Typical Timing Research Articles

1.8-µm pitch, 47-ps jitter SPAD array in a 130 nm SiGe BiCMOS process

We introduce the world’s first SPAD family design in 130 nm SiGe BiCMOS process. At 1.8 µm, we achieved the smallest pitch on record thanks to guard-ring sharing techniques, while keeping a relatively high fill factor of 24.2%. 4×4 SPAD arrays with two parallel selective readout circuits were designed to explore crosstalk and scalability. The SPAD family has a minimum breakdown voltage of 11 V, a maximum PDP of 40.6%, and a typical timing jitter of 47 ps FWHM. The development of silicon SPADs in SiGe process paves the way to Ge-on-Si SPADs for SWIR applications, and to cryogenic optical interfaces for quantum applications.

Analysis of dual biodiesel doped with different proportions of TiO2 nanoparticles

India is home of two species Madhuca indica and jatropha. Mahua, also referred to as Illupai maram in Tamil and Hippi in Kannada, is a plant that grows well in arid, barren areas. The seeds from the tree dubbed the “Indian butter tree.” With a compression ratio of 17.5:1, an inlet valve opening timing of 13O bTDC, and an injection pressure of 200 bars, a performance and emission analysis for various proportions of nano additives with biodiesel blend was conducted at various loads ranging from zero load to 100 % of brake power. Using a brake drum dynamometer, load was applied to the engine. It is noted how long it takes to use 10 ml of gasoline for each load. The diesel engine employed is a single-cylinder, direct-injection Kirloskar engine with typical inlet valve timing, compression ratio, and injection pressure, 1500 rpm is the continuous speed. The components of exhaust gases change depending on the load. Standard diesel is used to run the engine at first to gather baseline data, and then JME5MME15 blends with different amounts of nano additives added for the experiment. These amounts are 25 PPM, 50 PPM, and 75 PPM. The reading is taken using the same process. Among the various blends analyzed JME5MME15 has an SFC of 0.321 kg/kW h. The SFC results for JME5MME15T25 are 0.382 kg/kWh. JME5MME15T50 and JME5MME15T75 have similar values of 0.282 kg/kWh and 0.421 kg/kWh. The SFC of the JME5MME15T50 is almost identical to that of diesel.

Timing of sexual debut and associated sociodemographic and HIV risk factors among young people in Eswatini.

Young people in sub-Saharan Africa and specifically in Eswatini (previously Swaziland), continue to be disproportionately affected by HIV despite having equitable access to antiretroviral treatment. Early sexual debut is one of the many factors linked to HIV infection that is discussed in the context of general public health. Monitoring this behavior is essential for developing preventative, evidence-based interventions. This study aims to describe the early and/or typical sexual debut among young people in Eswatini and examines sociodemographic and HIV risk factors associated with early and typical sexual debut timing. We analyzed cross-sectional secondary data from the 2016/17 Swaziland HIV Incidence Measurement Survey (SHIMS), which had a representative sample of 2,383 young people aged 18-24. Respondents were selected using a two-stage stratified probability sampling design. We applied descriptive statistics and multivariable multinomial logistic regressions to examine the data. Out of the 2,383 respondents, 71.3% had sexual experience, with 4.1% and 26.5% reporting early sexual debut (<15 years) and typical sexual debut (<18 years), respectively. Our study found that age, sex, education, marital status, wealth, sexual partners in the past 12 months, and alcohol use were significantly associated with early and/or typical sexual debut. It is crucial to consider the sociodemographic factors and HIV risk factors of young people when designing programs and interventions aimed at preventing early sexual debut or transition. This approach is necessary to promote better sexual and reproductive health in alignment with sustainable development goals.

