bluuebunny/crossref_metadata_2025 huggingface dataset:
Motile microtubule crosslinkers require distinct dynamic properties for correct functioning during spindle organization inXenopusegg extract
Authors: Cahu Julie , Surrey Thomas
Published: April 2009

The organization of the microtubule cytoskeleton depends crucially on crosslinking motors that arrange microtubules in space. Kinesin-5 is such an essential motile crosslinker. It is unknown whether its organizing capacity during bipolar spindle formation depends on its characteristic kinetic properties, or whether simply crosslinking combined with any plus-end-directed motility is sufficient for its function in a physiological context. To address this question, we replaced the motor domain of Xenopus Kinesin-5 by motor domains of kinesins belonging to other kinesin subfamilies, without changing the overall architecture of the molecule. This generated novel microtubule crosslinkers with altered kinetic properties. The chimeric crosslinkers mislocalized in spindles and consequently caused spindle collapse into tightly bundled microtubule arrays. This demonstrates that plus-end directionality and microtubule crosslinking are not the only characteristics required for proper functioning of Kinesin-5 during spindle assembly in Xenopus egg extract. Instead, its motor domain properties appear to be fine-tuned for the specific function of this kinesin.
An Algorithm and a Core Set Result for the Weighted Euclidean One-Center Problem
Authors: Kumar Piyush , Yıldırım E. Alper
Published: April 2009

Given a set 𝒜 of m points in n-dimensional space with corresponding positive weights, the weighted Euclidean one-center problem, which is a generalization of the minimum enclosing ball problem, involves the computation of a point c𝒜 ∈ ℝn that minimizes the maximum weighted Euclidean distance from c𝒜 to each point in 𝒜. In this paper, given ϵ > 0, we propose and analyze an algorithm that computes a (1 + ϵ)-approximate solution to the weighted Euclidean one-center problem. Our algorithm explicitly constructs a small subset 𝒳 ⫅ 𝒜, called an ϵ-core set of 𝒜, for which the optimal solution of the corresponding weighted Euclidean one-center problem is a close approximation to that of 𝒜. In addition, we establish that ∣ 𝒳∣ depends only on ϵ and on the ratio of the smallest and largest weights, but is independent of the number of points m and the dimension n. This result subsumes and generalizes the previously known core set results for the minimum enclosing ball problem. Our algorithm computes a (1 + ϵ)-approximate solution to the weighted Euclidean one-center problem for 𝒜 in 𝒪(mn∣𝒳∣) arithmetic operations. Our computational results indicate that the size of the ϵ-core set computed by the algorithm is, in general, significantly smaller than the theoretical worst-case estimate, which contributes to the efficiency of the algorithm, especially for large-scale instances. We shed some light on the possible reasons for this discrepancy between the theoretical estimate and the practical performance.
Effectiveness of Valsartan for Treatment of Hypertension: Patient Profiling and Hierarchical Modeling of Determinants and Outcomes (the Preview Study)
Authors: Niepen Patricia Van Der , Woestenburg Annemie , Brié Heidi , Vancayzeele Stefaan , Macdonald Karen , Denhaerynck Kris , Lee Christopher , Hermans Christine , Abraham Ivo
Published: April 2009

Background

Patient- and clinician-related factors may explain variability in blood pressure (BP) outcomes and the differences between real-world effectiveness and efficacy seen in randomized trials of antihypertensive agents.

Objective

To examine the effectiveness of 90 days of second-line valsartan treatment and identify patient- and physician-level determinants that impact BP outcomes.

Methods

A prospective, multicenter, multilevel pharmacoepidemiologic study was conducted in 3194 hypertensive patients (systolic BP [SBP] ≥140 mm Hg, diastolic BP [DBP] ≥90 mm Hg; for diabetic patients, ≥130 and ≥80 mm Hg, respectively) treated by 504 general practitioners (GPs). Statistical analysis included heuristic data mining, and hierarchical linear and logistic modeling.

Results

With valsartan treatment, mean ± SD SBP decreased from 154.4 ± 15.5 mm Hg to 139.0 ± 12.0 mm Hg and mean DBP decreased from 91.3 ± 9.2 mm Hg to 82.6 ± 7.4 mm Hg. SBP control rates increased from 9.0% to 38.6%, DBP from 25.5% to 65.5%, and combined SBP/DBP from 7.3% to 34.4%. A highly vulnerable cohort (n = 1063;35.4%) of patients was identified. Twenty-four percent of variability in SBP and 25% of variability in DBP at 90 days were attributable to physician-related variables: guideline-compliant BP management, hypertension, practice patterns, hypertensive patient volume, and years in practice. The remaining 76% and 75% of variability in SBP and DBP, respectively, were due to patient factors, notably diabetes and related complications, vulnerability to uncontrolled BP, nonadherence, cardiovascular risk, and age. Simitar factors increased the odds of treatment nonresponse, with diabetes being the single largest determinant of uncontrolled SBP (OR 8.99), DBP (OR 20.35), and combined SBP/DBP (OR = 18.64).

