Variation Of Mobility Research Articles

Ultrafast terahertz conductivity in epitaxial graphene nanoribbons: an interplay between photoexcited and secondary hot carriers

Abstract Optical pump-terahertz probe spectroscopy has been used to investigate ultrafast photo-induced charge carrier transport in 3.4 µm wide graphene ribbons upon scaling the optical pump intensity. For low pump fluences, the deposited pump energy is rapidly redistributed through carrier-carrier scattering, producing secondary hot carriers: the picosecond THz photoconductivity then acquires a negative sign and scales linearly with an increasing pump fluence. At higher fluences, there are not enough equilibrium carriers able to accept the deposited energy, directly generated (excess) carriers start to contribute significantly to the photoconductivity with a positive sign leading to its saturation behavior. This leads to a non-monotonic variation of the carrier mobility and plasmonic resonance frequency as a function of the pump fluence and, at high fluences, to a balance between a decreasing carrier scattering time and an increasing Drude weight. In addition, a weak carrier localization observed for the polarization parallel to the ribbons at low pump fluences is progressively lifted upon increasing the pump fluence as a result of the rise of initial carrier temperature.

A Fingerprint of Source-specific Health Risk of PM2.5-bound Components Over A Coastal Industrial City

The influence of specific local land-use activities (continuously redistributing elements across environments) and environmental conditions (altering the chemical composition of airborne particulate matter) on the intrinsic health risk of PM2.5 exposure is sparsely reported. To fill this gap, we employed a novel integrated approach to address the influence of short-term changes in source-specific PM2.5 composition on the exposure-response risk, while controlling for weather conditions. We combine receptor-based source apportionment with conditional logistic regression in a space-time-stratified case-crossover design. This approach is different from previous studies as it: i) controls the impact of spatiotemporal variations in air pollution and human mobility using multilocation-specific fixed and disjointed space-time strata ii) addresses the spatial heterogeneity of personal exposure separating its variable effect from other predictors by allowing different baseline hazards for each space-time stratum; iii) aligns case/control periods with strong/regular episodes of source-specific PM-multipollutant fingerprint contributions rather than health outcomes. This enabled comprehensive examination of the association between source-specific PM2.5-bound species and cardiorespiratory disease hospitalizations. The epidemiological findings were that primary anthropogenic emissions [industrial (ORs 2.5 – 4.8)] were associated with higher 1-day moving average PM-induced risks. Natural-related sources [fresh / aged sea salt aerosol, dust, soil resuspension] and secondary sulfate formation were consistently associated with higher health risks (ORs 1.0 – 1.54) after 1 to 5-days since exposure. The results emphasize the importance of source-specific air quality management in complex areas and our research provides an adaptable universal tool to support targeted place-based policy interventions to mitigate air pollution impacts on health. Environmental ImplicationsPM2.5 is a heterogeneous mixture of chemicals from multiple sources These fine particles can deeply penetrate the lungs when inhaled, causing a wide range of cardiorespiratory diseases. Their prolonged suspension in the air results in varying toxicity and hazards, influenced by local land use, and weather conditions that affect exposure risks. Our research uses a novel approach, combining receptor-based source apportionment with conditional logistic regression models. This innovative methodology elucidates the source-specific hazardous effects of PM2.5-bound species on human health, providing a valuable policy tool to mitigate the environmental and health risks posed by air pollutants.

Differences in Changes of Mobility Patterns Across the Globe—Evidence From a Natural Experiment

ABSTRACTThe impact of population mobility and transportation choices on the environment is significant. Sustainable mobility policies require an understanding of evolving mobility patterns. This study examines global mobility variations across countries using COVID‐19 Community Mobility Reports. Employing the k‐medoids algorithm and Dynamic Time Warping, we analyzed mobility dynamics. Results reveal diverse changes in population mobility. Around 52 Global North countries exhibit approximately 10% reduction in professional activity‐related traffic post‐COVID‐19. Regarding urban green space mobility, only 29 countries exhibit strong seasonality, with summer traffic in the northern hemisphere peaking at about 150% higher than winter traffic. Three groups of countries are identified concerning public transport mobility: returning to pre‐pandemic levels, experiencing a 25% increase, and nearly doubling from pre‐pandemic levels. This underscores the key determinants for sustainable mobility policy implementation. Fifteen highly developed countries share similar mobility patterns across six areas studied, facilitating the exchange of sustainable mobility solutions and best practices. This research underscores the importance of understanding and addressing evolving mobility patterns for effective environmental policy planning.

