Total Width Research Articles

Strong decays of the isovector-scalar D*D¯* hadronic molecule

We adopt the effective Lagrangian approach to study the strong decays of the 1−(0++)D*D¯* molecular state [denoted as Tψ0a(4010) according to the LHCb naming convention] through triangle diagrams. The decay channels include the open-charm DD¯, and the hidden-charm ηcπ, J/ψρ, and χc1π. The coupling between the Tψ0a(4010) and its constituents D*D¯* is obtained by solving for the residue of the scattering T-matrix at the pole. Our calculations yield a total width of few tens MeV for the Tψ0a(4010) state using three different form factors, with its main decay channels being ηcπ and χc1π. The X(4100) and X(4050) have similar masses and widths, with both masses being close to the D*D¯* threshold. Additionally, their decay final states are consistent with those of the Tψ0a(4010). Therefore, it is likely that they represent the same state and both potentially correspond to the Tψ0a(4010). We suggest that future experiments focus on searching for the Tψ0a(4010) signal in the final states ηcπ−, χc1π−, and D0D− of the B0→ηcπ−K+, χc1π−K+, and D0D−K+ processes, respectively, as well as further investigating its resonance parameters with Flatté-like formula. Published by the American Physical Society 2024

Application of remote sensing and GIS to understand the spatio-temporal shifting of Bagmati River of Nepal

Geomorphology, hydrological conditions and human activities, alter river morphology and shift channels, causing environmental and socio-economic impacts. River shifting in Nepal is well-documented for large rivers like the Koshi and Karnali, while smaller rivers like the Bagmati have received less attention. This study employs geospatial tools and techniques to understand the morphological changes, quantify the spatio-temporal shifting, and erosion and deposition of the Bagmati River channel in Nepal over a 30-year period (1988–2018). The morphological changes were measured in terms of sinuosity index, river width and water area. The entire river maintained a generally sinuous character throughout the study period. The total average width of the river decreased by more than four times from 1287.17 m to 300.01 m from 1988 to 2018, and the water area also decreased by 6.59 km2 over the same period, reflecting a transition of the river into a narrower channel over the decades. Overall, the Bagmati River channel slightly shifted eastward in the upstream and downstream sections while significantly shifting westward in the midstream section with an annual rate of 9.94 m, 4.83 m and 41.5 m respectively. The annual rate of bank erosion was found to be one-fourth of the deposition (0.72 km2 per year), with the higher erosion and deposition in the east bank and midstream section of the river. This study highlighted the morphological changes, spatio-temporal channel shifting, and erosion and deposition of the Bagmati River located in the floodplain of Tarai region of Nepal.

Improved light-cone harmonic oscillator model for the ϕ -meson longitudinal leading-twist light-cone distribution amplitude and its effects to Ds+→ϕℓ+νℓ

In the present paper, we study the properties of ϕ-meson longitudinal leading-twist light-cone distribution amplitude ϕ2;ϕ∥(x,μ) by starting from a light-cone harmonic oscillator model for its wave function. To fix the input parameters, we derive the first ten order ξ moments of ϕ2;ϕ∥(x,μ) by using the QCD sum rules approach under the background field theory. The curves of ϕ2;ϕ∥(x,μ=2 GeV) tend to be a single-peak behavior, which is consistent with the latest lattice QCD result. To show how the twist-3 light-cone distribution amplitudes (LCDAs) affect the results, we consider two scenarios for the ϕ-meson chiral twist-3 LCDAs ϕ3;ϕ⊥(x) and ψ3;ϕ⊥(x), i.e., the ones using the Wandzura-Wilczek approximation with ϕ2;ϕ∥(x,μ) (S1) and the ones using self-consistent conformal expansion with second-order Gegenbauer moments a2;ϕ2 in this work (S2). As an application, we derive the Ds+→ϕ transition form factors (TFFs) by using the QCD light-cone sum rules. The TFFs at large recoil point for those two scenarios are given separately. As for the two TFF ratios γV and γ2, we obtain γV(S1)=1.755−0.005+0.008, γ2(S1)=0.852−0.133+0.135, γV(S2)=1.723−0.021+0.023, and γ2(S2)=0.785−0.104+0.100. After extrapolating those TFFs to the physically allowable region, we then obtain the transverse, longitudinal, and total decay widths for semileptonic decay Ds+→ϕℓ+νℓ. Then the branching fractions are B(S1)(Ds+→ϕe+νe)=(2.347−0.191+0.342)×10−3, B(S1)(Ds+→ϕμ+νμ)=(2.330−0.190+0.341)×10−3, B(S2)(Ds+→ϕe+νe)=(2.367−0.132+0.256)×10−3, and B(S2)(Ds+→ϕμ+νμ)=(2.349−0.132+0.255)×10−3, which show good agreement with the data issued by the BESIII, CLEO, and Collaborations. We finally calculate Ds+→ϕℓ+νℓ polarization and asymmetry parameters, which can be measured and tested in future experiments. Published by the American Physical Society 2024

