The inactivation of the basolateral nucleus of the rat amygdala has an anxiolytic effect in the elevated T-maze and light/dark transition tests

Pharmacological evidence indicates that the basolateral nucleus of the amygdala (BLA) is involved in the mediation of inhibitory avoidance but not of escape behavior in the elevated T-maze test. These defensive responses have been associated with generalized anxiety disorder (GAD) and panic disorder, respectively. In the present study, we determined whether the BLA plays a differential role in the control of inhibitory avoidance and escape responses in the elevated T-maze. Male Wistar rats (250-280 g, N = 9-10 in each treatment group) were pre-exposed to one of the open arms of the maze for 30 min and 24 h later tested in the model after inactivation of the BLA by a local injection of the GABA A receptor agonist muscimol (8 nmol in 0.2 µL). It has been shown that a prior forced exposure to one of the open arms of the maze, by shortening latencies to withdrawal from the open arm during the test, improves the escape task as a behavioral index of panic. The effects of muscimol in the elevated T-maze were compared to those caused by this GABA agonist in the avoidance reaction generated in the light/dark transition test. This defensive behavior has also been associated with GAD. In the elevated T-maze, intra-BLA injection of muscimol impaired inhibitory avoidance (control: 187.70 ± 14.90 s, muscimol: 37.10 ± 2.63 s), indicating an anxiolytic effect, without interfering with escape performance. The drug also showed an anxiolytic effect in the light/dark transition test as indicated by the increase in the time spent in the lighted compartment (control: 23.50 ± 2.45 s, muscimol: 47.30 ± 4.48 s). The present findings point to involvement of the BLA in the modulation of defensive responses that have been associated with GAD.

Plant-Herbivore Interaction in a Fragmented Landscape: Local Adaptation and Inbreeding

Reciprocal selection between interacting species is a major driver of biodiversity at both the genetic and the species level. This reciprocal selection, or coevolution, has led to the diversification of two highly diverse and abundant groups of organisms, flowering plants and their insect herbivores. In heterogeneous environments, the outcome of coevolved species interactions is influenced by the surrounding community and/or the abiotic environment. The process of adaptation allows species to adapt to their local conditions and to local populations of interacting species. However, adaptation can be disrupted or slowed down by an absence of genetic variation or by increased inbreeding, together with the following inbreeding depression, both of which are common in small and isolated populations that occur in fragmented environments. I studied the interaction between a long-lived plant Vincetoxicum hirundinaria and its specialist herbivore Abrostola asclepiadis in the southwestern archipelago of Finland. I focused on mutual local adaptation of plants and herbivores, which is a demonstration of reciprocal selection between species, a prerequisite for coevolution. I then proceeded to investigate the processes that could potentially hamper local adaptation, or species interaction in general, when the population size is small. I did this by examining how inbreeding of both plants and herbivores affects traits that are important for interaction, as well as among-population variation in the effects of inbreeding. In addition to bi-parental inbreeding, in plants inbreeding can arise from self-fertilization which has important implications for mating system evolution. I found that local adaptation of the plant to its herbivores varied among populations. Local adaptation of the herbivore varied among populations and years, being weaker in populations that were most connected. Inbreeding caused inbreeding depression in both plants and herbivores. In some populations inbreeding depression in herbivore biomass was stronger in herbivores feeding on inbred plants than in those feeding on outbred ones. For plants it was the other way around: inbreeding depression in anti-herbivore resistance decreased when the herbivores were inbred. Underlying some of the among-population variation in the effects of inbreeding is variation in plant phenolic compounds. However, variation in the modification of phenolic compounds in the digestive tract of the herbivore did not explain the inbreeding depression in herbivore biomass. Finally, adult herbivores had a preference for outbred host plants for egg deposition, and herbivore inbreeding had a positive effect on egg survival when the eggs were exposed to predators and parasitoids. These results suggest that plants and herbivores indeed exert reciprocal selection, as demonstrated by the significant local adaptation of V. hirundinaria and A. asclepiadis to one another. The most significant cause of disruption of the local adaptation of herbivore populations was population connectivity, and thus probably gene flow. In plants local adaptation tended to increase with increasing genetic variation. Whether or not inbreeding depression occurred varied according to the life-history stage of the herbivore and/or the plant trait in question. In addition, the effects of inbreeding strongly depended on the population. Taken together, inbreeding modified plant-herbivore interactions at several different levels, and can thus affect the strength of reciprocal selection between species. Thus inbreeding has the potential to affect the outcome of coevolution.