Conclusions

Valsartan is effective and well tolerated in a broad range of patients in whom first-line antihypertensive treatment failed or was not tolerated. Mitigating the impact of BP-elevating variables and optimizing the effect of BP-lowering factors provides therapeutic benefits incremental to valsartan's pharmacologic effect. Improving outcomes in hypertensive patients involves 3 steps: (1) identifying, intuitively rather than formally, patients less likely to achieve BP control; (2) targeting modifiable or manageable patient- and physician-level determinants with BP-elevating or BP-lowering effects; and (3) managing variables that increase the odds and optimizing those that lower the odds of uncontrolled BP.
Kinetics and mechanism of the aminolysis of thioesters and thiocarbonates in solution
Authors: Castro Enrique A.
Published: April 2009

The aminolysis reactions of thioesters and thiocarbonates, in either aqueous solution or in 44 wt % aqueous ethanol at 25 °C, are subjected to a kinetic investigation. The Brønsted-type plots (lgkNvs. amine pKa, wherekNis the nucleophilic rate constant) obtained for these reactions can be grouped in three categories: linear plots with slopes 0.8-1, biphasic plots (two linear portions and a curve in between), and linear plots with slopes 0.4-0.6. The two former plots are attributed to stepwise reactions through a zwitterionic tetrahedral intermediate. The latter plots are associated with a concerted mechanism. The fact that some reactions are stepwise and others concerted depends on the stability of the zwitterionic tetrahedral intermediate. This work shows how the experimental data allows one to assess the mechanism of these reactions. Also discussed are the factors that affect the stability of this intermediate, which in turn determines the pathway followed by the reaction. The factors analyzed in this work are (i) the leaving group of the substrate, (ii) the nature of the amine, (iii) the non-leaving group of the substrate, (iv) the electrophilic group of the substrate (CS vs. CO), and (v) the solvent.
Proton transfers in aromatic systems: How aromatic is the transition state?
Authors: Bernasconi Claude F.
Published: April 2009

The question as to what extent aromaticity in a reactant or product is expressed in the transition state of a reaction has only recently received serious attention. Inasmuch as aromaticity is related to resonance, one might expect that, in a reaction that leads to aromatic products, its development at the transition state should lag behind bond changes as is invariably the case for the development of resonance in reactions that lead to delocalized products. However, recent experimental and computational studies on proton transfers from carbon acids suggest the opposite behavior, i.e., the development of aromaticity at the transition state is more advanced than the proton transfer. The evidence for this claim is based on the determination of intrinsic barriers that show a decrease with increasing aromaticity. According to the Principle of Nonperfect Synchronization (PNS), this decrease in the intrinsic barrier implies a disproportionately large amount of aromatic stabilization of the transition state. Additional evidence for the high degree of transition state aromaticity comes from the calculation of aromaticity indices such as HOMA, NICS, and the Bird Index. Possible reasons why the degree to which aromaticity and resonance are expressed at the transition state is different are discussed.
Steric and electronic effects in SN2 reactions
Authors: Uggerud Einar
Published: April 2009

This article gives an overview of recently published literature on the factors that govern SN2 reactivity. By comparing reactivity in solution with that in the isolated gas phase, it has become possible to dissect the contribution of the solvent from that of the intrinsic molecular properties. This has proven to be an extremely important and fruitful step forward in obtaining key knowledge not available before. The gas-phase studies have made it clear that organic chemists need to revise radically their concepts and ideas about this crucial reaction type. This is particularly true with regard to the commonly used term "steric effect".
Divalent carbon(0) compounds
Authors: Frenking Gernot , Tonner Ralf
Published: April 2009

Quantum chemical studies show that there is a class of carbon compounds with the general formular CL2where the carbon atom retains its four valence electrons as two lone pairs. The C-L bonds come from L → C donor-acceptor interactions where L is a strong σ-donor. Divalent C(0) compounds (carbones) are conceptually different from divalent C(II) compounds (carbenes) and tetravalent carbon compounds, but the bonding situation in a real molecule may be intermediate between the three archetypes. There are molecules like tetraaminoallenes which may be described in terms of two double bonds (R2N)2C=C=C(NR2)2where the extraordinary donor strength of the dicoordinated carbon atom comes only to the fore through the interactions with protons and Lewis acids. They may be considered as "hidden divalent C(0) compounds". The donor strength of divalent C(0) molecules has been investigated by calculations of the binding energies with protons and with main-group Lewis acids and the bond dissociation energies (BDEs) of transition-metal complexes.
Muscarinic Receptors in Perirhinal Cortex Control Trace Conditioning
Authors: Bang Sun Jung , Brown Thomas H.
Published: April 2009

Trace conditioning requires that a transient representation of the conditional stimulus (CS) persists during the time interval between the CS offset and the onset of the unconditional stimulus. According to one hypothesis, this transient CS representation is supported by endogenous activity in “persistent-firing” neurons of perirhinal cortex (PR). By definition, persistent-firing neurons discharge for tens of seconds or minutes after the termination of the original spike-initiating stimulus. This continued spiking does not depend on recurrent circuit activity and can be reliably and completely blocked by muscarinic receptor antagonists. The present study evaluated the role of PR muscarinic receptors in trace fear conditioning. Before conditioning, rats received bilateral intra-PR infusions with either saline or scopolamine, a nonselective muscarinic receptor antagonist. Scopolamine infusions profoundly impaired trace conditioning but had no effect on delay conditioning or context conditioning. The results encourage a more general understanding of muscarinic receptors in PR and they motivate additional tests of the emerging theory that persistent-firing neurons support aspects of transient memory.
Rank-Order-Selective Neurons Form a Temporal Basis Set for the Generation of Motor Sequences
Authors: Salinas Emilio
Published: April 2009

