3,616 research outputs found

    Complexity as Fitness for Evolved Cellular Automata Update Rules

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    We investigate the state change behavior of one-dimensional cellular automata during the solution of the binary density-classification task. Update rules of high, low and un- known fitness are applied to cellular au- tomata, thereby providing examples of high and low rates of successful classification. A spread factor, ω, is introduced and investi- gated as a numerical marker of state change behavior. The nature of ω describes complex or particle-like behavior on the part of the cellular automata over the middle region of initial configuration density-distribution, but breaks down at the ends. Because of the lim- itation on ω, a related jump-out term, jot, is selected for incorporation into the finess func- tion for genetic algorithm evolution of update rules. The inclusion of jot in the fitness func- tion significantly reduces the number of gen- erations required to reach high rates of suc- cessful classification (≥90%)

    Complexity as Fitness for Evolved Cellular Automata Update Rules

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    We investigate the state change behavior of one-dimensional cellular automata during the solution of the binary density-classification task. Update rules of high, low and un- known fitness are applied to cellular au- tomata, thereby providing examples of high and low rates of successful classification. A spread factor, ω, is introduced and investi- gated as a numerical marker of state change behavior. The nature of ω describes complex or particle-like behavior on the part of the cellular automata over the middle region of initial configuration density-distribution, but breaks down at the ends. Because of the lim- itation on ω, a related jump-out term, jot, is selected for incorporation into the finess func- tion for genetic algorithm evolution of update rules. The inclusion of jot in the fitness func- tion significantly reduces the number of gen- erations required to reach high rates of suc- cessful classification (≥90%)

    Complexity as Fitness for Evolved Cellular Automata Update Rules

    Get PDF
    We investigate the state change behavior of one-dimensional cellular automata during the solution of the binary density-classification task. Update rules of high, low and un- known fitness are applied to cellular au- tomata, thereby providing examples of high and low rates of successful classification. A spread factor, ω, is introduced and investi- gated as a numerical marker of state change behavior. The nature of ω describes complex or particle-like behavior on the part of the cellular automata over the middle region of initial configuration density-distribution, but breaks down at the ends. Because of the lim- itation on ω, a related jump-out term, jot, is selected for incorporation into the finess func- tion for genetic algorithm evolution of update rules. The inclusion of jot in the fitness func- tion significantly reduces the number of gen- erations required to reach high rates of suc- cessful classification (≥90%)

    Direct Conversion of Hydrazones to Amines using Transaminases

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    Transaminase enzymes (TAms) have been widely used for the amination of aldehydes and ketones, often resulting in optically pure products. In this work, transaminases were directly reacted with hydrazones in a novel approach to form amine products. Several substrates were investigated, including those with furan and phenyl moieties. It was determined that the amine yields increased when an additional electrophile was added to the reaction mixture, suggesting that they can sequester the hydrazine released in the reaction. Pyridoxal 5’-phosphate (PLP), a cofactor for transaminases, and polyethylene glycol (PEG)-aldehydes were both found to increase the yield of amine formed. Notably, the amination of (S)-(−)-1-amino-2-(methoxymethyl)pyrrolidine (SAMP) hydrazones gave promising results as a method to form chiral β-substituted amines in good yield

