Does Advice Help to Prove Propositional Tautologies?

One of the starting points of propositional proof complexity is the seminal paper by Cook and Reckhow [6], where they defined propositional proof systems as poly-time computable functions which have all propositional tautologies as their range. Motivated by provability consequences in bounded arithmetic, Cook and Krajíček [5] have recently started the investigation of proof systems which are computed by poly-time functions using advice. While this yields a more powerful model, it is also less directly applicable in practice. In this note we investigate the question whether the usage of advice in propositional proof systems can be simplified or even eliminated. While in principle, the advice can be very complex, we show that proof systems with logarithmic advice are also computable in poly-time with access to a sparse NP-oracle. In addition, we show that if advice is ”not very helpful” for proving tautologies, then there exists an optimal propositional proof system without advice. In our main result, we prove that advice can be transferred from the proof to the formula, leading to an easier computational model. We obtain this result by employing a recent technique by Buhrman and Hitchcock [4]

Loneliness and life satisfaction amongst three cultural groups

Abstract Studies into loneliness and life satisfaction have rarely assessed the role of culture in moderating the relationship between these variables. The present study examined the relationship between loneliness and life satisfaction using data from three nonstudent samples collected from Italian, Anglo-Canadian and Chinese-Canadian populations. A total of 206 respondents completed the Revised UCLA Loneliness Scale (Russell, Peplau, & Cutrona, 1980) and the Satisfaction with Life Scale (Diener, Emmons, Larsen, & Griffin, 1985). Two contrasting hypotheses were compared: one, a “postmodern” hypothesis, predicting that the relationship between life satisfaction and loneliness would be stronger in our individualist sample of Anglo-Canadians, and a second, “relational” hypothesis predicting this association to be strongest in our collectivist, Chinese-Canadian sample. Our findings demonstrated that culture has a small but significant impact on the relationship between loneliness and life satisfaction, and, consistent with the relational hypothesis, the relationship between the two concepts was strongest among our Chinese-Canadian respondents and weakest among our Anglo-Canadian participants This finding is discussed in the context of the strong expectations of social cohesion in collectivist societies

Supported Employment: A Best Practice for People with Psychiatric Disabilities

Over the past several decades, research from a variety of fields has presented powerful evidence of the importance of employment to people with psychiatric disabilities. Many of these people want to work and can successfully participate in the labor market in a variety of competitive jobs. Researchers have also shown how employment can alleviate poverty, reduce hospitalization, and improve quality of life. Society also benefits through taxes paid by workers, goods and services they purchase, and reductions in entitlements and the overall cost of care. However, the 1997 National Health Interview Survey (NHIS) reports employment rates for people with a wide range of mental disorders to be 37.1 percent (Harris et al., 2005; New Freedom Commission on Mental Health, 2003). Employment rates for people with schizophrenia and related disorders are 22 percent (Jans, et al., 2004). Recently, funding agencies and practitioners have begun to move towards evidence-based practice in serving people with psychiatric disabilities. A number of reviews and meta-analyses of single-site, randomized controlled trials of supported employment for this group have found it to be more effective at establishing competitive employment outcomes than prevocational training or non-vocational community care (Crowther et al., 2001; Twamley et al., 2003; Wewiorski & Fabian, 2004). Still in question at the time of this study\u27s funding, however, was the effectiveness of different models of supported employment, operating in a variety of organizational settings, for consumers with diverse demographic characteristics, in different regions of the country. Therefore, the Employment Intervention Demonstration Program (EIDP) was designed as a multi-site randomized controlled trial of the effectiveness of supported employment (SE) for people with psychiatric disabilities in eight locations across the U.S. SE programs use a rapid job search approach to help clients obtain jobs directly (rather than providing lengthy assessment, training, and counseling), and provide them with ongoing support to maintain and improve their earnings after they start work. This policy brief describes the EIDP, presents study findings, and suggests some policy and research implications

Zero gravity tissue-culture laboratory

Hardware was developed for performing experiments to detect the effects that zero gravity may have on living human cells. The hardware is composed of a timelapse camera that photographs the activity of cell specimens and an experiment module in which a variety of living-cell experiments can be performed using interchangeable modules. The experiment is scheduled for the first manned Skylab mission

Aquatic Nitrate Retention at River Network Scales Across Flow Conditions Determined Using Nested In Situ Sensors