Effect of Temperature and Electric Field Strength on Carrier Mobility of Oil-Impregnated Pressboard Under DC Voltage

The influence of carrier mobility on the space charge transport behavior inside the oil-impregnated pressboard insulation of converter transformers cannot be neglected. However, at present, current knowledge is usually derived from empirical or theoretical values, lacks experimental studies, and often ignores the effects of temperature and field strength under actual operating conditions. In this paper, based on the variable-temperature surface potential decay (SPD) method, a carrier mobility measurement platform for oil-impregnated pressboard is established, and the carrier mobility values for different combinations of oil and oil-impregnated pressboard are obtained experimentally to analyze and reveal the influence mechanisms of temperature and field strength on the carrier mobility. The results indicate the following: (1) The positive and negative carrier mobilities of oil-impregnated pressboard are in the range of 10−12–10−13 m2·V−1·s−1, and the negative carrier mobility is always higher than the positive carrier mobility. (2) The carrier mobility is positively correlated with the changes of temperature and field strength, and when the temperature increases from 20 °C to 80 °C, the positive and negative carrier mobilities increase by 4.01 times and 4.72 times, respectively; when the field strength increases from 1 kV/mm to 7 kV/mm, the positive and negative carrier mobility increases by 2.53 and 2.72 times, respectively. (3) The carrier mobility of the pressboard with a higher oil absorption rate changes more significantly with temperature; when the field strength is 7 kV/mm and the temperature increases from 20 °C to 80 °C, the positive polarity carrier mobility increases from 3.96 × 10−13 m2·V−1·s−1 to 2.64 × 10−11 m2·V−1·s−1, an increase of 66.67 times, while the increase in the carrier mobility of the pressboard with a lower oil absorption rate is only 1.59 times. (4) The carrier mobility of the naphthenic transformer oil-impregnated pressboard is higher than that of the paraffin-based transformer oil-impregnated pressboard, and the carrier mobility of two kinds of naphthenic transformer oil-impregnated pressboard is 3.16 times and 2.47 times higher than that of the paraffin-based transformer oil-impregnated pressboard, respectively, under the conditions of 60 °C and 7 kV/mm. (5) Utilizing the Darcy model and microscopic scanning results of the pressboard morphology, it was revealed that permeability and fiber structure are key factors influencing the variation in carrier mobility. The research results of this paper can provide theoretical basis for the calibration and optimization of the oil-pressboard insulation structure of converter transformers.

Changes in Fuel Prices and the Use of Public Transport: Insights from the European Union following the Invasion of Ukraine

Rising fuel prices are known to affect public transport (PT) demand. However, the impact of the oil market inflation and subsequent energy crisis following the 2022 Russian invasion of Ukraine on mobility behaviour in Europe has received little attention. This study examines shifts in fuel prices and PT mobility across 25 Europe-an Union countries between February and May 2022. Weekly variations in PT mobility were correlated with diesel and gasoline prices, and a multiple linear regression was conducted to assess the influence of contextual factors in explaining variations in PT usage. The results indicate a significant increase in PT mobility across all countries after February 2022, which was positively associated with rising fuel prices. Approximately 84% of the variance in mobility was explained, with more pronounced increases observed in countries characterised by lower telecommuting prevalence, higher housing costs relative to household income, greater price differentials between gasoline and diesel, lower adoption of alternative fuels, and higher motorisation rates. These findings suggest that the surge in fuel prices, driven by the 2022 energy crisis, may have stimulated an increase in transit ridership.

