Super-resonant dark matter Csáki, Csaba; Gomes, Andrew; Hochberg, Yonit ...
The journal of high energy physics,
11/2022, Letnik:
2022, Številka:
11
Journal Article
Recenzirano
Odprti dostop
A
bstract
We introduce
Super-Resonant Dark Matter
, a model of self-interacting dark matter based on the low energy effective theory of supersymmetric QCD. The structure of the theory ensures a ...resonant enhancement of the self-interactions of the low energy mesons, since their mass ratio is set by the number of colors and flavors. The velocity dependence of the resonantly enhanced self-interactions allows such theories to accommodate puzzles in small scale structure that arise from dark matter halos of different sizes. The dark matter mass is then predicted to be around 3–4 MeV, with its abundance set by freeze-in via a kinetically mixed dark photon.
Abstract The motivation to accurately model the dynamics of flexible aircraft grew with the development of energy-efficient aircraft, consequently, great aspect ratio aircraft. The development of an ...accurate model that represents the flight dynamics of a flexible aircraft has been pursued by industry and aeronautical research organizations during the last decades. One of these approaches is to find a flexible aircraft model using systems identification methods. This research aims to apply an integrated model containing longitudinal and lateral directional rigid body dynamics, coupled to the first four flexible body modes, for identification and validation from flight test data. The Unmanned Aerial Vehicle (UAV) Eolo with the flexible wing is used during the experiments. Initially, a finite element structural model (FEM) based on beam elements, concentrated masses, and rigid bars was used. The quasi-stationary panel model based on the Vortex Lattice Method (VLM) was adopted for the aerodynamic model. Two diagonal matrices were used to correct the aerodynamic influence coefficients (AIC) matrix obtained via VLM before and post-multiplication for aircraft identification. The estimation of the main diagonal elements of each matrix was obtained through the Output Error Method in the time domain. A model validation analysis was carried out, which shows a good correlation between the model and measurement data. In conclusion, getting correction matrices instead of stability derivatives is beneficial because matrices can be used more directly during the aeronautical design and observe the behavior concerning loads.
Several optical techniques and fiber-optic probe systems have been designed to measure the optical properties of tissue. While a wide range of options is often beneficial, it poses a problem to ...investigators selecting which method to use for their biomedical application of interest. We present a methodology to optimally select a probe that matches the application requirements. Our method is based both on matching a probe's mean sampling depth with the optimal diagnostic depth of the clinical application and on choosing a probe whose interrogation depth and path length is the least sensitive to alterations in the target medium's optical properties. Satisfying these requirements ensures that the selected probe consistently assesses the relevant tissue volume with minimum variability. To aid in probe selection, we have developed a publicly available graphical user interface that takes the desired sampling depth and optical properties of the medium as its inputs and automatically ranks different techniques in their ability to robustly target the desired depth. Techniques investigated include single fiber spectroscopy, differential path length spectroscopy, polarization-gating, elastic light scattering spectroscopy, and diffuse reflectance. The software has been applied to biological case studies.
Several biomedical applications, such as detection of dysplasia, require selective interrogation of superficial tissue structures less than a few hundred micrometers thick. Techniques and methods ...have been developed to limit the penetration depth of light in tissue, including the design of systems such as fiber-optic probes that have overlapping illumination and collection areas on the tissue surface. For such geometries, the diffusion approximation to the light-transport equation typically does not apply, and as a result there is no general model to extract tissue optical properties from reflectance measurements. In the current study, we employ Monte Carlo (MC) simulations to develop simple and compact analytical models for the light reflectance from these overlapping geometries. These models incorporate the size of the illumination and collection areas, the collection angle, the polarization of the incident light, and the optical properties of the sample. Moreover, these MC simulations use the Whittle-Matérn model to describe scattering from spatially continuous refractive index media such as tissue, which is more general than models based on the conventionally used Henyey-Greenstein model. We validated these models on tissue-simulating phantoms. The models developed herein will facilitate the extraction of optical properties and aid in the design of optical systems employing overlapping illumination and collection areas, including fiber-optic probes for in vivo tissue diagnosis.
The present study aimed to investigate the role of blood supply in early tumorigenesis in colorectal cancer. We leveraged the renin angiotensin system (RAS) to alter colonic blood supply and ...determine the effect on tumor initiation and progression.
To test the effect of blood supply on tumorigenesis, 53 male A/J mice were randomly assigned to one of three RAS modulation groups and one of two AOM treatments. The RAS modulation groups were I) water (RAS-unmodulated) as a control group, II) angiotensin-II and III) the angiotensin receptor blocker, Losartan. The mice in each group were then randomly split into either the saline control condition or the AOM-treated condition in which tumors were induced with a standard protocol of serial azoxymethane (AOM) injections. To monitor microvascular changes in the rectal mucosa during the study, we used confocal laser endomicroscopy (CLE) with FITC-Dextran for in-vivo imaging of vessels and polarization-gated spectroscopy (PGS) to quantify rectal hemoglobin concentration (Hb) and blood vessel radius (BVR).
