Quantities In Response Research Articles

Rigid production networks

This paper studies a production network model with quantity rigidities and informational frictions, where (i) firms may be restricted in how effectively they can adjust (some or all of) their intermediate input quantities in response to changes in the economic environment and (ii) they need to choose their quantities under incomplete information about the realizations of shocks. Our characterization results show that these two frictions lead to a reduction in aggregate output, as firms may find it optimal to rely more heavily on less volatile suppliers, even if it comes at the cost of forgoing more efficient ones. We also find that the interaction between informational frictions and quantity rigidities dampens the impact of productivity and aggregate demand shocks on aggregate output, while increasing the inflationary effects of positive shocks to nominal aggregate demand. The magnitudes of these effects depend on the distribution of the two frictions over the production network.

Hydroxy proline and gamma-aminobutyric acid: markers of susceptibility to vine decline disease caused by the fungus Monosporascus cannonballus in melons (Cucumis melo L.).

Vine decline disease caused by the fungus Monosporascus cannonballus, is a threat to melon production (Cucumis melo L.) worldwide. Nonetheless, little is known about the metabolites produced during the host pathogen interaction. Thus, the objective of this study was to measure quantities of amino acids produced over time during such an interaction. Two melon genotypes named TAM-Uvalde (susceptible) and USDA PI 124104 (resistant) were grown and inoculated with M. cannonballus. The metabolites previously stated were measured before inoculation (0 hours) and 24, 48 and 72 hours after inoculation, using high performance liquid chromatography analysis. The production of some amino acids during the interaction of the resistant and susceptible melon genotypes with the fungus M. cannonballus was different regarding quantities over time. Interestingly, hydroxy proline was always up-regulated in higher quantities in response to pathogen infection in the genotype TAM-Uvalde. Also, the up-regulation in higher quantities of gamma-aminobutyric acid in the genotype TAM-Uvalde 48 and 72 hours after inoculation, suggests more penetration of the pathogen in its roots. Hence, taken together, hydroxy proline and gamma-aminobutyric acid levels could be used as markers of susceptibility to vine decline disease caused by M. cannonballus, which could be useful in developing resistant varieties.

Extracellular Microvesicles Released From Brain Endothelial Cells are Detected in Animal Models Of HIV-1 Signifying Unresolved Inflammation

Treatment of HIV-infected patients with antiretroviral therapy (ART) has effectively suppressed viral replication; however, the central nervous system is still a major target and reservoir of the virus leading to the possible development of HIV-associated neurocognitive disorders (HAND). Furthermore, a hallmark feature of HAND is the disruption of the blood–brain barrier that leads to loss of tight junction protein (TJP) complexes. Extracellular vesicles (EVs), released by every cell type in the body, occur in greater quantities in response to cellular activation or injury. We have found that inflammatory insults activate brain endothelial cells (EC) and induce the release of EVs containing TJPs such as Occludin. We thus hypothesized that HIV infection and unresolved neuroinflammation will result in the release of brain-EC derived EVs. Herein, our results show elevated levels of brain-EC EVs in a humanized mouse model of HIV infection. Furthermore, while ART reduced brain-EC EVs, it was unable to completely resolve increased vesicles detectable in the blood. In addition to inflammatory insults, HIV-1 viral proteins (Tat and gp120) increased the release of Occludin + vesicles from human brain microvasculature ECs. This increase in vesicle release could be prevented by knock-down of the small GTPase ARF6. ARF6 has been shown to regulate EV biogenesis in other cell types, and we provide further evidence for the involvement of ARF6 in brain EC derived EVs. Overall, this study offers insight into the process of brain vascular remodeling (via EVs) in the setting of neuroinflammation and thus provides possibilities for biomarker monitoring and targeting of ARF6.Graphical abstract

Electroactive Silk Fibroin Films for Electrochemically Enhanced Delivery of Drugs

