Computational modeling of spike generation in serotonergic neurons of the dorsal raphe nucleu

We consider here a single-compartment model of these neurons which is capable of describing many of the known features of spike generation, particularly the slow rhythmic pacemaking activity often observed in these cells in a variety of species. Included in the model are ten kinds of voltage dependent ion channels as well as calcium-dependent potassium current. Calcium dynamics includes buffering and pumping. In sections 3-9, each component is considered in detail and parameters estimated from voltage clamp data where possible. In the next two sections simplified versions of some components are employed to explore the effects of various parameters on spiking, using a systematic approach, ending up with the following eleven components: a fast sodium current $I_{Na}$, a delayed rectifier potassium current $I_{KDR}$, a transient potassium current $I_A$, a low-threshold calcium current $I_T$, two high threshold calcium currents $I_L$ and $I_N$, small and large conductance potassium currents $I_{SK}$ and $I_{BK}$, a hyperpolarization-activated cation current $I_H$, a leak current $I_{Leak}$ and intracellular calcium ion concentration $Ca_i$. Attention is focused on the properties usually associated with these neurons, particularly long duration of action potential, pacemaker-like spiking and the ramp-like return to threshold after a spike. In some cases the membrane potential trajectories display doublets or have kinks or notches as have been reported in some experimental studies. The computed time courses of $I_A$ and $I_T$ during the interspike interval support the generally held view of a competition between them in influencing the frequency of spiking. Spontaneous spiking could be obtained with small changes in a few parameters from their values with driven spiking.Comment: The abstract has been truncate

Attitudes Towards and Satisfaction with Credit Unions in Alberta. A Regression and Scale Analysis.

Credit unions have played an important historical role in the Canadian economy. However, recent changes in the financial, agricultural and agri-food industry are posing great challenges to Credit unions in Western Canada. Much attention has been given to the impact of competitive rates and the environment offered by banks on credit union performance to the neglect of issues relating to member satisfaction and commitment which may be adding to other problems in the credit union sector. Studies by Feinberg (2001), Sibbald, et al (1999), Loser et. al (1999) , Fried, et. al (1999), Karels and McClatchey (1999) and Tokle, and Tokle (2001) among others have identified key issues relating to the competitive financial roles of credit unions in small financial services, in comparative analysis studies as well as merger related issues. However many of these studies have focused on the financial aspects of credit unions, and have not dealt with broader issues of whether or not the public understands the nature of credit unions, why people stop or intend to continue being members of credit unions. A mailed questionnaire, designed to elicit understanding of and attitudes towards credit unions was sent out to 1500 Alberta residents. In spite of the fact that the survey was complex with no reminder notice sent, the response rate was 12%. Analysis was conducted with a series of scale and logit regression analyses based on the Theory of Planned Behaviour (TpB) (Ajzen and Fishbein 1975, 1980 and Ajzen (2001) to elicit respondents´ beliefs, satisfaction and attitudes towards credit unions, and to measure the factors affecting their intention to patronize credit unions. Results indicate 78% of respondents were familiar with and understood the concept of credit unions. The majority (58%) was male, and 71% were aged 45 or older. Respondents who are active members of a credit union generally held positive attitudes towards their credit unions, and 89% rated their credit unions as performing well under a set of six performance categories. Analysis from the logit models found credit unions involvement with the local community and customer service to be the major reasons for credit union patronage. Elicitation of respondents´ intentions to patronize a credit union from the TpB analysis show that among the three attributes (attitude, subjective norm, and perceived behavior control), respondents´ subjective norm (siblings influence) and perceived behavioral control significantly explained patronization intentions. Results suggest that a 22 percentage of the public is unaware of credit unions, a further 30 percentage was once and is no longer a member of a credit union. For the 58% of the population that remain committed to credit union, there are still significant issues around member involvement in decision making, communication and provision of education/training to them.Agricultural Finance,

Cloning, expression, and localization of a rat brain high-affinity glycine transporter

A cDNA clone encoding a glycine transporter has been isolated from rat brain by a combined PCR and plaque-hybridization strategy. mRNA synthesized from this clone (designated GLYT1) directs the expression of sodium-and chloride-dependent, high-affinity uptake of [3H]glycine by Xenopus oocytes. [3H]Glycine transport mediated by clone GLYT1 is blocked by sarcosine but is not blocked by methylaminoisobutyric acid or L-alanine, a substrate specificity similar to that described for a previously identified glycine-uptake system called system Gly. In situ hybridization reveals that GLYT1 is prominently expressed in the cervical spinal cord and brainstem, two regions of the central nervous system where glycine is a putative neurotransmitter. GLYT1 is also strongly expressed in the cerebellum and olfactory bulb and is expressed at lower levels in other brain regions. The open reading frame of the GLYT1 cDNA predicts a protein containing 633 amino acids with a molecular mass of ≈70 kDa. The primary structure and hydropathicity profile of GLYT1 protein reveal that this protein is a member of the sodium- and chloride-dependent superfamily of transporters that utilize neurotransmitters and related substances as substrates

The Stellar Activity - Rotation Relationship

Using a new catalog of 824 solar and late-type stars with X-ray luminosities and rotation periods we have studied the relationship between rotation and stellar activity. From an unbiased subset of this sample the power law slope of the unsaturated regime, $L_X/L_{bol}\propto Ro^\beta$, is fit as $\beta=-2.70\pm0.13$. This is inconsistent with the canonical $\beta=-2$ slope to a confidence of 5$\sigma$ and argues for an interface-type dynamo. Super-saturation is observed for the fastest rotators in our sample and its parametric dependencies are explored. Significant correlations are found with both the corotation radius and the excess polar updraft, the latter theory being supported by other observations. We also present a new X-ray population synthesis model of the mature stellar component of our Galaxy and use it to reproduce deep observations of a high Galactic latitude field. The model, XStar, can be used to test models of stellar spin-down and dynamo decay, as well as for estimating stellar X-ray contamination rates for non-stellar studies.Comment: 4 pages, 4 figures. To appear in the proceedings of Cool Stars 17: 17th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, AN 334, 1-2, Eds Klaus Strassmeier and Mercedes Lopez-Morale

The Green Tray - Nutritional Auditing Service

The Green Tray is a nutritional auditing service that will reduce nutrition-related health problems and their associated costs by connecting educational, business, and health institutions to small, healthy food service providers. The Green Tray is seeking a $250,000 capital investment to enter the$137.8 billion non-commercial food services market. By the end of year 3 of our operations, The Green Tray projects to achieve $3.36 million in net revenue and will be recognized as a leader in institutional nutrition auditing services