The plant in a field of energy, or in any considered area in which gradients exist, reacts passively to its surroundings . . . it should be clear that the sun, or even outer space, is not more removed from the plant than the next millimeter of air; it is the specific part of heat exchange being considered that determines what should be included in the plant’s environment.Klaus Raschke (1960)
To evaluate the long-term durability properties of materials for microelectromechanical systems (MEMS), the stress-life (S/N) cyclic fatigue behavior of a 2-μm thick polycrystalline silicon film was evaluated in laboratory air using an electrostatically actuated notched cantilever beam resonator. A total of 28 specimens were tested for failure under high frequency (∼40kHz) cyclic loads with lives ranging from about 10s to 34 days (3×105 to 1.2×1011 cycles) over fully reversed, sinusoidal stress amplitudes varying from ∼2.0 to 4.0GPa. The thin-film polycrystalline silicon cantilever beams exhibited a time-delayed failure that was accompanied by a continuous increase in the compliance of the specimen. This apparent cyclic fatigue effect resulted in an endurance strength, at greater than 109 cycles, of ∼2GPa, i.e. roughly one-half of the (single cycle) fracture strength. Based on experimental and numerical results, the fatigue process is attributed to a novel mechanism involving the environmentally-assisted cracking of the surface oxide film (termed reaction-layer fatigue). These results provide the most comprehensive, high-cycle, endurance data for designers of polysilicon micromechanical components available to date.
Classifications on the DDO system are given for the host galaxies of 177 supernovae (SNe) that have been discovered since 1997 during the course of the Lick Observatory Supernova Search with the Katzman Automatic Imaging Telescope. Whereas SNe Ia occur in all galaxy types, it is found, at a high level of statistical confidence, that SNe Ib, Ic, and II are strongly concentrated in late-type galaxies. However, attention is drawn to a possible exception provided by SN 2001I. This SN IIn occurred in the E2 galaxy UGC 2836, which was not expected to harbor a massive young supernova progenitor.
Objective Numerous epidemiological studies have been conducted to examine the prevalence and comorbidities of insomnia and document sleep duration, but a common limitation in many studies is the lack of use of agreed-upon definitions of insomnia, as well as insufficient statistical power to examine comorbid mental and physical disorders/conditions. Aim To examine the prevalence of insomnia operationalized according to formal DSM-5 criteria and differences in mean sleep duration across a wide range of mental and physical disorders, examining men and women separately. Materials and Methods Data stem from the SHoT study (Students’ Health and Wellbeing Study), a national survey of all college and university students in Norway. In all, 162,512 students aged 18–35 received an invitation to participate, of whom 50,054 students completed the internet-based survey (attendance rate: 30.8%). Insomnia was defined according to the Diagnostic and Statistical Manual of Mental Disorders (5th ed.) criteria and sleep duration was calculated separately for weekdays and weekends. Self-reported mental and physical disorders/conditions were assessed using a pre-defined list modified to fit this age group. Pearson chi-squared tests were used to examine the prevalence of insomnia across the various mental and physical disorders/conditions in men and women separately, and log-link binomial regression analysis were used to calculate effect-sizes, adjusting for age. Results The prevalence of insomnia in both sexes was significantly higher across all mental disorders compared with a healthy reference group. Among females, the prevalence of insomnia ranged from 61.3% for comorbid depression (adj. RR = 2.49, 95% CI: 2.40) to 83.3% for comorbid schizophrenia (adj. RR = 3.37, 95% CI: 2.61–4.35). For males, the insomnia prevalence ranged from 32.3% for comorbid autism/Asperger (adj. RR = 2.02, 95% CI: 1.39–2.92) to 74.2% for comorbid eating disorder (adj. RR = 4.51, 95% CI: 3.87–5.27). The overall prevalence of insomnia was also significantly higher across most physical conditions compared with the healthy reference group, although generally lower compared to the mental disorders. For females, the insomnia prevalence ranged from 25% for comorbid multiple sclerosis (not significant) to 65.4% for comorbid chronic fatigue syndrome/ME (adj. RR = 2.66, 95% CI: 2.44–2.89). For males, the insomnia prevalence ranged from 20% for both comorbid cancer and diabetes (not significant) to 74.2% for comorbid fibromyalgia (adj. RR = 4.35, 95% CI: 2.96–6.39). Similar patterns were observed for sleep duration, with a significantly shorter sleep duration for across many physical disorders, but especially mental disorders. Conclusion Insomnia and short sleep duration are strongly associated with a range of different disorders and conditions. Insomnia is most strongly associated with mental disorders, and physical conditions characterized by some level of psychological or psychosomatic properties.