Comparison of pre- versus post-incision administration of intraplantar indomethacin and MK886 in a rat model of postoperative pain

The amplification of pain long after the initial stimulus may be avoided if the treatment of pain is introduced before its initiation. However, conflicting evidence exists about the efficacy of such preemptive analgesia for the management of postoperative pain. This study compares the efficacy of intraplantar administration of indomethacin (a non-selective inhibitor of cyclooxygenase) and MK886 (an inhibitor of 5-lipoxygenase-activating protein), separately or in combination to produce preemptive analgesia in a model of surgical incisional pain in male Wistar rats. All incised rats (5 to 6 rats per group) had allodynia at 2, 6, and 24 h after surgery as evaluated using von Frey filaments. MK886, but not indomethacin (50 to 200 µg/paw), reduced the allodynia when injected either 1 h before or 1 h after surgery. The effect of preoperative MK886 (160 µg/paw) against incisional allodynia had a magnitude apparently similar to that produced by postoperative MK886. Pre-, but not postoperative MK886 (80 µg/paw) reduced the allodynia but the effect was seen only at 6 h after surgery. In contrast, MK886 (40 µg/paw) intensified the allodynia observed 2 h after the incision either injected before or after surgery. MK886 or indomethacin alone did not provide preemptive analgesia in the model of incisional pain. In contrast, the combination of MK886 with indomethacin reduced the allodynia more effectively when used before than after surgery, thus fulfilling the criteria for preemptive analgesia. In conclusion, preoperative inhibition of the local generation of both prostaglandins and leukotrienes by surgical incision may be an alternative to provide preemptive analgesia.

Antinociception synergy between the peripheral and spinal sites of the heme oxygenase-carbon monoxide pathway

We have shown that the peripheral and spinal cord heme oxygenase (HO)-carbon monoxide (CO)-soluble guanylate cyclase-cGMP pathways play an important role in antinociception in the rat experimental formalin model. Our objective was to determine if there is synergism between peripheral (paw) and spinal HO-CO pathways in nociception. Rats were handled and adapted to the experimental environment for a few days before the formalin test, in which 50 µL of a 1% formalin was injected subcutaneously into the dorsal surface of the right hind paw. The animals were then observed for 1 h and the frequency of flinching behavior was taken to represent the nociceptive response. Thirty minutes before the test, rats were pretreated with intrathecal injections of the HO inhibitor, zinc deuteroporphyrin 2,4-bis glycol (ZnDPBG) or heme-lysinate, which is a substrate of the HO pathway. The paw treatments took place 20 min before the test. Low doses of ZnDPBG did not increase nociception, while a low heme-lysinate dose did not change flinching behavior after paw or spinal injections. Combined subactive spinal (50 nmol) and peripheral (40 nmol) low doses of ZnDPBG induced hypernociception (increase of 80% in the first and 25% in the second phase flinching), whereas combined spinal-peripheral heme-lysinate (50 and 30 nmol) led to second phase antinociception (40% reduction in flinching). These findings suggest a synergy between the peripheral and spinal HO-CO pathways. Local activation of the HO system probably regulates the nociception initiation in peripheral tissue and participates in buffering the emerging nociceptive signals at the peripheral and spinal sites of action. In short, an antinociceptive synergy exists between peripheral and spinal HO pathways, which may reduce the doses required and side effects.