Congenital Central Hypoventilation Syndrome (Ondine’s Curse): Clinical Case

Background. Congenital central hypoventilation syndrome (CCHS), or Ondine’s Curse, is rare, incurable and life-threatening disease characterized by autonomic nervous system disorders, it manifests with disability to maintain ventilation function during sleep. Sensitivity to hypoxia and hypercapnia is reduced in case of CCHS, thus, it leads to recurrent episodes of deep apnea. The world literature describes just over 1000 cases of this disease. Clinical case description. An infant born at 37th week of gestation, weight of 3330 g, had episodes of apnea and hypercapnia from the first day of life. CCHS was suspected by the 28th day of life after excluding other causes of respiratory disorders, and it was genetically confirmed by the 43rd day of life — pathogenic variant of PHOX2B gene was revealed. Mechanical ventilation has been initiated by the age of 1 month after disease worsening. Analysis of CCHS cases published in Russian-language medical literature was performed. Typical symptoms and timing of their manifestation, as well as the time before correct diagnosis were mentioned. Conclusion. Symptoms that can be suggestive of CCHS presence early after birth and can urge to perform all the necessary genetic testing that are crucial for timely treatment onset and for minimizing the negative effect of hypoxemia and hypercapnia on the child are described.

0816 Actigraphy-Measured Sleep Timing and Risk of Breast Cancer in the UK Biobank

Abstract Introduction Shift work leading to circadian disruption is associated with increased breast cancer risk, but it remains unclear whether typical sleep timing variation in the general population that may cause less extreme disruption is also associated with increased risk. Prior studies relied on sleep timing assessed using self-report, but research using actigraphy is limited. Our goal was to characterize the association between sleep timing and breast cancer risk using actigraphy-based measures. Methods Our sample included 43,109 women without a history of breast cancer in the UK Biobank cohort who wore Axivity-AX3 accelerometers over 7 days. We estimated sleep midpoints, the median of sleep onset and waking. Social jetlag was estimated as the absolute difference in average weekend and weekday sleep midpoints. We used multivariable Cox models to estimate hazards ratios (HRs) and 95% confidence intervals (CI), adjusting for age, body mass index, participant characteristics, socioeconomic status, physical activity, menopause, parity, and oral contraceptive use. We conducted a sensitivity analysis excluding shift workers to control for potential strong confounding from shift work. Results Over 6.2 years of follow-up, there were 683 incident breast cancer cases. Earlier and later sleep midpoints were not associated with breast cancer (Early, &amp;lt; 4:00AM HR:1.08 [95%CI: 0.89-1.32]; Later, ≥5:00AM HR:1.24 [0.86-1.81]; vs. Reference 4:00-4:59 AM). Per-hour increases in social jetlag were suggestively associated with greater breast cancer risk (HR:1.09 [0.96-1.24]), but significantly higher risk was only noted at the highest levels of social jetlag comparing ≥2 hours to &amp;lt; 1 hour (HR:1.58 [1.13-2.20]). Results were unchanged when excluding shift workers. Conclusion Higher levels of social jetlag among UK women appeared to be associated with elevated breast cancer risk, possibly due to circadian disruption. While our results suggest that minimizing variation between weekday and weekend sleep timing may be related to lower breast cancer risk, replication of our findings in future studies using actigraphy-based measures and larger case numbers is needed. Support (if any) Supported by the Intramural Research Program of the National Cancer Institute, National Institutes of Health.

Effect of rice leaf stage on tolerance to benzobicyclon in a drill‐seeded production system

AbstractBenzobicyclon is a new postflood‐applied herbicide that was registered for use in U.S. rice (Oryza sativa L.) in 2021 by Gowan Company. Therefore, research was conducted to evaluate tolerance of commonly grown rice cultivars to benzobicyclon. In 2018 and 2019, field experiments were conducted near Stuttgart, AR to evaluate the influence of growth stage on rice tolerance to benzobicyclon, and to evaluate pure line and hybrid rice tolerance to benzobicyclon following repeated use of acetolactate synthase‐inhibiting herbicides. In one of two years, rice growth stage (leaf number) at application impacted tolerance to benzobicyclon. In 2018, the two‐leaf application of benzobicyclon was generally more injurious to the rice cultivars, ‘CL153’, ‘Diamond’, ‘PVL01’, and ‘CLXL745’ than when applied at four‐leaf or tillering growth stages. In the second year, all rice cultivars, except ‘Rondo’, were not injured by benzobicyclon applied at any growth stage. In both years, benzobicyclon applied to indica rice cultivar Rondo elicited ≥97% crop injury, regardless of application timing. Findings from these experiments suggest that rice cultivar tolerance can vary across environments and that smaller‐sized rice could be more prone to injury than when applications occur at a typical timing for a postflood‐applied herbicide. In general, four‐leaf and tillering rice will exhibit sufficient tolerance to benzobicyclon. It is especially not recommended to apply benzobicyclon on rice cultivars that have a predominant indica‐type genealogical background. Benzobicyclon following repeated applications of acetolactate synthase‐inhibiting herbicides to the pure line cultivar CL153 and the hybrid cultivar CLXL745 did not pose increased risk for injury to rice.

