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1.
We propose a simple model for genetic adaptation to a changing environment, describing a fitness landscape characterized by two maxima. One is associated with “specialist” individuals that are adapted to the environment; this maximum moves over time as the environment changes. The other maximum is static, and represents “generalist” individuals not affected by environmental changes. The rest of the landscape is occupied by “maladapted” individuals. Our analysis considers the evolution of these three subpopulations. Our main result is that, in presence of a sufficiently stable environmental feature, as in the case of an unchanging aspect of a physical habitat, specialists can dominate the population. By contrast, rapidly changing environmental features, such as language or cultural habits, are a moving target for the genes; here, generalists dominate, because the best evolutionary strategy is to adopt neutral alleles not specialized for any specific environment. The model we propose is based on simple assumptions about evolutionary dynamics and describes all possible scenarios in a non-trivial phase diagram. The approach provides a general framework to address such fundamental issues as the Baldwin effect, the biological basis for language, or the ecological consequences of a rapid climate change. 相似文献
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Microperimetric Biofeedback in AMD Patients 总被引:1,自引:0,他引:1
Vingolo EM Cavarretta S Domanico D Parisi F Malagola R 《Applied psychophysiology and biofeedback》2007,32(3-4):185-189
To analyse biofeedback training by microperimeter MP-1 (Nidek Technologies) on patients with Age Related Maculopathy (AMD).
We enrolled 15 patients (10 female and 5 male) and examined total of 27 eyes with AMD. All the patient underwent 10 training
sessions of 10 min for each eye, performed once a week using the MP-1 biofeedback examination. Statistical analysis was performed
using Student’s t-test. p values less than 0.05 were considered statistically significant. All patients displayed an improvement in visual acuity,
fixation behaviour, retinal sensitivity an reading speed. The mean character size value improved from 36.4 to 11.7; this result
was statistically significant (p = 0.031). A biofeedback examination using the MP-1 microperimeter can help the brain to memorize the final fixation location
by increasing attention modulation, thereby providing an efficient preferred retinal locus for visual tasks in patients with
macular disease and central scotoma. 相似文献
4.
The lipidic beta-amino acid 2-(aminomethyl)-2-pentadecylheptadecanoic acid (1) was synthesized via the alkylation of the C(alpha)-atom of fully protected beta-alanine. Mixed large unilamellar vesicles with a diameter between 100 and 200 nm containing POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) and 1 at a molar ratio of 9 : 1 were prepared and found to have a surface charge which is dependent on pH. At slightly acidic pH, the vesicles were positively charged, and at alkaline pH negatively charged. Dynamic light scattering, zeta potential, and cryo-transmission electron-microscopy measurements indicated that the mixed vesicles fused at pH 4-5 with negatively charged mixed vesicles composed of POPC and POPG (9.8 : 1, molar ratio), POPG being 1-palmitoyl-2-oleoyl-sn-glycero-3-[phospho-rac-(1-glycerol)]. 相似文献
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Romualdo Caputo Marina DellaGreca Ivan de Paola Domenico Mastroianni Luigi Longobardo 《Amino acids》2010,38(1):305-310
The synthesis of new substituted prolines carrying at C-4 a second α-amino acid residue is reported. The amino acid, l-cysteine or l-selenocysteine, is linked to the proline ring through the sulfur or the selenium atom, respectively. The products were prepared
with different stereochemistry at C-4, in few and clean high-yielding steps, with suitable protections for solid phase applications.
The introduction of both sulfur and selenium atoms at C-4 of the proline ring seems to enhance significantly the cis geometry
at the prolyl amide bond. 相似文献
7.
Belardinelli R Muçaj A Lacalaprice F Solenghi M Principi F Tiano L Littarru GP 《BioFactors (Oxford, England)》2005,25(1-4):137-145
BACKGROUND: There is evidence that plasma CoQ(10) levels decrease in patients with advanced chronic heart failure (CHF). OBJECTIVE: To investigate whether oral CoQ(10) supplementation could improve cardiocirculatory efficiency in patients with CHF. METHODS: We studied 21 patients in NYHA class II and III (18M, 3W, mean age 59 +/- 9 years) with stable CHF secondary to ischemic heart disease (ejection fraction 37 +/- 7%), using a double-blind, placebo-controlled cross-over design. Patients were assigned to oral CoQ(10) (100 mg tid) and to placebo for 4 weeks, respectively. RESULTS: CoQ(10) supplementation resulted in a threefold increase in plasma CoQ(10) level (P < 0.0001 vs placebo). Systolic wall thickening score index (SWTI) was improved both at rest and peak dobutamine stress echo after CoQ(10) supplementation (+12.1 and 15.6%, respectively, P < 0.05 vs placebo). Left ventricular ejection fraction improved significantly also at peak dobutamine (15% from study entry P < 0.0001) in relation to a decrease in LV end-systolic volume index (from 57 +/- 7 mL/m(2) to 45 mL/m(2), P < 0.001). Improvement in the contractile response was more evident among initially akinetic (+33%) and hypokinetic (+25%) segments than dyskinetic ones (+6%). Improvement in SWTI was correlated with changes in plasma CoQ(10) levels (r = -0.52, P < 0.005). Peak VO(2) was also improved after CoQ(10) as compared with placebo (+13%, <0.005). No side effects were reported with CoQ(10). CONCLUSIONS: Oral CoQ(10) improves LV contractility in CHF without any side effects. This improvement is associated with an enhanced functional capacity. 相似文献
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Eight diterpent acids of the labdane or clerodane type were obtained from the oleoresin of Araucaria bidwilli and characterized as their methyl esters. 相似文献
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The terpene fraction from the leaves of Olea europaea has been shown to contain the known oleanolic and maslinic acids, together with oleanane hydroxy acids which have never been found before in nature. 相似文献
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Laura Milazzo Anna Maria Peri Cristina Mazzali Romualdo Grande Chiara Cazzani Davide Ricaboni Antonio Castelli Ferdinando Raimondi Carlo Magni Massimo Galli Spinello Antinori 《Mycopathologia》2014,178(3-4):227-241