1,716 research outputs found
Synthesis and Recognition Properties of Higher Order Tetrathiafulvalene (Ttf) Calix N Pyrroles (N=4-6)
Two new benzoTTF-annulated calix[n]pyrroles (n = 5 and 6) were synthesized via a one-step acid catalyzed condensation reaction and fully characterized via single crystallographic analyses. As compared to the known tetra-TTF annulated calix[4]pyrrole, which is also produced under the conditions of the condensation reaction, the expanded calix[n]pyrroles (n = 5 and 6) are characterized by a larger cavity size and a higher number of TTF units (albeit the same empirical formula). Analysis of the binding isotherms obtained from UV-Vis spectroscopic titrations carried out in CHCl3 in the presence of both anionic (Cl-, Br-, I-, CH3COO-, H2PO4-, and HSO4-) and neutral (1,3,5-trinitrobenzene (TNB) and 2,4,6-trinitrotoluene (TNT)) substrates revealed that as a general rule the calix[6]pyrrole derivative proved to be the most efficient molecular receptor for anions, while the calix[4]pyrrole congener proves most effective for the recognition of TNB and TNT. These findings are rationalized in terms of the number of electron rich TTF subunits and NH hydrogen bond donor groups within the series, as well as an ability to adopt conformations suitable for substrate recognition, and are supported by solid state structural analyses.National Science Foundation CHE 1057904, 0741973Robert A. Welch Foundation F-1018Danish Natural Science Research Council (FNU) 272-08-0047, 11-106744WCU (World Class University) program of Korea R32-2010-10217-0Villum FoundationChemistr
Problematic smartphone use and the quantity and quality of peer engagement among adolescents: A longitudinal study
Problematic smartphone use (PSU) has recently attracted a lot of attention, especially among adolescents. The knowledge about the role peer engagement might play in the development of PSU is still limited. We aimed to investigate the bidirectional relationships between PSU, the quantity of online (i.e., passive and active social media messaging on smartphone) and offline peer engagement (i.e., intensity of face-to-face meeting with friends) and the quality of peer engagement (i.e., perceived competence in close friendships) among adolescents. Data from a three-wave longitudinal study among 2100 Dutch high school students (56.7% boys) was used. Cross-lagged models indicated that: (1) perceived competence in close friendships at T1 negatively predicted PSU at T2 and PSU at T2 negatively predicted perceived competence in close friendships at T3; (2) there were positive and reciprocal cross-lagged correlations between PSU and passive social media messaging on smartphone; (3) there were positive and reciprocal cross-lagged correlations between intensity of face-to-face meeting with friends and active social media messaging on smartphone. This implies that adolescents who perceive a low competence in close friendships and/or intensively check their smartphone for messages from their peers may be particularly vulnerable to developing problematic smartphone use over time
From everyday life to measurable problematic smartphone use:The development and validation of the Smartphone Use Problems Identification Questionnaire (SUPIQ)
BACKGROUND AND AIMS: Problematic smartphone use (PSU) has gained attention, but its definition remains debated. This study aimed to develop and validate a new scale measuring PSU-the Smartphone Use Problems Identification Questionnaire (SUPIQ).METHODS: Using two separate samples, a university community sample (N = 292) and a general population sample (N = 397), we investigated: (1) the construct validity of the SUPIQ through exploratory and confirmatory factor analyses; (2) the convergent validity of the SUPIQ with correlation analyses and the visualized partial correlation network analyses; (3) the psychometric equivalence of the SUPIQ across two samples through multigroup confirmatory factor analyses; (4) the explanatory power of the SUPIQ over the Short Version of Smartphone Addiction Scale (SAS-SV) with hierarchical multiple regressions.RESULTS: The results showed that the SUPIQ included 26 items and 7 factors (i.e., Craving, Coping, Habitual Use, Social Conflicts, Risky Use, Withdrawal, and Tolerance), with good construct and convergent validity. The configural measurement invariance across samples was established. The SUPIQ also explained more variances in mental health problems than the SAS-SV.DISCUSSION AND CONCLUSIONS: The findings suggest that the SUPIQ shows promise as a tool for assessing PSU. Further research is needed to enhance and refine the SUPIQ as well as to investigate its clinical utility.</p
From everyday life to measurable problematic smartphone use:The development and validation of the Smartphone Use Problems Identification Questionnaire (SUPIQ)