AbstractBiomaterials capable of controlling the delivery of drugs have the potential to treat a variety of conditions. Herein, the preparation of electrically conductive silk fibroin film‐based drug delivery devices is described. Casting aqueous solutions of Bombyx mori silk fibroin, followed by drying and annealing to impart β‐sheets to the silk fibroin, assure that the materials are stable for further processing in water; and the silk fibroin films are rendered conductive by generating an interpenetrating network of a copolymer of pyrrole and 3‐amino‐4‐hydroxybenzenesulfonic acid in the silk fibroin matrix (characterized by a variety of techniques including circular dichroism, Fourier‐transform infrared spectroscopy, nuclear magnetic resonance, Raman spectroscopy, resistance measurements, scanning electron microscopy‐energy dispersive X‐ray spectroscopy, thermogravimetric analysis, X‐ray diffraction, and X‐ray photoelectron spectroscopy). Fibroblasts adhere on the surface of the biomaterials (viability assessed using an (3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide) assay and visualized using a confocal microscope), and a fluorescently labeled drug (Texas‐Red Gentamicin) can be loaded electrochemically and released (µg cm−2 quantities) in response to the application of an electrical stimulus.

Differential ROS Generation in Response to Stress in Symbiodinium spp.

Oxidative stress inside cells occurs when the production of reactive oxygen species (ROS) is no longer efficiently counterbalanced by the generation of antioxidants. In this study, we measured the intracellular production of ROS, including hydrogen peroxide (H2O2), superoxide (O2-), and singlet oxygen (1O2), in cultured dinoflagellates of the genus Symbiodinium under thermal and oxidative stress. ROS tagged with fluorescent probes were measured by flow cytometry. Dissimilar Symbiodinium internal transcribed spacer 2 (ITS2) clades or phylotypes (A1, B2, E, F1) produced ROS in different quantities in response to stress. For example, when comparing the control (26 °C) to the high-temperature treatment (35 °C), Symbiodinium E showed no change in the intracellular concentrations of any of the ROS; but phylotype A1 displayed a 10-fold increase in the overall ROS concentration and a 4-fold increase in O2-. Under oxidative stress, when 8 mmol l-1 H2O2 was added to the cells, these same two Symbiodinium phylotypes increased their overall concentrations of ROS, but only Symbiodinium E showed an increase in the concentrations of O2- (2×) and 1O2 (3×). Therefore, not only were the stress responses of the various Symbiodinium phylotypes different but also the responses of individual phylotypes to thermal and oxidative stress were different in terms of ROS production. Variation in the quality and quantity of ROS generation and its implications for subsequent antioxidant production suggest that different stress mechanisms are at play. While our experiments were done under laboratory conditions that did not necessarily mirror ecological ones, these results provide new insight into processes inside Symbiodinium cells during stress events and add new explanations for a phylotype's susceptibility to stress.

Optimal ordering policies in a multi-sourcing supply chain with supply and demand disruptions-a CVaR approach

In this study, we propose a conditional value at risk (CVaR) model for supply chain disruptions planning of a multi-agent, multi-product supply chain subject to supply and demand disruptions. Our focus is on building and comparing ordering policies under CVaR and expected cost criteria. The proposed formulation is illustrated through some numerical instances. The results present that the CVaR model shows a considerable difference in response policies compared to the expected cost model. Ordering quantities in response to supply and demand disruption are lower in the CVaR model than the expected cost model. In many instances, it is also seen that ordering quantities in response to disruptions tend to become lower when a decision maker becomes more risk-averse. It is expected that the proposed CVaR model would outperform to optimise the supply chain of an organisation, in particular, for the purpose of reducing the risk of high cost.

Do High and Low Inventory Turnover Retailers Respond Differently to Demand Shocks?

This paper examines the differences in the behaviors of high (HIT) and low inventory turnover (LIT) retailers in responding to demand shocks. We identify quantity and price responsiveness as two mediating mechanisms that distinguish how high and low inventory turnover retailers manage demand shocks. Using quarterly firm-level data of 183 U.S. retailers between 1985 and 2012, we find that HIT retailers are able to respond quickly by changing their purchase quantities in response to demand shocks, whereas LIT retailers primarily rely on price changes to manage demand shocks. In addition, we examine the differential implications of these mechanisms on the financial performance of HIT and LIT retailers. We find price responsiveness to be a less effective strategy, compared to quantity responsiveness, in reducing excesses and shortages of inventory. Finally, the negative financial impact of a given amount of excess and shortage of inventory is eight times more severe for LIT retailers compared to HIT retailers.

