Inverse square L\'evy walks are not optimal search strategies for d≥2d\ge 2

The L\'evy hypothesis states that inverse square L\'evy walks are optimal search strategies because they maximise the encounter rate with sparse, randomly distributed, replenishable targets. It has served as a theoretical basis to interpret a wealth of experimental data at various scales, from molecular motors to animals looking for resources, putting forward the conclusion that many living organisms perform L\'evy walks to explore space because of their optimal efficiency. Here we provide analytically the dependence on target density of the encounter rate of L\'evy walks for any space dimension $d$ ; in particular, this scaling is shown to be {\it independent} of the L\'evy exponent $\alpha$ for the biologically relevant case $d\ge 2$, which proves that the founding result of the L\'evy hypothesis is incorrect. As a consequence, we show that optimizing the encounter rate with respect to $\alpha$ is {\it irrelevant} : it does not change the scaling with density and can lead virtually to {\it any} optimal value of $\alpha$ depending on system dependent modeling choices. The conclusion that observed inverse square L\'evy patterns are the result of a common selection process based purely on the kinetics of the search behaviour is therefore unfounded.Comment: Accepted in Phys. Rev. Let

Single-molecule tracking in live cells reveals distinct target-search strategies of transcription factors in the nucleus

Gene regulation relies on transcription factors (TFs) exploring the nucleus searching their targets. So far, most studies have focused on how fast TFs diffuse, underestimating the role of nuclear architecture. We implemented a single-molecule tracking assay to determine TFs dynamics. We found that c-Myc is a global explorer of the nucleus. In contrast, the positive transcription elongation factor P-TEFb is a local explorer that oversamples its environment. Consequently, each c-Myc molecule is equally available for all nuclear sites while P-TEFb reaches its targets in a position-dependent manner. Our observations are consistent with a model in which the exploration geometry of TFs is restrained by their interactions with nuclear structures and not by exclusion. The geometry-controlled kinetics of TFs target-search illustrates the influence of nuclear architecture on gene regulation, and has strong implications on how proteins react in the nucleus and how their function can be regulated in space and time.Nikon France (Research contract)France. Agence nationale de la recherche (PCV DYNAFT 08-PCVI-0013)France. Agence nationale de la recherche (DynamIC ANR-12-BSV5-0018)Fondation pour la recherche médicaleNetherlands Organization for Scientific Research (Rubicon fellowship

GAMBARAN TINGKAT PENGETAHUAN MASYARAKAT TENTANG PENYAKIT ASAM URAT DI RT 04 RW 04 DESA KRANJI KECAMATAN PACIRAN KABUPATEN LAMONGAN

Penyakit asam urat menyerang masyarakat yang mempunyai kadar asam urat tinggi, masyarakat yang terkena asam urat biasanya mengeluh badan capek, linu-linu dan nyeri sendi. Tujuan penelitian ini adalah mengetahui gambaran tingkat pengetahuan warga tentang penyakit asam urat pada warga RT 04 RW 04 Desa Kranji Kecamatan Paciran Kabupaten Lamongan. Desain penelitian ini diskriptif. Populasinya semua warga yang mengeluh badan capek, linu-linu dan nyeri sendi sebesar 25 orang. Cara pengambilan sampel dengan menggunakan tehnik total sampling. Dengan jumlah sampel 25 responden. Variabelnya adalah tingkat pengetahuan warga tentang penyakit asam urat di RT 04 RW 04 Desa Kranji Kecamatan Paciran Kabupaten Lamongan. Pengumpulan data dengan menggunakan instrumen kuesioner dianalisis data dengan distribusi frekuensi. Hasil penelitian didapatkan dari 25 responden sebagian besar (56%) responden memiliki tingkat pengetahuan yang kurang, (24%) responden memiliki tingkat pengetahuan yang cukup dan (20%) memiliki tingkat pengetahuan yang baik. Disimpulkan bahwa warga di RT 04 sebagian besar memiliki tingkat pengetahuan tentang penyakit asam urat yang kurang. Sehingga bagi warga yang sudah mempunyai keluhan badan capek, linu-linu dan nyeri sendi diharapkan untuk menghindari semua makanan yang mengandung kadar purin tinggi

Universal scaling of plasmon coupling in metal nanostructures: Checking the validity for higher plasmonic modes using second harmonic generation

The universal scaling of plasmon coupling in metallic nanostructures is now a well-established feature. However, if the interaction between dipolar plasmon modes has been intensively studied, this is not the case of the coupling between higher order ones. Using Mie theory extended to second harmonic generation, we investigate the coupling between quadrupolar plasmon modes in metallic nanoshells. Like in the case of dipolar plasmon modes, a universal scaling behavior is observed in agreement with the plasmon hybridization model

The safety of agomelatine in standard medical practice in depressed patients : a 26‐week international multicentre cohort study

© 2020 The Authors. Human Psychopharmacology: Clinical and Experimental published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.Objective: The present observational cohort study documented the safety of agomelatine in current medical practice in out-patients suffering from major depressive disorder. Method: The 6-month evolution of agomelatine-treated patients was assessed with a focus on safety (emergent adverse events, liver acceptability), severity of depression using the Clinical Global Impression Severity (CGI-S) score, and functioning measured by the Sheehan Disability Scale (SDS). Results: A total of 8453 depressed patients from 761 centres in 6 countries were analysed (female: 67.7%; mean age: 49.1 ± 14.8 years). Adverse events reported were in accordance with the known safety profile of agomelatine. Cutaneous events were reported in 1.7% of the patients and increased hepatic transaminases values were reported in 0.9 % of the patients. The incidence of events related to suicide/self-injury was 1.0%. Two completed suicides, not related to the study drug, were reported. CGI-S total scores and SDS sub-scores improved and numbers of days lost or underproductive decreased over the treatment period. Conclusions: In standard medical practice, agomelatine treatment was associated with a low incidence of side effects. No unexpected events were reported. A decrease in the severity of the depressive episode and improved functioning were observed.info:eu-repo/semantics/publishedVersio

Second harmonic scattering from silver nanocubes

The second harmonic light scattered from silver nanocubes dispersed in an aqueous suspension is investigated. The first hyperpolarizability is determined and corrected for resonance enhancement. It is shown to be similar to that of silver nanospheres with a comparable volume. The polarization-resolved analysis of the scattered harmonic intensity exhibits a surface response strongly modulated by the different multipolar field contributions. As a result, the shape does not play a leading role anymore for nanoparticles with a centrosymmetric shape when retardation must be considered. Comparing the right angle and forward-scattered polarized intensity responses, the unequal balance of the eight nanocube corners' contribution to the total response is revealed despite the high degree of centrosymmetry of the cubic shape. It is then demonstrated with a simple model that the nanocubes' first hyperpolarizability exhibits an octupolar tensorial symmetry. The surface integral equation method calculations are finally provided to investigate further the role of the corners’ and edges’ rounding