Small Spread Research Articles

Model Predictive Temperature Control for Retinal Laser Treatments.

Manual, individual adjustment of the laser power in retinal laser therapies is time-consuming, is inaccurate with respect to uniform effects, and can only prevent over- or undertreatment to a limited extent. Automatic closed-loop temperature control allows for similar temperatures at each irradiated spot despite varying absorption. This is of crucial importance for subdamaging hyperthermal treatments with no visible effects and the safety of photocoagulation with short irradiation times. The aim of this work is to perform extensive experiments on porcine eye explants to demonstrate the benefits of automatic control in retinal laser treatments. To ensure a safe and reliable temperature rise, we utilize a model predictive controller. For model predictive control, the current state and the spot-dependent absorption coefficients are estimated by an extended Kalman filter (EKF). Therein, optoacoustic measurements are used to determine the temperature rise at the irradiated areas in real time. We use fluorescence vitality stains to measure the lesion size and validate the proposed control strategy. By comparing the lesion size with temperature values for cell death, we found that the EKF accurately estimates the peak temperature. Furthermore, the proposed closed-loop control scheme works reliably with regard to similar lesion sizes despite varying absorption with a smaller spread in lesion size compared to open-loop control. Our closed-loop control approach enables a safe subdamaging treatment and lowers the risk for over- and undertreatment for mild coagulations in retinal laser therapies. We demonstrate that modern control strategies have the potential to improve retinal laser treatments for several diseases.

Survey of extended main-sequence turn-offs in galactic open clusters: stellar rotations from Gaia RVS spectra

ABSTRACT The origin of extended main-sequence turn-offs (eMSTO) in star clusters younger than 2 Gyr still challenges our current understanding of stellar evolution. Exploiting data from Gaia Data Release 3 (DR3), we investigate eMSTOs in a large sample of 32 Galactic open clusters younger than 2.4 Gyr. We first validate Gaia rotational velocities from radial velocity spectrometer spectra by comparing them with literature values and assessing their correlation with magnetic activity measurements from LAMOST spectra. We detect a general positive correlation between turn-off colour and projected stellar rotation, with slow-rotating stars predominantly found on the bluer side of the turn-off. Comparing our observations with theoretical models, we find that the eMSTO morphology is well reproduced by a single population formed with a high rotation rate, and observed with rotation axis inclination ranging between 0° (pole-on) and 90° (edge-on). This contrasts with observations of Magellanic Cloud clusters, where a population of non-rotating stars appears to be ubiquitous in clusters younger than 700 Myr. However, we note that our interpretation, while successfully explaining the overall eMSTO morphology, cannot fully explain the observed projected rotational velocities. Additionally, two young clusters, NGC 3532 and NGC 2287, exhibit moderate evidence of a split-main sequence in colour and rotation, suggesting a possible small spread in the initial rotation rate. Finally, we advise caution in determining the ages of young clusters from non-rotating isochrones, as neglecting the effects of stellar rotation can impact the isochrone dating by up to factors of 5–20 per cent.

The Gaia-ESO Survey: No sign of multiple stellar populations in open clusters from their sodium and oxygen abundances

Context. The light element (anti-)correlations shown by globular clusters (GCs) are the main spectroscopic signature of multiple stellar populations. These internal abundance variations provide us with fundamental constraints on the formation mechanism of stellar clusters. Aims. Using Gaia-ESO, the largest and most homogeneous survey of open clusters (OCs), we intend to check whether these stellar aggregates display the same patterns. Based on previous studies of many GCs, several young and massive clusters in the Magellanic Clouds, as well as a few OCs, we do not expect to find any anti-correlation, given the low mass of Milky Way OCs. Methods. We used the results based on UVES spectra of stars in Gaia-ESO to derive the distribution of Na and O abundances and see whether they show an unexplained dispersion or whether they are anti-correlated. By selecting only high-probability members with high-precision stellar parameters, we ended up with more than 700 stars in 74 OCs. We examined the O-Na distribution in 28 OCs with at least 4 stars available as well as the Na distribution in 24 OCs, with at least 10 stars available. Results. We find that the distribution of Na abundances is compatible with a single-value population, within the errors. The few apparent exceptions can be explained by differences in the evolutionary phase (main sequence and giant post first dredge-up episode) or by difficulties in analysing low gravity giants. We did not find any indication of an Na-O anti-correlation in any of the clusters for which O has been derived. Conclusions. Based on the very small spread we find, OCs maintain the status of single stellar populations. However, a definitive answer requires studying more elements and larger samples covering different evolutionary phases. This will be possible with the next generation of large surveys.