Reprint of: Price and quantity collars for stabilizing emission allowance prices: Laboratory experiments on the EU ETS market stability reserve

We report on laboratory experiments, with financially motivated participants, comparing alternative proposals for managing the time path of emission allowance prices in the face of random firm-specific and market-level structural shocks. Market outcome measures such as social surplus and price variability are improved by the use of a price collar (auction reserve price and soft price cap). Comparable performance enhancements are not observed with the implementation of a quantity collar that adjusts auction quantities in response to privately held inventories of unused allowances. In some specifications, the quantity collar performed worse than no stabilization policy at all. The experiment implemented a specific set of structural elements, and extrapolation to other settings should be done with caution. Nevertheless, an examination of the observed behavioral patterns and deviations from optimal behavior suggests that a price collar has an important (although perhaps not exclusive) role to play in constructing an effective market stability policy.

Price and Quantity 'Collars' for Stabilizing Emissions Allowance Prices: An Experimental Analysis of the EU ETS Market Stability Reserve

This paper reports the results of a laboratory experiment with financially motivated participants that is used to compare alternative proposals for managing the time path of emissions allowance prices in the face of random firm-specific and market-level structural shocks. In this setting, market performance measures such as social surplus are enhanced by the use of a price collar (auction reserve price and soft price cap). Comparable performance enhancements are not observed with the implementation of a quantity collar that adjusts auction quantities in response to privately held inventories of unused allowances. In fact, in some specifications, the quantity collar performed worse than no stabilization policy at all. The experiment implemented a specific set of structural elements, and extrapolation to other settings should be done with caution. Nevertheless, an examination of the observed behavioral patterns and deviations from optimal behavior suggests that a price collar has an important (although perhaps not exclusive) role to play in constructing an effective market stability reserve policy.

The Aerobic Energy Production and the Lactic Acid Excretion are both Impeded in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Background: In this study the muscle bioenergetic function in response to exercise in severe ME was explored to see if the underlying metabolic problem in ME, responsible for the severe difficulties with trivial and the severe loss of muscle power, could be discovered. Methods: Inorganic phosphate, creatine kinase and lactate were measured in a former Dutch National Field Hockey Champion, who is now a patient bedridden with severe ME, before and 5 minutes after very trivial exercise, from which his muscles needed 12 hours to recover. Results: Inorganic phosphate and creatine kinase were both normal, however, lactate after this trivial exercise was very high, and further testing showed that a second batch of lactic acid was excreted after the same exercise with a 6-fold delay, showing that the lactic acid excretion was impaired and split into two. And this was delayed up to 11- fold by eating closer to the exercise. Conclusion: This study found that in severe ME, both the oxidative phosphorylation and the lactic acid excretion are impaired, and the combination of these two is responsible for the main characteristic of ME, the abnormally delayed muscle recovery after doing trivial things. The muscle recovery is further delayed by immune changes, including intracellular immune dysfunctions, and by lengthened and accentuated oxidative stress, but also by exercise metabolites, which work on the sensitive receptors in the dorsal root ganglions, which in severe ME are chronically inflamed, and are therefore much more sensitive to these metabolites, which are produced in high quantities in response to trivial which for ME patients, due to the underlining metabolic problem, is strenuous exercise. And a similar problem is most likely responsible for the abnormally delayed brain recovery after doing trivial things. This study also shows that the two metabolic problems are the result of an impaired oxygen uptake into the muscle cells or their mitochondria and in combination with the Norwegian Rituximab studies, which suggest that ME is an autoimmune disease, it is suggestive that antibodies are directly or indirectly blocking the oxygen uptake into the muscle cells or their mitochondria.

