIV infection, making anal cancer one of the most common non-AIDS tumors. All MSM should be offered Hepatitis A and B vaccination and the inclusion of boys in HPV vaccination programs must be considered. The aim of this article is to describe asymptomatic and symptomatic bacterial and viral STIs of the oral cavity, penis/urethra and rectum and the sexually transmittable viral Hepatitis and HIV in MSM and to inspire the medical establishment to adhere to testing guidelines in this group. This article is built on a review of published findings, the presentation of own data on Gonorrhoea and chlamydia and our own experience in treating all STIs including HIV in MSM since 1982 at a Gay Men's Health Clinic (Venhälsan) at Stockholm South General Hospital, Sweden