Selection of train traffic managers activities in training process using functional resonance analysis method

In training process of rail traffic manager (controller) using virtual reality technology, selection of activities among those assigned to a workplace and scenarios that should be taken in training is an important issue. The selection method that is based on performance variability of her/his activities has been proposed in the paper. This variability has been characterized by timing and precision. The traditional reliability and safety analysis methods are not sufficient when building the training program for traffic managers. In the paper the train controller work has been modelled using Functional Resonance Analysis Method (FRAM) that is system oriented approach. Scales of values of timing and precision that are train transport driven have been presented. They are different when comparing with typical timing and precision scales given in FRAM literature. In the paper the estimation of prob-abilities of occurring of values of timing and precision scales for these activities has been calculated as the mean from the values obtained by questionnaire done in traffic manager community or using Analytic Hierarchy Process (AHP) method. In FRAM with AHP approaches presented in literature, AHP pairwise comparison is executed using natural numbers and their reciprocals what is typical in AHP method. In our paper the AHP is used for estimating the probabilities, so in pairwise comparing the rational numbers are applied, because natural numbers and their reciprocals would limit the set of values of probabilities. The activities and scenarios that the training should be concentrated on are selected from those with the greatest variability.

Once a remedy, later a disease

Radiation-induced lung injury (RILI) encompasses any lung toxicity induced by radiation therapy (RT). It manifests acutely as radiation pneumonitis (RP) and chronically as radiation pulmonary fibrosis. It is usually seen in patients who have undergone thoracic irradiation for the treatment of lung, breast, or hematologic malignancies. The volume of lung irradiated and the mean lung dose are important risk factors. The diagnosis is usually based on a combination of typical symptoms (e.g., cough, dyspnea, and occasionally fever), timing, dose, and location of radiation therapy, compatible imaging findings, and exclusion of other causes. We report a case of a patient with breast cancer, who had received locoregional radiotherapy (RT) and then palliative RT for metastasis in the rib, following which she developed symptoms and radiological manifestations consistent with RILI. The patient recovered clinically and radiologically with conservative management. It was important to accurately diagnose the entity early since RP with moderate-to-severe symptoms and impaired respiratory function needs to be treated early to prevent irreversible lung damage.

Optimal scheduling of island integrated energy systems considering multi-uncertainties and hydrothermal simultaneous transmission: A deep reinforcement learning approach

Multi-uncertainties from power sources and loads have brought significant challenges to the stable demand supply of various resources at islands. To address these challenges, a comprehensive scheduling framework is proposed by introducing a model-free deep reinforcement learning (DRL) approach based on modeling an island integrated energy system (IES). In response to the shortage of freshwater on islands, in addition to the introduction of seawater desalination systems, a transmission structure of “hydrothermal simultaneous transmission” (HST) is proposed. The essence of the IES scheduling problem is the optimal combination of each unit’s output, which is a typical timing control problem and conforms to the Markov decision-making solution framework of deep reinforcement learning. Deep reinforcement learning adapts to various changes and timely adjusts strategies through the interaction of agents and the environment, avoiding complicated modeling and prediction of multi-uncertainties. The simulation results show that the proposed scheduling framework properly handles multi-uncertainties from power sources and loads, achieves a stable demand supply for various resources, and has better performance than other real-time scheduling methods, especially in terms of computational efficiency. In addition, the HST model constitutes an active exploration to improve the utilization efficiency of island freshwater.