Many behaviors are composed of a series of elementary motor actions that must occur in a specific order, but the neuronal mechanisms by which such motor sequences are generated are poorly understood. In particular, if a sequence consists of a few motor actions, a primate can learn to replicate it from memory after practicing it for just a few trials. How do the motor and premotor areas of the brain assemble motor sequences so fast? The network model presented here reveals part of the solution to this problem. The model is based on experiments showing that, during the performance of motor sequences, some cortical neurons are always activated at specific times, regardless of which motor action is being executed. In the model, a population of such rank-order-selective (ROS) cells drives a layer of downstream motor neurons so that these generate specific movements at different times in different sequences. A key ingredient of the model is that the amplitude of the ROS responses must be modulated by sequence identity. Because of this modulation, which is consistent with experimental reports, the network is able not only to produce multiple sequences accurately but also to learn a new sequence with minimal changes in connectivity. The ROS neurons modulated by sequence identity thus serve as a basis set for constructing arbitrary sequences of motor responses downstream. The underlying mechanism is analogous to the mechanism described in parietal areas for generating coordinate transformations in the spatial domain.
Presynaptic Defects Underlying Impaired Learning and Memory Function in Lipoprotein Lipase-Deficient Mice
Authors: Xian Xunde , Liu Tingting , Yu Jia , Wang Yuhui , Miao Yifei , Zhang Jianjun , Yu Yan , Ross Colin , Karasinska Joanna M. , Hayden Michael R. , Liu George , Chui Dehua
Published: April 2009

Lipoprotein lipase (LPL) is predominantly expressed in adipose and muscle where it plays a crucial role in the metabolism of triglyceride-rich plasma lipoproteins. LPL is also expressed in the brain with highest levels found in the pyramidal cells of the hippocampus, suggesting a possible role for LPL in the regulation of cognitive function. However, very little is currently known about the specific role of LPL in the brain. We have generated a mouse model of LPL deficiency which was rescued from neonatal lethality by somatic gene transfer. These mice show no exogenous and endogenous LPL expression in the brain. To study the role of LPL in learning and memory, the performance of LPL-deficient mice was tested in two cognitive tests. In a water maze test, LPL-deficient mice exhibited increased latency to escape platform and increased mistake frequency. Decreased latency to platform in the step-down inhibitory avoidance test was observed, consistent with impaired learning and memory in these mice. Transmission electron microscopy revealed a significant decrease in the number of presynaptic vesicles in the hippocampus of LPL-deficient mice. The levels of the presynaptic marker synaptophysin were also reduced in the hippocampus, whereas postsynaptic marker postsynaptic density protein 95 levels remained unchanged in LPL-deficient mice. Theses findings indicate that LPL plays an important role in learning and memory function possibly by influencing presynaptic function.
Is That within Reach? fMRI Reveals That the Human Superior Parieto-Occipital Cortex Encodes Objects Reachable by the Hand
Authors: Gallivan Jason P. , Cavina-Pratesi Cristiana , Culham Jody C.
Published: April 2009

Macaque neurophysiology and human neuropsychology results suggest that parietal cortex encodes a unique representation of space within reach of the arm. Here, we used slow event-related functional magnetic resonance imaging (fMRI) to investigate whether human brain areas involved in reaching are more activated by objects within reach versus beyond reach. In experiment 1, graspable objects were placed at three possible locations on a platform: two reachable locations and one beyond reach. On some trials, participants reached to touch or grasp objects at the reachable location; on other trials participants passively viewed objects at one of the three locations. A reach-related area in the superior parieto-occipital cortex (SPOC) was more activated for targets within reach than beyond. In experiment 2, we investigated whether this SPOC response occurred when visual and motor confounds were controlled and whether it was modulated when a tool extended the effective range of the arm. On some trials, participants performed grasping and reaching actions to a reachable object location using either the hand alone or a tool; on other trials, participants passively viewed reachable and unreachable object locations. SPOC was significantly more active for passively viewed objects within reach of the hand versus beyond reach, regardless of whether or not a tool was available. Interestingly, these findings suggest that neural responses within brain areas coding actions (such as SPOC for reaching) may reflect automatic processing of motor affordances (such as reachability with the hand).
Sonic Hedgehog Signaling Controls Thalamic Progenitor Identity and Nuclei Specification in Mice
Authors: Vue Tou Yia , Bluske Krista , Alishahi Amin , Yang Lin Lin , Koyano-Nakagawa Naoko , Novitch Bennett , Nakagawa Yasushi
Published: April 2009