Reservoir-Free Decoherence in Flying Qubits.

An effective time-dependent Hamiltonian can be implemented by making a quantum system fly through an inhomogeneous potential, realizing, for example, a quantum gate on its internal degrees of freedom. However, flying systems have a spatial spread that will generically entangle the internal and spatial degrees of freedom, leading to decoherence in the internal state dynamics, even in the absence of any external reservoir. We provide formulas valid at all times for the dynamics, fidelity, and change of entropy for ballistic particles with small spatial spreads, quantified by Δx. This non-Markovian decoherence can be significant for ballistic flying qubits (scaling as Δx^{2}) but usually not for flying qubits carried by a moving potential well (scaling as Δx^{6}). We also discuss a method to completely counteract this decoherence for a ballistic qubit later measured.

Simulations of a cryogenic, buffer-gas filled Paul trap for low-emittance ion bunches

Many experiments with pulsed ion beams benefit from or even require ion bunches with both small temporal width as well as small energy spread. To achieve optimal ion-beam preparation, a buffer-gas filled cryogenic Paul trap is being developed in the context of the Multi Ion Reflection Apparatus for Collinear Laser Spectroscopy (MIRACLS). There, ion bunches of short-lived radionuclides are trapped in a Multi-Reflection Time-of-Flight (MR-ToF) device. Thus, the ions can be repeatedly probed by a laser beam compared to only once in conventional, single-passage collinear laser spectroscopy. To fulfill MIRACLS’ opposing requirements of a small temporal ion-bunch width and small energy spread, a buffer-gas filled cryogenic Paul trap is envisioned. Ion-optical simulations confirm the advantages of cryogenic temperatures and the linear scaling of the beam emittance as a function of the buffer-gas temperature. Beyond MIRACLS, high-quality ion beams from a cryogenic Paul trap will be beneficial for other precision experiments at radioactive ion beam facilities.

Primary healthcare professionals’ attitudes toward patients with current or previous drug use

Objective People with current or previous drug use (PCPDU) often lack long-term healthcare contacts in primary healthcare (PHC). While international research has shown negative attitudes toward PCPDU in healthcare, PHC professionals’ attitudes toward PCPDU have not been assessed in Sweden. The aim of this study was to investigate PHC professionals’ attitudes to PCPDU, and to compare attitudes toward people who actively use illicit drugs with those toward patients in opioid assisted treatment (OAT). Design In this survey study, respondents were asked for background data, and their attitudes toward patients using illicit drugs, OAT patients and patients with depression were assessed by using an adapted version of the Medical Condition Regard Scale (MCRS). Setting and subjects Nurses and physicians at primary healthcare centers (PHCCs) in Skåne, Sweden. Main outcome measures Mean MCRS scores, dichotomized responses to MCRS items, and associations between MCRS score and background covariates (age, sex, profession and duration of professional experience). Results Eighty-nine PHC professionals from 13 PHCCs responded (approximately 39% of relevant workforce). The median MCRS score was 44 for patients with illicit drug use and patients in OAT, and 51 for patients with depression. Drug use and OAT displayed similar minimum, maximum and interquartile range values as well, while scores regarding depression displayed a higher minimum value and smaller spread. No significant associations were found between background covariates and MCRS scores for either drug use or OAT. Conclusions The results indicate widespread negative attitudes to PCPDU, with implications for health equity in the clinic. Further studies are needed to see if the results reflect attitudes in Swedish PHC in general. Key Points People with current or previous drug use (PCPDU) often lack necessary primary healthcare (PHC) and are commonly subject to prejudice. Swedish PHC professionals held more negative attitudes toward PCPDU than toward patients with depression. Attitudes toward patients with active drug use and patients in opioid assisted treatment (OAT) were almost identical. Study findings have potential implications for the health of PCPDU as well as health equity in the clinic. Widespread negative attitudes to PCPDU in our sample indicate the need of larger-scale studies of attitudes toward PCPDU in Swedish PHC.

