On the algebraic K-theory of the complex K-theory spectrum

Let p>3 be a prime, let ku be the connective complex K-theory spectrum, and let K(ku) be the algebraic K-theory spectrum of ku. We study the p-primary homotopy type of the spectrum K(ku) by computing its mod (p,v_1) homotopy groups. We show that up to a finite summand, these groups form a finitely generated free module over a polynomial algebra F_p[b], where b is a class of degree 2p+2 defined as a higher Bott element.Comment: Revised and expanded version, 42 pages

Navigating new sexual partnerships in midlife: a socioecological perspective on factors shaping STI risk perceptions and practices

OBJECTIVE: Despite increases in STIs among those over 40, little is known about the social context of STI transmission among people experiencing relationship transition in midlife, and few sexual health promotion initiatives are targeted at this group. This study sought to identify factors shaping STI risk perceptions and practices among midlife individuals either contemplating or having sex with new partners following the end of a long-term relationship. METHODS: Participants were purposively selected from respondents to Britain's third National Survey of Sexual Attitudes and Lifestyles, using three eligibility criteria: aged 40-59, reported experience of the end of a marital or cohabiting relationship with an opposite-sex partner in the past 5 years, and willingness to participate in a qualitative interview. Qualitative data were generated via face-to-face interviews with 10 women and 9 men and analysed inductively using thematic analysis, with themes then organised using a socioecological framework. RESULTS: Participants' accounts of new sexual partnerships in midlife indicate that STI risk perceptions and practices are shaped by factors operating at multiple levels across the socioecological arena (individual, partnership, peers and communities, societal). Constraints on, and resources for, the navigation of sexual safety include self-perceived STI risk rooted in past rather than present circumstances; legacies of mistrust within former relationships; intersecting gender-age dynamics in negotiation of risk prevention strategies with new partners; peers and younger relatives' influences on understandings of sexual risk and safety; postrelationship change in social networks that increase or mitigate vulnerability to sexual risk; age-related barriers to accessing condoms; and disconnection from safer sex messaging and services culturally coded as for the young. CONCLUSIONS: Improving sexual health among midlife adults requires age-sensitive interventions designed to address multilevel constraints, and harness positive influences, on the navigation of sexual safety at this stage of life

The Natsal-SF measure of sexual function: comparison of three scoring methods

The Natsal-SF is a psychometrically-validated measure of sexual function for use in community health surveys, derived from 17 questions reflecting three components of sexual function. Scoring requires knowledge of complex statistical modelling and, given the methodological complexities, we assess the validity of two simplified scoring methods calculated using the factor loadings produced when originally modelling the Natsal-SF items. Method 1 uses these factor loadings to three decimal places while method 2 assigns whole numbers to each item based on the factor loadings. Scores from these simplified methods are compared to the original score using correlation coefficients, by comparing the distributions, and the scores of each method in a linear regression model with key variables. We found scores from the simplified methods both correlate highly with the original score, and the distributions of scores closely match. The simplified methods result in different regression coefficients for gender and relationship context, but estimate the coefficients of all other variables similarly to the original method. While the Natsal-SF should ideally be scored using latent variable modelling, the simplified methods perform well so can be used in similar contexts, increasing the utility of the Natsal-SF and enabling future studies to measure sexual function more comprehensively

What factors are associated with reporting lacking interest in sex and how do these vary by gender? Findings from the third British national survey of sexual attitudes and lifestyles

