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Jamaica experienced net deforestation during the period 2001–2010. Yet, the proximate causes of deforestation and the reasons why a forest transition might be absent, particularly at the local-level, which can explain national scale changes, have been little studied. Long-term changes in socio-economic and land cover data over 68-years, for the moist forest of the Cockpit Country, Jamaica, and predictors of land cover change, were assessed using generalized linear and non-linear regression models. These were used to determine if the classic theorized determinants of a forest transition were present at different spatial scales and to identify the proximate cause(s) of deforestation. Some theorized determinants were present (improvements in national and sub-national economic development, and a decline in agricultural production); however, rural/local scale population density and growth rates were stable. As such, pressure on the unprotected (non-reserves) marginal/agricultural lands in the Cockpit Country was not reduced and this prevented them from reverting to forest. Forest cover for the entire Cockpit Country and the non-reserves therefore fluctuated significantly over time (nonlinear trend), peaking twice (1980 and 2002). The implementation of trade liberalization policies in the 1980s resulted in increased yam cultivation, which was the proximate cause of forest cover change in the non-reserves (a significant non-linear relationship). As a result, deforestation increased significantly during this period and again during the 2000s, at which time it was driven largely by other factors. A forest transition is unlikely to occur via an economic pathway, but it can possibly be achieved via the enforcement of existing forest protection laws and active promotion of forest cover expansion.

The chemical degradation of farglitazar (1) was investigated using a series of controlled stress testing experiments. Farglitazar drug substance was stressed under acidic, natural pH, basic, and oxidative conditions in solution. In the solid state, the drug substance was stressed with heat, high humidity, and light. Farglitazar was found to be most labile toward oxidative stress. A series of mechanistic experiments are described in which the use of 18O-labelled oxygen demonstrated that oxidative degradation of farglitazar is caused primarily by singlet oxygen formed under thermal conditions. Major degradation products were isolated and fully characterized. Mechanisms for the formation of degradation products are proposed. Drug product tablets were also stressed in the solid state with heat, high humidity, and light. Stressed tablets afforded many of the same degradation products observed during drug substance stress testing, with oxidation again being the predominant degradation pathway. Evidence for the activity of singlet oxygen, formed during thermal stress testing of the solid oral dosage form, is presented. The degradation pathways observed during stress testing matched those observed during long-term stability trials of the drug product.

An invasive crayfish, Cherax quadricarinatus, and several native shrimp species (Macrobrachium acanthurus, Macrobrachium faustinum, Macrobrachium carcinus, Xiphocaris elongata, and Atyidae sp.) found in the Black River Lower Morass (BRLM), a Ramsar Wetland in Jamaica, support subsistence and artisanal fisheries. Management of this fishery requires information on factors that influence their abundance. Consequently, we assessed the effects of seasonality, extreme and double La Nina episodes (in 2011) and elevated atmospheric temperature (in 2011 and 2012) on weekly Decapoda landing data, collected over a period of two years (2010–2012). The catch of native species showed a cyclical trend every 6 months, coinciding with the dry and wet seasons. The invasive crayfish landing showed a reverse trend during the first year, after which no pattern could be discerned. A dynamic factor analysis (DFA) model with two common trends and four explanatory variables (conductivity, mean weekly number of traps hauled, weekly mean water level, and mean dissolved oxygen) was the optimal model to characterize the variation in wet-weight landings. A generalized additive mixed model with an auto-regressive moving average (ARMA) error structure was used to show that the extreme and double La Ninas were associated with lower monthly atmospheric temperature. Sea surface temperature anomaly in region 3 (a proxy to ENSO) and the trend in temperature were then used to predict the wet weight of native shrimp (U-shaped relationship) and the invasive crayfish (reverse-j shaped relationship), respectively. The native shrimp (mean sustainable yield, MSY = 3469 kg and mean catch per fisher = 2.67 kg) and invasive crayfish (MSY = 11 kg and mean catch per fisher = 0.67 kg) are under fished, although populations of the native shrimp are possibly declining, whereas that of the invasive crayfish may be growing. The declining trend may have adverse implications for the stock of the native shrimp species, which has a higher economic value, if fishing pressure is not reduced/restricted or increased on the invasive crayfish, especially during seasonal and/or ENSO related declines in native shrimp stocks.

