Fixed-distance multipoint formulas for the scattering amplitude from phaseless measurements

We give new formulas for finding the complex (phased) scattering amplitude at fixed frequency and angles from absolute values of the scattering wave function at several points $x_1,..., x_m$. In dimension $d\geq 2$, for $m>2$, we significantly improve previous results in the following two respects. First, geometrical constraints on the points needed in previous results are significantly simplified. Essentially, the measurement points $x_j$ are assumed to be on a ray from the origin with fixed distance $\tau=|x_{j+1}- x_j|$, and high order convergence (linearly related to $m$) is achieved as the points move to infinity with fixed $\tau$. Second, our new asymptotic reconstruction formulas are significantly simpler than previous ones. In particular, we continue studies going back to [Novikov, Bull. Sci. Math. 139(8), 923-936, 2015].

Manufacturing and assessing new samplers to measure wind soil erosion

Wind soil erosion is one of the most important causes of soil degradation that impede the process of sustainable agricultural development. The first step to mitigating wind erosion hazards is to find an effective and accurate way to assess its severity. Therefore, the main objective of this research was to raise and evaluate the efficiency of the new four traps to measure eroded soil, Fixed Distance trap (FD), Fixed Point trap (FP), Rotary Distance trap (RD) and Rotary Point trap (RP). The study traps RP and FP compared with the Big Spring Number Eight trap (BSNE) (traditional trap) and the traps RD and FD compared with the Bagnold trap (traditional trap). The results indicated that the order of study traps in terms of soil collection efficiency and soil retention efficiency were RD>FD>Bagnold>RP>FP>BSNE and FP>RP>RD>FD>Bagnold>BSNE, respectively. Results proved that the best traps in collecting eroded soil were RP trap followed by FP trap, compared to BSNE trap. Also, the best traps in collecting eroded soil were RD trap, followed by FD trap, compared to the Bagnold trap. The most important results showed that the relative efficiency of RP and FP traps were 181% and 159%, respectively, compared to BSNE and the relative efficiency of RD and FD traps were 186% and 172%, respectively, compared to the Bagnold trap. The study proved high accuracy of new traps in measuring soil eroded material, separating soil particles according to their size directly inside traps and determining the direction of the wind compared to traditional traps.

Exploring the signaling space of a GPCR using bivalent ligands with a rigid oligoproline backbone

G protein–coupled receptors (GPCRs) are one of the most important drug–target classes in pharmaceutical industry. Their diversity in signaling, which can be modulated with drugs, permits the design of more effective and better-tolerated therapeutics. In this work, we have used rigid oligoproline backbones to generate bivalent ligands for the gastrin-releasing peptide receptor (GRPR) with a fixed distance between their recognition motifs. This allows the stabilization of GPCR dimers irrespective of their physiological occurrence and relevance, thus expanding the space for medicinal chemistry. Specifically, we observed that compounds presenting agonists or antagonists at 20- and 30-Å distance induce GRPR dimerization. Furthermore, we found that 1) compounds with two agonists at 20- and 30-Å distance that induce dimer formation show bias toward Gq efficacy, 2) dimers with 20- and 30-Å distance have different potencies toward β-arrestin-1 and β-arrestin-2, and 3) the divalent agonistic ligand with 10-Å distance specifically reduces Gq potency without affecting β-arrestin recruitment, pointing toward an allosteric effect. In summary, we show that rigid oligoproline backbones represent a tool to develop ligands with biased GPCR signaling.

Conditions for guaranteed destruction and explosion resistance of beam structural elements in the event of an explosion in water

По данным проведенных ранее исследований авторов найдены условия гарантированного разрушения и гарантированной взрывостойкости балки, свободно лежащей на недеформируемых опорах в воде. Импульсная динамическая нагрузка создана взрывом сосредоточенного заряда конденсированного взрывчатого вещества (ВВ), расположенного в воде на фиксированном расстоянии от балки. Под разрушением понимается потеря несущей способности балки вследствие возникновения в ней пластических зон (шарниров), трещин, разделений на фрагменты. Использован обобщенный на действия динамической нагрузки критерий разрушения, основанный на достижении максимальным изгибающим моментом критических значений. According to the data of the authors’ earlier studies, the conditions of guaranteed destruction and guaranteed explosion resistance of a beam freely lying on non-deformable supports in water were found. The impulse dynamic load is created by the explosion of a concentrated charge of a condensed explosive (HE) located in water at a fixed distance from the beam. Destruction is understood as the loss of the bearing capacity of the beam due to the appearance of plastic zones (hinges), cracks, and fragmentation in it. The criterion of destruction generalized to the action of dynamic load is used, based on the achievement of critical values by the maximum bending moment.

What matters in making demand-based decisions: Time alone or difficulty too?