Regular, intermittent, and spontaneous: Patterns of preschool Children's nap behavior and their correlates

BackgroundDaytime sleep during the preschool years (i.e., 1-5-years-old) is characterized by high inter-child variability in several components of nap behavior, including nap duration, nap timing, and the proportion of sleep during daytime. We used an empirical approach to examine variations amongst children in these aspects of napping and investigated correlates of these components of nap behavior. MethodsA large, nationally representative sample (N = 702) of Canadian parents completed an online survey, including a one-month retrospective report of their 1.5–5 year old's daytime and nighttime sleep behavior and other questionnaires. To understand patterns of children's nap behaviors we applied Latent Profile Analysis (LPA) to typical nap duration, typical timing of naps, frequency of naps, proportion of sleep during the daytime, and the proportion of naps which were spontaneous (i.e., child just fell asleep). Then, multinominal logistic regression was used to examine correlates of profile membership. ResultsFour profiles of children emerged: (1) regular nappers; (2) intermittent nappers; (3) spontaneous nappers; and (4) non-nappers. After controlling for demographic variables (e.g., child age, sex, ethnicity) and known correlates of napping behaviors (e.g., birthweight, nighttime sleep duration), profile membership was related to parents' beliefs about napping, parents’ own nap behaviors, family functioning, and child nighttime sleep problems in a multinominal logistic regression. ConclusionsAn empirical approach aided in understanding the inter-child variability in napping amongst preschool-age children. Parental beliefs about napping and the home environment were shown to be critical factors influencing this variability.

Changes in rainfall amount and seasonality modulate taxonomic, functional, and phylogenetic diversity in a gypsophilous plant community in the Chihuahuan Desert

ABSTRACT Background Climate change is expected to alter future rainfall regime in arid zones, which may impact gypsophilous plant diversity components in the Chihuahuan Desert. Aims We investigated the effects of different rainfall timings and amounts on the taxonomic, functional, and phylogenetic components of a gypsophilous plant community. Methods We used soil monoliths extracted from the southern Chihuahuan Desert in a greenhouse experiment with three rainfall timings (typical, early, and late) and two rainfall amounts (100% and 50%) and evaluated the effects on taxonomic, functional, and phylogenetic diversity. Results Irrigation treatment with 50% of average rainfall reduced species richness and plant abundance and altered species composition. At 100% irrigation, specific leaf area was lower in the treatments with typical and late rainfall timing than in the treatment with early rainfall. Phylogenetic diversity was significantly lower in the late timing treatment in November. Conclusion Our study evidence that the water shortage impacted drastically on the plant community by decreased species richness and diversity. Nevertheless, late rainfall can buffer the effects of water diminution but only on taxonomic and functional diversity, with the opposite effect on the phylogenetic diversity, in the gypsophilous communities in the Chihuahuan Desert.

Influence of Areca Nutshell-Reduced Graphene Oxide, Isopropanol, and Exhaust Gas Recirculation in an Internal Combustion Engine.

Regulations governing pollution, declining fossil fuel supply, and technological breakthroughs in renewable fuels all have a profound influence on the development of alternative fuels. This current research focuses on the influence of nanoadditives with alcohol in an exhaust gas recirculation-cooled engine. As nanoadditives have high thermal conductivity and alcohol has high oxygen content, they work synergistically to speed up the catalytic process and increase the combustion rate. The areca nutshell-reduced graphene oxide with a mass fraction of 25 pmm was ultrasonically blended with two isopropanol-diesel mixtures 10% isopropanol + 90% diesel (IDR10) and 20% isopropanol + 80% diesel (IDR20), respectively, and tested in a single-cylinder, 4-stroke internal-combustion engine at a typical injection timing of 23° TDC with an EGR rate of 20%. The results of experiments showed that IDR10 has better combustion and emission parameters than other fuel blends. Compared to other biodiesel blends, the IDR10 blend has 2.3% less BSFC and 2.45% more BTE. The IDR10 blend has lower HC emissions by 42.85%, CO emissions by 33.34%, NO x emissions by 2.42%, and smoke emissions by 15.4%.

