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Parallel Shift (parallel + shift)
Selected AbstractsRegional analysis of bedrock stream long profiles: evaluation of Hack's SL form, and formulation and assessment of an alternative (the DS form)EARTH SURFACE PROCESSES AND LANDFORMS, Issue 5 2007Geoff Goldrick Abstract The equilibrium form of the fluvial long profile has been used to elucidate a wide range of aspects of landscape history including tectonic activity in tectonic collision zones, and in continental margin and other intraplate settings, as well as other base-level changes such as due to sealevel fluctuations. The Hack SL form of the long profile, which describes a straight line on a log,normal plot of elevation (normal) versus distance (logarithmic), is the equilibrium long profile form that has been most widely used in such studies; slope,area analysis has also been used in recent years. We show that the SL form is a special case of a more general form of the equilibrium long profile (here called the DS form) that can be derived from the power relationship between stream discharge and downstream distance, and the dependence of stream incision on stream power. The DS form provides a better fit than the SL form to river long profiles in an intraplate setting in southeastern Australia experiencing low rates of denudation and mild surface uplift. We conclude that, if an a priori form of the long profile is to be used for investigations of regional landscape history, the DS form is preferable. In particular, the DS form in principle enables equilibrium steepening due to an increase in channel substrate lithological resistance (parallel shift in the DS plot) to be distinguished from disequilibrium steepening due to long profile rejuvenation (disordered outliers on the DS plot). Slope,area analysis and the slope,distance (DS) approach outlined here are complementary approaches, reflecting the close relationship between downstream distance and downstream catchment area. Copyright © 2006 John Wiley & Sons, Ltd. [source] Molecular analysis of the A322D mutation in the GABAA receptor ,1 -subunit causing juvenile myoclonic epilepsyEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2005Klaus Krampfl Abstract Juvenile myoclonic epilepsy (JME) belongs to the most common forms of hereditary epilepsy, the idiopathic generalized epilepsies. Although the mode of inheritance is usually complex, mutations in single genes have been shown to cause the disease in some families with autosomal dominant inheritance. The first mutation in a multigeneration JME family has been recently found in the ,1 -subunit of the GABAA receptor (GABRA1), predicting the single amino acid substitution A322D. We further characterized the functional consequences of this mutation by coexpressing ,1 -, ,2 - and ,2 -subunits in human embryonic kidney (HEK293) cells. By using an ultrafast application system, mutant receptors have shown reduced macroscopic current amplitudes at saturating GABA concentrations and a highly reduced affinity to GABA compared to the wild-type (WT). Dose,response curves for current amplitudes, activation kinetics, and GABA-dependent desensitization parameters showed a parallel shift towards 30- to 40-fold higher GABA concentrations. Both deactivation and resensitization kinetics were considerably accelerated in mutant channels. In addition, mutant receptors labelled with enhanced green fluorescent protein (EGFP) were not integrated in the cell membrane, in contrast to WT receptors. Therefore, the A322D mutation leads to a severe loss-of-function of the human GABAA receptor by several mechanisms, including reduced surface expression, reduced GABA-sensitivity, and accelerated deactivation. These molecular defects could decrease and shorten the resulting inhibitory postsynaptic currents (IPSCs) in vivo, which can induce a hyperexcitability of the postsynaptic membrane and explain the occurrence of epileptic seizures. [source] Gastrointestinal, selective airways and urinary bladder relaxant effects of Hyoscyamus niger are mediated through dual blockade of muscarinic receptors and Ca2+ channelsFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 1 2008Anwarul Hassan Gilani Abstract This study describes the spasmolytic, antidiarrhoeal, antisecretory, bronchodilatory and urinary bladder relaxant properties of Hyoscyamus niger to rationalize some of its medicinal uses. The crude extract of H. niger seeds (Hn.Cr) caused a complete concentration-dependent relaxation of spontaneous contractions of rabbit jejunum, similar to that caused by verapamil, whereas atropine produced