The mammalian thalamus is located in the diencephalon and is composed of dozens of morphologically and functionally distinct nuclei. The majority of these nuclei project axons to the neocortex in unique patterns and play critical roles in sensory, motor, and cognitive functions. It has been assumed that the adult thalamus is derived from neural progenitor cells located within the alar plate of the caudal diencephalon. Nevertheless, how a distinct array of postmitotic thalamic nuclei emerge from this single developmental unit has remained largely unknown. Our recent studies found that these thalamic nuclei are in fact derived from molecularly heterogeneous populations of progenitor cells distributed within at least two distinct progenitor domains in the caudal diencephalon. In this study, we investigated how such molecular heterogeneity is established and maintained during early development of the thalamus and how early signaling mechanisms influence the formation of postmitotic thalamic nuclei. By using mouse genetics andin uteroelectroporation, we provide evidence that Sonic hedgehog (Shh), which is normally expressed in ventral and rostral borders of the embryonic thalamus, plays a crucial role in patterning progenitor domains throughout the thalamus. We also show that increasing or decreasing Shh activity causes dramatic reorganization of postmitotic thalamic nuclei through altering the positional identity of progenitor cells.
Effort-Based Cost–Benefit Valuation and the Human Brain
Authors: Croxson Paula L. , Walton Mark E. , O'Reilly Jill X. , Behrens Timothy E. J. , Rushworth Matthew F. S.
Published: April 2009

In both the wild and the laboratory, animals' preferences for one course of action over another reflect not just reward expectations but also the cost in terms of effort that must be invested in pursuing the course of action. The ventral striatum and dorsal anterior cingulate cortex (ACCd) are implicated in the making of cost–benefit decisions in the rat, but there is little information about how effort costs are processed and influence calculations of expected net value in other mammals including humans. We performed a functional magnetic resonance imaging study to determine whether and where activity in the human brain was available to guide effort-based cost–benefit valuation. Subjects were scanned while they performed a series of effortful actions to obtain secondary reinforcers. At the beginning of each trial, subjects were presented with one of eight different visual cues that they had learned indicated how much effort the course of action would entail and how much reward could be expected at its completion. Cue-locked activity in the ventral striatum and midbrain reflected the net value of the course of action, signaling the expected amount of reward discounted by the amount of effort to be invested. Activity in ACCd also reflected the interaction of both expected reward and effort costs. Posterior orbitofrontal and insular activity, however, only reflected the expected reward magnitude. The ventral striatum and anterior cingulate cortex may be the substrate of effort-based cost–benefit valuation in primates as well as in rats.
Different Subtypes of Striatal Neurons Are Selectively Modulated by Cortical Oscillations
Authors: Sharott Andrew , Moll Christian K. E. , Engler Gerhard , Denker Michael , Grün Sonja , Engel Andreas K.
Published: April 2009

The striatum is the key site for cortical input to the basal ganglia. Cortical input to striatal microcircuits has been previously studied only in the context of one or two types of neurons. Here, we provide the first description of four putative types of striatal neurons (medium spiny, fast spiking, tonically active, and low-threshold spiking) in a single data set by separating extracellular recordings of sorted single spikes recorded under halothane anesthesia using waveform and burst parameters. Under halothane, the electrocorticograms and striatal local field potential displayed spontaneous oscillations at both low (2–9 Hz) and high (35–80 Hz) frequencies. Putative fast spiking interneurons were significantly more likely to phase lock to high-frequency cortical oscillations and displayed significant cross-correlations in this frequency range. These findings suggest that, as in neocortex and hippocampus, the coordinated activity of fast spiking interneurons may specifically be involved in mediating oscillatory synchronization in the striatum.
Ritka lokalizációjú méhen kívüli terhesség – májterhesség eseter
Authors: Jáné Zoltán , Farkasdi József , Jáger László , Kneffel Pál , Koppány Csaba , Márkus Béla , Puskás Tamás
Published: April 2009

Absztrakt

A méhen kívüli terhesség az életet közvetlenül veszélyeztető leggyakoribb kórkép a mindennapi szülészet-nőgyógyászati gyakorlatban. A szerzők egy 28 éves nő esetét mutatják be, aki epigastrialis fájdalom miatt jelentkezett kórházukban. Az elvégzett diagnosztika 16 hetes májterhességet igazolt. A szerzők hangsúlyozzák a méhen kívüli terhesség korai felismerésének és ellátásának fontosságát, melyek fontos szerepet játszanak az anyai mortalitás csökkentésében.
Dynamic compaction of saturated sands and silty sands: results
Authors: Nashed R. , Thevanayagam S. , Martin G. R.
Published: April 2009

Numerical simulations of dynamic compaction of three loose saturated sands and silty sand sites are presented. The theory associated with the numerical model is presented in a companion paper. First, a case history of dynamic compaction in a clean sand site without pre-installed wick drains is considered. Second, a case history involving a sandy silt site with pre-installed wick drains is simulated. Third, a silty sand site without pre-installed wick drains is simulated. In all cases the numerical results for post-improvement cone resistance and standard penetration test (SPT) penetration resistance profiles agree fairly well with observed field data. The results show the effectiveness of pre-installed wick drains for dynamic compaction of saturated silty sands. The numerical simulation tool presented is a valuable tool for feasibility studies of dynamic compaction of saturated sands and silty sands.
A New Retrievable Wire Line Cementing
Authors: Caldwell Blake M. , Briggs George E.
Published: April 2009

This paper describes a new retrievable wire line cementing tool, its field operation, well applications, well conditions, and performance data.