Blind Estimation of GPS M-Code Signals under Noncooperative Conditions

In the process of Global Positioning System (GPS) modernization, M-code signals with better immunity to interference have been proposed and used in place of P(Y) signals as new authorization signals. A typical positioning, navigation, and timing (PNT) service is based on the local interrelation operation between the reference signal and the received signal. To obtain a PNT, the receiver should generate replicas of the pseudorandom code for acquisition and tracking. However, due to the use of an encryption algorithm, the receiver cannot use the M-code signal under noncooperative conditions. This paper presents an algorithm for estimating M-code sequences without prior knowledge. This algorithm adopts a waveform matching technique and a time domain filtering method to extract M-code from the in-phase channel and quadrature channel of the GPS L1 band. A high-gain antenna is used to receive GPS signals to keep the signal from being drowned out by noise. The experimental results show the feasibility of the method. Therefore, it is helpful for studying and evaluating the performance achieved without prior knowledge of the GPS signals.

An Updated Ephemeris for K2-138 d

Abstract K2-138 d (EPIC 245950175 d) is one of five planets in a chain of 3:2 mean motion resonances discovered by Christiansen et al. in K2 Campaign 12. An additional planet, confirmed with the Spitzer Space Telescope by Hardegree-Ullman et al., is not in the resonant chain. The near first-order resonances, coupled with the planets being locked in a set of three-body Laplace resonances, make this system a unique target to study for transit timing variations (TTVs). As the predicted transit timing amplitude (∼7 minutes) was below the typical transit timing uncertainty (∼10 minutes) of the K2 data, Christiansen et al. were unable to detect TTVs for K2-138 d in the K2 time series. Here, we describe new observations that allow us to refine the ephemeris for K2-138 d and perform a brief search for TTVs. Our efforts result in a refined orbital period that is 19 times more precise than previously available measurements, but our data are insufficient to confirm a TTV signal for K2-138 d.

Fall cover crop nitrogen uptake drives reductions in winter-spring leaching.

Cover crops can reduce nitrate leaching after cash crop harvest. Despite widespread cover crop implementation, there has been a limited effect on water quality in the Chesapeake Bay watershed. We hypothesize that typical timing for Maryland cover crop planting after cash crop harvest is too late to allow roots to take up substantial nitrate from the soil profile before it is leached by winter drainage water. Across four site-years (including sandy and silty soils), we compared various planting dates for a radish (Raphanus sativus L.)-crimson clover (Trifolium incarnatum L.)-triticale (Triticosecale) cover crop mixture. Also, across two site-years we compared early-planted pure rye, radish, and a three-species mixture with no cover. We measured cover crop biomass and N content and used tension lysimeters to measure deep soil porewater nitrate concentrations. Cumulative nitrate leaching was calculated from these concentrations and weather-based drainage estimates. Cover crops were planted on four dates over a 6-wk period. Overall, cover crops planted first, second, third, fourth, and no cover crop (just weeds) resulted in 3,340, 3,160, 1,600, 303, and 164kg ha-1 of biomass; biomass N accumulation of 65.5, 68.6, 44.0, 9.88, and 4.79kg N ha-1 ; and mean porewater concentrations of 2.71, 2.57, 4.72, 10.0, 17.1mg L-1 of nitrate-N, respectively. Over two site-years, the three-species mix performed as well or better than pure rye or radish. Early planting altered cover crop species proportions, increased cover crop productivity, and reduced nitrate leaching from agricultural fields.