3D Antenna array for multi-user massive MIMO system to minimize unfavorable propagation

Unfavorable propagation in massive multiple input multiple output (MIMO) systems is an underlying channel condition that reduces the gains offered by the system in terms of parallel channels. This paper presents a study on different types of antenna array configurations at base station (BS) to minimize unfavorable propagation conditions. Unfavorable propagation results in increased correlation between channel vectors of two or more mobile terminals (MTs) which arises when the signals from two or more MTs have small angular separation and small angular spread. The study starts with the investigation of the conventional uniform linear array (ULA) under different propagation conditions using a geometrical channel model based on a single cluster of scatterers per MT to quantify the performance degradation in unfavorable propagation. Subsequently, the performance of other types of array geometries is investigated. A custom cluster-based geometrical channel model is used in this study which includes practical propagation aspects like multipath fading, shadow fading, and the effect of BS height. Further, the study considers two cases: micro-cell and macro-cell. Under space constraint settings in terms of the maximum dimension of the array, the proposed technique uses randomized antenna locations in the array to minimize the effect of unfavorable propagation. Based on the results on performance parameters like user correlation and capacity, the study reveals that an antenna array configuration comprising of elements distributed random-homogeneously in a spherical shell outperforms other configurations.

Dynamic characteristics of droplets impacting an inclined wall based on a front-tracking method

In the current study, the dynamic characteristics of droplets impacting a hydrophilic/hydrophobic inclined wall are investigated using the front-tracking method. The morphological and kinematic features of the droplets are examined across various contact angles (θ), low Weber numbers (We≤10), and inclination angles (α). A sequence of events, including deposition, spreading, contraction, rebound, and subsequent re-spreading, is observed when a droplet impacts a hydrophobic wall, according to the results. The droplet exhibits both a small dimensionless spreading area (A*) and significant fluctuation, along with a noticeable slip on the wall. As We increases, the spread and rebound effects become more pronounced, and the slipping velocity also increases. As α increases, the slipping velocity becomes greater, and both A* and the dimensionless tangential spreading diameter (β) decrease. When a droplet impacts a hydrophilic wall, continuous deposition, spreading, and a subtle slip with inconspicuous rebound are observed. As We increases, A* expands at an accelerating rate. Furthermore, the wetting effect of hydrophilic surfaces on droplets cannot be overlooked. Consequently, it also shows that as α increases, there is a larger diffusion range along the wall with a longer diffusion film and a larger β. Such behaviors stand in contrast to a droplet impacting a hydrophobic wall.

Stellar Variability and Distance Indicators in the Near-infrared in Nearby Galaxies. I. RR Lyrae and Anomalous Cepheids in Draco Dwarf Spheroidal

The Draco Dwarf spheroidal (dSph) galaxy is one of the nearest and the most dark-matter-dominated satellites of the Milky Way. We obtained multiepoch near-infrared (NIR, JHK s ) observations of the central region of Draco dSph covering a sky area of ∼21′ × 21′ using the WIRCam instrument at the 3.6 m Canada–France–Hawaii Telescope. Homogeneous JHK s time-series photometry for 212 RR Lyrae (173 fundamental-mode, 24 first-overtone, and 15 mixed-mode variables) and five Anomalous Cepheids in Draco dSph are presented and used to derive their period–luminosity relations at NIR wavelengths for the first-time. The small scatter of ∼0.05 mag in these empirical relations for RR Lyrae stars is consistent with those in globular clusters and suggests a very small metallicity spread, up to ∼0.2 dex, among these centrally located variables. Based on empirically calibrated NIR period–luminosity–metallicity relations for RR Lyrae in globular clusters, we determined a distance modulus to Draco dSph of μ RRL = 19.557 ± 0.026 mag. The calibrated K s -band period–luminosity relations for Anomalous Cepheids in the Draco dSph and the Large Magellanic Cloud exhibit statistically consistent slopes but systematically different zero points, hinting at possible metallicity dependence of ∼ − 0.3 mag dex−1. Finally, the apparent magnitudes of the tip of the red-giant branch in I and J bands also agree well with their absolute calibrations with the adopted RR Lyrae distance to Draco. Our recommended ∼1.5% precise RR Lyrae distance, D Draco = 81.55 ± 0.98(statistical) ± 1.17(systematic) kpc, is the most accurate and precise distance to Draco dSph galaxy.