OBJECTIVES: To investigate factors associated with reporting lacking interest in sex and how these vary by gender. SETTING: British general population. DESIGN: Complex survey analyses of data collected for a cross-sectional probability sample survey, undertaken 2010-2012, specifically logistic regression to calculate age-adjusted OR (AOR) to identify associated factors. PARTICIPANTS: 4839 men and 6669 women aged 16-74 years who reported ≥1 sexual partner (opposite-sex or same-sex) in the past year for the third National Survey of Sexual Attitudes and Lifestyles (Natsal-3). MAIN OUTCOME MEASURE: Lacking interest in sex for ≥3 months in the past year. RESULTS: Overall, 15.0% (13.9-16.2) of men and 34.2% (32.8-35.5) of women reported lacking interest in sex. This was associated with age and physical and mental health for both men and women, including self-reported general health and current depression. Lacking interest in sex was more prevalent among men and women reporting sexually transmitted infection diagnoses (ever), non-volitional sex (ever) and holding sexual attitudes related to normative expectations about sex. Some gender similarities in associated relationship and family-related factors were evident, including partner having had sexual difficulties in the last year (men: AOR 1.41 (1.07-1.86); women: AOR 1.60 (1.32-1.94)), not feeling emotionally close to partner during sex (men: 3.74 (1.76-7.93); women: 4.80 (2.99-7.69) and ease of talking about sex (men: 1.53 (1.23-1.90);women: 2.06 (1.77-2.39)). Among women only, lack of interest in sex was higher among those in a relationship of >1 year in duration and those not sharing the same level of interest (4.57 (3.87-5.38)) or preferences (2.91 (2.22-3.83)) with a partner. CONCLUSIONS: Both gender similarities and differences were found in factors associated with lacking interest in sex, with the most marked differences in relation to some relationship variables. Findings highlight the need to assess, and if appropriate, treat lacking interest in sex in a holistic and relationship-specific way

Most vital segment barriers

We study continuous analogues of "vitality" for discrete network flows/paths, and consider problems related to placing segment barriers that have highest impact on a flow/path in a polygonal domain. This extends the graph-theoretic notion of "most vital arcs" for flows/paths to geometric environments. We give hardness results and efficient algorithms for various versions of the problem, (almost) completely separating hard and polynomially-solvable cases

Quantum Noise and Superluminal Propagation

Causal "superluminal" effects have recently been observed and discussed in various contexts. The question arises whether such effects could be observed with extremely weak pulses, and what would prevent the observation of an "optical tachyon." Aharonov, Reznik, and Stern (ARS) [Phys. Rev. Lett., vol. 81, 2190 (1998)] have argued that quantum noise will preclude the observation of a superluminal group velocity when the pulse consists of one or a few photons. In this paper we reconsider this question both in a general framework and in the specific example, suggested by Chiao, Kozhekin, and Kurizki [Phys. Rev. Lett., vol. 77, 1254 (1996)], of off-resonant, short-pulse propagation in an optical amplifier. We derive in the case of the amplifier a signal-to-noise ratio that is consistent with the general ARS conclusions when we impose their criteria for distinguishing between superluminal propagation and propagation at the speed c. However, results consistent with the semiclassical arguments of CKK are obtained if weaker criteria are imposed, in which case the signal can exceed the noise without being "exponentially large." We show that the quantum fluctuations of the field considered by ARS are closely related to superfluorescence noise. More generally we consider the implications of unitarity for superluminal propagation and quantum noise and study, in addition to the complete and truncated wavepackets considered by ARS, the residual wavepacket formed by their difference. This leads to the conclusion that the noise is mostly luminal and delayed with respect to the superluminal signal. In the limit of a very weak incident signal pulse, the superluminal signal will be dominated by the noise part, and the signal-to-noise ratio will therefore be very small.Comment: 30 pages, 1 figure, eps

Help-seeking for genitourinary symptoms: a mixed methods study from Britain's Third National Survey of Sexual Attitudes and Lifestyles (Natsal-3)

