Electron quantum metamaterials in van der Waals heterostructures

In recent decades, scientists have developed the means to engineer synthetic periodic arrays with feature sizes below the wavelength of light. When such features are appropriately structured, electromagnetic radiation can be manipulated in unusual ways, resulting in optical metamaterials whose function is directly controlled through nanoscale structure. Nature, too, has adopted such techniques -- for example in the unique coloring of butterfly wings -- to manipulate photons as they propagate through nanoscale periodic assemblies. In this Perspective, we highlight the intriguing potential of designer sub-electron wavelength (as well as wavelength-scale) structuring of electronic matter, which affords a new range of synthetic quantum metamaterials with unconventional responses. Driven by experimental developments in stacking atomically layered heterostructures -- e.g., mechanical pick-up/transfer assembly -- atomic scale registrations and structures can be readily tuned over distances smaller than characteristic electronic length-scales (such as electron wavelength, screening length, and electron mean free path). Yet electronic metamaterials promise far richer categories of behavior than those found in conventional optical metamaterial technologies. This is because unlike photons that scarcely interact with each other, electrons in subwavelength structured metamaterials are charged, and strongly interact. As a result, an enormous variety of emergent phenomena can be expected, and radically new classes of interacting quantum metamaterials designed

An Integrated Micro- and Macroarchitectural Analysis of the Drosophila Brain by Computer-Assisted Serial Section Electron Microscopy

A new software package allows for dense electron microscopy reconstructions of neuronal networks in the fruit fly brain, and reveals specific differences in microcircuits between insects and vertebrates

Compressive Inverse Scattering I. High Frequency SIMO Measurements

Inverse scattering from discrete targets with the single-input-multiple-output (SIMO), multiple-input-single-output (MISO) or multiple-input-multiple-output (MIMO) measurements is analyzed by compressed sensing theory with and without the Born approximation. High frequency analysis of (probabilistic) recoverability by the $L^1$-based minimization/regularization principles is presented. In the absence of noise, it is shown that the $L^1$-based solution can recover exactly the target of sparsity up to the dimension of the data either with the MIMO measurement for the Born scattering or with the SIMO/MISO measurement for the exact scattering. The stability with respect to noisy data is proved for weak or widely separated scatterers. Reciprocity between the SIMO and MISO measurements is analyzed. Finally a coherence bound (and the resulting recoverability) is proved for diffraction tomography with high-frequency, few-view and limited-angle SIMO/MISO measurements.Comment: A new section on diffraction tomography added; typos fixed; new figures adde

Estimation of the number of synapses in the hippocampus and brain-wide by volume electron microscopy and genetic labeling

Determining the number of synapses that are present in different brain regions is crucial to understand brain connectivity as a whole. Membrane-associated guanylate kinases (MAGUKs) are a family of scaffolding proteins that are expressed in excitatory glutamatergic synapses. We used genetic labeling of two of these proteins (PSD95 and SAP102), and Spinning Disc confocal Microscopy (SDM), to estimate the number of fluorescent puncta in the CA1 area of the hippocampus. We also used FIB-SEM, a three-dimensional electron microscopy technique, to calculate the actual numbers of synapses in the same area. We then estimated the ratio between the three-dimensional densities obtained with FIB-SEM (synapses/µm) and the bi-dimensional densities obtained with SDM (puncta/100 µm). Given that it is impractical to use FIB-SEM brain-wide, we used previously available SDM data from other brain regions and we applied this ratio as a conversion factor to estimate the minimum density of synapses in those regions. We found the highest densities of synapses in the isocortex, olfactory areas, hippocampal formation and cortical subplate. Low densities were found in the pallidum, hypothalamus, brainstem and cerebellum. Finally, the striatum and thalamus showed a wide range of synapse densities.This work was supported by grants from the following entities: the Spanish “Ministerio de Ciencia, Innovación y Universidades” (Grant PGC2018-094307-B-I00 and the Cajal Blue Brain Project [C080020-09; the Spanish partner of the Blue Brain Project initiative from EPFL, Switzerland]; the European Union’s Horizon 2020 Research and Innovation Programme under grant agreement No. 785907 (Human Brain Project, SGA2); the Wellcome Trust (Technology Development Grant 202932); and the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (695568 SYNNOVATE). L.T.-R. is a recipient of grants from the EMBO Long-term fellowship 2016–2018 and the IBRO-PERC InEurope grants programme

A functional variant in the Stearoyl-CoA desaturase gene promoter enhances fatty acid desaturation in pork

There is growing public concern about reducing saturated fat intake. Stearoyl-CoA desaturase (SCD) is the lipogenic enzyme responsible for the biosynthesis of oleic acid (18:1) by desaturating stearic acid (18:0). Here we describe a total of 18 mutations in the promoter and 3′ non-coding region of the pig SCD gene and provide evidence that allele T at AY487830:g.2228T>C in the promoter region enhances fat desaturation (the ratio 18:1/18:0 in muscle increases from 3.78 to 4.43 in opposite homozygotes) without affecting fat content (18:0+18:1, intramuscular fat content, and backfat thickness). No mutations that could affect the functionality of the protein were found in the coding region. First, we proved in a purebred Duroc line that the C-T-A haplotype of the 3 single nucleotide polymorphisms (SNPs) (g.2108C>T; g.2228T>C; g.2281A>G) of the promoter region was additively associated to enhanced 18:1/18:0 both in muscle and subcutaneous fat, but not in liver. We show that this association was consistent over a 10-year period of overlapping generations and, in line with these results, that the C-T-A haplotype displayed greater SCD mRNA expression in muscle. The effect of this haplotype was validated both internally, by comparing opposite homozygote siblings, and externally, by using experimental Duroc-based crossbreds. Second, the g.2281A>G and the g.2108C>T SNPs were excluded as causative mutations using new and previously published data, restricting the causality to g.2228T>C SNP, the last source of genetic variation within the haplotype. This mutation is positioned in the core sequence of several putative transcription factor binding sites, so that there are several plausible mechanisms by which allele T enhances 18:1/18:0 and, consequently, the proportion of monounsaturated to saturated fat.This research was supported by grants from the Spanish Ministry of Science and Innovation (AGL2009-09779 and AGL2012-33529). RRF is recipient of a PhD scholarship from the Spanish Ministry of Science and Innovation (BES-2010-034607). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of manuscript