Research on Carbon Dioxide Computational Fluid Dynamics Simulation of Urban Green Spaces under Different Vegetation Spatial Layout Morphologies

Urban green spaces (UGSs) are considered an important natural approach for improving urban climatic conditions, promoting sustainable urban development, and advancing the global “Carbon Peak and Carbon Neutrality” targets. Previous studies have found that different vegetation spatial morphologies significantly impact the capacity to obstruct and absorb CO2, but it is not yet well understood which morphology can retain and absorb more CO2. This study takes Nantong Central Park as an example and conducts a CFD (Computational Fluid Dynamics) carbon flow simulation for CO2 under different vegetation spatial morphologies to identify their CO2 retention and absorption effects. First, the carbon sink benefits of elements such as “vegetation, soil, and wetlands” within the park were calculated, and the elements with the highest carbon sink benefits were identified. Then, the park was divided into carbon welcoming zones, carbon flow zones, and carbon shadow zones for carbon flow simulation with the highest carbon sink benefits. The results show that in the carbon welcome area, the one-block long fan-shaped plant community with a spatial density of 40 m thickness can best meet the requirements of absorption and induction of a small amount of carbon dioxide, with the smallest air vortex and uniform distribution of carbon dioxide in the surrounding area. In the carbon flow area, combined with the visual effect, the planting pattern of 6 m spacing herringbone combined with natural structure was adopted, which has a good carbon dioxide blocking and absorption capacity. In the carbon-shaded area, a herringbone planting pattern with a total width of 40 m and a base angle of 60° was chosen, which had the strongest hindrance and absorption capacity. Urban park environment optimization can use Fluent simulation to analyze the flow of carbon dioxide between different elements affected by wind dynamics at the same time. Based on the results, the form, layout, and spatial distance are adjusted and optimized. This study can better guide the spatial layout of vegetation and contribute to the realization of the goal of “carbon peak and carbon neutrality”.

Experimental and numerical investigation of the influence of varying micro-channel width on flow and heat transfer uniformity

This study integrates experimental and numerical methods to investigate the heat transfer and flow characteristics of microchannel heat sinks with varying width distributions. Water is used as the working fluid and laminar flow model is applied for simulation. Specifically, ten different width distribution structures were designed, including uniform-width configurations and nine non-uniform-width structures (I to IX) with progressively refined intermediate channel widths. Numerical simulations were employed to analyze the flow and heat transfer behaviors, and experimental validations were conducted on both the uniform-width structure and structures II, IV, V, VI, and IX. Results indicate that in uniform-width channel structures, the pressure drop and mass flow rate in intermediate channels exceed those in side channels, resulting in uneven temperature distribution at the base. Conversely, refining the intermediate channel widths under constant total width promotes more uniform flow and wall temperature distributions. A Performance Evaluation Criterion for Non-uniform Channels (PECNC) was introduced to identify the optimal structure. Ultimately, structure VI, characterized by continuously refined intermediate widths, emerged as the optimal design for achieving uniform temperature distribution. A mathematical expression for calculating the optimal microchannel width distribution conducive to uniform temperature distribution was also established.