A HOMEMADE SEMIAUTOMATIC GRAPHITIZATION DEVICE FOR AMS 14C DATING AT NTUAMS LAB

ABSTRACT A low-cost and computer-controlled graphitization system connected to an elemental analyzer (EA) has been designed and built at the NTUAMS Lab. This semiautomatic system equips 6-unit reactors for the graphitization of CO2 with H2 on the iron catalyst. The entire procedure takes about 7 hours for iron conditioning, sample combustion and loading, and graphitization. The system can produce good-quality graphite for samples containing 0.5–1.6 mg carbon mass, with the pressure yield of graphitization ranging from 57.7% to 87.1%. The average values of OXI and OXII agree well with the consensus value, but the result of ANU sucrose was observed to be slightly higher than the reported one. The background samples of anthracite over ten months yielded an average of 0.38±0.10 pMC (n=21) corresponding to a 14C age of 45 kyr BP. Intercomparison samples L and M of FIRI exhibit that the measured 14C ages are almost identical to the consensus values and have a small spread in these values. The system has been carrying out graphitization for total organic carbon (TOC) of peat samples, and providing a more efficient and convenient way for AMS 14C dating.

Terahertz polarimetric imaging of biological tissue: Monte Carlo modeling of signal contrast mechanisms due to Mie scattering.

Many promising biomedical applications have been proposed for terahertz (THz) spectroscopy and diagnostic imaging techniques. Polarimetric imaging systems are generally useful for enhancing imaging contrasts, yet the interplay between THz polarization changes and the random discrete structures in biological samples is not well understood. In this work, we performed Monte Carlo simulations of the propagation of polarized THz waves in skin and adipose tissues based on the Mie scattering from intrinsic structures, such as hair follicles or sweat glands. We show that the polarimetric contrasts are distinctly affected by concentration, size and dielectric properties of the scatterers, as well as the frequency and polarization of the incident THz waves. We describe the experimental requirements for observing and extracting these polarimetric signals due to the low energy and small angular spread of the back-scattered THz radiation. We analyzed the spatially integrated Mueller matrices of samples in the normal-incidence back-scattering geometry. We show that the frequency-dependent degree of polarization (DOP) can be used to infer the concentrations and dielectric contents of the scattering structures. Our modeling approach can be used to inform the design of the imaging modalities and the interpretation of the spectroscopic data in future terahertz biomedical imaging applications.

A Gap in the Densities of Small Planets Orbiting M Dwarfs: Rigorous Statistical Confirmation Using the Open-source Code RhoPop

Using mass–radius composition models, small planets (R ≲ 2 R ⊕) are typically classified into three types: iron-rich, nominally Earth-like, and those with solid/liquid water and/or atmosphere. These classes are generally expected to be variations within a compositional continuum. Recently, however, Luque & Pallé observed that potentially Earth-like planets around M dwarfs are separated from a lower-density population by a density gap. Meanwhile, the results of Adibekyan et al. hint that iron-rich planets around FGK stars are also a distinct population. It therefore remains unclear whether small planets represent a continuum or multiple distinct populations. Differentiating the nature of these populations will help constrain potential formation mechanisms. We present the RhoPop software for identifying small-planet populations. RhoPop employs mixture models in a hierarchical framework and a nested sampler for parameter and evidence estimates. Using RhoPop, we confirm the two populations of Luque & Pallé with >4σ significance. The intrinsic scatter in the Earth-like subpopulation is roughly half that expected based on stellar abundance variations in local FGK stars, perhaps implying M dwarfs have a smaller spread in the major rock-building elements (Fe, Mg, Si) than FGK stars. We apply RhoPop to the Adibekyan et al. sample and find no evidence of more than one population. We estimate the sample size required to resolve a population of planets with Mercury-like compositions from those with Earth-like compositions for various mass–radius precisions. Only 16 planets are needed when σMp=5% and σRp=1% . At σMp=10% and σRp=2.5% , however, over 154 planets are needed, an order of magnitude increase.

Simulation of shot noise effects in the EIC strong hadron cooling accelerator using real number of electrons

In the electron ion collider design, in order to achieve the peak luminosity 1034/cm 2/s with a reasonable lifetime, an efficient coherent electron cooling scheme was proposed to reduce the hadron beam emittance growth. Such a cooling scheme requires a good electron beam quality with a small energy spread. However, the shot noise in the electron beam through the accelerator might be amplified due to the microbunching instability and degrades the electron beam quality in the modulator section of the strong hadron cooling channel and correspondingly cooling rate. In this study, we report on self-consistent simulations of these effects using a real number of electrons to capture the details of shot noise and analysis of the shot noise growth through the accelerator.