PQ strategies in monopolistic competition: Some insights from the lab

We present results from 50-rounds experimental markets in which firms decide repeatedly both on price and quantity of a perishable good. The experiment is designed to study the price–quantity setting behavior of subjects acting as firms in monopolistic competition. In the implemented treatments subjects are asked to make both production and pricing decisions given different information sets. We investigate how subjects decide on prices and quantities in response to signals from the firms׳ internal conditions, i.e., individual profits, excess demand, and excess supply, and the market environment, i.e., aggregate price level. We find persistent heterogeneity in individual behavior, with about 46% of market followers, 28% profit-adjusters and 26% demand adjusters. Nevertheless, prices and quantities tend to converge to the monopolistically competitive equilibrium and we find that subjects׳ behavior is well described by learning heuristics.

The implications of microbial and substrate limitation for the fates of carbon in different organic soil horizon types of boreal forest ecosystems: a mechanistically based model analysis

Abstract. The large amount of soil carbon in boreal forest ecosystems has the potential to influence the climate system if released in large quantities in response to warming. Thus, there is a need to better understand and represent the environmental sensitivity of soil carbon decomposition. Most soil carbon decomposition models rely on empirical relationships omitting key biogeochemical mechanisms and their response to climate change is highly uncertain. In this study, we developed a multi-layer microbial explicit soil decomposition model framework for boreal forest ecosystems. A thorough sensitivity analysis was conducted to identify dominating biogeochemical processes and to highlight structural limitations. Our results indicate that substrate availability (limited by soil water diffusion and substrate quality) is likely to be a major constraint on soil decomposition in the fibrous horizon (40–60% of soil organic carbon (SOC) pool size variation), while energy limited microbial activity in the amorphous horizon exerts a predominant control on soil decomposition (>70% of SOC pool size variation). Elevated temperature alleviated the energy constraint of microbial activity most notably in amorphous soils, whereas moisture only exhibited a marginal effect on dissolved substrate supply and microbial activity. Our study highlights the different decomposition properties and underlying mechanisms of soil dynamics between fibrous and amorphous soil horizons. Soil decomposition models should consider explicitly representing different boreal soil horizons and soil–microbial interactions to better characterize biogeochemical processes in boreal forest ecosystems. A more comprehensive representation of critical biogeochemical mechanisms of soil moisture effects may be required to improve the performance of the soil model we analyzed in this study.

Hotspots of the sensitivity of the land surface hydrological cycle to climate change

Due to the shortage of the global observational data of the terrestrial hydrological variables, the understanding of how surface hydrological processes respond to climate change is still limited. In this study, the Community Land Model (CLM4.0) with high resolution atmospheric forcing data is selected to simulate the global surface hydrological quantities during the period 1948–2006 and to investigate the spatial features of these quantities in response to climate change at the regional scales. The sensitivities of evaporation and runoff with respect to the dominant climate change factors (e.g. temperature and precipitation) derived from the concept of climate elasticity are introduced. Results show that evaporation has a declining trend with a rate of 0.7 mm per decade, while runoff shows a weak increasing trend of 0.15 mm per decade over the global land surface. Analyses of the hotspots in the hydrological cycle indicate that the spatial distributions for evaporation and runoff are similar over many areas in central Asia, Australia, and southern South America, but differ largely in high latitudes. It is also found that, the evaporation hotspots in arid regions are mainly associated with the changes in precipitation. Our sensitive analysis suggests that the hydrological quantities show a rather complicated spatial dependency of response of the water cycle to the different climate factors (temperature and precipitation).

Detection of phosphatase activity in aquatic and terrestrial cyanobacterial strains