We use species distribution modeling to create easily testable hypotheses about the current and future distributions of Jamaican frogs, a little studied but highly endangered group. Our models simultaneously represent the best possible current estimate of the frogs’ ranges and provide clear guidelines for future survey work and habitat preservation efforts. We identify areas that contain the highest frog biodiversity, the highest per-unit area frog conservation benefit, and areas that are putative climatic refuges from outbreaks of the frog disease chytridiomycosis. In addition, we use the distribution models to create a set of easily falsifiable predictions about frog presence or absence. Testing these predictions using presence/absence surveys will provide management-ready information about model quality, population trajectories, changes in realized climate tolerance, and disease presence. We present a method of generating targeted conservation recommendations that will be applicable to many little-studied, cryptic taxa worldwide.

Invasive species have caused widespread economic and environmental disruption, which have been widely studied. However, their potential benefits have received much less attention. If invasive species contribute to livelihoods, their eradication may negatively impact wellbeing. Failing to value these benefits may lead to an undervaluation of invaded ecosystems. We assess the potential economic benefits of an invasive species within an artisanal fishery in Jamaica. We monitored catches over 259 fisherman-days, and conducted 45 semi-structured interviews, with 76 fishermen. We show that the invasive Australian Red Claw crayfish (Cherax quadricarinatus) is an important source of income for fishermen within the Black River Lower Morass of Jamaica and supplement incomes during periods when native shrimp (Macrobrachium spp.) catches decline. We also show that full-time fishermen and those who have no alternative occupations expend the greatest fishing effort. We use the intra-annual variation of fishermen's harvest effort between seasons (when catch per unit effort changes) as a proxy for dependence. Using this measure, we found that the least wealthy appear to be the most dependent on fishing, and consequently benefit the most from the invasive crayfish. Our results demonstrate the importance of considering the potential benefits of invasive species within integrated landscape management.

Very little research has considered the underlying drivers of land cover change in Caribbean islands, particularly in those islands that are still experiencing a net loss of forest cover. We investigated the underlying driving forces (socio-economic drivers) and spatial pattern drivers (biophysical features) of both deforestation and reforestation in the Cockpit Country, Jamaica. This area is one of the most globally important sites for plant diversity, but is threatened by clearance for small-scale agriculture. Drivers of change were assessed for both the individual time steps within the study period (1942–2010) and for the entire 68 years using multivariate, spatially explicit, statistical models. The primary drivers of deforestation over the study period were accessibility (gentler slopes, closer to forest edges, more fragmented forests) and greater relative wealth/socio-economic status (increased access to piped water). Reforestation generally increased closer to forest edges and in areas with lower market access (greater distances to roads and towns) and lower wealth/status (increased reliance on pit latrines). We found considerable temporal variation among the most important drivers for each time step, including climate, employment status, population density, population age structure and relative wealth. Forest reserve status was not a key determinant of deforestation but did increase the probability of reforestation between 1961 and 1980. During the final time step (2001–2010) access was less important as a deterrent to deforestation, which increased within the most contiguous forest blocks. If the deforestation drivers of the last decade do not change, deforestation is predicted to occur within the forest reserves, and in the largest, least fragmented forest blocks. Thus, conservation and management strategies for our study site must seek to address issues related to both enforcement and the socio-economic factors that influence deforestation and habitat fragmentation.

Early childhood lead exposure is associated with numerous adverse health effects. Eliminating blood lead poisoning is a national health objective for 2020.To assess temporal trends in childhood elevated blood lead level (EBLL) rates.Laboratory surveillance data were collected from 1997 to 2011 and analyzed in 2013 using linear regression to assess trends in confirmed EBLL rates among children aged6 years in the U.S., New York State ([NYS], excluding New York City), and Monroe County NY. Monroe County was also examined as a case study of local public health efforts to reduce childhood lead exposures. Blood lead screening and home lead hazard inspection data were collected from 1990 to 2012 and analyzed in 2013.The prevalence of EBLL≥10 μg/dL per 100 tested children decreased from 13.4 to 1.1 in Monroe County, 6.3 to 1.0 in NYS, and 7.6 to 0.6 in the U.S. between 1997 and 2011. The absolute yearly rate of decline in Monroe County (slope=-0.0083, p0.001) occurred 2.4-fold faster than that in NYS (slope=-0.0034, p0.001) and 1.8-fold faster than that in the U.S. (slope=-0.0046, p0.001). The childhood blood lead testing rate was consistently higher in Monroe County than in NYS and the U.S.; however, testing increased for all three areas (all slopes0, p0.05), with greater improvements observed for U.S. children overall (slope=0.0075, p0.001).In addition to national and statewide policies, local efforts may be important drivers of population-based declines in childhood EBLL rates.