    Cronkhite-Canada syndrome associated with rib fractures: a case report

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    <p>Abstract</p> <p>Background</p> <p>Cronkhite-Canada syndrome (CCS) is a rare multiple gastrointestinal polyposis. Up till now, many complications of CCS have been reported in the literature, but rib fracture is not included.</p> <p>Case Presentation</p> <p>We report a case of a 58-year-old man who was admitted to our hospital with a 6-month history of frequent diarrhea, intermittent hematochezia and a weight loss of 13 kg. On admission, physical examination revealed alopecia of the scalp, hyperpigmentation of the hands and soles, and dystrophy of the fingernails. Laboratory data revealed hypocalcaemia and hypoproteinemia. Esophagogastroduodenoscopy, video capsule endoscopy and colonoscopy revealed various sizes of generalized gastrointestinal polyps. Histological examination of the biopsy specimens obtained from the stomach and the colon showed adenomatous polyp and inflammatory polyp respectively. Thus, a diagnosis of CCS was made. After treatment with corticosteroids for 24 days and nutritional support for two months, his clinical condition improved. Two months later, he was admitted to our hospital for the second time with frequent diarrhea and weight loss. The chest radiography revealed fractures of the left sixth and seventh ribs. Examinations, including emission computed tomography, bone densitometry test, and other serum parameters, were performed, but could not identify the definite etiology of the rib fractures. One month later, the patient suffered from aggravating multiple rib fractures due to the ineffective treatment, persistent hypocalcaemia and malnutrition.</p> <p>Conclusions</p> <p>This is the first case of a CCS patient with multiple rib fractures. Although the association between CCS and multiple rib fractures in this case remains uncertain, we presume that persistent hypocalcaemia and malnutrition contribute to this situation, or at least aggravate this rare complication. Besides, since prolonged corticosteroid therapy will result in an increased risk of osteoporotic fracture, CCS patients who accept corticosteroid therapy could be potential victims of rib fracture.</p

    Pharmacokinetics of Antituberculosis Drugs in HIV-Positive and HIV-Negative Adults in Malawi

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    Limited data address the impact of HIV co-infection on the pharmacokinetics of anti-tuberculosis drugs in Sub-Saharan Africa. 47 Malawian adults underwent rich pharmacokinetic sampling at 0-0.5-1-2-3-4-6-8 and 24 hours post-dose. 51% were male; mean age was 34 years. 65% were HIV-positive with a mean CD4 count of 268 cells/μL. Anti-tuberculosis drugs were administered as fixed-dose combinations (rifampicin150mg/isoniazid75mg/pyrazinamide400mg/ethambutol275mg) according to recommended weight bands. Plasma drug concentrations were determined by high-performance liquid chromatography (rifampicin and pyrazinamide) or liquid chromatography-mass spectrometry (isoniazid and ethambutol). Data were analysed by non-compartmental methods and analysis of variance of log-transformed summary parameters. Pharmacokinetic parameters were: rifampicin Cmax 4.129 (2.474-5.596)μg/mL, AUC0-24 21.32 (13.57-28.60)μg/mL*h, half-life 2.45 (1.86-3.08)h; isoniazid Cmax 3.97 (2.979-4.544)μg/mL, AUC0-24 22.5 (14.75-34.59)μg/mL*h, half-life 3.93 (3.18-4.73)h.; pyrazinamide Cmax 34.21 (30.00-41.60)μg/mL, AUC0-24 386.6 (320.0-463.7)μg/mL*h, half-life 6.821 (5.71-8.042)h; ethambutol Cmax 2.278 (1.694-3.098)μg/mL, AUC0-24 20.41 (16.18-26.27)μg/mL*h, half-life 7.507 (6.517-8.696)h. Isoniazid PK data analysis suggested that around two-thirds were slow acetylators. Dose, weight and weight-adjusted dose were not significant predictors of PK exposure probably due to weight-banded dosing. In this first pharmacokinetic study of tuberculosis drugs in Malawian adults, measures of pharmacokinetic exposure were comparable with other studies for all first line drugs except for rifampicin, for which Cmax and AUC0-24 were notably lower. Contrary to some earlier observations, HIV status did not significantly affect AUC of any of the drugs. Increasing the dose of rifampicin could be beneficial in African adults, irrespective of HIV status. Current co-trimoxazole prophylaxis was associated with an increase in half-life of isoniazid of 41% (p=0.022). Possible competitive interactions between isoniazid and sulphamethoxazole mediated by the N-acetyltransferase pathway should therefore be explored further

    Inflammatory status, body composition and ethnic differences in bone mineral density: The Southall and Brent Revisited Study