Cyanobacteria, as highly adaptable microorganisms, are characterized by an ability to survive in different environmental conditions, in which a significant role belongs to their enzymes. Phosphatases are enzymes produced by algae in relatively large quantities in response to a low orthophosphate concentration and their activity is significantly correlated with their primary production. The activity of these enzymes was investigated in 11 cyanobacterial strains in order to determine enzyme synthesis depending on taxonomic and ecological group of cyanobacteria. The study was conducted with 4 terrestrial cyanobacterial strains, which belong to Nostoc and Anabaena genera, and 7 filamentous water cyanobacteria of Nostoc, Oscillatoria, Phormidium and Microcystis genera. The obtained results showed that the activity of acid and alkaline phosphatases strongly depended on cyanobacterial strain and the environment from which the strain originated. Higher activity of alkaline phosphatases, ranging from 3.64 to 85.14 ?molpNP/s/dm3, was recorded in terrestrial strains compared to the studied water strains (1.11-5.96 ?molpNP/s/dm3). The activity of acid phosphatases was higher in most tested water strains (1.67-6.28 ?molpNP/s/dm3) compared to the activity of alkaline phosphatases (1.11-5.96 ?molpNP/s/dm3). Comparing enzyme activity of nitrogen fixing and non-nitrogen fixing cyanobacteria, it was found that most nitrogen fixing strains had a higher activity of alkaline phosphatases. The data obtained in this work indicate that activity of phosphatases is a strain specific property. The results further suggest that synthesis and activity of phosphatases depended on eco-physiological characteristics of the examined cyanobacterial strains. This can be of great importance for the further study of enzymes and mechanisms of their activity as a part of cyanobacterial survival strategy in environments with extreme conditions.

Do High- and Low-Inventory Turnover Retailers Respond Differently to Demand Shocks?

This paper shows the benefits of high inventory turnover in responding to demand shocks. We identify quantity- and price-responsiveness as two mediating mechanisms that distinguish how high- and low-inventory-turnover retailers (HIT and LIT retailers, respectively) can manage demand shocks. Using quarterly firm-level data of 460 U.S. retailers between 1985 and 2009, we find that HIT retailers are able to respond quickly by changing their purchase quantities in response to demand shocks, while LIT retailers primarily rely on price changes to manage demand shocks. We demonstrate the responsiveness of HIT retailers by showing that they can postpone ordering to a later time period compared to LIT retailers, who react to older demand signals. In addition, we examine the differential implications of these mechanisms on the financial performance of HIT and LIT retailers. On average, HIT and LIT retailers appear to be adept at using quantity- and price-responsiveness to avoid excesses and shortages during demand shocks. However, the negative financial impact of excesses and shortages, when they occur, can be 20 times more severe for LIT retailers compared to HIT retailers.

Greenland uplift and regional sea level changes from ICESat observations and GIA modelling

We study the implications of a recently published mass balance of the Greenland ice sheet (GrIS), derived from repeated surface elevation measurements from NASA’s ice cloud and land elevation satellite (ICESat) for the time period between 2003 and 2008. To characterize the effects of this new, high-resolution GrIS mass balance, we study the time-variations of various geophysical quantities in response to the current mass loss. They include vertical uplift and subsidence, geoid height variations, global patterns of sea level change (or fingerprints), and regional sea level variations along the coasts of Greenland. Long-wavelength uplifts and gravity variations in response to current or past ice thickness variations are obtained solving the sea level equation, which accounts for both the elastic and the viscoelastic components of deformation. To capture the short-wavelength components of vertical uplift in response to current ice mass loss, which is not resolved by satellite gravity observations, we have specifically developed a high-resolution regional elastic rebound (ER) model. The elastic component of vertical uplift is combined with estimates of the viscoelastic displacement fields associated with the process of glacial-isostatic adjustment (GIA), according to a set of published ice chronologies and associated mantle rheological profiles. We compare the sensitivity of global positioning system (GPS) observations along the coasts of Greenland to the ongoing ER and GIA. In notable contrast with past reports, we show that vertical velocities obtained by GPS data from five stations with sufficiently long records and from one tide gauge at the GrIS margins can be reconciled with model predictions based on the ICE-5G deglaciation model and the ER associated with the new ICESat-derived mass balance.

Quantitative proteomic analysis of lignocellulolytic enzymes by Phanerochaete chrysosporium on different lignocellulosic biomass

