3,185 research outputs found
Extending the functional equivalence of radial basis functionnetworks and fuzzy inference systems
We establish the functional equivalence of a generalized class of Gaussian radial basis function (RBFs) networks and the full Takagi-Sugeno model (1983) of fuzzy inference. This generalizes an existing result which applies to the standard Gaussian RBF network and a restricted form of the Takagi-Sugeno fuzzy system. The more general framework allows the removal of some of the restrictive conditions of the previous result
The formation of sulfate, nitrate and perchlorate salts in the martian atmosphere
Funding: 2011 NAI Directorâs Discretionary Fund award titled ââPerchlorate, Water, and Lifeââ, along with a NASA postdoctoral program award to work at the Virtual Planetary Laboratory.In extremely arid regions on Earth, such as the Atacama Desert, nitrate, sulfate and perchlorate salts form in the atmosphere and accumulate on the surface from dry deposition according to diagnostic evidence in their oxygen isotopes. Salts of similar oxyanions should have formed in the atmosphere of Mars because of comparable photochemical reactions. We use a 1-D photochemical model to calculate the deposition rates of sulfate, nitrogen oxyanions, and perchlorate from Mars' atmosphere, given a plausible range of volcanic fluxes of sulfur- and chlorine-containing gases in the past. To calculate integrated fluxes over time, we assume that throughout the last 3. byr (the Amazonian eon), the typical background atmosphere would have been similar to today's cold and dry environment. If the soil has been mixed by impact perturbations to a characteristic depth of ~2. m during this time, given a time-average volcanic flux 0.1% of the modern terrestrial volcanic flux, the model suggests that the soil would have accumulated 1.0-1.7. wt.% SO42- and 0.2-0.4. wt.% N in the form of pernitrate (peroxynitrate) or nitrate. The calculated sulfate concentration is consistent with in situ observations of soils from rovers and landers and orbital gamma ray spectroscopy. However, nitrates or pernitrates are yet to be detected. The modeled formation of perchlorate via purely gas-phase oxidation of volcanically-derived chlorine is insufficient by orders of magnitude to explain 0.4-0.6. wt.% ClO4- measured by NASA's Phoenix Lander. The far smaller amount of ozone in the martian atmosphere compared to the terrestrial atmosphere and the colder, drier conditions are the cause of lower rates of gas phase oxidation of chlorine volatiles to perchloric acid. Our calculations imply that non-gas-phase processes not included in the photochemical model, such as heterogeneous reactions, are likely important for the formation of perchlorate and are yet to be identified.Publisher PDFPeer reviewe
Screening for amblyopia : a contentious issue
Letter to the Editor:
The appropriateness of screening for amblyopia is an emotive issue, both within the United Kingdom (UK) and worldwide. Recommendations within the UK state that children should
be screened for visual impairment; yet there is evidence to suggest that such programmes are not cost-effective. We aim to identify possible reasons as to why clinicians find the prospect
of removing screening programmes unacceptable
The Role of Mitochondria in Amyotrophic Lateral Sclerosis
Mitochondria are unique organelles that are essential for a variety of cellular processes including energy metabolism, calcium homeostasis, lipid biosynthesis, and apoptosis. Mitochondrial dysfunction is a prevalent feature of many neurodegenerative diseases including motor neuron disorders such as amyotrophic lateral sclerosis (ALS). Disruption of mitochondrial structure, dynamics, bioenergetics and calcium buffering has been extensively reported in ALS patients and model systems and has been suggested to be directly involved in disease pathogenesis. Here we review the alterations in mitochondrial parameters in ALS and examine the common pathways to dysfunction
Resistance training enhances delayed memory in healthy middle-aged and older adults: A randomised controlled trial
Objectives
High-intensity exercise is a potential therapeutic tool to postpone or prevent the onset of cognitive decline. However, there is a lack of sufficient evidence regarding the longitudinal effects of structured resistance training on cognitive function in healthy adults. The purpose of this study was to investigate the effect of two ecologically valid, intense 12-week resistance training programs on cognitive function in late middle-aged adults.
Design
Single-site parallel randomised controlled trial at the Department of Exercise Science strength and conditioning laboratory. Groups allocated by minimisation randomisation.
Methods
Forty-five healthy adults (age rangeâ=â41-69 years) were enrolled and randomised into A.) high-load, long rest resistance training (nâ=â14), or B.) moderate-load, short rest resistance training (nâ=â15) twice per week for 12 weeks, or a non-exercising control (nâ=â16). Follow-up within 7 days. Data were collected September 2016-December 2017. Cognitive function assessed using the CogState computerised battery. Assessors were blinded to participant group allocation. Secondary outcomes were maximal muscle strength and body composition.
Results
Forty-four participants were analysed in 2018. Delayed verbal memory performance was improved (pâ=â0.02) in resistance training groups (gâ=â0.67-0.79) when compared to the control group, with no differences between training groups. Likewise, increases in maximal muscle strength were observed (pâ<â0.01) in resistance training groups when compared to the control group, with no differences between training groups. No differences in body composition were observed. There were no adverse events or side-effects of the intervention.
Conclusions
12 weeks of intense resistance training improves delayed verbal memory irrespective of training design (i.e., high-load vs. moderate-load)
Heavy Quark Photoproduction in Ultra-peripheral Heavy Ion Collisions
Heavy quarks are copiously produced in ultra-peripheral heavy ion collisions.
In the strong electromagnetic fields, c c-bar and b b-bar are produced by
photonuclear and two-photon interactions; hadroproduction can occur in grazing
interactions. We present the total cross sections, quark transverse momentum
and rapidity distributions, as well as the Q Q-bar invariant mass spectra from
the three production channels. We consider AA and pA collisions at the
Relativistic Heavy Ion Collider and Large Hadron Collider. We discuss
techniques for separating the three processes and describe how the AA to pA
production ratios might be measured accurately enough to study nuclear
shadowing.Comment: Minor changes to satisfy referees and typo fixes; 52 pages including
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