Hypertensive effects of the iv administration of picomoles of ouabain

Ouabain, an endogenous digitalis compound, has been detected in nanomolar concentrations in the plasma of several mammals and is associated with the development of hypertension. In addition, plasma ouabain is increased in several hypertension models, and the acute or chronic administration of ouabain increases blood pressure in rodents. These results suggest a possible association between ouabain and the genesis or development and maintenance of arterial hypertension. One explanation for this association is that ouabain binds to the α-subunit of the Na+ pump, inhibiting its activity. Inhibition of this pump increases intracellular Na+, which reduces the activity of the sarcolemmal Na+/Ca2+ exchanger and thereby reduces Ca2+ extrusion. Consequently, intracellular Ca2+ increases and is taken up by the sarcoplasmic reticulum, which, upon activation, releases more calcium and increases the vascular smooth muscle tone. In fact, acute treatment with ouabain enhances the vascular reactivity to vasopressor agents, increases the release of norepinephrine from the perivascular adrenergic nerve endings and promotes increases in the activity of endothelial angiotensin-converting enzyme and the local synthesis of angiotensin II in the tail vascular bed. Additionally, the hypertension induced by ouabain has been associated with central mechanisms that increase sympathetic tone, subsequent to the activation of the cerebral renin-angiotensin system. Thus, the association with peripheral mechanisms and central mechanisms, mainly involving the renin-angiotensin system, may contribute to the acute effects of ouabain-induced elevation of arterial blood pressure.

Contrasting effects of nitric oxide and corticotropin- releasing factor within the dorsal periaqueductal gray on defensive behavior and nociception in mice

The anxiogenic and antinociceptive effects produced by glutamate N-methyl-D-aspartate receptor activation within the dorsal periaqueductal gray (dPAG) matter have been related to nitric oxide (NO) production, since injection of NO synthase (NOS) inhibitors reverses these effects. dPAG corticotropin-releasing factor receptor (CRFr) activation also induces anxiety-like behavior and antinociception, which, in turn, are selectively blocked by local infusion of the CRF type 1 receptor (CRFr1) antagonist, NBI 27914 [5-chloro-4-(N-(cyclopropyl)methyl-N-propylamino)-2-methyl-6-(2,4,6-trichlorophenyl)aminopyridine]. Here, we determined whether i) the blockade of the dPAG by CRFr1 attenuates the anxiogenic/antinociceptive effects induced by local infusion of the NO donor, NOC-9 [6-(2-hydroxy-1-methyl-2-nitrosohydrazino)-N-methyl-1-hexanamine], and ii) the anxiogenic/antinociceptive effects induced by intra-dPAG CRF are prevented by local infusion of Nω-propyl-L-arginine (NPLA), a neuronal NOS inhibitor, in mice. Male Swiss mice (12 weeks old, 25-35 g, N = 8-14/group) were stereotaxically implanted with a 7-mm cannula aimed at the dPAG. Intra-dPAG NOC-9 (75 nmol) produced defensive-like behavior (jumping and running) and antinociception (assessed by the formalin test). Both effects were reversed by prior local infusion of NBI 27914 (2 nmol). Conversely, intra-dPAG NPLA (0.4 nmol) did not modify the anxiogenic/antinociceptive effects of CRF (150 pmol). These results suggest that CRFr1 plays an important role in the defensive behavior and antinociception produced by NO within the dPAG. In contrast, the anxiogenic and antinociceptive effects produced by intra-dPAG CRF are not related to NO synthesis in this limbic midbrain structure.