The cementing tool is "run" into a well on an armored electric cable in the same manner as a conventional perforating gun. The tool utilizes gases from the burning of a high energy propellant to expand a rubber packer against either casing or an open hole section. Further expansion of gases shears an aluminum retaining plug from the bottom of the cement container, forcing cement into the desired position. The complete tool with the exception of the small aluminum plug and gun seal is retrieved from the well. Additional cementing"runs" may be made for additional cement fill.

This wire line tool has been used successfully to eliminate bottom-hole water from an open hole section, to squeeze cement either a complete or partial set of perforations, to squeeze leaky casing shoes, to seal leaky bridging plugs, and to seal channels in the annulus.

Introduction

In the past few years with deeper drilling and new well completion techniques, the cementing of oil wells has become a more highly developed operation with specialized equipment and trained personnel.

During primary casing cementing operations, neat cement is placed in the annulus to accomplish any or all of the following:Separate formationsSeal formation for deeper drillingForm a support and protective cement sheath around the casing

Squeeze cementing may be defined as a secondary cementing operation in which cement or other sealing material is forced into an open section or into perforations to obtain a seal or a "shut off" of undesirable fluids or gas.

The quantity of cement usually necessary to actually seal perforations, channels, and voids, or to successfully seal an open hole section has generally been found to be relatively small. It is necessary only to fill the desired channel or perforations with cement, allowing it to harden in position. The problem is to place the cement where it is needed, and with conventional methods, this sometimes requires many times the amount of cement actually needed for sealing.
Mechanical Simulator That Duplicates Behavior Of Sucker Rod Pumping Systems
Authors: Halderson M.H.
Published: April 2009

Introduction

Study of the sucker rod pumping problem shows (1) that the numerous formulas being used to calculate load and stroke in sucker rod pumping systems are not derived from the differential equations that define the behavior of the system,(2) that the formulas being used give sufficiently accurate results only in certain limited portions of the wide range of conditions to which sucker rod pumping systems are applied, and (3) that the sucker rod pumping system is so complicated that the equations which define its behavior cannot be solved mathematically.

Problems like the sucker rod pumping problem have occurred in other fields of engineering. These have been solved by the use of special analog systems or simulators. The objective of this paper is to present the background and details of a mechanical simulator that is being constructed to solve the sucker rod pumping problem.

Sponsor

The simulator for sucker rod pumping systems is being financed by Sucker Rod Pumping Research, Inc., with headquarters in Bartlesville, Okla. This is a nonprofit organization which has the objective of solving the sucker rod pumping problem.

Sucker Rod Pumping Research, Inc., was chartered in the state of Delaware on Jan. 18, 1954. It has a board of directors, consisting of one representative for each member desiring representation, and an Executive Committee that is appointed by the directors. The organization also includes a Technical Advisory Committee with a representative from each member, Within the Technical Advisory Committee is a smaller group called the Operating Committee which handles a large part of the detail work.

Membership in Sucker Rod Pumping Research, Inc., now includes 29 producing and manufacturing companies These are listed in Table I. Membership is open at any time to any interested individual, producing organization, manufacturer, or supplier. There are no penalties for joining late. Those who join after the charter date are required to contribute only what they would have contributed had they been charter members.
Chemical Composition of Residue from Cereal Crops and Cultivars in Dryland Ecosystems
Authors: Stubbs T. L. , Kennedy A. C. , Reisenauer P. E. , Burns J. W.
Published: April 2009

Cropping systems in the dryland farming region of eastern Washington State are dominated by winter and spring wheat (Triticum aestivum L.) and spring barley (Hordeum vulgare L.). Excessive levels of residue may be an obstacle in the adoption of conservation farming systems. Decomposition of cereal crop residues is associated with fiber and nutrient content, and growers have observed differences in decomposition among cultivars; however, little information exists on their residue characteristics. Cultivars of spring barley (SB), spring wheat (SW), and winter wheat (WW) grown at four locations over two crop years were analyzed for neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), C, and N contents, and winter wheat decomposition was tested in a laboratory incubation study. Acid detergent lignin was highest in spring barley (9.9%), and least in winter wheat (9.2%) and hard white spring wheat (9.5%). Fiber components and nutrient content varied by location, precipitation zone, and cultivar. Residue in the drier year of the study had lower NDF, ADF, ADL, C, and C/N ratio. Foot rot (Fusarium spp.)–resistant winter wheat cultivars had higher NDF, ADF, and ADL than susceptible cultivars. Laboratory incubation studies showed decomposition of winter wheat straw in soil was correlated with ADF (R2 > 0.66, P = 0.002) and total N (R2 > 0.67, P = 0.04). Fiber and nutrient characteristics of residue from wheat and barley cultivars currently produced in the Pacific Northwest can be used to predict residue decomposition in cropping systems that conserve soil and water, and enhance build‐up of organic matter.
Simulating Yield Response of Quinoa to Water Availability with AquaCrop
Authors: Geerts Sam , Raes Dirk , Garcia Magali , Miranda Roberto , Cusicanqui Jorge A. , Taboada Cristal , Mendoza Jorge , Huanca Ruben , Mamani Armando , Condori Octavio , Mamani Judith , Morales Bernardo , Osco Victor , Steduto Pasquale
Published: April 2009