Assessing of a Radiation Therapy Sessionʼs Duration at the Stage of Pre-Radiation Preparation

The treatment planning process includes a review of the radiation treatment plan which leads to a decision on the patientʼs treatment technique. The scope of this study was to create a mathematical model for calculating of a radiation therapy session duration during the pre-radiation planning stage.For dosimetric planning of radiation treatment the authors provided a formula and an algorithm for determining of a patientʼs irradiation session duration. Radiation therapy session parameters such as radiation technique, number of monitor units, characteristics of radiotherapy equipment, number of radiation fields, radiation field parameters (angles of rotation of the radiotherapy coach, collimator, gantry), presence / absence of dose-modulating devices, dose rate, and duration of patient position verification procedures have all been taken into account during the development of software. The developed application explains how to define typical timing characteristics for various items as well as how to select a template from a built-in drop-down menu. If the dosimetric plan does not match for one of the templates, the program provides a space for defining of all parameters manually.The anticipated deviations of the true indicators from the expected indicators of the duration of the radiation therapy session were assessed. A total of 300 cases have been completely measured, with 100 cases studied for each irradiation technique (IMRT, VMAT, 3D). The maximum detection confidence value for the 3DCRT irradiation technique is 2.3 %, while the deviation for the IMRT and VMAT irradiation techniques is less than 1 %. The magnitude and degree of the deviation of the measured value from the expected one for a variety of characteristics and features have been revealed to depend on the actions of the personnel.The program developed allows medical physicists to analyze the timing parameters of the specified dosimetric planning methodologies directly on the treatment planning workstation. Evaluation of the duration of a radiation therapy session during the treatment planning stage, selection of various radiation treatment modalities, and consideration of the characteristics of the radiation session in each clinical case are available for analysis and further justified action.

Global patterns of seasonal influenza activity, duration of activity and virus (sub)type circulation from 2010 to 2020.

BackgroundSeasonal influenza viruses undergo unpredictable changes, which may lead to antigenic mismatch between circulating and vaccine strains and to a reduced vaccine effectiveness. A continuously updated knowledge of influenza strain circulation and seasonality is essential to optimize the effectiveness of influenza vaccination campaigns. We described the global epidemiology of influenza between the 2009 A(H1N1)p and the 2020 COVID‐19 pandemic.MethodsInfluenza virological surveillance data were obtained from the WHO‐FluNet database. We determined the median proportion of influenza cases caused by the different influenza virus types, subtypes, and lineages; the typical timing of the epidemic peak; and the median duration of influenza epidemics (applying the annual average percentage method with a 75% threshold).ResultsWe included over 4.6 million influenza cases from 149 countries. The median proportion of influenza cases caused by type A viruses was 75.5%, highest in the Southern hemisphere (81.6%) and lowest in the intertropical belt (73.0%), and ranged across seasons between 60.9% in 2017 and 88.7% in 2018. Epidemic peaks typically occurred during winter months in Northern and Southern hemisphere countries, while much more variability emerged in tropical countries. Influenza epidemics lasted a median of 25 weeks (range 8–42) in countries lying between 30°N and 26°S, and a median of 9 weeks (range 5–25) in countries outside this latitude range.ConclusionsThis work will establish an important baseline to better understand factors that influence seasonal influenza dynamics and how COVID‐19 may have affected seasonal activity and influenza virus types, subtypes, and lineages circulation patterns.

A comparative analysis of the epidemiology of influenza and respiratory syncytial virus in Russia, 2013/14 to 2018/19.

BackgroundInfluenza and respiratory syncytial virus (RSV) are among the leading causes of lower respiratory tract infections worldwide. We conducted a comparative analysis of the age distribution and spatiotemporal epidemiology of influenza and RSV in Russia using sentinel surveillance data from 2013-14 to 2018-19 in six cities located in the western, central, and eastern regions of the country.MethodsWe calculated the positivity rate for influenza and RSV (by month, season, and overall) in each city, separately for patients seen at the primary and secondary care level (out-patients medical centres housing GP practices and infectious diseases hospitals, respectively). We compared the age distribution of patients infected with the different influenza virus (sub)types and RSV.ResultsA total of 17 551 respiratory specimens were included: the overall positivity rate was 13.5% for influenza and 4.4% for RSV. The A(H1N1)pdm09, A(H3N2) and B virus (sub)types caused 31.3%, 44.0% and, respectively, 24.7% of all influenza cases. The median age was older among influenza (15 years) than among RSV patients (3 years); differences across influenza virus (sub)types were seen only at the primary care level, with influenza A(H3N2) patients being significantly older than A(H1N1)pdm09 or B influenza patients. The timing of influenza epidemics was similar across cities, with the peak typically occurring in February or March. In contrast, the typical peak timing of RSV epidemics varied largely across cities, and the virus was often detected also in spring and summer months (unlike influenza).ConclusionsInfluenza and RSV epidemiology differed in many regards in Russia, especially in the timing of epidemics and the age distribution of infected subjects. Health policies aimed at containing the burden of diseases of viral respiratory infections in Russia should take these findings into account.