Plasma-based particle sources

High-brightness particle beams generated by advanced accelerator concepts have the potential to become an essential part of future accelerator technology. In particular, high-gradient accelerators can generate and rapidly accelerate particle beams to relativistic energies. The rapid acceleration and strong confining fields can minimize irreversible detrimental effects to the beam brightness that occur at low beam energies, such as emittance growth or pulse elongation caused by space charge forces. Due to the high accelerating gradients, these novel accelerators are also significantly more compact than conventional technology. Advanced accelerators can be extremely variable and are capable of generating particle beams with vastly different properties using the same driver and setup with only modest changes to the interaction parameters. So far, efforts have mainly been focused on the generation of electron beams, but there are concepts to extend the sources to generate spin-polarized electron beams or positron beams.The beam parameters of these particle sources are largely determined by the injection and subsequent acceleration processes. Although, over the last decade there has been significant progress, the sources are still lacking a sufficiently high 6-dimensional (D) phase-space density that includes small transverse emittance, small energy spread and high charge, and operation at high repetition rate. This is required for future particle colliders with a sufficiently high luminosity or for more near-term applications, such as enabling the operation of free-electron lasers (FELs) in the X-ray regime. Major research and development efforts are required to address these limitations in order to realize these approaches for a front-end injector for a future collider or next-generation light sources. In particular, this includes methods to control and manipulate the phase-space and spin degrees-of-freedom of ultrashort plasma-based electron bunches with high accuracy, and methods that increase efficiency and repetition rate. These efforts also include the development of high-resolution diagnostics, such as full 6D phase-space measurements, beam polarimetry and high-fidelity simulation tools.A further increase in beam luminosity can be achieve through emittance damping. Emittance cooling via the emission of synchrotron radiation using current technology requires kilometer-scale damping rings. For future colliders, the damping rings might be replaced by a substantially more compact plasma-based approach. Here, plasma wigglers with significantly stronger magnetic fields are used instead of permanent-magnet based wigglers to achieve similar damping performance but over a two orders of magnitude reduced length.

TYPOMORPHISM OF THE CHEMICAL COMPOSITION OF BIOGENIC CARBONATES WITHIN THE PRADNIPROV METHANE ANOMALY ON THE BLACK SEA SHELF

Problem Statement and Purpose. The aim of the article is to study the typomorphism of the chemical composition of biogenic calcium carbonates within methane anomalies formed by deep fluids in the bottom sediments of the Black Sea shelf. Gas chromatography was performed at the «Pradniprovska» study area. The results of the site`s bottom sediments analysis confirmed the content of pure methane and its homologues in the samples. Due to the presence of methane homologues, oxygen and carbon isotope analysis of the sediment shells was performed (it is known that the most stable information about the chemical composition of the mineral formation environment can be stored in biogenic carbonates of benthic organisms’ shells). The values obtained from the analysis had a small spread and did not show any visible variability. Data & Methods. Data on the chemical composition of benthic organisms’ shells can be obtained using inductively coupled plasma atomic emission spectrometry. This method requires large samples by weight, so only the shells of the Mytilus mollusks were taken for the study due to their relatively large size. The gas-geochemical studies were based on the methodology of the NDL‑3 laboratory. The extracted gas was stored in glass tubes under a saturated saline solution, which ensured minimal losses from gas dissolution in the seal fluid, followed by studying it using a «Tsvet‑400» gas chromatograph. The separation of hydrocarbon gases was carried out on a chromatographic column filled with aluminum oxide. The detector is flame ionization. Calibration was carried out before the start of each cycle with calibration gas mixtures of standard composition. The spectrometric analysis was performed on a Thermo Scientific inductively coupled plasma atomic emission spectrometer with a CID or CMOS detector operating in the range of 167–820 nm. The method is based on the dissolution of substances in a mixture of nitric, hydrochloric and hydrofluoric acids at a temperature of at least 125 °C, followed by the determination of elements in solutions by inductively coupled plasma atomic emission. To consider matrix effects and improve measurement accuracy, calibration using internal standard lines is used. Results. The analysis of the obtained material allowed the author to draw the following conclusions: a) chemical elements in shells are unevenly distributed, and this unevenness is determined by two main reasons – the peculiarity of the formation of biogenic carbonate of shells and the ability of the carbonate to isomorphically capture a number of elements from the mineral-forming environment; b) according to the quantitative characteristics, three groups of elements can be distinguished: macroelements, mesoelements and trace elements. The first group of elements (macroelements) includes Na, S, Mg, Sr, Fe, Si, Mn, P, K. Among them, one can clearly distinguish elements that are isomorphically included in the structure of calcite or aragonite (Na, Mg, Sr, Fe, Mn, K) and elements captured as non-structural impurities in the agglutination process during the growth of biogenic carbonate (Si, S and P). The second group (mesoelements) includes Ba, Al, As, Zn, Cu, Ti, among which two groups can also be distinguished. One is associated with the formation of sulfide minerals paragenetic to biogenic calcite (As, Zn, Cu), and the other with agglutination of clay minerals in sediments (Al, Ti), or a feature of isomorphism in the biogenic formation of calcium carbonate (Ba). The third group (trace elements) is associated with elements of low content and uneven distribution (Ni, Mo, Pb, Se). The main group here is Ni, Cr, Co, V. These groups, taking into account the fact that they were found in the areas of penetration of deep-sea fluids into the sedimentary strata, allows to consider them as typomorphic signs of biogenic carbonate formation in the areas of fluid influence, and, consequently, as a search sign of such areas on the Black Sea shelf.