BACKGROUND AND AIMS: Problematic smartphone use (PSU) has gained attention, but its definition remains debated. This study aimed to develop and validate a new scale measuring PSU-the Smartphone Use Problems Identification Questionnaire (SUPIQ).METHODS: Using two separate samples, a university community sample (N = 292) and a general population sample (N = 397), we investigated: (1) the construct validity of the SUPIQ through exploratory and confirmatory factor analyses; (2) the convergent validity of the SUPIQ with correlation analyses and the visualized partial correlation network analyses; (3) the psychometric equivalence of the SUPIQ across two samples through multigroup confirmatory factor analyses; (4) the explanatory power of the SUPIQ over the Short Version of Smartphone Addiction Scale (SAS-SV) with hierarchical multiple regressions.RESULTS: The results showed that the SUPIQ included 26 items and 7 factors (i.e., Craving, Coping, Habitual Use, Social Conflicts, Risky Use, Withdrawal, and Tolerance), with good construct and convergent validity. The configural measurement invariance across samples was established. The SUPIQ also explained more variances in mental health problems than the SAS-SV.DISCUSSION AND CONCLUSIONS: The findings suggest that the SUPIQ shows promise as a tool for assessing PSU. Further research is needed to enhance and refine the SUPIQ as well as to investigate its clinical utility.</p
Energy Complexity for Sorting Algorithms in Java
This study extends the concept of time complexity to energy, i.e., energy
complexity, by showing a strong correlation between time complexity and energy
consumption for sorting algorithms: Bubble Sort, Counting Sort, Merge Sort and
Quick Sort, written in Java and run on single kernels. We investigate the
correlation between wall time and time complexity, as well as the correlation
between energy consumption and wall time. The primary finding is that time
complexity can be used as a guideline to estimate the energy consumption of
O(n*n), O(nlog(n)) and O(n + k) sorting algorithms. The secondary finding is
that the inputs producing the theoretical worst cases for Merge Sort and Bubble
Sort did not produce the worst case wall time nor the worst case energy
consumption
Differential expression of two types of sucrose synthase-encoding genes in wheat in response to anaerobiosis, cold shock and light
The expression of two types of sucrose synthase-encoding genes, Ss1 and Ss2, in hexaploid wheat (Triticum aestivum, L.), has been investigated using type-specific probes, corresponding to the 250–270 bp C-terminal portions of the respective cDNA clones. Both types of genes are highly expressed in developing endosperm, where the expression of the Ss2 type slightly precedes in time that of the Ss1 type. Expression of Ss genes is lower in etiolated leaves and in roots than in endosperm. In the first two tissues, the Ss1 mRNA is much more abundant than the Ss2 mRNA, and the Ss1 mRNA level sharply increases in response to anerobiosis and to cold shock (6°C), while the level of Ss2 mRNA is not significantly affected. Upon illumination of etiolated leaves, the Ss1 level mRNA decreases significantly and the Ss2 mRNA level increases
A Hybrid Godunov Method for Radiation Hydrodynamics
From a mathematical perspective, radiation hydrodynamics can be thought of as
a system of hyperbolic balance laws with dual multiscale behavior (multiscale
behavior associated with the hyperbolic wave speeds as well as multiscale
behavior associated with source term relaxation). With this outlook in mind,
this paper presents a hybrid Godunov method for one-dimensional radiation
hydrodynamics that is uniformly well behaved from the photon free streaming
(hyperbolic) limit through the weak equilibrium diffusion (parabolic) limit and
to the strong equilibrium diffusion (hyperbolic) limit. Moreover, one finds
that the technique preserves certain asymptotic limits. The method incorporates
a backward Euler upwinding scheme for the radiation energy density and flux as
well as a modified Godunov scheme for the material density, momentum density,
and energy density. The backward Euler upwinding scheme is first-order accurate
and uses an implicit HLLE flux function to temporally advance the radiation
components according to the material flow scale. The modified Godunov scheme is
second-order accurate and directly couples stiff source term effects to the
hyperbolic structure of the system of balance laws. This Godunov technique is
composed of a predictor step that is based on Duhamel's principle and a
corrector step that is based on Picard iteration. The Godunov scheme is
explicit on the material flow scale but is unsplit and fully couples matter and
radiation without invoking a diffusion-type approximation for radiation
hydrodynamics. This technique derives from earlier work by Miniati & Colella
2007. Numerical tests demonstrate that the method is stable, robust, and
accurate across various parameter regimes.Comment: accepted for publication in Journal of Computational Physics; 61
pages, 15 figures, 11 table
Breast cancer risk reduction:is it feasible to initiate a randomised controlled trial of a lifestyle intervention programme (ActWell) within a national breast screening programme?