partial inhibition. Hn.Cr inhibited contractions induced by carbachol (1 ,m) and K+ (80 mm) in a pattern similar to that of dicyclomine, but different from verapamil and atropine. Hn.Cr shifted the Ca2+ concentration,response curves to the right, similar to that caused by verapamil and dicyclomine, suggesting a Ca2+ channel-blocking mechanism in addition to an anticholinergic effect. In the guinea-pig ileum, Hn.Cr produced a rightward parallel shift of the acetylcholine curves, followed by a non-parallel shift with suppression of the maximum response at a higher concentration, similar to that caused by dicyclomine, but different from that of verapamil and atropine. Hn.Cr exhibited antidiarrhoeal and antisecretory effects against castor oil-induced diarrhoea and intestinal fluid accumulation in mice. In guinea-pig trachea and rabbit urinary bladder tissues, Hn.Cr caused relaxation of carbachol (1 ,m) and K+ (80 mm) induced contractions at around 10 and 25 times lower concentrations than in gut, respectively, and shifted carbachol curves to the right. Only the organic fractions of the extract had a Ca2+ antagonist effect, whereas both organic and aqueous fractions had anticholinergic effect. A constituent, ,-sitosterol exhibited Ca2+ channel-blocking action. These results suggest that the antispasmodic effect of H. niger is mediated through a combination of anticholinergic and Ca2+ antagonist mechanisms. The relaxant effects of Hn.Cr occur at much lower concentrations in the trachea and bladder. This study offers explanations for the medicinal use of H. niger in treating gastrointestinal and respiratory disorders and bladder hyperactivity. [source] Advertising's effect on the market demand elasticity: A noteAGRIBUSINESS : AN INTERNATIONAL JOURNAL, Issue 2 2004Henry W. Kinnucan Using a simple market model and Frisch's duality relation, this report develops propositions about the relationship between advertising and the market demand elasticity that may prove useful in empirical research. In particular, we find that a parallel shift in a linear demand function always alters the market demand elasticity unless supply is unitary elastic. However, the elasticity change in most cases will be negligible. We also find that curve rotation does not imply that the demand elasticity has changed, and vice versa. Lastly, if the price level affects advertising's ability to shift the market demand curve, it must also be true that advertising affects the demand elasticity. The converse is also true, i.e., if advertising affects the demand elasticity, the price level must affect advertising's ability to shift the demand curve. [JEL citations: Q130, Q170, Q180.] © 2004 Wiley Periodicals, Inc. Agribusiness 20: 181,188, 2004. [source] Ketamine and its preservative, benzethonium chloride, both inhibit human recombinant ,7 and ,4,2 neuronal nicotinic acetylcholine receptors in Xenopus oocytesBRITISH JOURNAL OF PHARMACOLOGY, Issue 4 2001Kristen M Coates Ketamine is a dissociative anaesthetic that is formulated as Ketalar, which contains the preservative benzethonium chloride (BCl). We have studied the effects of pure racemic ketamine, the preservative BCl and the Ketalar mixture on human neuronal nicotinic acetylcholine receptors (nAChRs) composed of the ,7 subunit or ,4 and ,2 subunits expressed in Xenopus laevis oocytes. Ketamine inhibited responses to 1 mM acetylcholine (ACh) in both the human ,7 and ,4,2 nAChRs, with IC50 values of 20 and 50 ,M respectively. Inhibition of the ,7 nAChRs occurred within a clinically relevant concentration range, while inhibition of the ,4,2 nAChR was observed only at higher concentrations. The Ketalar formulation inhibited nAChR function more effectively than was expected given its ketamine concentration. The surprising increased inhibitory potency of Ketalar compared with pure ketamine appeared to be due to the activity of BCl, which inhibited both ,7 (IC50 value of 122 nM) and ,4,2 (IC50 value of 49 nM) nAChRs at concentrations present in the clinical formulation of Ketalar. Ketamine is a noncompetitive inhibitor at both the ,7 and ,4,2 nAChR. In contrast, BCl causes a parallel shift in the ACh dose-response curve at the ,7 nAChR suggesting competitive inhibition. Ketamine causes both voltage-dependent and use-dependent inhibition, only in the ,4,2 nAChR. Since ,7 nAChRs are likely to be inhibited during clinical use of Ketalar, the actions of ketamine and BCl on this receptor subtype may play a role in the profound analgesia, amnesia, immobility and/or autonomic modulation produced by this anaesthetic. British Journal of Pharmacology (2001) 134, 