The modeling of yield response to water is expected to play an increasingly important role in the optimization of crop water productivity (WP) in agriculture. During 3 yr (2004–2007), field experiments were conducted to assess the crop response to water stress of quinoa (Chenopodium quinoa Willd.) in the Bolivian Altiplano (4000 masl) under different watering conditions (from rain fed, RF, to full irrigation, FI). Crop physiological measurements and comparisons between simulated and observed soil water content (SWC), canopy cover (CC), biomass production, and final seed yield of a selected number of fields were used to calibrate the AquaCrop model. Subsequently, the model was validated for different locations and varieties using data from other experimental fields and from farmers' fields. Additionally, a sensitivity analysis was performed for key input variables of the parameterized model. AquaCrop simulated well the decrease of the harvest index (HI) of quinoa in response to drought during early grain filling as observed in the field. Further‐on, the procedure for triggering early canopy senescence was deactivated in the model as observed in the field. Biomass WP (g m−2) decreased by 9% under fully irrigated conditions compared with RF and deficit irrigation (DI) conditions, most probably due to severe nutrient depletion. Satisfactory results were obtained for the simulation of total biomass and seed yield [validation regression R2 = 0.87 and 0.83, and Nash‐Sutcliff efficiency (EF) = 0.82 and 0.79, respectively]. Sensitivity analysis demonstrated the robustness of the AquaCrop model for simulation of quinoa growth and production, although further improvements of the model for soil nutrient depletion, pests, diseases, and frost are also possible.
AquaCrop—The FAO Crop Model to Simulate Yield Response to Water: I. Concepts and Underlying Principles
Authors: Steduto Pasquale , Hsiao Theodore C. , Raes Dirk , Fereres Elias
Published: April 2009

This article introduces the FAO crop model AquaCrop. It simulates attainable yields of major herbaceous crops as a function of water consumption under rainfed, supplemental, deficit, and full irrigation conditions. The growth engine of AquaCrop is water‐driven, in that transpiration is calculated first and translated into biomass using a conservative, crop‐specific parameter: the biomass water productivity, normalized for atmospheric evaporative demand and air CO2 concentration. The normalization is to make AquaCrop applicable to diverse locations and seasons. Simulations are performed on thermal time, but can be on calendar time, in daily time‐steps. The model uses canopy ground cover instead of leaf area index (LAI) as the basis to calculate transpiration and to separate out soil evaporation from transpiration. Crop yield is calculated as the product of biomass and harvest index (HI). At the start of yield formation period, HI increases linearly with time after a lag phase, until near physiological maturity. Other than for the yield, there is no biomass partitioning into the various organs. Crop responses to water deficits are simulated with four modifiers that are functions of fractional available soil water modulated by evaporative demand, based on the differential sensitivity to water stress of four key plant processes: canopy expansion, stomatal control of transpiration, canopy senescence, and HI. The HI can be modified negatively or positively, depending on stress level, timing, and canopy duration. AquaCrop uses a relatively small number of parameters (explicit and mostly intuitive) and attempts to balance simplicity, accuracy, and robustness. The model is aimed mainly at practitioner‐type end‐users such as those working for extension services, consulting engineers, governmental agencies, nongovernmental organizations, and various kinds of farmers associations. It is also designed to fit the need of economists and policy specialists who use simple models for planning and scenario analysis.
Deficit Irrigation Optimization of Cotton with AquaCrop
Authors: García‐Vila M. , Fereres E. , Mateos L. , Orgaz F. , Steduto P.
Published: April 2009

Given the current pressures to reduce irrigation water use, it is important to optimize the use of water in irrigated agriculture. This work was aimed at determining the optimum level of applied irrigation water (AIW) for cotton (Gossypium hirsutum L.) production in southern Spain under several climatic and agricultural policy scenarios. To generate the yield response to variations in AIW, we used the FAO crop water productivity (WP) model, AquaCrop. Model calibration and validation using four experiments conducted in the region showed that AquaCrop adequately simulated the yield response to AIW. The model was then used to determine the yield–AIW functions for different scenarios, assuming the best deficit irrigation (DI) strategy. An economic optimization procedure showed that maximum profits occurred at AIW values between 540 and 740 mm, depending on the climatic scenario. However, profits stayed close to the maximum (above 95%) for AIW levels exceeding 300–350 mm, indicating that under DI, AIW may be reduced significantly with little impact on profits. A sensitivity analysis suggested that increasing the price of water above the current level will have only a limited impact on optimum AIW, and that the current Common Agricultural Policy (CAP) of the European Union does not encourage water conservation in cotton irrigation. We conclude that AquaCrop is a useful tool to assist managers for making decisions in cotton irrigation under water supply restrictions.
Parameterization and Evaluation of the AquaCrop Model for Full and Deficit Irrigated Cotton
Authors: Farahani Hamid J. , Izzi Gabriella , Oweis Theib Y.
Published: April 2009