Оценка токсичности и эффективности терапии комбинацией FOLFIRI и афлиберцепта при метастатическом раке толстой кишки в РФ: первые результаты многоцентрового ретроспективного исследования

oai:oai.tumors.elpub.ru:article/629Purpose. To assess the incidence and severity of adverse events; to explore clinical factors associated with grade 3–4 non-hematologic toxicity; to assess the immediate efficacy and progression-free survival during treatment with the FOLFIRI regimen in combination with aflibercept in Russia.Materials and Methods. A retrospective multicenter study has been conducted with data collected from 20 clinics in 15 regions of Russia. There was no statistical hypothesis. Progression-free survival was the main efficacy criterion. The statistical analysis was performed using IBM SPPS Statistics v. 20 software.Results. FOLFIRI and Aflibercept combination was administered to 264 patients. The mean number of treatment cycles was 6 (1 to 29). The toxicity of aflibercept was addressed by dose reduction and dosing delay in 10.1 % and 11.4 % of patients, respectively, and dose reductions and dosing delays in any of FOLIFRI components were reported in 20.1 % of participants. The objective response rate was 20.3 %. The median progression-free survival in patients receiving second-line treatment was 6 months (95 % CI: 5.3–6.6 months). Seventy-two percent of patients experienced any grade of adverse events most of which were limited to grade 1–2 (62.1 %). Non-hematologic toxicity was reported in 64 % of patients (grade 3–4 in 17.9 %). Hematologic events were detected in only 17.9 % of patients. Multifactorial analysis has shown that drug therapy for concomitant diseases (OR 1.98, 95 % CI: 1.04–3.78, p = 0.037) and the number of chemotherapy lines prior to aflibercept (ОR 1.5, 95 % CI: 1.06–2.11, p = 0.02) were independent predictors of grade 3–4 non-hematologic toxicity.Conclusions. Objective response rate, progression-free survival, and frequency of toxicity-related aflibercept discontinuations in the Russian study with patients receiving aflibercept in combination with FOLFIRI regimen as a second-line treatment has shown the results that were comparable with VELOUR study. Comorbidities requiring drug treatment and the number of prior chemotherapy lines appear to be risk factors for grade 3–4 nonhematological toxicity events. Цель исследования. Оценить частоту развития и тяжесть нежелательных явлений; изучить клинические факторы, ассоциированные с развитием негематологической токсичности 3-4 степени; оценить непосредственную эффективность выживаемость без прогрессирования при применении комбинации FOLFIRI с афлиберцептом в РФ.Материалы и методы. Проведено ретроспективное многоцентровое исследование. Собраны данные 20 клиник 15 регионов РФ. Статистическая гипотеза отсутствовала. В качестве основного критерия эффективности рассматривалась выживаемость без прогрессирования. Статистический анализ проводился с помощью программ статистического пакета SPSS (IBM SPPS Statistics v. 20).Результаты. Режим FOLFIRI афлиберцепт был назначен у 264 пациентов. Среднее число составило 6 (от 1 до 29). В связи с токсичностью доза афлиберцепта в процессе терапии была редуцирована у 10,1% пациентов, задержали очередное введение афлиберцепта — у 11,4%; отсрочка и редукция доз химиопрепаратов в режиме FOLFIRI описана у 20,1 %. Частота объективных эффектов составила 20,3%. Во второй линии терапии медиана выживаемости без прогрессирования составила 6 месяцев (95% ДИ 5,3-6,6 месяцев). Нежелательные явления любой степени зарегистрированы у 72 % пациентов и чаще были ограничены 1-2 степенью (62,1%). Негематологические осложнения развились у 64% (3-4 степень — у 17,9%). Гематологические осложнения представлены только у 17,9 % пациентов. По результатам многофакторного анализа лекарственная терапия по поводу сопутствующей патологии (ОШ 1,98, 95%ДИ 1,04-3,78, р=0,037) и число линий терапии (ОШ 1,5, 95%ДИ 1,06-2,11, р=0,02), предшествующих афлиберцепту, явились независимыми предсказывающими факторами развития нежелательных явлений негематологического профиля 3-4 степени.Выводы. Частота объективных эффектов, выживаемость без прогрессирования и частота отмены афлиберцепта в связи с токсическими реакциями при применении комбинации FOLFIRI + афлиберцепт во второй линии среди пациентов в РФ аналогична результатам исследования VELOUR. Сопутствующая патология, требующая медикаментозной коррекции, и число линий терапии предшествующих афлиберцепту, по-видимому, являются факторами риска развития негематологических явлений 3-4 степени