Historical data on landuse changes are important for interpreting the current status of natural systems such as forests. Analyses of road network dynamics can be particularly useful as network expansion is often a precursor to and an indicator of increased human activity. Legal protection is often seen as the most viable option available for protecting natural forests; but over the past decade, its effectiveness has been questioned. We assessed the impact of roads and the designation of a forest reserve on deforestation and forest fragmentation in a tropical moist forest, Cockpit Country, Jamaica, from 1942 to 2010. Specifically, we classified multi-temporal images (black and white aerial photographs, IKONOS and GeoEye images) using an object based image analysis and we included a vector of digitized roads for each year of assessment during the classification process. We then conducted a fragmentation analysis of the classified images and assessed the relationship between road density and several fragmentation metrics over time, and the spatial influence of the reserves (presence/absence) and roads (Euclidean distance from roads) on deforestation and several fragmentation metrics using generalized linear models. Between 1942 and 2010, road density nearly doubled (from 0.67 km/km2 to 1.22 km/km2), with significant increases occurring within forest reserves, and was significantly related to the area-weighted mean shape index of the forest (forest patches became more regularly shaped and linear). Initially, relatively high deforestation rates and high levels of fragmentation between 1942 and 1961 were likely related to the large increase in road density. Deforestation and forest fragmentation were more likely to occur closer to roads over all time periods, and the magnitude/significance of this relationship peaked in subsequent time periods after road density doubled; but in the final time period, its influence declined. Legal protection afforded to the forest in the 1950s and 1960s coincided with an increase in total and core forest area and a reduction in deforestation rate, and deforestation and forest fragmentation were significantly lower inside the reserve. Therefore, the Forest Reserves were initially effective; however, their effectiveness waned after 1980. Increased deforestation and fragmentation in the 1980s and the 2000s indicate a more complex pattern of human encroachment, as these changes do not appear to have been influenced by changes to the road network, or by the presence of the Forest Reserves. Further research into the factors influencing human use of these forested areas is needed for effective management of the area.

Long-term tree and seedling growth and survivorship data from permanent sample plots established in a neotropical dry forest in Jamaica from 1998 to 2008 were used to (1) model growth (periodic annual increment) and survivorship dynamics, (2) cluster structural and functional types, and (3) estimate the age of selected tropical dry forest tree species. A statistical comparison of parameter estimates derived from a generalized linear model (GLM) of each species to a reference species was used to group individuals based on size (DBH and height), and demographic dynamics (periodic annual increment and survivorship). We identified two groups of species based on structural types (canopy and sub-canopy species), three groups of species based on periodic annual increment (fast, intermediate, and slow growing) and four groups of species based on the probability of survivorship of seedlings and trees (very low probability of seedling survivorship but high tree survivorship (two groups); high survivorship throughout the DBH classes; very low survivorship, regardless of stem size). The composition of the groups was mixed, and included individuals of both structural types, and with different periodic annual increment and survival probabilities. The dichotomy of guilds found in tropical rainforests (pioneer and climax species) was not found in this forest. Individual and group GLMs incorporating empirical relationships between periodic annual increment and survivorship, across a spectrum of ontogenies and DBH’s, were also generated. The periodic annual increment models were then used to estimate the time taken by a newly germinated seedling to reach the largest recorded DBH. The fastest growing species was the hemi-cryptophyte Clusia flava which was estimated to take 74 years to reach its maximum recorded size (12.1 cm DBH), whereas the slowest growing species, Ziziphus sarcomphalus, was estimated to take 399 years to reach its maximum size (24.4 cm DBH). These dry forest trees were estimated to reach their maximum size (which was one-half or one-third of the largest DBH recorded for tropical rainforests) in a time similar to tropical rainforest trees. Some of the tree species are ubiquitous to other neotropical dry forests; therefore, our equations for periodic annual increment and survivorship can be applied elsewhere in the region.