Effect of physical training on liver expression of activin A and follistatin in a nonalcoholic fatty liver disease model in rats

Nonalcoholic fatty liver disease (NAFLD) is characterized by fat accumulation in the liver and is associated with obesity and insulin resistance. Activin A is a member of the transforming growth factor beta (TGF)-β superfamily and inhibits hepatocyte growth. Follistatin antagonizes the biological actions of activin. Exercise is an important therapeutic strategy to reduce the metabolic effects of obesity. We evaluated the pattern of activin A and follistatin liver expression in obese rats subjected to swimming exercise. Control rats (C) and high-fat (HF) diet-fed rats were randomly assigned to a swimming training group (C-Swim and HF-Swim) or a sedentary group (C-Sed and HF-Sed). Activin βA subunit mRNA expression was significantly higher in HF-Swim than in HF-Sed rats. Follistatin mRNA expression was significantly lower in C-Swim and HF-Swim than in either C-Sed or HF-Sed animals. There was no evidence of steatosis or inflammation in C rats. In contrast, in HF animals the severity of steatosis ranged from grade 1 to grade 3. The extent of liver parenchyma damage was less in HF-Swim animals, with the severity of steatosis ranging from grade 0 to grade 1. These data showed that exercise may reduce the deleterious effects of a high-fat diet on the liver, suggesting that the local expression of activin-follistatin may be involved.

Thick Section Laser Beam Welding of Structural Steels: Methods for Improving Welding Efficiency

Laser beam welding (LBW) is applicable for a wide range of industrial sectors and has a history of fifty years. However, it is considered an unusual method with applications typically limited to welding of thin sheet metal. With a new generation of high power lasers there has been a renewed interest in thick section LBW (also known as keyhole laser welding). There was a growing body of publications during 2001-2011 that indicates an increasing interest in laser welding for many industrial applications, and in last ten years, an increasing number of studies have examined the ways to increase the efficiency of the process. Expanding the thickness range and efficiency of LBW makes the process a possibility for industrial applications dealing with thick metal welding: shipbuilding, offshore structures, pipelines, power plants and other industries. The advantages provided by LBW, such as high process speed, high productivity, and low heat input, may revolutionize these industries and significantly reduce the process costs. The research to date has focused on either increasing the efficiency via optimizing process parameters, or on the process fundamentals, rather than on process and workpiece modifications. The argument of this thesis is that the efficiency of the laser beam process can be increased in a straightforward way in the workshop conditions. Throughout this dissertation, the term “efficiency” is used to refer to welding process efficiency, specifically, an increase in efficiency refers an increase in weld’s penetration depth without increasing laser power level or decreasing welding speed. These methods are: modifications of the workpiece – edge surface roughness and air gap between the joining plates; modification of the ambient conditions – local reduction of the pressure in the welding zone; modification of the welding process – preheating of the welding zone. Approaches to improve the efficiency are analyzed and compared both separately and combined. These experimentally proven methods confirm previous findings and contribute additional evidence which expand the opportunities for laser beam welding applications. The focus of this research was primarily on the effects of edge surface roughness preparation and pre-set air gap between the plates on weld quality and penetration depth. To date, there has been no reliable evidence that such modifications of the workpiece give a positive effect on the welding efficiency. Other methods were tested in combination with the two methods mentioned above. The most promising - combining with reduced pressure method - resulted in at least 100% increase in efficiency. The results of this thesis support the idea that joining those methods in one modified process will provide the modern engineering with a sufficient tool for many novel applications with potential benefits to a range of industries.

Effects of Fin Parameters on Gas-Side Heat Transfer Performance of H-Type Finned Tube Bundle in a Waste Heat Recovery Boiler

