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Abstract We compute in conventional dimensional regularisation the tree-level splitting amplitudes for a gluon parent which splits into four collinear partons. This is part of the universal infrared behaviour of the QCD scattering amplitudes at next-to-next-to-next-to-leading order (N3LO) in the strong coupling constant. Combined with our earlier results for a quark parent, this completes the set of tree-level splitting amplitudes required at this order. We also study iterated collinear limits where a subset of the four collinear partons become themselves collinear.

Abstract We compute in conventional dimensional regularisation the tree-level splitting amplitudes for a quark parent in the limit where four partons become collinear to each other. This is part of the universal infrared behaviour of the QCD scattering amplitudes at next-to-next-to-next-to-leading order (N3LO) in the strong coupling constant. Further, we consider the iterated limit when m ′ massless partons become collinear to each other within a bigger set of m collinear partons, as well as the limits when one gluon or a q q ¯ $$ \overline{q} $$ pair or two gluons become soft within a set of m collinear partons.

The heterogeneous properties of dermal cell populations have been posited to contribute toward fibrotic, imperfect wound healing in mammals. Here we characterize an adult population of dermal fibroblasts that maintain an active Prrx1 enhancer which originally marked mesenchymal limb progenitors. In contrast to their abundance in limb development, postnatal Prrx1 enhancer-positive cells (Prrx1enh+) make up a small subset of adult dermal cells (∼0.2%) and reside mainly within dermal perivascular and hair follicle niches. Lineage tracing of adult Prrx1enh+ cells shows that they remain in their niches and in small numbers over a long period of time. Upon injury however, Prrx1enh+ cells readily migrate into the wound bed and amplify, on average, 16-fold beyond their uninjured numbers. Additionally, following wounding dermal Prrx1enh+ cells are found out of their dermal niches and contribute to subcutaneous tissue. Postnatal Prrx1enh+ cells are uniquely injury-responsive despite being a meager minority in the adult skin.

This protocol is intended for use in 96 well plates (1,200 μl wells) but it can similarly be applied to standard test tubes (Levant, 2007). D2, D3, and D4 dopamine receptors are members of the D2-like class of dopamine receptors. They can be studied using the radioligand [3H]-spiperone, which is an antagonist binding to D2, D3, and D4 receptors with comparable affinity. A competition experiment is usually performed to determine the affinity of a compound for a receptor. If multiple subtypes or states of the receptor are present and the competing compound differentiates them, a competition binding experiment can quantify the relative contribution of the two subtypes or states; while resolution of more than two subtypes or states is theoretically possible, in practical terms it is almost never feasible. Thus, radioligand binding to a receptor is quantified in the presence of various concentrations of the unlabelled compound of interest. The concentration of the radioligand in a competition study should be about 2-3 its Kd value as determined in saturation binding; this will allow a sufficient occupancy of the receptor to obtain a strong signal and at the same time avoid that competition becomes too difficult due to high radioligand concentration. The incubation time and temperature are chosen to allow formation of equilibrium between association and dissociation with the receptor for both radioligand and competitor. Of note, a simple competition experiments does not necessarily prove a competitive nature of the interaction between unlabelled drug and receptor. If the specific radioactivity is low (tritiated) relative to the affinity of the radioligand (< 1 nM), a high assay volume (≥ 1 ml) is required to avoid ligand depletion; this is of particular importance if a receptor source with high expression density is used (e.g. expressed recombinant receptors). The number of required competitor concentrations depends on the goal of the experiment. If only a rough estimate of antagonist potency is required, 1-2 concentration per log increment will be sufficient. However, if it is the aim to test for possible subtypes or states of the receptor, 3-5 concentrations per log increment are needed. If possible, the lowest competitor concentrations in the assays should not cause any detectable inhibition, whereas the highest concentrations should completely abolish specific binding. Each experiment can be divided into different steps such as assay preparation, membrane preparation, incubation, filtration, counting of the samples and data analysis. To minimize experimental error all assays are performed at least in duplicate. Additionally, duplicates of total binding and non-specific binding should be included in the assay; the agent used for the definition of non-specific binding (NSB) should be chemically (different family) and physically (avoid combination of two lipophilic compounds) distinct from the radioligand to avoid artifacts. For discussion of specific benefits of chosen assay conditions see van Wieringen et al., (2013) (copy can be obtained from the author).

This protocol is intended for use in 96 well plates (1,200 μl wells) but it can similarly be applied to standard test tubes (Levant, 2007). D2, D3, and D4 dopamine receptors are members of the D2-like class of dopamine receptors. They can be studied using the radioligand [3H]-spiperone, which is an antagonist binding to D2, D3, and D4 receptors with comparable affinity. A saturation assay can be used to determine the affinity of a radioligand to a receptor (Kd) and to determine the total number of receptors present in the assay (Bmax). If saturation binding experiments are performed in the absence and presence of a fixed concentration of another, not radiolabeled ligand, it can also be determined whether the other ligand acts in a competitive manner. If the specific radioactivity is low (tritiated) relative to the affinity of the radioligand (< 1 nM), a high assay volume (≥ 1 ml) is required to avoid ligand depletion; this is of particular importance if a receptor source with high expression density is used (e.g. expressed recombinant receptors). To obtain reliable estimates of these parameters at least 6 different concentrations of radioligand must be tested, but particularly when a receptor is first detected in a given tissue or cell type a greater number of concentrations are helpful. The incubation time and temperature are chosen to allow formation of equilibrium between association and dissociation with the receptor for both radioligand and competitor. Each experiment can be divided into different steps such as assay preparation, membrane preparation, incubation, filtration, counting of the samples and data analysis. To minimize experimental error all assays are performed at least in duplicate. Radioligand dilutions should be prepared to cover the desired concentration range. Optimally these concentrations should cover both the high range (corresponding to 5-10x Kd and hence saturation of the receptor) and the low range (around Kd), so that both Kd and Bmax can reliably be estimated without undue extrapolation. At each radioligand concentration total and non-specific binding should be determined; the agent used for the definition of non-specific binding (NSB) should be chemically (different family) and physically (avoid combination of two lipophilic compounds) distinct from the radioligand to avoid artifacts. For discussion of specific benefits of chosen assay conditions see van Wieringen et al. (2013) (copy can be obtained from the author).