Testicular tissues from Anolis lineatopus were examined histologically to determine testicular structure, germ cell morphologies, and the germ cell development strategy employed during spermatogenesis. Anoles (N = 36) were collected from southern Jamaica from October 2004 to September 2005. Testes were extracted and fixed in Trump’s fixative, dehydrated, embedded in Spurr’s plastic, sectioned, and stained with basic fuchsin/toluidine blue. The testes of Jamaican Anoles were composed of seminiferous tubules lined with seminiferous epithelia, similar to birds and mammals, and were spermatogenically active during every month of the year. However, spermatogenic activity fluctuated based on morphometric data for February, May and June, and September‐December. Sequential increases for these months and decreases in between months in tubular diameters and epithelial heights were due to fluctuations in number of elongating spermatids and spermiation events. Cellular associations were not observed during spermatogenesis in A. lineatopus, and three or more spermatids coincided with mitotic and meiotic cells within the seminiferous epithelium. Although the germ cell generations were layered within the seminiferous epithelium, similar to birds and mammals, the actual temporal development of germ cells and bursts of sperm release more closely resembled that reported recently for other reptilian taxa. All of these reptiles were temperate species that showed considerable seasonality in terms of testis morphology and spermatogenesis. The Jamaican Gray Anole has continuous spermatogenesis yet maintains this temporal germ cell development pattern. Thus, a lack of seasonal spermatogenesis in this anole seems to have no influence on the germ cell development strategy employed during sperm development.

Background: It is generally assumed that initial and recurrent strokes are of the same type, but data from South London, United Kingdom; Lausanne, Switzerland; and other studies suggest this may not be true for certain subtypes. In these studies, however, the number of recurrent strokes observed during the follow-up period was small, thereby limiting the ability of these studies to provide reliable estimates of stroke type concordance. Methods: Using a large, diverse, inpatient database, this study sought to: (1) estimate the relative agreement (Cohen's kappa) between initial and recurrent stroke types for blacks and whites; and (2) develop a risk-adjusted logistic model for readmission stroke type, with the initial admission stroke type as the main predictor and race, other sociodemographic variables, and clinical and hospital characteristics as potential covariates. Results: Stroke type concordance was similar for blacks (kappa = 0.77, 95% confidence interval [CI] = 0.71-0.83) and whites (kappa = 0.77, 95% CI=0.74-0.79). In the adjusted logistic regression models, the initial admission stroke type strongly predicted the readmission stroke type (subarachnoid hemorrhage: odds ratio [OR] = 738.31, 95% CI=422.58-1289.93; intracerebral hemorrhage [ICH]: OR=80.86, 95% CI=61.57-106.19; ischemic: OR=125.81, 95% CI=96.12-164.67). Other patient factors, but not race, also predicted readmission stroke type (e.g., younger age increased the odds of having an subarachnoid hemorrhage readmission; atrial fibrillation increased the odds of having an ICH readmission; older age, diabetes mellitus, and heart failure increased the odds of having an ischemic stroke readmission). Conclusion: This study showed that the initial stroke type and other factors were independently associated with the readmission stroke type and that patterns of stroke type concordance were similar for blacks and whites. These results may help to identify patients in high-risk subgroups who are more likely to have a recurrent hemorrhagic stroke, which could inform patient treatment decisions. For example, patients with atrial fibrillation may be at greater risk for having an ICH readmission because of the adverse effects of anticoagulant therapy, antiplatelet treatment, or both, which should be investigated further.