Alfa Laval Aalborg Oy designs and manufactures waste heat recovery systems utilizing extended surfaces. The waste heat recovery boiler considered in this thesis is a water-tube boiler where exhaust gas is used as the convective heat transfer medium and water or steam flowing inside the tubes is subject to cross-flow. This thesis aims to contribute to the design of waste heat recovery boiler unit by developing a numerical model of the H-type finned tube bundle currently used by Alfa Laval Aalborg Oy to evaluate the gas-side heat transfer performance. The main objective is to identify weaknesses and potential areas of development in the current H-type finned tube design. In addition, numerical simulations for a total of 15 cases with varying geometric parameters are conducted to investigate the heat transfer and pressure drop performance dependent on H-type fin geometry. The investigated geometric parameters include fin width and height, fin spacing, and fin thickness. Comparison between single and double tube type configuration is also conducted. Based on the simulation results, the local heat transfer and flow behaviour of the H-type finned tube is presented including boundary layer development between the fins, the formation of recirculation zone behind the tubes, and the local variations of flow velocity and temperature within the tube bundle and on the fin surface. Moreover, an evaluation of the effects of various fin parameters on heat transfer and pressure drop performance of H-type finned tube bundle has been provided. It was concluded that from the studied parameters fin spacing and fin width had the most significant effect on tube bundle performance and the effect of fin thickness was the least important. Furthermore, the results suggested that the heat transfer performance would increase due to enhanced turbulence if the current double tube configuration is replaced with single tube configuration, but further investigation and experimental measurements are required in order to validate the results.

Hypercalcemia and acute kidney injury caused by abuse of a parenteral veterinary compound containing vitamins A, D, and E

A previously healthy 19 year-old male presented to the hospital with anorexia, nausea, and vomiting. Laboratory studies were significant for hypercalcemia (peak calcium value of 14.8 mg/dL) and acute kidney injury (peak serum creatinine of 2.88 mg/dL). He admitted to using a parenteral formulation of vitamins A, D and E restricted for veterinary use containing 20,000,000 IU of vitamin A; 5,000,000 IU of vitamin D3; and 6,800 IU of vitamin E per 100 mL vial. The patient stated to have used close to 300 mL of the product over the preceding year. Interestingly, the young man was not interested in the massive amounts of vitamins that the product contained; he was only after the local effects of the oily vehicle. The swelling produced by the injection resulted in a silicone-like effect, which gave the impression of bigger muscles. Nevertheless, the product was absorbed and caused hypervitaminosis. The serum level of 25(OH) vitamin D was clearly elevated at 150 ng/mL (reference range from 30 to 60 ng/mL), but in most published cases of vitamin D toxicity, serum levels have been well above 200 ng/mL. His PTH level was undetectable and other potential causes of hypercalcemia were excluded. Therefore, we posit that the severity of the hypercalcemia observed in this case was the result of a synergistic effect of vitamins A and D. The patient was treated with normal saline, furosemide and zolendronic acid, with rapid normalization of calcium levels and renal function.

A modified nominal stress method for fatigue assessment of steel plates with thermally cut edges

Thermal cutting methods, are commonly used in the manufacture of metal parts. Thermal cutting processes separate materials by using heat. The process can be done with or without a stream of cutting oxygen. Common processes are Oxygen, plasma and laser cutting. It depends on the application and material which cutting method is used. Numerically-controlled thermal cutting is a cost-effective way of prefabricating components. One design aim is to minimize the number of work steps in order to increase competitiveness. This has resulted in the holes and openings in plate parts manufactured today being made using thermal cutting methods. This is a problem from the fatigue life perspective because there is local detail in the as-welded state that causes a rise in stress in a local area of the plate. In a case where the static utilization of a net section is full used, the calculated linear local stresses and stress ranges are often over 2 times the material yield strength. The shakedown criteria are exceeded. Fatigue life assessment of flame-cut details is commonly based on the nominal stress method. For welded details, design standards and instructions provide more accurate and flexible methods, e.g. a hot-spot method, but these methods are not universally applied to flame cut edges. Some of the fatigue tests of flame cut edges in the laboratory indicated that fatigue life estimations based on the standard nominal stress method can give quite a conservative fatigue life estimate in cases where a high notch factor was present. This is an undesirable phenomenon and it limits the potential for minimizing structure size and total costs. A new calculation method is introduced to improve the accuracy of the theoretical fatigue life prediction method of a flame cut edge with a high stress concentration factor. Simple equations were derived by using laboratory fatigue test results, which are published in this work. The proposed method is called the modified FAT method (FATmod). The method takes into account the residual stress state, surface quality, material strength class and true stress ratio in the critical place.