B→Xc(u)ℓν¯ℓγ and determination of nonperturbative parameters

This paper explores the calculation of nonperturbative parameters present in the matrix element of semileptonic inclusive B decays. These are important for the inclusive determination of the Cabbibo-Kobayashi-Maskawa parameters in the Standard Model. We focus on calculating the rate for radiative inclusive decay, B→Xcℓν¯ℓγ, where γ is hard. Both the radiative and nonradiative (B→Xcℓν¯ℓ) modes are found to require the same nonperturbative parameters. We propose forming ratios from B→Xcℓν¯ℓγ and B→Xcℓν¯ℓ widths in different lepton energy ranges. Our results provide an efficient way to unambiguously calculate the nonperturbative parameters, especially when combined with total width calculations of B→Xcℓν¯ℓ. This is shown explicitly by working to O(1/mb) and determining λ1 and λ2. Published by the American Physical Society 2024

Optimization of novel plate acoustic metamaterials and modulation of the low-frequency bandgap

Based on the local resonance mechanism, five new acoustic metamaterial plate structures with low-frequency bandgaps are proposed in this paper. The two new structures obtained by heuristic structural design are capable of suppressing vibrations over a large frequency range in the low-frequency range of 0-400 Hz, which is promising for practical applications. The mechanism of bandgap generation is found to be a shift in the form of local resonance. Among the three original models, model C has the smallest transmission coefficient T min of −154.6. Analysis of the group and phase velocity diagrams reveals that the change in frequency has a great influence on the energy transfer, speed and direction of the wave in the structure. The heuristic structural design allows the mass block of model B1 to undergo angular state changes, which ultimately realizes the regulation of the bandgap position and the total bandgap width within a certain range. It is also found that the variation of the bandgap properties has a certain regularity with the change of the structural parameters.

Damming of streams due to the construction of a highway in the Amazon rainforest favors individual trophic specialization in the fish (Bryconops giacopinii).

In Amazonian streams, damming caused by road construction changes the system's hydrological dynamics and biological communities. We tested whether the degree of specialization in fish (Bryconops giacopinii) individuals is higher in pristine stream environments with intact ecological conditions than in streams dammed due to the construction of a highway in the Amazon rainforest. To achieve this, stomach content data and stable isotopes (δ13C and δ15N) in tissues with varying isotopic incorporation rates (liver, muscle, and caudal fin) were used to assess the variation in consumption of different prey over time. The indices within-individual component (WIC)/total niche width (TNW) and individual specialization were employed to compare the degree of individual specialization between pristine and dammed streams. The condition factor and stomach repletion of sampled individuals were used to infer the intensity of intraspecific competition in the investigated streams. The species B. giacopinii, typically considered a trophic generalist, has been shown to be, in fact, a heterogeneous collection of specialist and generalist individuals. Contrary to our expectations, a higher degree of individual specialization was detected in streams dammed by the highway. In dammed streams, where intraspecific competition was more intense, individuals with narrower niches exhibited poorer body conditions than those with broader niches. This suggests that individuals adopting more restricted diets may have lower fitness, indicating that individual specialization may not necessarily be beneficial for individuals. Our results support the notion that intraspecific competition is an important mechanism underlying individual specialization in natural populations. Our results suggest that environmental characteristics (e.g., resource breadth and predictability) and competition for food resources interact in complex ways to determine the degree of individual specialization in natural populations.

Risky Business: Predator Chemical Cues Mediate Morphological Changes in Freshwater Snails.