Predicting yield is increasingly important to optimize irrigation under limited available water for enhanced sustainability and profitable production. Food and Agriculture Organization (FAO) of the United Nations addresses this need by providing a yield response to water simulation model (AquaCrop) with limited sophistication. In this study, AquaCrop was parameterized and tested for cotton (Gossypium hirsutum L.) under full (100%) and deficit (40, 60, and 80% of full) irrigation regimes in the hot, dry, and windy Mediterranean environment of northern Syria. Model parameterization used the 2006 data and was straightforward within the designed user‐interface, owing to the limited number of key parameters. Accurate simulation of canopy cover was central to sound prediction of evapotranspiration and biomass accumulation. Key user‐input parameters for this purpose were identified as the coefficients defining canopy development and the threshold soil water depletion levels for the water stress indices. The parameterized model was tested using data from the 2004 and 2005 seasons, resulting in accurate prediction of evapotranspiration (<13% error). The predicted yield values were within 10% of measurements, except in the 60 and 80% irrigation regimes in 2004, with errors up to 32%. The model closely predicted the trend in total soil water, but deviation existed for individual soil layers. This study provides first estimate values for cotton parameters useful for future model testing and use. Model parameterization is site‐specific, and thus the applicability of key calibrated parameters must to be tested under different climate, soil, variety, irrigation methods, and field management.
Effects of Estimating Soil Hydraulic Properties and Root Growth Factor on Soil Water Balance and Crop Production
Authors: Ma Liwang , Hoogenboom Gerrit , Saseendran S. A. , Bartling P. N. S. , Ahuja Lajpat R. , Green Timothy R.
Published: April 2009

Accurate simulation of plant growth depends not only on plant parameters, but also on soil parameters. Although there is uncertainty in measured soil parameters and root distributions, their effects on simulated plant growth have been much less studied. This study evaluates the simulated responses of six crops, wheat (Triticum aestivum L.), maize (Zea mays L.), barley (Hordeum vulgare L.), soybean (Glycine max L. Merr.), peanut (Arachis hypogaea L.), and chickpea (Cicer arietinum L.), under various water and N management to different methods of estimating soil hydraulic properties and soil root growth factor (SRGF) in root zone water quality model (RZWQM2) that contains the decision support system for agrotechnology transfer (DSSAT) Version 4.0 plant growth models. The two methods of obtaining the soil water retention curve (SWRC) in RZWQM2 were based on (i) known soil water contents at both 33 and 1500 kPa suctions, or (ii) soil water content at 33 kPa only. The two methods of estimating saturated hydraulic conductivity (Ksat) were (i) soil texture class based average Ksat or (ii) Ksat calculated from effective porosity (difference between soil water contents at saturation and at 33 kPa). For the six crops, simulation results showed that the soil water balance was affected more by Ksat than by SWRC, whereas the simulated crop growth was affected by both Ksat and SWRC. Small variations in the SRGF did not affect soil and crop simulations, and SRGF could be estimated with a simple exponential equation.
Individual Differences in Emotional Clarity and Complex Problem Solving
Authors: Otto Jürgen H. , Lantermann Ernst-Dieter
Published: April 2009

Complex problem solving can be predicted to a fair degree by test intelligence. But if emotions are informative, emotional intelligence scores might increase this prediction even more. Therefore, we assessed problem solving behavior, performance, and mood in a quasi-experimental design with 63 students who varied in emotional clarity and solved problems low or high in complexity. Processing capacity served as a covariate. Results revealed that high clarity participants show more conducive problem-solving behavior with high complex problems and generally reach better performance than low clarity participants. Hierarchical regression analyses revealed that emotional clarity predicts performance independent of and to the same degree as processing capacity. Finally, the ability- and mixed-model conceptions of emotional intelligence are discussed and the relationship between subjective and objective components of intelligence is questioned.
Current Smoking Practices among Jordanian College Students: A Pilot Study
Authors: Madanat Hala N. , Barnes Michael D. , Cole Eugene C. , Wells Parker , Finnigan Charla
Published: April 2009

This pilot study gauges the smoking rates among college students in Jordan, attitudes toward tobacco policies, knowledge of smoking hazards, and identifies methods of quitting for former smokers. The sample ( n = 296) was taken from students attending a General Education course at the University of Jordan. Results show that the majority of respondents (70.3%) had never smoked, 2.8% were former smokers, while 26.9% were current smokers. For former smokers, the main reported reason for quitting was concern for health (63.6%) and the two methods used to quit smoking were: 1) cold turkey (by themselves) (66. 7%); and 2) cut-down smoking and then quit by themselves (33.3%). In addition, a higher level of knowledge related to health effects of tobacco and a higher need for tobacco-related policies was identified by the former/never smokers. Implications for health education are discussed.
The effect of calcium substitution on the afterglow of Eu2+/Dy3+ doped Sr4Al14O25
Authors: Dacyl Danuta , Uhlich Dominik , Jüstel Thomas
Published: April 2009