Nonpoint pollution sources are strongly influenced by hydrology and are therefore sensitive to climate variability. Some pollutants entering aquatic ecosystems, e.g., nitrate, can be mitigated by in‐stream processes during transport through river networks. Whole river network nitrate retention is difficult to quantify with observations. High frequency, in situ nitrate sensors, deployed in nested locations within a single watershed, can improve estimates of both nonpoint inputs and aquatic retention at river network scales. We deployed a nested sensor network and associated sampling in the urbanizing Oyster River watershed in coastal New Hampshire, USA, to quantify storm event‐scale loading and retention at network scales. An end member analysis used the relative behavior of reactive nitrate and conservative chloride to infer river network fate of nitrate. In the headwater catchments, nitrate and chloride concentrations are both increasingly diluted with increasing storm size. At the mouth of the watershed, chloride is also diluted, but nitrate tended to increase. The end member analysis suggests that this pattern is the result of high retention during small storms (51–78%) that declines to zero during large storms. Although high frequency nitrate sensors did not alter estimates of fluxes over seasonal time periods compared to less frequent grab sampling, they provide the ability to estimate nitrate flux versus storm size at event scales that is critical for such analyses. Nested sensor networks can improve understanding of the controls of both loading and network scale retention, and therefore also improve management of nonpoint source pollution

Quantifying fusion born ion populations in magnetically confined plasmas using ion cyclotron emission

Ion cyclotron emission (ICE) offers unique promise as a diagnostic of the fusion born alpha-particle population in magnetically confined plasmas. Pioneering observations from JET and TFTR found that ICE intensity $P_{ICE}$ scales approximately linearly with the measured neutron flux from fusion reactions, and with the inferred concentration, $n_\alpha/n_i$, of fusion-born alpha-particles confined within the plasma. We present fully nonlinear self-consistent kinetic simulations that reproduce this scaling for the first time. This resolves a longstanding question in the physics of fusion alpha-particle confinement and stability in MCF plasmas. It confirms the magnetoacoustic cyclotron instability (MCI) as the likely emission mechanism and greatly strengthens the basis for diagnostic exploitation of ICE in future burning plasmas

Nondeterministic Instance Complexity and Proof Systems with Advice

Motivated by strong Karp-Lipton collapse results in bounded arithmetic, Cook and Krajíček [1] have recently introduced the notion of propositional proof systems with advice. In this paper we investigate the following question: Given a language L , do there exist polynomially bounded proof systems with advice for L ? Depending on the complexity of the underlying language L and the amount and type of the advice used by the proof system, we obtain different characterizations for this problem. In particular, we show that the above question is tightly linked with the question whether L has small nondeterministic instance complexity

Potential health impacts of heavy metals on HIV-infected population in USA.

Noninfectious comorbidities such as cardiovascular diseases have become increasingly prevalent and occur earlier in life in persons with HIV infection. Despite the emerging body of literature linking environmental exposures to chronic disease outcomes in the general population, the impacts of environmental exposures have received little attention in HIV-infected population. The aim of this study is to investigate whether individuals living with HIV have elevated prevalence of heavy metals compared to non-HIV infected individuals in United States. We used the National Health and Nutrition Examination Survey (NHANES) 2003-2010 to compare exposures to heavy metals including cadmium, lead, and total mercury in HIV infected and non-HIV infected subjects. In this cross-sectional study, we found that HIV-infected individuals had higher concentrations of all heavy metals than the non-HIV infected group. In a multivariate linear regression model, HIV status was significantly associated with increased blood cadmium (p=0.03) after adjusting for age, sex, race, education, poverty income ratio, and smoking. However, HIV status was not statistically associated with lead or mercury levels after adjusting for the same covariates. Our findings suggest that HIV-infected patients might be significantly more exposed to cadmium compared to non-HIV infected individuals which could contribute to higher prevalence of chronic diseases among HIV-infected subjects. Further research is warranted to identify sources of exposure and to understand more about specific health outcomes

Optical shaping of gas targets for laser plasma ion sources

We report on the experimental demonstration of a technique to generate steep density gradients in gas-jet targets of interest to laser–plasma ion acceleration. By using an intentional low-energy prepulse, we generated a hydrodynamic blast wave in the gas to shape the target prior to the arrival of an intense CO$_{2}$ (${\it\lambda}\approx 10~{\rm\mu}\text{m}$) drive pulse. This technique has been recently shown to facilitate the generation of ion beams by shockwave acceleration (Tresca et al., Phys. Rev. Lett., vol. 115 (9), 2015, 094802). Here, we discuss and introduce a model to understand the generation of these blast waves and discuss in depth the experimental realisation of the technique, supported by hydrodynamics simulations. With appropriate prepulse energy and timing, this blast wave can generate steepened density gradients as short as $l\approx 20~{\rm\mu}\text{m}$ ($1/e$), opening up new possibilities for laser–plasma studies with near-critical gaseous targets.</jats:p

The deduction theorem for strong propositional proof systems

This paper focuses on the deduction theorem for propositional logic. We define and investigate different deduction properties and show that the presence of these deduction properties for strong proof systems is powerful enough to characterize the existence of optimal and even polynomially bounded proof systems. We also exhibit a similar, but apparently weaker condition that implies the existence of complete disjoint NP-pairs. In particular, this yields a sufficient condition for the completeness of the canonical pair of Frege systems and provides a general framework for the search for complete NP-pairs