Reconfigurable Intelligent Surfaces and Capacity Optimization: A Large System Analysis

Reconfigurable Intelligent Surfaces (RISs) have been recently proposed as an enabling technology for programmable wireless environments. In this paper, we present asymptotic closed-form expressions for the mean and variance of the mutual information for a multi-antenna transmitter-receiver pair in the presence of RISs, using statistical physics methods. While nominally valid in the large-system limit, we show that the derived Gaussian approximation for the mutual information can be quite accurate, even for modest-sized antenna arrays and metasurfaces. The above results are particularly useful when fast-fading conditions are present, which renders channel estimation challenging. We find that, when the channel close to an RIS is correlated, for instance due to small angle spread, which is reasonable for wireless systems with increasing carrier frequencies, the communication link benefits significantly from statistical RIS optimization, resulting in gains that are surprisingly higher than the nearly uncorrelated case. Using our novel asymptotic properties of the correlation matrices of the impinging and outgoing signals at the RISs, we can optimize the metasurfaces without brute-force numerical optimization. When the desired reflection from any of the RISs departs significantly from geometrical optics, the metasurfaces can be optimized to provide robust communication links, without significant need for their optimal placement.

Revisiting “Eye of the day”

Abstract A particular lexical construction for “sun” composed of morphemes for “eye” and either “day” or “sky” has been widely reported for Austronesian languages. Urban (2010) made the case for this phenomenon as an areal feature originating in Austronesian, with attestation in Austroasiatic and Tai-Kadai varieties, but absent in Sino-Tibetan. A follow-up (Blust 2011) argued for the possibility of independent genesis across the languages, while reiterating the absence of the feature in Sino-Tibetan. This paper presents a large scale survey of Tibeto-Burman language varieties. Data from this region show widespread occurrence of the phenomenon in distinct constructions, arguing against contact as the inciting factor. Instead, this paper argues for multiple innovation events, with only small scale regional spread through contact. Data are analysed from approximately 250 doculects from a wide range of sources, including newly elicited data for Bodo-Garo, Maringic and Northern Naga varieties.