Advanced, Cutting-Edge RP-HPLC Methodology for the Comprehensive Quantitative Analysis of Assay of Bictegravir, Emtricitabine, and Tenofovir Alafenamide in Co-Formulated Pharmaceutical Products.

In the current study, a simple and economic stability-indicating RP-HPLC method development and validation was carried out to estimate the bictegravir, emtricitabine and tenofovir from the pharmaceutical dosage form. 0.1M ammonium acetate in 0.5% v/v acetic acid solution and 1g of 1-octane sulfonic acid and adjustment of pH to 4.2 with dilute orthophosphoric acid done and methanol (40:60 v/v) was utilized as the mobile phase. The analysis was done using Inertsil ODS 3V (250 x 4.6 mm x 5 µm) column with column temperature kept at 30°C with an injection volume of 20 μL, flow rate of 1.0 ml/ minute and detection was carried out at 260 nm. The method was developed and it was validated according to ICH Q2 (R1) guidelines. The RT of bictegravir, emtricitabine and tenofovir were determined to be 12.23, 3.0 and 8.5 minutes, providing a reliable marker for its identification. The method was found linear from about 50 To 150% Of the target concentration of bictegravir emtricitabine and tenofovir with of 0.999. Significant degradation was observed in acidic, basic and peroxide stress conditions. Hence, it can be concluded that tablets are sensitive to acidic, basic and oxidation stress conditions. RSD for the peak area responses of emtricitabine, 0.03 and 0.03, respectively, indicating that the system is precise. The testing procedure was accurate from about 50 to 150%. Of the target concentration of emtricitabine, tenofovir alafenamide and bictegravir. The method was robust In relation to flow variation, column oven temperature variation, mobile phase variation and pH variation. In conclusion, our proposed RP-HPLC method provides a sensitive, accurate, and precise means of analyzing emtricitabine, tenofovir alafenamide and bictegravir from pharmaceutical dosage forms.

Residential mobility amongst children and young people in Wales: A longitudinal study using linked administrative records

BackgroundChild poverty remains a major global concern and a child's experience of deprivation is heavily shaped by where they live and the stability of their local neighbourhood. This study examines frequencies and patterns of residential mobility in children and young people (CYP) at a population level using novel geospatial techniques to assess how often their physical environment changes and to identify geographical variations in social mobility.MethodsWe used routinely collected administrative records held in the Secure Anonymised Information Linkage (SAIL) Databank for CYP aged under 18 years living in Wales between 2012 and 2022. We calculated the Moran's I statistic to assess the magnitude of Lower layer Super Output Area (LSOA)-level geographic variation in residential mobility and used the Local Indicator of Spatial Association (LISA) to identify clusters of LSOAs where there are higher rates of residential mobility.ResultsThis study included 923,531 CYP, with 58% having moved at least once during the study period. A total number of 1,209,102 house moves were recorded, 59% of which occurred between the ages of 0 and 5 years. Almost 10% of the cohort resided in five or more dwellings before the age of 18 years. In terms of area-level (LSOA) deprivation, 75% of house moves were to areas with the same or higher levels of deprivation, leaving only 25% of house moves that achieved upward social mobility. Clustering of residential mobility was identified predominantly in areas of high deprivation.ConclusionThe findings of this study show that residential mobility is linked with socio-economic circumstances and is experienced by over half of CYP in Wales. Understanding where CYP live, their mobility patterns and which areas have high levels of influx and efflux is crucial for policymakers to generate well-informed, targeted and effective child-focused interventions.

Independent mobility and outdoor play time: Insights from urban informal settlements in India

