The matching law

This article introduces the quantitative analysis of choice behavior by describing a number of equations developed over the years to describe the relation between the allocation of behavior under concurrent schedules of reinforcement and the consequences received for alternative responses. Direct proportionality between rate of responding and rate of reinforcement was observed in early studies, suggesting that behavioral output matched environmental input in a mathematical sense. This relation is termed "strict matching," and the equation that describes it is referred to as "the matching law." Later data showed systematic departures from strict matching, and a generalized version of the matching equation is now used to describe such data. This equation, referred to as "the generalized matching equation," also describes data that follow strict matching. It has become convention to refer to either of these equations as "the matching law." Empirical support for the matching law is briefly summarized, as is the applied and practical significance of matching analyses

Electromagnetic properties of the Delta(1232) and decuplet baryons in the self-consistent SU(3) chiral quark-soliton model

We examine the electromagnetic properties of the Delta(1232) resonance within the self-consistent chiral quark-soliton model. In particular we present the Delta form factors of the vector-current GE0, GE2 and GM1 for a momentum-transfer range of $Q^{2} \leq 1GeV^{2}$. We apply the symmetry-conserving quantization of the soliton and take 1/N_c rotational corrections into account. Values for the magnetic moments of all decuplet baryons as well as for the N-Delta transition are given. Special interest is also given to the electric quadrupole moment of the Delta.Comment: 24 pages, 8 figure

CPI motif interaction is necessary for capping protein function in cells

Capping protein (CP) has critical roles in actin assembly in vivo and in vitro. CP binds with high affinity to the barbed end of actin filaments, blocking the addition and loss of actin subunits. Heretofore, models for actin assembly in cells generally assumed that CP is constitutively active, diffusing freely to find and cap barbed ends. However, CP can be regulated by binding of the ‘capping protein interaction' (CPI) motif, found in a diverse and otherwise unrelated set of proteins that decreases, but does not abolish, the actin-capping activity of CP and promotes uncapping in biochemical experiments. Here, we report that CP localization and the ability of CP to function in cells requires interaction with a CPI-motif-containing protein. Our discovery shows that cells target and/or modulate the capping activity of CP via CPI motif interactions in order for CP to localize and function in cells

Quantifying and contextualizing disinfection byproducts during the Flint Water Crisis: a case study, and framework for broader application

Total trihalomethanes (TTHMs) and other disinfection byproducts (DBPs) have been a concern in Flint, Michigan, in both delivered water and water from home water heaters. Historical TTHM data and DBP sampling results from Flint were combined with models for predicting hot water TTHMs to assess the probability of certain DBP concentrations. Results were compared with hot and cold water DBPs from a water system in Florida. Flint results were used to estimate cancer risk resulting from chronic exposure to hot water TTHMs, and compared to similar risk assessments in other water systems. Results indicate TTHM concentrations decreased in Flint following a return to water from the Detroit Water and Sewerage Department, and were very near the mean value for public drinking water systems in the United States. Measurement of other unregulated DBPs also indicated levels within the typical ranges. Monte Carlo simulations coupled with modeling of hot water TTHMs indicated a low probability of TTHMs exceeding 80 μg/L in Flint in 2016. The estimated cancer risk from exposure to TTHMs in Flint is similar to other areas. The methods used in this work can apply broadly to other water systems to de-escalate perceptions of risk following a water crisis

The Mathematics of a Successful Deconvolution: A Quantitative Assessment of Mixture-Based Combinatorial Libraries Screened Against Two Formylpeptide Receptors

In the past 20 years, synthetic combinatorial methods have fundamentally advanced the ability to synthesize and screen large numbers of compounds for drug discovery and basic research. Mixture-based libraries and positional scanning deconvolution combine two approaches for the rapid identification of specific scaffolds and active ligands. Here we present a quantitative assessment of the screening of 32 positional scanning libraries in the identification of highly specific and selective ligands for two formylpeptide receptors. We also compare and contrast two mixture-based library approaches using a mathematical model to facilitate the selection of active scaffolds and libraries to be pursued for further evaluation. The flexibility demonstrated in the differently formatted mixture-based libraries allows for their screening in a wide range of assays