Many prey organisms respond to the nonconsumptive effects of predators by altering their physiology, morphology, and behavior. These inducible defenses can create refuges for prey by decreasing the likelihood of consumption by predators. Some prey, as in marine mollusks, have been shown to alter their morphology in response to the presence of size-limited predation. To extend this work, we exposed pointed campeloma snails (Campeloma decisum) to chemical cues from a natural predator, the rusty crayfish (Faxonius rusticus), to better understand how snail morphology changes under the threat of predation. The total force needed to crush shells, total shell length, aperture width, and total weight, along with changes to these 3 body measurements, were recorded for each individual and used to quantify morphological changes as a function of risk. Snails exposed to crayfish chemical cues had shells that required significantly more force to crush their shells than controls (P=0.023). Total shell length was greater in crayfish-exposed snails than in control snails (P=0.012), and snails in the crayfish treatment also showed significantly more change in shell length than control snails (P=0.007). Similarly, aperture width was significantly greater in exposed snails (P=0.011). However, exposed snails exhibited significantly less change in aperture width than controls (P=0.03). Finally, we found that snails exposed to crayfish weighed significantly more than snails in the control (P=0.008). Thus, the results of this study show that morphology of gastropods is altered in the presence of predators, and this may be an antipredator tactic directly related to predation risk.

Predictive Analysis of Crack Growth in Bearings via Neural Networks

Machine learning (ML) and artificial intelligence (AI) have emerged as the most advanced technologies today for solving issues as well as assessing and forecasting occurrences. The use of AI and ML in various organizations seeks to capitalize on the benefits of vast amounts of data based on scientific approaches, notably machine learning, which may identify patterns of decision-making and minimize the need for human intervention. The purpose of this research work is to develop a suitable neural network model, which is a component of AI and ML, to assess and forecast crack propagation in a bearing with a seeded crack. The bearing was continually run for many hours, and data were retrieved at time intervals that might be utilized to forecast crack growth. The variables root mean square (RMS), crest factor, signal-to-noise ratio (SNR), skewness, kurtosis, and Shannon entropy were collected from the continuously running bearing and utilized as input parameters, with the total crack area and crack width regarded as output parameters. Finally, utilizing several methodologies of the Neural Network tool in MATLAB, a realistic ANN model was trained to predict the crack area and crack width. It was observed that the ANN model performed admirably in predicting data with a better degree of accuracy. Through analysis, it was observed that the SNR was the most relevant parameter in anticipating data in bearing crack propagation, with an accuracy rate of 99.2% when evaluated as a single parameter, whereas in multiple parameter analysis, a combination of kurtosis and Shannon entropy gave a 99.39% accuracy rate.

What Degree of Radiological Compression Predicts Cauda Equina Syndrome: A Retrospective Study at a National Tertiary Center

ObjectiveCauda Equina Syndrome (CES) is diagnosed both clinically and radiologically. However, it's unclear if a specific degree of cauda equina compression (CEC) on imaging can confirm the diagnosis. This study aimed to identify an optimal percentage of prolapse to canal ratio (PCR) on MRI that correlates with CEC, facilitating reliable decision-making for CES symptoms. MethodsA single-center retrospective case series analysis was conducted from 2020 to 2021. Sixty-one patients who underwent emergency lumbar discectomy within 48 hours of presentation were included, divided into a CES group and a disc prolapse (DP) group. CES cases were identified using ICD-10 code G83.4. PCR was calculated by dividing the width of the disc herniation by the total width of the spinal canal at the level of the herniation on single mid-sagittal T2 MRI scans, using the IC Measure software on Windows. ResultsCES most frequently occurred at the L4/5 level (37/61). The median PCR in CES cases was 76.19% (66.67 – 85.71), significantly higher than in DP cases, 48.08% (31.33 – 55.56) (p<0.001). A PCR threshold of 40% maximized sensitivity at 100% but had a specificity of 45%. Conversely, a threshold of 75% maximized specificity at 100% with a sensitivity of 50%. The optimal PCR, determined by the Youden index, was 66%, yielding a sensitivity of 75% and specificity of 97%, with an area under the curve (AUC) of 0.923. ConclusionsSimple radiological measurements of PCR can potentially triage CES patients and guide their management. Future studies should correlate PCR with clinical signs and symptoms for a comprehensive assessment.