Food, especially milk, is such a familiar material to all of us that it is easy to overlook the scientific input required to assure the quality of existing milk products and/or to come up with new and better processed dairy foods. A major input comes from the research fields of Colloid and Interface science and Soft Condensed Matter Physics, since it becomes more and more evident that relevant properties of foods, such as texture, taste, color, viscosity, stability, mouth-feel or nutritional functionality, are not simply the result of the presence of the ingredients mixed together during processing, but are also the result of the created three-dimensional structure. Recognizing that food materials can be described as colloidal systems allows food technologists to better control the quality of the end product. In the present work we discuss how colloidal concepts can be used to describe the behavior of milk products. We will consider the colloidal properties of milk characterized by the properties of its colloidal entities, i.e. the fat globules, the casein micelles and the whey protein aggregates.

Purpose: The aim of the study was to investigate the relationship between dividend policy and stock price volatility in the tech industry in France. Methodology: This study adopted a desk methodology. A desk study research design is commonly known as secondary data collection. This is basically collecting data from existing resources preferably because of its low cost advantage as compared to a field research. Our current study looked into already published studies and reports as the data was easily accessed through online journals and libraries. Findings: The relationship between dividend policy and stock price volatility in France's tech industry reveals that high dividend payouts may initially attract investors seeking income but can also increase stock price volatility. This volatility often arises from market reactions to dividend announcements and shifts in investor sentiment about company financial health and growth prospects. Effective management of dividend policies is crucial for tech firms to balance investor expectations with strategic growth initiatives while mitigating market risks. Unique Contribution to Theory, Practice and Policy: Agency theory, signaling theory & market timing theory may be used to anchor future studies on the relationship between dividend policy and stock price volatility in the tech industry in France. Developing dividend policies that balance the need for capital reinvestment in innovation with shareholder expectations for income stability. Tailoring regulatory frameworks to accommodate the unique dynamics of the tech industry, including its rapid growth and innovation cycles. [ABSTRACT FROM AUTHOR]

The influence of water deficits and drought on tree physiological processes, growth, and survival has been the focus of substantial research efforts and debate over the past decades, but there is still a need to quantitatively link finer scale mechanistic explanations of the influence of water status with the physiological responses of trees, particularly for those past the sapling stage. Hence, the objective of this study was to link accumulated water stress during the growing season to leaf physiological response mechanisms of Juglans nigra L. trees. Results showed that trees subjected to higher cumulative water stress had lower maximum light-saturated photosynthesis ([A.sub.max]), initiated net photosynthesis at higher light levels (Ic), and displayed reduced effectiveness of C[O.sub.2] fixation per photons absorbed ([Q.sub.e]) at the bottom and upper positions along the vertical canopy gradient. Results suggest that water stress integral ([S.sub.[psi]]), a variable that takes into account accumulated water deficits, would be useful to help future research efforts aimed at investigating responses to drought in trees past the sapling stage. Key words: climate change, drought, gas exchange, walnut, water stress. L'influence des deficits hydriques et de la secheresse sur les processus physiologiques, la croissance et la survie des arbres a ete le centre d'interet d'importants efforts de recherche et de discussions au cours de la derniere decennie, mais encore faudrait-il relier quantitativement a une echelle plus fine les explications mecanistes de l'influence du statut hydrique aux reactions physiologiques des arbres, particulierement chez ceux qui ont franchi le stade de gaule. Par consequent, l'objectif de cette etude consistait a relier le stress hydrique accumule durant la saison de croissance aux mecanismes de reaction physiologique des feuilles de Juglans nigra L. Les resultats montrent que les arbres soumis a un stress hydrique cumulatif plus eleve avaient un niveau maximum de photosynthese au point de saturation lumineuse ([A.sub.max]) inferieur, atteignaient la photosynthese nette a des niveaux de lumiere plus eleves (Ic) et montraient une efficacite de fixation du C[O.sub.2] par photon absorbe ([Q.sub.e]) reduite dans les positions inferieure et superieure le long d'un gradient vertical dans le couvert forestier. Les resultats indiquent que l'integrale du stress hydrique ([S.sub.[psi]]), une variable qui tient compte des deficits hydriques accumules, serait utile pour assister les futurs efforts de recherche visant a etudier les reactions a la secheresse chez les arbres qui ont franchi le stade de gaule. [Traduit par la Redaction] Mots-cles: changement climatique, secheresse, echange gazeux, noyer, stress hydrique., Introduction The influence of water deficits and drought on tree physiological processes, growth, and survival has been the focus of substantial research efforts and debate over the past decades (e.g., [...]