The progestin receptor interactome in the female mouse hypothalamus: Interactions with synaptic proteins are isoform specific and ligand dependent

Progestins bind to the progestin receptor (PR) isoforms, PR-A and PR-B, in brain to influence development, female reproduction, anxiety, and stress. Hormone-activated PRs associate with multiple proteins to form functional complexes. In the present study, proteins from female mouse hypothalamus that associate with PR were isolated using affinity pull-down assays with glutathione S-transferase–tagged mouse PR-A and PR-B. Using complementary proteomics approaches, reverse phase protein array (RPPA) and mass spectrometry, we identified hypothalamic proteins that interact with PR in a ligand-dependent and isoform-specific manner and were confirmed by Western blot. Synaptic proteins, including synapsin-I and synapsin-II, interacted with agonist-bound PR isoforms, suggesting that both isoforms function in synaptic plasticity. In further support, synaptogyrin-III and synapsin-III associated with PR-A and PR-B, respectively. PR also interacted with kinases, including c-Src, mTOR, and MAPK1, confirming phosphorylation as an integral process in rapid effects of PR in the brain. Consistent with a role in transcriptional regulation, PR associated with transcription factors and coactivators in a ligand-specific and isoform-dependent manner. Interestingly, both PR isoforms associated with a key regulator of energy homeostasis, FoxO1, suggesting a novel role for PR in energy metabolism. Because many identified proteins in this PR interactome are synaptic proteins, we tested the hypothesis that progestins function in synaptic plasticity. Indeed, progesterone enhanced synaptic density, by increasing synapsin-I–positive synapses, in rat primary cortical neuronal cultures. This novel combination of RPPA and mass spectrometry allowed identification of PR action in synaptic remodeling and energy homeostasis and reveals unique roles for progestins in brain function and disease

Comparison of axillofemoral and aortofemoral bypass for aortoiliac occlusive disease

AbstractPurpose: A comparison of aortofemoral bypass grafting (AOFBG) and axillofemoral bypass grafting (AXFBG) for occlusive disease performed by the same surgeons during a defined interval forms the basis for this report.Methods: Data regarding all patients who underwent AOFBG or AXFBG for lower-extremity ischemia caused by aortoiliac occlusive disease were prospectively entered into a computerized vascular registry. The decision to perform AOFBG rather than AXFBG was based on assessment of surgical risk and the surgeon's preference. This report describes results for surgical morbidity, mortality, patency, limb salvage, and patient survival for procedures performed from January 1988 through December 1993.Results: We performed 108 AXFBGs and 139 AOFBGs. AXFBG patients were older (mean age, 68 years compared with 58 years for AOFBG, p < 0.001), more often had heart disease (84% compared with 38%, p < 0.001), and more often underwent surgery for limb-salvage indications (80% compared with 42%, p < 0.001). No significant differences were found in operative mortality (AXFBG, 3.4%; AOFBG, <1.0%, p = NS), but major postoperative complications occurred more frequently after AOFBG (AXFBG, 9.2%; AOFBG, 19.4%; p < 0.05). Follow-up ranged from 1 to 83 months (mean, 27 months). Five-year life-table primary patency, limb salvage, and survival rates were 74%, 89%, and 45% for AXFBG and 80%, 79%, and 72% for AOFBG, respectively. Although the patient survival rate was statistically lower with AXFBG, primary patency and limb salvage rates did not differ when compared with AOFBG.Conclusion: When reserved for high-risk patients with limited life expectancy, the patency and limb salvage results of AXFBG are equivalent to those of AOFBG. (J VASC SURG 1996;23:263-71.