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    Ethnic differences in bone mineral density (BMD) and fracture risk are well-described; the aim of this study was to investigate whether central adiposity or inflammatory status contribute to these ethnic differences in BMD in later life. The Southall and Brent Revisited study (SABRE) is a UK-based tri-ethnic cohort of men and women of European, South Asian or African Caribbean origin. At the most recent SABRE follow-up (2014-2018), in addition to measures of cardiometabolic phenotype, participants had dual-energy X-ray absorptiometry (DXA) bone and body composition scans. Multiple linear regression was used to determine whether markers of body composition, central adiposity or inflammatory status contributed to ethnic differences in BMD. In men and women, age- and height-adjusted BMD at all sites was higher in African Caribbeans compared to Europeans (femoral neck: standardised β (95% confidence interval): men: 1.00SD (0.75, 1.25); women: 0.77SD (0.56, 0.99)). South Asian men had higher BMD than European men at the hip (femoral neck: 0.34SD (95%CI: 0.15, 0.54)). Although adjustment for body mass index (BMI) or lean mass index (LMI) at the lumbar spine reduced the size of the difference in BMD between African Caribbean and European men (age and height adjusted difference: 0.35SD (0.08, 0.62); age and BMI adjusted difference: 0.25SD (-0.02, 0.51)), in both men and women ethnic differences remained after adjustment for measures of central adiposity (estimated visceral adipose tissue mass (VAT mass) and android to gynoid ratio) and inflammation (interleukin-6 (logIL-6) and C-reactive protein (logCRP)). Furthermore, in women, we observed ethnic differences in the relationship between BMI (overall interaction: p = 0.04), LMI (p = 0.04) or VAT mass (p = 0.009) and standardised lumbar spine BMD. In this tri-ethnic cohort, ethnic differences in BMD at the femoral neck, total hip or lumbar spine were not explained by BMI, central adiposity or inflammatory status. Given ethnic differences in fracture incidence, it is important to further investigate why ethnic differences in BMD exist

    Fast and flexible selection with a single switch

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    Selection methods that require only a single-switch input, such as a button click or blink, are potentially useful for individuals with motor impairments, mobile technology users, and individuals wishing to transmit information securely. We present a single-switch selection method, "Nomon," that is general and efficient. Existing single-switch selection methods require selectable options to be arranged in ways that limit potential applications. By contrast, traditional operating systems, web browsers, and free-form applications (such as drawing) place options at arbitrary points on the screen. Nomon, however, has the flexibility to select any point on a screen. Nomon adapts automatically to an individual's clicking ability; it allows a person who clicks precisely to make a selection quickly and allows a person who clicks imprecisely more time to make a selection without error. Nomon reaps gains in information rate by allowing the specification of beliefs (priors) about option selection probabilities and by avoiding tree-based selection schemes in favor of direct (posterior) inference. We have developed both a Nomon-based writing application and a drawing application. To evaluate Nomon's performance, we compared the writing application with a popular existing method for single-switch writing (row-column scanning). Novice users wrote 35% faster with the Nomon interface than with the scanning interface. An experienced user (author TB, with > 10 hours practice) wrote at speeds of 9.3 words per minute with Nomon, using 1.2 clicks per character and making no errors in the final text.Comment: 14 pages, 5 figures, 1 table, presented at NIPS 2009 Mini-symposi

    Photodissociation dynamics of methyl iodide probed using femtosecond extreme ultraviolet photoelectron spectroscopy

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    Femtosecond pump-probe photoelectron spectroscopy measurements using an extreme ultraviolet probe have been made on the photodissociation dynamics of UV (269 nm) excited CH3I. The UV excitation leads to population of the 3Q0 state which rapidly dissociates. The dissociation is manifested as shifts in the measured photoelectron kinetic energy that map the extending C-I bond. The increased energy available in the XUV probe relative to a UV probe means the dynamics are followed over the chemically important region as far as C-I bond lengths of approximately 4 Ã…
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