Lignocellulosic biomass from agricultural crop residues and forest waste represents an abundant renewable resource for bioenergy and future biofuel. The current bottleneck of lignocellulosic biofuel production is the hydrolysis of biomass to sugar. To understand the enzymatic hydrolysis of complex biomasses, in this report, lignocellulolytic enzymes secretion by Phanerochaete chrysosporium cultivated in different natural lignocellulosic biomass such as corn stover, hay, sawdust, sugarcane baggase, wheat bran and wood chips were quantitatively analyzed with the iTRAQ technique using LC-MS/MS. A diverse groups of enzymes, including cellulases, glycoside hydrolases, hemicellulases, lignin degrading enzymes, peroxidases, esterases, lipases, chitinases, peptidases, protein translocating transporter and hypothetical proteins were quantified, of which several were novel lignocellulosic biomass hydrolyzing enzymes. The quantitative expression and regulation of lignocellulolytic enzymes by P. chrysosporium were dependent on the nature and complexity of lignocellulosic biomass as well as physical size of the biomass. The iTRAQ data revealed oxidative and hydrolytic lignin degrading mechanism of P. chrysosporium. Numerous proteins presumed to be involved in natural lignocellulosic biomass transformation and degradation were expressed and produced in variable quantities in response to different agricultural and forest wastes.

Expression of human c-reactive protein in different systems and its purification from Leishmania tarentolae

With its homo-pentameric structure and calcium-dependent specificity for phosphocholine (PCh), human c-reactive protein (CRP) is produced by the liver and secreted in elevated quantities in response to inflammation. CRP is widely accepted as a cardiac marker, e.g. in point-of-care diagnostics, however, its heterologous expression has proven difficult. Here, we demonstrate the expression of CRP in different Escherichia coli strains as well as by in vitro transcription/translation. Although expression in these systems was straightforward, most of the protein that accumulated was insoluble. We therefore expanded our study to include the expression of CRP in two eukaryotic hosts, namely the yeast Kluyveromyces lactis and the protozoon Leishmania tarentolae. Both expression systems are optimized for secretion of recombinant proteins and here allowed successful expression of soluble CRP. We also demonstrate the purification of recombinant CRP from Leishmania growth medium; the purification of protein expressed from K. lactis was not successful. Functional and intact CRP pentamer is known to interact with PCh in Ca 2+-dependent manner. In this report we verify the binding specificity of recombinant CRP from L. tarentolae (2 μg/mL culture medium) for PCh.

Ballistic transport, chiral anomaly, and emergence of the neutral electron-hole plasma in graphene

The process of coherent creation of particle - hole excitations by an electric field in graphene is quantitatively described using a dynamic "first quantized" approach. We calculate the evolution of current density, number of pairs and energy in ballistic regime using the tight binding model. The series in electric field strength $E$ up to third order in both DC and AC are calculated. We show how the physics far from the two Dirac points enters various physical quantities in linear response and how it is related to the chiral anomaly. The third harmonic generation and the imaginary part of conductivity are obtained. It is shown that at certain time scale $t_{nl}\propto E^{-1/2}$ the physical behaviour dramatically changes and the perturbation theory breaks down. Beyond the linear response physics is explored using an exact solution of the first quantized equations. While for small electric fields the I-V curve is linear characterized by the universal minimal resistivity $\sigma =\pi /2(e^{2}/h)$%, at $t>t_{nl}$ the conductivity grows fast. The copious pair creation (with rate $E^{3/2}$), analogous to Schwinger's electron - positron pair creation from vacuum in QED, leads to creation of the electron - hole plasma at ballistic times of order $t_{nl}$. This process is terminated by a relaxational recombination.

STUDY OF LUBRICATION CONDITIONS IN SLIPPER-SWASHPLATE CONTACT IN WATER HYDRAULIC AXIAL PISTON PUMP TEST RIG

In water hydraulic systems, requirements for better energy efficiency call for the development of variable displacement axial piston pumps. Most axial piston units utilizing water as pressure medium lack the possibility of adjusting the swash plate tilt angle. because of difficulties in constructing robust water compatible swash plate pivot bearings. Without smooth enough adjustment motion, the lubrication conditions between the swash plate and the piston slipper pads become disturbed and loss of fluid film may lead to early pump failure.This study reports on measurements made with a test rig built for investigating tribological phenomena in variable displacement axial piston pumps. In the tests, the effects of changing the swash plate tilt angle were measured in a test setup with constant high pressure which loaded the piston. Lubricating film thickness and lateral force acting on the piston were measured together with changes in these quantities in response to changes in swash plate tilt angle.