Which task is easier, doing arithmetic problems of specified form for some specified duration, or carrying a bucket of specified weight over some specified distance? If it is possible to choose between the “more cognitive” task and the “more physical” task, how are the difficulty levels of the tasks compared? We conducted two experiments in which participants chose the easier of two tasks, one that involved solving addition or multiplication problems (Experiment 1) or addition problems with different numbers of addends (Experiment 2) for varying amounts of time (in both experiments), and one that involved carrying a bucket of different weights over a fixed distance (in both experiments). We found that the probability of choosing to do the bucket task was higher when the bucket was empty than when it was weighted, and increased when the cognitive task was harder and its duration grew. We could account for the choice probabilities by mapping the independent variables onto one abstract variable, Φ. The functional identity of Φ remains to be determined. It could be interpreted as an inferred effort variable, subjective duration, or an abstract, amodal common code for difficulty.

SETTING OF THE ANGLE OF INCIDENCE FOR GENERATING LAMB WAVES BY NON-CONTACT METHODEFFECT OF FRICTION ON THE MICROMECHANICAL PROPERTIES OF AISI 316L AUSTENITIC STEEL

The article examined the problem of the experimental setting of incidence angles for the generation of Lamb waves in plate-type parts by the non-contact ultrasonic control method. This type of control is mainly done by the use of two types of waves: Rayleigh, which detects invisible defects on the surface of parts, and Lamb waves mode A0 and S0. Mostly used is the mode A0 due to the propagation over distances of interest in the tested materials. One of the primary aim during the testing process is to position the ultrasonic transducers (transmitter and receiver) at oblique angles of incidence on a surface. The transducers should be positioned on an access face of the plate, as is common in industrial practice, at a fixed distance from the measured plate, and leaving an air gap between transducers and the tested plate. The ultrasonic transducers are moved simultaneously linearly or in zigzag on the surface of the plate-type part to measure the hidden defects (cracks, pores, inclusions) that appear in the composite materials during the manufacturing process or during the operation. The presented work brings new insights into the setting of the angle of incidence for generating lamb waves by non-contact method.

Microfabrication of a Chamber for High-Resolution, In Situ Imaging of the Whole Root for Plant–Microbe Interactions

Fabricated ecosystems (EcoFABs) offer an innovative approach to in situ examination of microbial establishment patterns around plant roots using nondestructive, high-resolution microscopy. Previously high-resolution imaging was challenging because the roots were not constrained to a fixed distance from the objective. Here, we describe a new ‘Imaging EcoFAB’ and the use of this device to image the entire root system of growing Brachypodium distachyon at high resolutions (20×, 40×) over a 3-week period. The device is capable of investigating root–microbe interactions of multimember communities. We examined nine strains of Pseudomonas simiae with different fluorescent constructs to B. distachyon and individual cells on root hairs were visible. Succession in the rhizosphere using two different strains of P. simiae was examined, where the second addition was shown to be able to establish in the root tissue. The device was suitable for imaging with different solid media at high magnification, allowing for the imaging of fungal establishment in the rhizosphere. Overall, the Imaging EcoFAB could improve our ability to investigate the spatiotemporal dynamics of the rhizosphere, including studies of fluorescently-tagged, multimember, synthetic communities.

Structural basis for target site selection in RNA-guided DNA transposition systems

CRISPR-associated transposition systems allow guide RNA–directed integration of a single DNA cargo in one orientation at a fixed distance from a programmable target sequence. We used cryo–electron microscopy (cryo-EM) to define the mechanism that underlies this process by characterizing the transposition regulator, TnsC, from a type V-K CRISPR-transposase system. In this scenario, polymerization of adenosine triphosphate–bound TnsC helical filaments could explain how polarity information is passed to the transposase. TniQ caps the TnsC filament, representing a universal mechanism for target information transfer in Tn7/Tn7-like elements. Transposase-driven disassembly establishes delivery of the element only to unused protospacers. Finally, TnsC transitions to define the fixed point of insertion, as revealed by structures with the transition state mimic ADP•AlF3. These mechanistic findings provide the underpinnings for engineering CRISPR-associated transposition systems for research and therapeutic applications.

The functional form of specialized predation dramatically affects whether Janzen-Connell effects can prevent competitive exclusion

Janzen Connell Effects (JCEs), specialized predation of seeds and seedlings near conspecific trees, are hypothesized to promote high species richness. While past modeling studies show JCEs can maintain higher diversity than a neutral community, recent theoretical work indicates JCEs may weakly inhibit competitive exclusion when species exhibit interspecific fitness variation. However, recent models make somewhat restrictive assumptions about the functional form of specialized predation -- that JCEs occur at a fixed rate when seeds/seedlings are within a fixed distance of a conspecific tree. Using a theoretical model, I show that the functional form of JCEs largely impacts their ability to promote coexistence. If specialized predation pressure increases additively with adult tree density and decays exponentially with distance, JCEs maintain considerably higher diversity than predicted by recent models. Parameterizing the model with values from a Panamanian tree community indicates JCEs can maintain high diversity in communities exhibiting high interspecific fitness variation.