At 12 weeks post-AOM injections and before tumor formation, CLE images revealed many traditional hallmarks of angiogenesis including vessel dilation, loss of co-planarity, irregularity, and vessel sprouting in the pericryptal capillaries of the rectal mucosa in AOM-Water tumor bearing mice. PGS measurements at the same time-point showed increased rectal Hb and decreased BVR. At later time points, CLE images showed pronounced angiogenic features including irregular networks throughout the colon. Notably, the AOM-Losartan mice had significantly lower tumor multiplicity and did not exhibit the same angiogenic features observed with CLE, or the increase in Hb or decrease in BVR measured with PGS. The AOM-AngII mice did not have any significant trends.
In-vivo PGS measurements of rectal colonic blood supply as well as CLE imaging revealed angiogenic disruptions to the capillary network prior to tumor formation. Losartan demonstrated an effective way to mitigate the changes to blood supply during tumorigenesis and reduce tumor multiplicity. These effects can be used in future studies to understand the early vessel changes observed.
The scarcity of fresh water resources and the need for additional water supplies are critical in many regions of the world. Treatment of wastewater and its reuse can partially resolve this issue. Due ...to the increase in use and number of heavy duty vehicles for transportation purpose the wastewater generated from truck wash has been escalated during last several decades. Our results show that electrocoagulation (EC) can be an effective technique to treat truck wash water (TWW), and this treated TWW is reusable. Effects of different combination of electrodes, such as Fe–Fe, Al–Fe, and Al–Al, operating time, current density (CD), and pH inside the EC reactor were studied to optimize treatment conditions for lowering chemical oxygen demand (COD), and concentrations of some selected toxic metal ions in TWW. The best removal efficiency of 79% for COD was obtained by Fe–Fe combination after 8 min of operating time and at 2 mA/cm2 of CD. Iron, zinc, and lead concentrations were reduced below EPA maximum contaminant levels for all three types of electrode combinations. The EC-floc was characterized using X-ray diffraction, scanning electron microscope/energy dispersive X-ray spectroscopy, and Fourier transform-infrared spectrometer. The ionic substitution of iron by aluminum was confirmed in the isomorphs subsisted in the floc.
Polarization-gating has been widely used to probe superficial tissue structures, but the penetration depth properties of this method have not been completely elucidated. This study employs a ...polarization-sensitive Monte Carlo method to characterize the penetration depth statistics of polarization-gating. The analysis demonstrates that the penetration depth depends on both the illumination-collection geometry illumination-collection area (R) and collection angle (θ(c)) and on the optical properties of the sample, which include the scattering coefficient (μ(s)), absorption coefficient (μ(a)), anisotropy factor (g), and the type of the phase function. We develop a mathematical expression relating the average penetration depth to the illumination-collection beam properties and optical properties of the medium. Finally, we quantify the sensitivity of the average penetration depth to changes in optical properties for different geometries of illumination and collection. The penetration depth model derived in this study can be applied to optimizing application-specific fiber-optic probes to target a sampling depth of interest with minimal sensitivity to the optical properties of the sample.
Field carcinogenesis detection represents a promising means for colorectal cancer (CRC) screening, although current techniques (e.g., flexible sigmoidoscopy) lack the requisite sensitivity. The novel ...optical technology low-coherence enhanced backscattering (LEBS) spectroscopy, allows identification of microscale architectural consequences of the field carcinogenesis in preclinical CRC models with unprecedented accuracy. To investigate the potential clinical translatability of this approach, we obtained biopsies from the normal-appearing rectal mucosa from patients undergoing colonoscopy (n = 219). LEBS signals were recorded through a bench-top instrument. Four parameters characterizing LEBS signal were linearly combined into a single marker. We found that LEBS signal parameters generally mirrored neoplasia progression from patients with no neoplasia, to 5 to 9 mm adenoma and to advanced adenomas. The composite LEBS marker calculated from the LEBS signal paralleled this risk status (ANOVA P < 0.001). Moreover, this was independent of CRC risk factors, benign colonic findings, or clinically unimportant lesions (diminutive adenomas, hyperplastic polyps). For advanced adenomas, the LEBS marker had a sensitivity of 100%, specificity of 80%, and area under the receiver operator characteristic curve of 0.895. Leave-one-out cross-validation and an independent data set (n = 51) supported the robustness of these findings. In conclusion, we provide the first demonstration that LEBS-detectable alterations in the endoscopically normal rectum were associated with the presence of neoplasia located elsewhere in the colon. This study provides the proof of concept that rectal LEBS analysis may potentially provide a minimally intrusive CRC screening technique. Further studies with an endoscopically compatible fiber optic probe are under way for multicenter clinical validation.
Polarization-gated spectroscopy is an established method to depth-selectively interrogate the structural properties of biological tissue. We employ this method in vivo in the azoxymethane ...(AOM)-treated rat model to monitor the morphological changes that occur in the field of a tumor during early carcinogenesis. The results demonstrate a statistically significant change in the shape of the refractive-index correlation function for AOM-treated rats versus saline-treated controls. Since refractive index is linearly proportional to mass density, these refractive-index changes can be directly linked to alterations in the spatial distribution patterns of macromolecular density. Furthermore, we found that alterations in the shape of the refractive-index correlation function shape were an indicator of both present and future risk of tumor development. These results suggest that noninvasive measurement of the shape of the refractive-index correlation function could be a promising marker of early cancer development.
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