COMPARATIVE ANALYSIS OF GEOMETRIC BROWNIAN MOTION, ARTIFICIAL NEURAL NETWORK AND NAIVE BAYESIAN TECHNIQUES USING NIGERIA STOCK EXCHANGE DATA

This paper presents a comparative analysis of three market price forecast models, namely Geometric Brownian Motion, Artificial Neural Network, and Naive Bayesian techniques, using data from the Nigeria Stock Exchange. The exploratory data analysis results indicate slight variations in the mean and median of the log stock price over a 5-year period. The data shows a relatively small spread from the mean and approximately symmetric distribution, as indicated by a skewness value close to zero. The normality test confirms that the log stock price data follows a normal distribution. The forecast using Artificial Neural Network (ANN) shows a minimal change in future stock price, suggesting low returns and moderate risk in the Nigerian stock market. The graphical representation of the ANN model demonstrates a constant path with little variation. Similarly, the Naive Bayesian technique provides a similar forecast to the ANN model, indicating limited profit potential. The Geometric Brownian Motion model also forecasts little variation in future stock prices, with 2023 showing slightly higher values. The accuracy of the forecast models is evaluated using the Mean Absolute Percentage Error (MAPE). The results indicate that the ANN model has an error of 4.60%, the Naive Bayesian model has an error of 9.29%, and the Geometric Brownian Motion model has an error of 12.67%. These findings suggest that the ANN model performs better in terms of accuracy compared to the other two models.

High-Throughput Multiparametric Quantification of Mechanics Driven Heterogeneity in Mesenchymal Stromal Cell Population.

Mesenchymal stromal or stem cells (MSCs) are one of the most promising candidates for a myriad of cell therapy applications. Despite showing promise in numerous preclinical and clinical studies, MSC-based therapy is not yet a reality for regenerative medicine due to its suboptimal outcome at the clinical endpoint. The mechanical environment is a critical determinant of MSC gene expression and function. This study reports that MSC population becomes phenotypically heterogenous and commits to an unwanted osteoprogenitor pathway when it experiences an abnormal mechanically stiff environment, compared to its native softer environment. A method is developed to measure the heterogeneity using nuclear shape, chromatin state, and CD73 marker. Heterogeneity is shown to be associated with a larger spread in the nuclear shape parameters and a smaller spread in the chromatin openness. Subsequently, intervention strategies are investigated to create a more homogeneous MSC population. Culturing MSCs on soft surfaces or inhibiting actomyosin on stiff surfaces can make them more homogeneous, while inhibiting YAP, Runx2, and actin polymerization helps maintain but does not fully homogenize them. This study offers insights for cell and tissue engineers, aiding in the design of optimal conditions and materials for MSC culture, ultimately enhancing their therapeutic potential.

Hybrid Assimilation of Snow Cover Improves Land Surface Simulations over Northern China

Abstract Ensemble data assimilation (DA) is an efficient approach to reduce snow simulation errors by combining observation and land surface modeling. However, there is a small spread between ensemble members of simulated snowpack, which typically occurs for a long time with 100% snow cover fraction (SCF) or snow-free conditions. Here, we apply a hybrid DA method, in which direct insertion (DI) is a supplement of the ensemble square root filter (EnSRF), to assimilate the spaceborne SCF into a land surface model, driven by China Meteorological Administration Land Data Assimilation System high-resolution climate forcings over northern China during the snow season in 2021/22. Compared to the open-loop experiment (without SCF assimilation), the root-mean-square error (RMSE) of SCF is reduced by 6% through the original EnSRF and is even lower (by 14%) in the combined DI and EnSRF (EnSRFDI) experiment. The results reveal the ability of both EnSRF and EnSRFDI to improve the SCF estimation over regions where the snow cover is low, while only EnSRFDI is able to efficiently reduce the RMSE over areas with high SCF. Moreover, the SCF assimilation is also observed to improve the snow depth and soil temperature simulations, with the Kling–Gupta efficiency (KGE) increasing at 60% and 56%–70% stations, respectively, particularly under conditions with near-freezing temperature, in which reliable simulations are typically challenging. Our results demonstrate that the EnSRFDI hybrid method can be applied for the assimilation of spaceborne observational snow cover to improve land surface simulations and snow-related operational products. Significance Statement Due to the small spread between the seasonal snowpack of ensemble simulations, ensemble snow cover fraction (SCF) data assimilation (DA) proves to be ineffective. Therefore, we apply a hybrid method that combines the direct insertion (DI) and ensemble square root filter (EnSRF) to assimilate the spaceborne SCF into a land surface model (LSM) driven by high-resolution climate forcings. Our results reveal the applicability of the EnSRFDI to further improve snow cover simulations over regions with high SCF. Furthermore, the DA experiments were validated through a large number of in situ observations from the China Meteorological Administration. The uncertainties of snow depth and soil temperature simulations are also slightly reduced by the SCF DAs, particularly over regions with a poor LSM performance.