Mediastinal Shift Index: A Novel Postnatal Measurement of Mediastinal Movement that Predicts Survival in Neonates With Congenital Diaphragmatic Hernia on Extracorporeal Membrane Oxygenation

PurposeMediastinal position varies in neonates with congenital diaphragmatic hernia (CDH), reflecting contralateral shift due to mass effect. We aimed to create and validate a postnatal measurement of mediastinal positioning using chest radiographs in neonates with CDH who require extracorporeal membrane oxygenation. MethodsChart review identified neonates with CDH who required veno-arterial extracorporeal membrane oxygenation between 2017 and 2022. Mediastinal shift index (MSI) is the ratio of the distance between the venous cannula tip and the contralateral chest wall divided by the total width of the contralateral hemithorax. Three raters completed MSI measurements at designated timepoints: after cannulation, post- CDH repair, and immediately before decannulation. Intraclass correlation coefficients (ICC) assessed inter-rater agreement. Initial MSI and observed/expected lung head ratio (O/E LHR) were correlated and compared between survivors and non-survivors. Receiver operative characteristic (ROC) curve analysis evaluated the ability of MSI and O/E LHR to predict survival. Results38 neonates were included. MSI demonstrated excellent agreement (ICC>0.98) amongst raters. Initial MSI and O/E LHR had a moderate positive correlation (Spearman correlation = 0.47, p = 0.014). Initial MSI differed significantly between survivors and non-survivors (0.52 vs. 0.33, p = 0.035) as did O/E LHR (0.36 vs. 0.26, p = 0.036). ROC analysis revealed initial MSI >0.35 was predictive of survival with 73% sensitivity and 70% specificity. ConclusionMediastinal shift index is reliable and predicted survival with a higher specificity than O/E LHR. Future studies will elucidate the role of trending MSI over a patient's course to inform interventions to optimize mediastinal position. Level of Evidence3.

Cerebral Vascular Toxicity after Developmental Exposure to Arsenic (As) and Lead (Pb) Mixtures.

Arsenic (As) and lead (Pb) are environmental pollutants found in common sites linked to similar adverse health effects. This study determined driving factors of neurotoxicity on the developing cerebral vasculature with As and Pb mixture exposures. Cerebral vascular toxicity was evaluated at mixture concentrations of As and Pb representing human exposures levels (10 or 100 parts per billion; ppb; µg/L) in developing zebrafish by assessing behavior, morphology, and gene expression. In the visual motor response assay, hyperactivity was observed in all three outcomes in dark phases in larvae with exposure (1-120 h post fertilization, hpf) to 10 ppb As, 10 ppb Pb, or 10 ppb mix treatment. Time spent moving exhibited hyperactivity in dark phases for 100 ppb As and 100 ppb mix treatment groups only. A decreased brain length and ratio of brain length to total length in the 10 ppb mix group was measured with no alterations in other treatment groups or other endpoints (i.e., total larval length, head length, or head width). Alternatively, measurements of cerebral vasculature in the midbrain and cerebellum uncovered decreased total vascularization at 72 hpf in all treatment groups in the mesencephalon and in all treatment groups, except the 100 ppb Pb and 10 ppb As groups, in the cerebellum. In addition, decreased sprouting and branching occurred in the mesencephalon, while only decreased branching was measured in the cerebellum. The 10 ppb Pb group showed several cerebral vasculature modifications that were aligned with a specific gene expression alteration pattern different from other treatment groups. Additionally, the 100 ppb As group drove gene alterations, along with several other endpoints, for changes observed in the 100 ppb mix treatment group. Perturbations assessed in this study displayed non-linear concentration-responses, which are important to consider in environmental health outcomes for As and Pb neurotoxicity.