Climate change and biocrust disturbance synergistically decreased taxonomic, functional and phylogenetic diversity in annual communities on gypsiferous soils

Rainfall and biocrusts are important sources of temporal and spatial environmental heterogeneity and niche differentiation for annual plants, a major component of diversity in drylands. Therefore, global change processes comprising shifts in rainfall timing and drought exacerbation, together with biocrust disturbance may affect species coexistence and result in disrupted diversity patterns. In this study, we experimentally evaluated the effects of the rainfall amount and timing as well as physical biocrust disturbance and their interaction on the taxonomic, phylogenetic and functional diversity of annual plant communities on gypsum soil drylands. All diversity estimates were determined at different times during community development in each experimental unit (α), as the contribution of each experimental unit to the total diversity in each treatment (β) and as the total diversity in each treatment (γ). Rainfall timings led to changes in all diversity dimensions, with higher diversity under the typical timing. The community was quite resilient to moderate reductions in rainfall, but extreme droughts decreased the alpha and beta taxonomic, functional and phylogenetic diversities. In addition, the simultaneous occurrence of biocrust disturbance and extreme drought led to consistent collapses in all diversity dimensions, probably because the effects of water shortage were exacerbated. Observations of the community at different times during its development highlighted the importance of regenerative strategies for niche differentiation and species coexistence, and their strong dependence on global change drivers. Indeed, our experimental study demonstrated that rainfall patterns and biocrusts are key factors related to the maintenance of diversity in semiarid annual plant communities. In particular, our results highlight the key role of biocrusts in modulating the effects of drought on plant diversity and the need for integrative approaches that consider both plants and biocrusts in order to elucidate the influence of climate change on the diversity of drylands.

A compact and lightweight small animal PET with uniform high-resolution for onboard PET/CT image-guided preclinical radiation oncology research

Objective: In contrast to clinical radiation therapy (RT) that ubiquitously uses PET/CT image to accurately guide RT, all current commercial animal irradiators can only provide CT image-guided preclinical RT that severely limits their capability for preclinical and compatibility for translational radiation oncology research. To address this problem, we have developed a compact and lightweight PET with uniform, high spatial resolution that is suited to be installed inside an existing animal irradiator for potential onboard PET/CT image-guided preclinical RT research. Approach: The design focused on the balance of achieving sufficient imaging performance for practical preclinical RT guidance with constrained size and weight. The detector head consists of a ring of 12 detector panels in a dodecagon configuration and 12 front-end electronics boards that are closely attached to the detector panels. The overall size and weight of the detector head are 33.0 cm diameter, 11.0 cm axial length and ∼6.5 kg weight that can be installed inside an existing irradiator. Each detector panel has a 30 × 30 array of 1 × 1 × 20 mm3 LYSO scintillators with depth-of-interaction (DOI) measurement. The front-end electronics boards process and convert detected signals to digital signals and transfer them to system electronics and data acquisition located outside the irradiator through low-voltage-differential-signaling cables. Main results: The typical energy, DOI and coincidence timing resolutions are around 22.1%, 3.1 mm, and 1.92 ns. The imaging field-of-view (FOV) is 8.0 cm diameter and 3.5 cm axial length. The performance evaluations show a 1.8% sensitivity at the center FOV, uniform ∼1.1 mm resolution within 6 cm diameter FOV, and all rods of 1.0 mm diameter can be clearly resolved from the image of an ultra-micro hot-rods phantom. Significance: Overall, this compact and lightweight PET has demonstrated its designed capability and performance sufficient for providing onboard functional/biological/molecular image to guide the preclinical RT research.