Objectives Quantify non-attendance at sexual health clinics and explore help-seeking strategies for genitourinary symptoms. Design Sequential mixed methods using survey data and semistructured interviews. Setting General population in Britain. Participants 1403 participants (1182 women) from Britain’s Third National Survey of Sexual Attitudes and Lifestyles (Natsal-3; undertaken 2010–2012), aged 16–44 years who experienced specific genitourinary symptoms (past 4 weeks), of whom 27 (16 women) who reported they had never attended a sexual health clinic also participated in semistructured interviews, conducted May 2014–March 2015. Primary and secondary outcome measures From survey data, non-attendance at sexual health clinic (past year) and preferred service for STI care; semistructured interview domains were STI social representations, symptom experiences, help-seeking responses and STI stigma. Results Most women (85.9% (95% CI 83.7 to 87.9)) and men (87.6% (95% CI 82.3 to 91.5)) who reported genitourinary symptoms in Natsal-3 had not attended a sexual health clinic in the past year. Around half of these participants cited general practice (GP) as their preferred hypothetical service for STI care (women: 58.5% (95% CI 55.2% to 61.6%); men: 54.3% (95% CI 47.1% to 61.3%)). Semistructured interviews elucidated four main responses to symptoms: not seeking healthcare, seeking information to self-diagnose and self-treat, seeking care at non-specialist services and seeking care at sexual health clinics. Collectively, responses suggested individuals sought to gain control over their symptoms, and they prioritised emotional reassurance over accessing medical expertise. Integrating survey and interview data strengthened the evidence that participants preferred their general practitioner for STI care and extended understanding of help-seeking strategies. Conclusions Help-seeking is important to access appropriate healthcare for genitourinary symptoms. Most participants did not attend a sexual health clinic but sought help from other sources. This study supports current service provision options in Britain, facilitating individual autonomy about where to seek help

Obtaining of Biologically Soluble Membranes Based on Polymeric Nanofibres and Hydroxyapatite of Calcium

In this paper, the possibility of obtaining a synthetic hydroxyapatite of calcium from a biological waste material is shown. The characteristics influencing the synthesis process are studied. Based on the results of the X-ray analysis and the obtained electron microscope images, it can be concluded that the synthesized HAP has a Ca/P ratio of 1.5 and with crystals with an average size of 2 microns. In work, experiments on obtaining biologically soluble films based on nanoscale polymer fibers and calcium hydroxyapatite were carried out. As a result, the main parameters of the process for the electroforming of nano-sized fibers with HAP are determined. The proposed method allows the laying of strictly directed nanofibers from a polymer with a diameter of 50 to 500 nm. The use of different types of electrodes makes it possible to vary the size of nanofibers. The characteristics such as solution viscosity, high voltage and optimum parameters were selected, which allowed obtaining films from biologically soluble polymer nanofibers and HAP. Also, experiments were conducted to introduce medicines into the film structure

Lorentz Invariant Superluminal Tunneling

It is shown that superluminal optical signalling is possible without violating Lorentz invariance and causality via tunneling through photonic band gaps in inhomogeneous dielectrics of a special kind.Comment: 10 pages revtex, no figure, more discussions added, submitted to Phys. Rev.

How does the sexual, physical and mental health of young adults not in education, employment or training (NEET) compare to workers and students?

BACKGROUND: Syndemic theory highlights the potential for health problems to interact synergistically, compounding impact. Young adults not in education, employment or training (NEET) are more likely to experience disadvantage and poorer general health outcomes. However, there is little research on their sexual health, or the extent to which this clusters with mental and physical health outcomes. METHODS: Analysis of data from 16 to 24 year olds (1729 men, 2140 women) interviewed 2010-12 for Britain's third National Survey of Sexual Attitudes and Lifestyles. Natsal-3 is a national probability sample survey using computer-assisted personal interviewing with computer-assisted self-interviewing. Participants were classified as workers, students or NEET. We used multivariable logistic regression to examine associations between being NEET (relative to worker or student) and risk behaviours and outcomes in physical, sexual and mental health domains. We then examined how risk behaviours and poor health outcomes cluster within and across domains. RESULTS: 15% men and 20% women were NEET; 36% men and 32% women were workers; and 49% men and 48% women were students. Young people who were NEET were more likely to report smoking and drug use (men) than other young people. There were few differences in sexual health, although NEETs were more likely to report condomless sex, and NEET women, unplanned pregnancy (past year). Risk behaviours clustered more within and across domains for NEET men. Among NEET women, poor health outcomes clustered across mental, physical and sexual health domains. CONCLUSIONS: Harmful health behaviours (men) and poor health outcomes (women) clustered more in those who are NEET. This points to a possible syndemic effect of NEET status on general ill health, especially for women. Our paper is novel in highlighting that elevated risk pertains to sexual as well as mental and physical health