The effect of calcium substitution on the afterglow of tetrastrontium aluminate phosphors (Sr4Al14O25:Eu2+, Dy3+) was investigated. A series of (Sr1-xCax)O⊎nAl2O3:Eu2+(1%), Dy3+(0.5%), with variation of calcium content (x = 0 − 1), were synthesized by a high temperature solid state reaction in a reducing atmosphere. The photoluminescence, persistent luminescence (afterglow), and lumen equivalents of these materials were studied and compared. It turned out that the afterglow properties of the phosphors were strongly dependent on the Sr/Ca ratio. As the Ca content increased, a phase transition and blue shift in emission spectra were observed.
An Efficient One-Pot Three-Component Synthesis of Fused 1,4-Dihydropyridines Using HY-Zeolit
Authors: Nikpassand Mohammad , Mamaghani Manouchehr , Tabatabaeian Khalil
Published: April 2009

A facile and convenient protocol was developed for the fast (2.5-3.5 h) and high yielding (70-90 %) synthesis of fused 1,4-dihydropyridines from dimedone in the presence of HY-zeolite as an efficient recyclable heterogeneous catalyst.
The Overdose Crisis in the 2024 Election—Political Fights and Practical Problems
Authors: Saloner Brendan
Published: April 2024

This Viewpoint discusses the 2024 presidential election in the context of the addiction and overdose crisis in the US, which has been a unifying challenge and a source of major ideological division in US politics.
State- and Territory-Level Nursing Home and Home Health Care COVID-19 Policies and Disease Burden
Authors: Stone Patricia W. , Zhao Suning , Chastain Ashley M. , Perera Uduwanage G. , Shang Jingjing , Glance Laurent , Dick Andrew W.
Published: April 2024

This cross-sectional study creates a dataset and dashboard of US state- and territory-level COVID-19 policies specific to nursing homes and home health care agencies.
Cold-Induced Reflex Epilepsy
Authors: Li Cathy Meng Fei , Kim David Dongkyung , Mirsattari Seyed M.
Published: April 2024

This case report describes a woman cold-induced reflex seizures.
Maintaining habitat diversity at small scales benefits wild bees and pollination services in mountain apple orchards
Authors: Zanini Sebastiano , Dainese Matteo , Kopf Timo , Leitinger Georg , Tappeiner Ulrike
Published: April 2024

Landscape context influences wild bee abundance and diversity, alongside pollination‐related services. Growing evidence supports the positive effects of landscape heterogeneity on bee diversity and fruit production for pollination‐dependent crops in flatlands. However, little remains known about these relationships in mountainous environments where the landscape matrix surrounding crops is often more complex than in lowlands.

We conducted our study in apple orchards in South Tyrol, an Alpine region in Italy, using pan‐traps, direct observations of visitation frequency and a pollinator exclusion experiment. We investigated the scale‐dependent effects of landscape heterogeneity and other parameters on wild bee assemblages and the related pollination service they provide at five spatial scales (radius 100–2000 m).

We found that landscape heterogeneity positively affected the abundance and richness of wild bees, with the strongest effect at 500 m. We calculated a multidiversity index, reflecting the land‐use intensity based on the species richness of vascular plants, grasshoppers, butterflies, birds and bats. We identified a positive relationship between this multidiversity index and wild bee richness. Additionally, we found that visitation rate of wild bees was negatively affected by crop cover and that abundance of honeybees did not influence wild bee visitation rate or reproductive success. Finally, reproductive success was positively related to semi‐natural habitat cover.

Landscape heterogeneity should be maintained in apple orchards to continue to reap the benefits of vital pollination‐related services. Diversification strategies should be implemented to promote habitat diversity at small scales, even in regions with more than 80% of (semi‐)natural habitats.
Bionic Olfactory Synaptic Transistors for Artificial Neuromotor Pathway Construction and Gas Recognition
Authors: Wu Xiaocheng , Jiang Longlong , Xu Honghuan , Wang Banghu , Yang Lu , Wang Xiaohong , Zheng Lei , Xu Wentao , Qiu Longzhen
Published: April 2024

The superior recognition ability and excitatory–inhibitory balance of the olfactory system has important applications in the efficient recognition, analysis, and processing of data. In this study, transistor synaptic devices are prepared utilizing poly‐diketo‐pyrrolopyrrole‐selenophene polymer (PTDPPSe‐5Si) with excellent electrical properties as the active layer, and dual‐gas pulses are applied for the first time to simulate excitatory and inhibitory behaviors in the olfactory system. Basic synaptic properties are successfully simulated, such as excitatory/inhibitory postsynaptic currents (EPSC/IPSC), and long‐term potentiation/depression (LTP/LTD). The regulation of excitatory–inhibitory balance in biomimetic olfaction is successfully simulated. This working mechanism is attributed to the capture and release of carriers in the channel induced by the gas's electron‐donating and electron‐withdrawing characteristics. The neuromotor pathway is constructed using synaptic devices as the key processing unit, which enables the integration of information from neurons and the output of information from motor neurons. A convolutional neural network is constructed to achieve recognition of eight common laboratory gas types and concentrations with a recognition accuracy of over 97%. The simulated excitatory and inhibitory behaviors exhibited by this device hold significant importance for the development of artificial neural networks, intelligent frameworks, and neural robots.