Charm physics with overlap fermions on 2+1-flavor domain wall fermion configurations* *Supported in part by the National Key Research and Development Program of China (2020YFA0406400, 2023YFA1606002), the National Natural Science Foundation of China (12075253, 11935017, 12192264, 12293060, 12293065, 12293063, 12070131001), CRC 110 by DFG and NNSFC. Keh-Fei Liu is supported by the U.S. DOE Grant (DE-SC0013065) and DOE Grant (DEAC05-06OR23177),

Decay constants of pseudoscalar mesons D, , and vector mesons , , are determined from the lattice QCD at a lattice spacing fm. For vector mesons, the decay constants defined by tensor currents are given in the scheme at GeV. The calculation is performed on domain wall fermion configurations generated by the RBC-UKQCD collaborations and the overlap fermion action is used for the valence quarks. Comparing the current results with our previous results at a coarser lattice spacing fm provides a better understanding of the discretization error. We obtain with a better precision than our previous result. Combining our MeV with the total width of determined in a recent study gives a branching fraction for leptonic decay.

Semileptonic and nonleptonic decays of in the covariant light-front approach* *This study was partly supported by the National Natural Science Foundation of China (11347030), the Program for Science and Technology Innovation Talents in Universities of Henan Province (14HASTIT037), and the Natural Science Foundation of Henan Province, China (232300420116)

The semileptonic and nonleptonic decays of the b-flavor vector mesons and are investigated within the covariant light-front quark model (CLFQM). By calculating the form factors of the transitions under the CLFQM, with P denoting a pseudoscalar meson, i.e., , we predict and discuss several physical observables, including the branching ratios, polarization fractions , and forward-backward asymmetries . The total widths of the single-photon radiative decay channels for these b-flavor vector mesons are estimated using their partial widths. In these considered decays, one can find that the semileptonic decays and , with being e or , and the nonleptonic channels have the largest branching ratios, which can reach up to the 10-7 order, and are most likely to be accessible at the future high-luminosity LHCb and Belle-II experiments.

The presence of an aberrant anterior tibial artery does not depend on the patient's morphotype.

The aberrant anterior tibial artery (ATA) runs along the posterior surface of the tibial cortex making it, particularly, at risk during high tibial osteotomy (HTO). This study aimed to analyze the prevalence of the ATA according to global morphotype and its anatomical features in consideration of knee surgery. This retrospective study included 1589 knees on magnetic resonance imaging (MRI) studies with long-leg radiographs. The anatomical characteristics of the ATA, its distance in surgical areas at risk and its lumen were defined on MRI. Its presence according to the patient's morphotype (varus, valgus or neutral) was assessed using a χ2 test. The ATA was present in 33 of 1589 knees, resulting in a prevalence of 2.1%. The anteroposterior distance of the ATA to the tibial head was 6.6 ± 2.5 mm at the height of the tibial plateau, 2.7 ± 1.6 mm at the footprint of the posterior cruciate ligament and 1.0 ± 0.6 mm under the top of the fibula (p < 0.01). For these three levels, the ratio between the distance from the ATA to the lateral tibial border and the total tibial width decreases progressively (p < 0.001). The mean lumen area of the ATA was 4.2 ± 2.5 mm2, and the lumen of the popliteal artery was 9.2 ± 3.6 mm2, representing a ratio of 49.4 ± 27.0%. The prevalence of ATA was similar between varus and valgus patients (n.s). The presence of an ATA is rare, found in one out of 50 cases, but can be easily identified on MRI in patients before knee surgery, especially before HTO. The patient's morphotype did not influence its presence, the lumen diameter is highly variable and its clinical impact has yet to be determined. Cross-sectional study. Level 3.