Integration of Logistics Systems across Companies’ Borders

The growth of the companies working in the Logistics area has raised the need for using several Logistics systems that can meet the increased requirements in business processes. Different companies may use one or more Logistics systems internally and may use different Logistics systems that other collaborated companies use. Furthermore, these Logistics systems are required to communicate with each other in order to process and manage the flow of the information. Integrating the Logistics systems is beneficial as it allows interaction between the whole systems and services instead of the need to replace them. In addition, it improves the efficiency, lowers the possible errors in the supply chain, reduces the costs and facilitates the access of suppliers and customers to the information. This in turn leads to better relationships with both suppliers and customers. Usually local integration of several Logistics systems is not very difficult, especially that mostly the companies buy their system from a single source. However, the case is different for integrating several logistics systems across the companies’ borders. In this case, there are many factors play major roles in limiting the integration, such as using different systems and different output. This thesis highlights these factors and challenges, demonstrates some solutions for the logistics inter-organizational integration from the perspective of information systems and presents some approaches for integrating these systems. There are many studies about the integration inside a company but fewer studies focused about the technical side and the information systems integration across company’s borders or what is called inter-organizational integration. This study is a literature review that aims at illustrating the challenges, the requirements and some approaches in inter-organizational logistics information systems integration of logistics systems across the companies’ borders.

Distribution of Smart Solutions for External Lighting in Switzerland - Case C2 Smartlight Ltd.

Establishing of export operations is the key to the competitiveness for all producing companies in high-tech industry. Distribution partnerships between exporting producer and local distributors of relevant foreign market are utilized by SMEs to gain cost-efficiency of operation. The purpose of this study was to investigate the Swiss market of outdoor lighting solutions and propose distribution channels for the case of company C2 SmartLight Ltd. The literature framework consists of three main parts: description of distribution channels for business products, the selection process of the distributor and management of the distributors. The empirical part of this study composed of the observation of Swiss lighting market, highlighting key customers, trends of energy efficiency and key industry players of the lighting market. The aim was to identify potential distribution channels, which reach the target customer groups and identify the market opportunity. Secondly, the data was collected through semi-structured phone interviews. The company, which operates in outdoor lighting business and has an established distributor in Switzerland, was interviewed and used as a benchmark. As a result of this research the market opportunity for distribution of C2 SmartLight products was identified based on potential customers and market need. C2 SmartLight Ltd. should establish a connection with wholesalers that distribute easy to handle and store electrical equipment. The results of this study can be used by other SME companies, operating in a similar field of economy, for selection of distributors.

The effects of quinpirole in eliciting 50 kHz calls from the rat nucleus accumbens /