This study assesses differences in children's independent mobility and outdoor play time between two urban informal housing settlements within India's in-situ slum redevelopment policy. This redevelopment policy involves replacement of existing slum housing with new apartment-style structures at the original site. One of the settlements under study has undergone redevelopment, while the other remains on the waitlist for redevelopment. Additionally, the study explores potential gender-based variations in independent mobility and outdoor play time, shedding light on the distinct effects of redevelopment on boys and girls. Questionnaires were administered to mothers, addressing aspects such as independent mobility licenses, the range of independent mobility, the age at which mobility licenses are granted, and the duration of outdoor play of children. Findings show that children in slum settlement were reported to have more mobility licenses, broader independent mobility range, and earlier licenses than children in redeveloped settlement. Gender differences are evident, with girls in redeveloped settlement receiving mobility licenses later than both boys and girls in slum settlement, but boys' age at which they received independent mobility licenses remained consistent regardless of their place of residence. Boys in the redeveloped settlement engage in more outdoor play time than boys and girls in slum settlement. Conversely, girls in slum settlement participate in more outdoor play time than those in redeveloped settlement. These findings have important implications for slum redevelopment policies, highlighting the need to consider morphological aspects of residential environments that support girls' outdoor play time and independent mobility. It is crucial that these considerations be integrated into the design of redeveloped settlements to ensure equitable development of children in such communities.

Residential mobility for young adults in extended foster care

BackgroundPlacement stability is tied to well-being among children living in foster care, yet residential mobility remains largely unexplored for transition-age youth residing in extended foster care (EFC) between ages 18 and 21. During the time young adults in EFC can remain in foster homes, child welfare agencies offer living arrangements tailored to the transition into adulthood. In supervised independent living placements (SILPs), residents receive monthly stipends to cover their housing expenses and are responsible for covering food, utilities, and other basic needs-related costs. Transitional housing placements (THPs) offer light-touch caregiving during the transition to independence to ensure that residents have their basic needs met. ObjectiveThe current study is the first comprehensive examination of factors associated with residential mobility in a statewide population of young adults residing in EFC. ParticipantsUsing California administrative Child Protective Services records, we identified young adults who turned 18 between 2016 and 2019 and lived in care for at least 1 week (N = 10,517). MethodsNegative binomial regression evaluated the association between residential characteristics and per-year EFC moves. ResultsWe found that young adults had a median number of 1.0 moves during EFC, with a median rate of 0.67 moves per year in EFC (i.e. roughly one move every 18 months). SILPs and THPs were the most common primary residence types among the study population (41.6 % and 26.0 %, respectively). The average duration of stay in EFC was two years, which varied by primary residence type. Regression results showed that predominant residence type in EFC was associated with EFC mobility, with young adults in SILPs being more likely to experience slightly higher mobility than those primarily living in other residence types (0.82 versus 0.75 moves per year in EFC). ConclusionsFindings suggest that housing for EFC residents tends to be long-lasting and relatively stable in California. Modest variations in mobility by residential type and by experiences in foster care before age 18 underscore the importance of integrating housing and psychosocial resources during independent living planning processes. The commonality of out-of-county residence should be considered when determining housing and transportation expenses for residents, given its potential implications for access to medical and behavioral health care, academic institutions, and employment opportunities for young adults receiving EFC services.

Temperature- and gate voltage-dependent I–V modeling of GaN HEMTs based on ASM-HEMT

Abstract In this paper, a temperature and gate voltage dependent current-voltage (I-V) model for Gallium nitride (GaN) high electron mobility transistors (HEMTs) devices is studied. In order to help researchers and designers simulate devices in the absence of experimental data and improve parameter extraction efficiency, the temperature and gate voltage dependence of mobility are discussed and incorporated into the proposed model which is revised from the standard advanced SPICE model (ASM) for GaN HEMTs. The mobility variations with gate voltage from -2 V to 6 V and temperature from 10 K to 1000 K are analyzed. The simulation results of our model are compared with the standard ASM-HEMT model, and the output and transfer characteristics of the device from 270 K to 420 K are simulated. Thereby, our model may simulate various applications of GaN HEMTs at different gate voltages and temperatures in the early stages of design and research.