Slip and stress in block-in-matrix shear zones: 2. numerical modelling of a serpentine-filled dilational jog

We use 2-D numerical models to explore slip and stress dynamics in a fault-bound dilational jog, informed by a field example from the Dun Mountain Ophiolite in New Zealand. The jog is hosted in a metre-scale phacoid of massive serpentinite embedded in a “block-in-matrix” creeping serpentinite shear zone. The models show how periodic exceedance of the tensile strength of the contact between the sealed jog and host rock leads to episodic opening and deposition of a new crack-seal band, with a thickness limited by the release of stress around the tips of the stepover-bounding faults. Jog stress release in the model is lower than that predicted from linear elastic fracture mechanics because additional crack opening can occur slowly due to post-failure creep on the bounding faults. For 10 km overburden and constant high fluid pressure, we predict event stress release of ca. 16 MPa and total crack opening of ∼22 μm on either side of the jog, consistent with crack-seal band widths in the field example. Because our models show that total crack width reflects both initial cracking and subsequent creep, we suggest caution when using crack-seal band widths to directly infer stress release in similar shear zone settings.

Correlation between deflection and crack propagation in reinforced concrete beams

An experimental study was conducted to investigate the correlation between crack propagation and deflection of reinforced concrete beams. A four-point loading test was performed on specimens having varying reinforcement ratios and concrete cover thicknesses. Digital image correlation (DIC) and traditional measuring instruments were used to evaluate and compare the deflection and crack width results. The DIC method accurately measured the deflection and single crack width progression. However, the total crack width was overestimated owing to elastic deformation. The experimental data revealed a linear relationship between the sum of the crack widths and the deflection of beams. Curvature idealization was utilized to propose a model that estimates the deflection based on the crack width measurements obtained by using the DIC method for serviceability evaluation. The results of the proposed model were comparable with the experimental results; the maximum error between them was 8.35%. The proposed model simplified the serviceability evaluation for deflection.

Numerical Analysis of Initialization of a Nanosecond-Pulsed Dielectric Barrier Discharge Actuator

In this work a nanosecond-pulsed dielectric barrier discharge actuator is simulated to investigate the plasma and surface charge behavior during the startup phases of a given pulse sequence. A potential of plus/minus 1.2 kV is applied sinusoidally with a total pulse width of 100 ns over five full pulses. These results show that plasma development changes substantially between the first three pulses, where the distribution of free electrons resulting from the previous pulse influences the development of the plasma sheath and hence the downstream extent of the bulk plasma. Between the third and fifth pulses, a negative surface charge region persists at the downstream extent of the plasma, which generates an electron void, thus inhibiting the development of a strongly ionizing plasma sheath. These results show that by five pulses the plasma has reached its maximum extent and that for the purposes of establishing average values the first two pulses should not be considered representative of the longer-term plasma behavior.

Sensitivity of sub-annual grey pine (Pinus sabiniana) stem growth to water supply and demand in central California

Pinus sabiniana (grey pine) is a common associate of Quercus douglasii (blue oak) in the iconic, ecologically-rich, and economically-relevant Mediterranean woodland savannah of California, USA. While there are dozens of Q. douglasii sites in the International Tree-Ring Data Bank, P. sabiniana was conspicuously absent, and little is known about its growth patterns or water relations. Here, we introduce a new tree-ring chronology of P. sabiniana collected in central California and assess climatic drivers of annual and sub-annual growth. Specifically, we examine earlywood, latewood, and total annual ring widths and analyse their relationships with variables related to water supply (precipitation, soil moisture) and water demand (air temperature, potential evaporation rate). Annual and earlywood widths had nearly identical responses to climate, likely because annual widths mostly consisted of earlywood (mean: 88 %). In both cases, growth was strongly and positively associated with water supply and negatively associated with water demand. Soil moisture was, by far, the strongest and most temporally-consistent correlate of P. sabiniana growth: correlations between soil moisture and annual growth were >0.8 for five contiguous 3-month seasons. Other variables were significant, in part, because of their influence on soil moisture. The association between latewood growth and climate was qualitatively similar but weaker and, with the exception of soil moisture, more seasonally localised (precipitation was relevant in winter and early spring and water demand variables were relevant in summer, somewhat later in the season than for total ring width and earlywood). Further, P. sabiniana growth was nearly always more sensitive to soil moisture than growth of either co-located Q. douglasii or P. ponderosa (ponderosa pine) at a neighbouring site, suggesting that it may act as a particularly sensitive harbinger of drought stress in this ecosystem.