Fifty kHz rat vocalizations are theorized to reflect a positive affective state, and index the reward value of stimuli (Knutson, Burgdorf & Panksepp, 2002; Panksepp & Burgdorf, 2003; Brudzynski,2005). Previous studies have identified the neurochemical substrate of this behaviour to be dependent on dopaminergic activity at the nucleus accumbens shell (Burgdorf, Knutson, Panksepp & Ikemoto, 2001; Thompson, Leonard & Brudzynski, 2006). The utilization of d-amphetamine (a non-selective dopamine agonist) in these studies does not address the specific dopamine receptor types involved. The present study aims to identify the role of the D2- like family of receptors in the nucleus accumbens shell in the production of 50 kHz vocalizations in adult rats. Single injections of quinpirole in a saline vehicle were administered to the nucleus accumbens shell of 57 rats, and the number of 50 kHz vocalizations were recorded. An inverted V-shaped relationship was found between quinpirole dose (0.5 ~g, 3 ~g, 6 ~g, 1 0 ~g and 20 ~g, all in 0.2~1 saline) and the mean number of 50 kHz calls produced. Quinpirole successfully elicited significantly more 50 kHz calls than did a saline control at the 6 ~g dose, as did 7 ~g/0.2 ~l of d-amphetamine injections into the same brain site. To test whether a selective D2 antagonist could reverse elicited 50 kHz calling, double injections were given that used either saline or raclopride as a pretreatment before quinpirole injections. Saline followed by 6 ~g/0.2 ~l of quinpirole elicited significantly more 50 kHz vocalizations than did a double injection of saline, while pretreatment with an equimolar dose of raclopride reduced elicited calls to control levels. Raclopride was also used as a pretreatment of 7 ~g/0.2 ~l d-amphetamine, which elicited significantly fewer 50 kHz vocalizations than saline followed by amphetamine, replicating the finding of Thompson, Leonard & Brudzynski (2006).Subcutaneous injections of 0.5 mg/kg and 1.5 mg/kg of quinpirole produced a similar number of 50 kHz vocalizations as subcutaneous injection of saline. Wider dose ranges may be explored in fiiture research. Thus, direct activation of the Da-like receptors in the nucleus accumbens shell was sufficient to elicit 50 kHz vocalizations in adult rats, an effect which was reversed with selective local antagonism of Da-like receptors. The Da-like receptor family also appears necessary for pharmacological activation of 50 kHz calling, as d-amphetamine was no longer able to effectively elicit these vocalizations from the nucleus accumbens shell when the Da-receptor family was antagonized with raclopride. The acoustic parameters of elicited vocalizations remained typical of rat 50 kHz calls. Detailed analyses of the acoustic characteristics of elicited calls indicated significant increases in call duration and peak frequency across drug injection groups, particularly among quinpirole dose groups. The implications of these findings are not yet clear, but may represent an important direction for future research into the coding of semiotic content into affective signals in rats.

Patterns of faunal change at an upper Cambrian trilobite extinction event, Nolichucky Formation, Tennessee and Virginia

During the Upper Cambrian there were three mass extinctions, each of which eliminated at least half of the trilobite families living in North American shelf seas. The Nolichucky Formation preserves the record of one of these extinction events at the base of the Steptoean Stage. Sixty-six trilobite collections were made from five sections In Tennessee and Virginia. The lower Steptoean faunas are assigned to one low diversity, Aphelaspis-dominated biofacies, which can be recognized in several other parts of North America. In Tennessee, the underlying upper Marjuman strata contain two higher diversity biofacies, the Coosella-Glaphyraspis Biofacies and the Tricrepicephalus-Norwoodiid Biofacies. At least four different biofacies are present in other parts of North America: the Crepicephalus -Lonchocephalus Biofacies, the Kingstonia Biofacies, the Cedaria Biofacies, and the Uncaspis Biofacies. A new, species-based zonation for the Nolichucky Formation imcludes five zones, three of which are new. These zones are the Crepicephalus Zone, the Coosella perplexa Zone, the Aphelaspis buttsi Zone, the A. walcotti Zone and the A. tarda Zone. The Nolichucky Formation was deposited within a shallow shelf basin and consists largely of subtidal shales with stormgenerated carbonate interbeds. A relative deepening is recorded In the Nolichucky Formation near the extinction, and is indicated In some sections by the appearance of shale-rich, distal storm deposits above a carbonate-rich, more proximal storm deposit sequence. A comparable deepening-upward sequence occurs near the extinction in the Great Basin of southwestern United States and in central Texas, and this suggests a possible eustatic control. In other parts of North America, the extinction IS recorded In a variety of environmental settings that range from near-shore to slope. In shelf environments, there is a marked decrease in diversity, and a sharp reduction in biofacies differentiation. Although extinctions do take place in slope environments, there IS no net reduction in diversity because of the immigration of several new taxa.