Impedimetric detection of chloride ions using two symmetric Ag/AgCl electrodes

The suitability of Ag/AgCl electrodes for specific detection of chloride ions in aqueous gels is investigated. In contrast to potentiometric sensors, we use an impedimetric approach and avoid the need for a separate reference electrode through a symmetric two-electrode configuration. As such, electrochemical impedance spectroscopy is employed to characterise the response of the Ag/AgCl electrodes in contact with gels at various hydration levels containing different types as well as concentrations of salt. In order to extract quantitative information related to e.g. the ion concentration and mobility from the impedance spectra, an equivalent circuit model is fitted to the data. Here, we develop a simple equivalent circuit model related to the physical parameters of the system, which can be reduced to a modified Randles circuit with only few circuit elements. Importantly, even though the equivalent circuit model contains the same elements as a Randles circuit, their physical origin is different. Systematic variations of ion mobility, ion concentration, and type of ions allow us to evaluate the relationship between those physical properties and the resulting fitting parameters of the modified Randles circuit. This finally enables us to determine chloride concentrations in complex liquids, containing other salts and long chain molecules.

Tensor Decomposition for Spatiotemporal Mobility Pattern Learning with Mobile Phone Data

Detecting urban mobility patterns is crucial for policymakers in urban and transport planning. Mobile phone data have been increasingly deployed to measure the spatiotemporal variations in human mobility. This work applied non-negative Tucker decomposition (NTD) to mobile phone-based origin–destination (O-D) matrices to explore mobility patterns’ latent spatial and temporal relationships in the province of Liège, Belgium. Four [Formula: see text] traffic tensors have been built for one regular weekday, one regular weekend day, one holiday weekday, and one holiday weekend day, respectively. The proposed method inferred spatial clusters and temporal patterns while interpreting the correlation between spatial clusters and temporal patterns through geographical visualization. As a result, we found the similarity of O-D and destination–origin (D-O) patterns and the symmetry for the trips of the temporal patterns with evening peak and morning peaks on the weekday. Moreover, we investigated the attraction of different spatial clusters with two temporal patterns on a regular weekday and validated the reconstructed demand using population counts and commuting matrices. Finally, the differences in spatial and temporal interactions have been addressed in detail.

Short-term impact of vitamin K2 supplementation on biochemical parameters and lipoprotein fractions.

This study explored the short-term effects of vitamin K2 (VK2) supplementation on biochemical parameters (vitamin D, vitamin E, vitamin A, alkaline phosphatase, calcium, phosphorus (P), magnesium, metallothionein, triglycerides, cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), and lipoprotein fractions (albumin, HDL, very low-density lipoprotein (VLDL), LDL, and chylomicrons). A short-term experiment (24h, six probands) was performed to track changes in VK2 levels after a single-dose intake (360µg/day). Liquid chromatography-tandem mass spectrometry was used to monitor vitamin K levels (menaquinone-4 (MK-4), menaquinone-7 (MK-7), and vitamin K1 [VK1]) with a limit of detection of 1.9pg/mL for VK1 and 3.8pg/mL for the two forms of VK2. Results showed that MK-7 levels significantly increased within 2-6h post-administration and then gradually declined. MK-4 levels were initially low, showing a slight increase, whereas VK1 levels rose initially and then decreased. Biochemical analyses indicated no significant changes in sodium, chloride, potassium, calcium, magnesium, albumin, or total protein levels. A transient increase in P was observed, peaking at 12h before returning to baseline. Agarose gel electrophoresis of lipoprotein fractions revealed distinct chylomicron bands and variations in VLDL and HDL mobility, influenced by dietary lipids and VK2 supplementation. These findings suggest effective absorption and metabolism of MK-7 with potential implications for bone metabolism and cardiovascular health.

Insights into enhanced thermoelectric performance of the n-type Mg3Sb2-based materials by amphoteric Al doping

Doping has the potential to alter the levels of anharmonicity in compounds by attenuating bonding strength. In this study, we explore the efficacy of amphoteric Al doping for stimulating anharmonicity in n-type Mg3.25AlxSb1.48Bi0.48Te0.04 to attain enhanced phonon scattering and thermoelectric performance. First-principles calculations and experimental data reveal the occupation of both Sb and Mg2 sites by amphoteric Al atoms in the anionic framework of Mg3.25AlxSb1.48Bi0.48Te0.04. A marginal variation in both carrier concentration and mobility sustains the high power factor without affecting the Seebeck coefficient, implying amphoteric doping induced charge compensation. While phonon velocity, Grüneisen parameter, and crystal orbital Hamilton population calculations results indicate that phonon softening and bond weakening are realized via Al doping, leading to an enhanced lattice anharmonicity and a reduced lattice thermal conductivity. A remarkable enhancement ∼16% in the peak figure of merit ZTpeak and the average ZTavg, was attained for the x = 0.015 sample, when compared with the un-doped sample. Hence, the amphoteric doping can serve as an effective means to optimize ZT values by decoupling the intertwined thermoelectric transport properties.