BackgroundBreast cancer is the most commonly diagnosed cancer and the second cause of cancer deaths amongst women in the UK. The incidence of the disease is increasing and is highest in women from least deprived areas. It is estimated that around 42% of the disease in post-menopausal women could be prevented by increased physical activity and reductions in alcohol intake and body fatness. Breast cancer control endeavours focus on national screening programmes but these do not include communications or interventions for risk reductionThis study aimed to assess the feasibility of delivery, indicative effects and acceptability of a lifestyle intervention programme initiated within the NHS Scottish Breast Screening Programme (NHSSBSP).MethodsA 1:1 randomised controlled trial (RCT) of the 3 month ActWell programme (focussing on body weight, physical activity and alcohol) versus usual care conducted in two NHSSBSP sites between June 2013 and January 2014. Feasibility assessments included recruitment, retention, and fidelity to protocol. Indicative outcomes were measured at baseline and 3 month follow-up (body weight, waist circumference, eating and alcohol habits and physical activity. At study end, a questionnaire assessed participant satisfaction and qualitative interviews elicited women¿s, coaches and radiographers¿ experiences. Statistical analysis used Chi squared tests for comparisons in proportions and paired t tests for comparisons of means. Linear regression analyses were performed, adjusted for baseline values, with group allocation as a fixed effectResultsA pre-set recruitment target of 80 women was achieved within 12 weeks and 65 (81%) participants (29 intervention, 36 control) completed 3 month assessments. Mean age was 58¿±¿5.6 years, mean BMI was 29.2¿±¿7.0 kg/m2 and many (44%) reported a family history of breast cancer.The primary analysis (baseline body weight adjusted) showed a significant between group difference favouring the intervention group of 2.04 kg (95%CI ¿3.24 kg to ¿0.85 kg). Significant, favourable between group differences were also detected for BMI, waist circumference, physical activity and sitting time. Women rated the programme highly and 70% said they would recommend it to others.ConclusionsRecruitment, retention, indicative results and participant acceptability support the development of a definitive RCT to measure long term effects.Trial registrationThe trial was registered with Current Controlled Trials (ISRCTN56223933)
Problematic smartphone use and the quantity and quality of peer engagement among adolescents: A longitudinal study
Problematic smartphone use (PSU) has recently attracted a lot of attention, especially among adolescents. The knowledge about the role peer engagement might play in the development of PSU is still limited. We aimed to investigate the bidirectional relationships between PSU, the quantity of online (i.e., passive and active social media messaging on smartphone) and offline peer engagement (i.e., intensity of face-to-face meeting with friends) and the quality of peer engagement (i.e., perceived competence in close friendships) among adolescents. Data from a three-wave longitudinal study among 2100 Dutch high school students (56.7% boys) was used. Cross-lagged models indicated that: (1) perceived competence in close friendships at T1 negatively predicted PSU at T2 and PSU at T2 negatively predicted perceived competence in close friendships at T3; (2) there were positive and reciprocal cross-lagged correlations between PSU and passive social media messaging on smartphone; (3) there were positive and reciprocal cross-lagged correlations between intensity of face-to-face meeting with friends and active social media messaging on smartphone. This implies that adolescents who perceive a low competence in close friendships and/or intensively check their smartphone for messages from their peers may be particularly vulnerable to developing problematic smartphone use over time
Cytological and transcript analyses reveal fat and lazy persister-like bacilli in tuberculous sputum
As nonreplicating tubercle bacilli are tolerant to the cidal action of antibiotics and resistant to multiple stresses, identification of this persister-like population of tubercle bacilli in sputum presents exciting and tractable new opportunities to investigate both responses to chemotherapy and the transmission of tuberculosis
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