871,879; doi:10.1038/sj.bjp.0704315 [source] Adaptation of soil microbial communities to temperature: comparison of fungi and bacteria in a laboratory experimentGLOBAL CHANGE BIOLOGY, Issue 12 2009GEMA BÁRCENAS-MORENO Abstract Temperature not only has direct effects on microbial activity, but can also affect activity indirectly by changing the temperature dependency of the community. This would result in communities performing better over time in response to increased temperatures. We have for the first time studied the effect of soil temperature (5,50 °C) on the community adaptation of both bacterial (leucine incorporation) and fungal growth (acetate-in-ergosterol incorporation). Growth at different temperatures was estimated after about a month using a short-term assay to avoid confounding the effects of temperature on substrate availability. Before the experiment started, fungal and bacterial growth was optimal around 30 °C. Increasing soil temperature above this resulted in an increase in the optimum for bacterial growth, correlated to soil temperature, with parallel shifts in the total response curve. Below the optimum, soil temperature had only minor effects, although lower temperatures selected for communities growing better at the lowest temperature. Fungi were affected in the same way as bacteria, with large shifts in temperature tolerance at soil temperatures above that of optimum for growth. A simplified technique, only comparing growth at two contrasting temperatures, gave similar results as using a complete temperature curve, allowing for large scale measurements also in field situations with small differences in temperature. [source] Young African American mothers' changing perceptions of their infants during the transition to parenthood,INFANT MENTAL HEALTH JOURNAL, Issue 5 2009Cynthia O. Lashley Although theory and empirical research with middle-class, mostly White women have suggested that motherhood is an important developmental transition for women, rarely have investigations of adolescent motherhood systematically examined developmental change. This study examines one aspect of change during the transition to parenthood: the mother's emerging perception of her infant. During pregnancy and at 4 months' postpartum, 220 urban African American mothers between the ages of 13 and 21 years were asked to describe their infants. Content analysis of their responses and ratings of the affective tone of the responses suggest that there are changes from pregnancy to 4 months after the birth that parallel shifts noted in literature on women going through the transition to motherhood as adults. Between pregnancy and 4 months, there was a decreasing focus on infant health and physical appearance and an increasing focus on infant behavioral achievements and personality characteristics. Of particular importance to mothers was that their infants be "good" babies who were easy to care for and were easily accepted by the family. Mothers imagined physical similarities with their infants during pregnancy and describe aspects of their interaction and emotional bond with their infants at 4 months. Overall, mothers' descriptions of their babies were quite positive, increasingly positive over time, and offered little evidence that for these young African American women the transition to parenthood was problematic. [source] Rethinking Research Ethics in Contemporary Applied Linguistics: The Tension Between Macroethical and Microethical Perspectives in Situated ResearchMODERN LANGUAGE JOURNAL, Issue 4 2008MAGDALENA KUBANYIOVA The prominent current tendency in applied linguistics to situate its theory and research has seen parallel shifts in the type of research methodologies being employed. Increasingly, decontextualized laboratory methodologies are giving way to more holistic approaches, and these, in turn, involve a significant shift in the researchers' roles, relationships, and ethical responsibilities. By providing examples of specific ethical dilemmas that arose in the process of a longitudinal classroom-based research project, I aim to illustrate that adherence to general "macroethical" principles established in professional codes of ethics may be inadequate for ensuring ethical research in the situated era, which warrants the expansion of the ethical lenses and consideration of alternative microethical models. I conclude with a call for developing a more contextualized code of practice that would integrate both perspectives and recognize the ability to reflect on the ethical consequences of research practice as a core competence of applied linguists. [source] | ||||||||||||||||