An integrated approach to analyze equitable access to food stores under disasters from human mobility patterns.

Limited access to food stores is often linked to higher health risks and lower community resilience. Socially vulnerable populations experience persistent disparities in equitable food store access. However, little research has been done to examine how people's access to food stores is affected by natural disasters. Previous studies mainly focus on examining potential access using the travel distance to the nearest food store, which often falls short of capturing the actual access of people. Therefore, to fill this gap, this paper incorporates human mobility patterns into the measure of actual access, leveraging large-scale mobile phone data. Specifically, we propose a novel enhanced two-step floating catchment area method with travel preferences (E2SFCA-TP) to measure accessibility, which extends the traditional E2SFCA model by integrating actual human mobility behaviors. We then analyze people's actual access to grocery and convenience stores across both space and time under the devastating winter storm Uri in Harris County, Texas. Our results highlight the value of using human mobility patterns to better reflect people's actual access behaviors. The proposed E2SFCA-TP measure is more capable of capturing mobility variations in people's access, compared with the traditional E2SFCA measure. This paper provides insights into food store access across space and time, which could aid decision making in resource allocation to enhance accessibility and mitigate the risk of food insecurity in underservedareas.

Exploring the interface dynamics of emulsion gel via a novel non-destructive technique provides insights into the underlying mechanism of gel formation, water mobility, functionality and structural variations

Tri-frequency ultrasound (TFU) at 20-40-60 kHz was used to systematically examine the effects on the multi-scale network structure of an emulsion gel containing orange essential oil prepared with glycosylated whey protein (WP). Treatment intervals of pre-and-post 10, 20, and 30 min were utilized to evaluate the influence and interactions on functional (particle size, zeta-potential), rheological (storage modulus (G′) and loss modulus (G″), and oxidative stability (conjugated diene and peroxide value). The optimized tri-frequency pre- and post-treated sample demonstrated enhanced physical stability as compared to the un-treated sample, as evidenced by droplet size, (from 468.14 ± 0.56 to 214.21 ± 0.42 nm), ζ-Potential (mV) (from −29.67 ± 0.31 to −39.98 ± 1.42), and structural morphology. Structure analysis using FTIR that the aforementioned improvements were made possible through TFU enhanced hydrogen bonds, molecular arrangements with greater order, and improved intermolecular compatibility. XRD results showed gradual shift from 8.32° to 8.64° and from 19.2° to 19.5°, respectively. TFU post-treatment gels exhibited higher viscosity, more pronounced pseudoplastic behavior compare to pre-treatment, attributed to strong interaction forces and three-dimensional gel network. Our results provide valuable insights into the application of multi-frequency ultrasound as a promising technique for designing protein emulsion gels tailored for nutrient delivery systems.

Evidence for isotopically light Fe mobility under oxidising conditions in subduction zone fluids: A record of Monviso meta-serpentinites, Western Alps

The isotopically light Fe signature of arc magmas relative to mid-oceanic ridge basalts (MORB) is expected to be related to the redox state of their source. This implies a link between Fe mobility and redox variations across subduction zones. Here we address slab chemical variations during prograde metamorphism through a comprehensive geochemical study, including major, trace elements and Fe stable isotope (δ56Fe) analyses, of meta-serpentinites composing the eclogitic meta-ophiolite of the Monviso massif (Western Alps, Italy). These rocks partly preserve mantle related geochemical heterogeneities, as supported by negative correlations between fluid immobile elements (High Field Strong Elements) and LREE/HREE (Light – Heavy Rare Earth Elements) ratios. They are however characterized by large Cs enrichments relative to U or alkali elements suggesting that abyssal fluid mobile elements signature was overprinted by subduction related processes. Meta-serpentinites display large δ56Fe variations, from -0.20 ± 0.05 ‰ to +0.09 ± 0.03 ‰. Mineral separate analyses of olivine bearing veins show low Δ56Fe between olivine and magnetite (∼ 0.4 ‰), which according to Fe isotope thermometry correspond to high temperature equilibration, estimated between 530 and 550 °C, compatible with Monviso metamorphic climax (520–570 °C and 2.6–2.7 GPa). These results, in combination with geochemical modelling, confirm a reset of δ56Fe signature of abyssal serpentinites during prograde metamorphism in subduction zones. The bulk rock δ56Fe values of Monviso meta-serpentinites are negatively correlated with their Fe3+/∑Fe and As concentrations (a redox-sensitive and fluid mobile element). These correlations can be attributed to a metasomatism by external fluids derived from slab serpentinites during subduction. It also concords with the oxygen fugacity (fO2) record in meta-serpentinites, with meta-serpentinites equilibrated at high fO2 displaying the lowest δ56Fe values while samples equilibrated at low fO2 display mantle like δ56Fe signatures. These results highlight that oxidising conditions during serpentinite dehydration are likely to boost isotopically light Fe mobility in slab derived fluids.

The effect of labor mobility on corporate investment and performance over the business cycle

We show that time-series variation in investment opportunities and labor demand create heterogeneity in the effects of labor mobility on corporate investment over the business cycle. To isolate variation in labor mobility, we create an annual state-level index from 1984 through 2017 that captures the degree to which state courts enforce covenants not to compete. We find that firms located in more mobile labor markets increase investment rates more during economic expansions but have similar investment rates during periods of low or negative growth. This increased investment during expansions is greater for firms that rely more on recruiting skilled and experienced workers to grow their businesses, and it translates into higher sales growth rates, profits, and valuations. Overall, our results suggest that the benefits of being able to recruit qualified workers with relevant experience during expansions outweigh the costs associated with losing key workers.

Photometric Properties within the Reiner Gamma Swirl: Constraining Formation Mechanisms

The area in the Reiner Gamma swirl studied by Weirich et al. for topographic correlations also displays correlations with the Hapke-model-derived single-scattering albedo, surface roughness, and particle scattering properties with swirl unit. The correlations with single-scattering albedo associate compositional variations in plagioclase and FeO content with swirl unit. The correlations with photometric surface roughness show a rougher surface on-swirl, implying a potentially more porous surface on-swirl compared to off-swirl. This suggests the variations in single-scattering albedo are dominated by the compositional differences and not structural differences, such as compaction. Grain-size differences could still contribute to the albedo variations. Differences in particle scattering properties between on-swirl and off-swirl are counter-indicative of the trend expected from variations in space weathering, unless there is a process to initiate either size sorting or compositional differences. The photometric properties point to a complex interaction of multiple processes to form the swirl units, not a singular dominant process. Variations in weathering, dust mobilization and entrapment, and impact modification may all play a key role.

The study of electron mobility on ultra-scaled silicon nanosheet FET

The nanosheet FET (NSFET) is the successor to FinFET, and its mobility significantly affects device performance. In this paper, we investigate the impact of phonon (ph) and surface roughness (SR) scattering on the electron mobility of n-type silicon NSFETs. The effects of channel width, thickness, and doping concentrations on NSFETs' mobility are also analyzed. Non-Equilibrium Green’s Function (NEGF) solver which incorporates scattering mechanisms using the self-energy formulation is employed. The mobility behavior in NSFETs is strongly affected by ph scattering and SR scattering. As for ultrathin nanosheets, severe mobility degradation is dominated by SR scattering. The mobility is slightly affected by the doping concentrations. Simulation results provide guidance to researchers and industry in understanding and predicting the variation of mobility under the trend of continuous scaling.