The lithological succession of the Guinea Corn Formation in the Slippery Rock River, central Jamaica, comprises 91 m of limestones and subsidiary mudstones. The biostratigraphic distribution of rudist bivalves and corals demonstrates that the succession of biostratigraphic markers is consistent with the previously documented standard Guinea Corn Formation succession in the Rio Minho between Grantham and Guinea Corn, central Jamaica. Additionally, the Slippery Rock River succession shows the boundary between the Chiapasella radiolitiformis and C. trechmanni zones that has not previously been documented. The marker horizons are also consistent with major facies changes within both sections, demonstrating that both lithological changes and biostratigraphic markers are synchronous within the limestone successions of central Jamaica. This may prove to be a valuable tool for stratigraphic correlation elsewhere in Jamaica and within the Antillean region. 2004 Elsevier Ltd. All rights reserved.

The anticonvulsant phenytoin causes a decrease in plasma concentrations of folate in epileptic patients. The mechanism underlying this depletion is unknown. To study this mechanism, phenytoin was administered to rats by addition to the diet (3 g phenytoin/kg diet) for up to 8 wk. At selected times during phenytoin administration (0, 3, 7, 10, 14, 28, 42 and 56 d), the composition of the folate pools of intestinal mucosa, liver, bile and brain was determined. The 0-d administration served as the control group. The controls were fed the same diet without phenytoin for the eight weeks of the experiment. Phenytoin administration had minimal effect on either the folate concentration or the composition of the folate pool in intestinal mucosa. Phenytoin administration did, however, cause a depletion of total hepatic folate to about 50% of control, causing the pentaglutamate derivatives of each of the pteridine derivatives to decline rapidly, with the formyl and dihydro derivatives of the pteridine moiety falling more rapidly than the methyl and methylene + tetrahydro derivatives. The monoglutamate of the methylene + unsubstituted tetrahydro derivative increased significantly with time of phenytoin treatment. The mono- and di-glutamate derivatives of the methyltetrahydrofolate increased transiently and significantly in the bile, and the polyglutamate chain length increased significantly in the brain with time of phenytoin treatment. We conclude that phenytoin inhibits the formation of polyglutamyl folates in rat liver.

The subcellular distribution of folate co- enzymes in the brain is unknown. Brain folate concen trations are low and hence require a sensitive assay to determine the subcellular distribution. Rat brain was fractionated by differential centrifugation into cyto- plasmic, mitochondrial and crude synaptosomal frac tions. The compositions of the folate pools in these subcellular fractions were determined by differential conversion of one-carbon forms enzymatically to 5,10- methylenetetrahydrofolate (5,10CH2H4PteGlun) fol lowed by reaction of the 5,1 OCH2H4PteGlunwith thymi- dylate synthetase and (3H)fluorodeoxyuridylate to form ternary complexes, which were then separated as a function of polyglutamate chain length by isoelectric focusing, visualized by fluorography and quantified by densitometry. The distribution of the pteridine deriva tives in brain was very similar to the distribution of these derivatives in liver. Cytoplasm contained pri marily 5-methyltetrahydropteroylpolyglutamates with smaller amounts of unsubstituted tetrahydropteroyl- polyglutamates, whereas mitochondria contained ap proximately equal concentrations of unsubstituted and formyl-substituted tetrahydropteroylpolyglutamates. The subcellular distribution of polyglutamate deriva tives in brain, however, was different from that in liver. In the brain, the mitochondrial folates exhibited longer polyglutamate chains than did the cytoplasmic folates, a pattern opposite to that in the liver. Whereas the brain cytoplasmic pteroylpolyglutamates were primar ily penta and hexa glutamates, the brain mitochondrial pteroylpolyglutamates were primarily hexa and hepta glutamates. The brain also contained small but mea surable levels of oxidized folates, which were seen in crude synaptosomal fractions but not in cytoplasmic or mitochondrial fractions. J. Nutr. 126: 3077- 3082, 1996. Folate-dependent one-carbon metabolism is vital to all living cells. The one-carbon units generated in this pathway are essential for the synthesis of the purines and thymidylate and for the synthesis of the methyl group de novo. Biological folates exist in many different forms with differences either in the pteridine moiety or in the length of the poly-gamma-glutamate chain. The pteridine moiety can differ in the oxidation state of the B ring from folie acid (PteGlu),4 in which posi tions 5,6, 7 and 8 are fully unsaturated, to tetrahydrofo- late (H4PteGlu), in which these positions are fully satu rated (i.e., reduced). Although the unsaturated forms, PteGlu and dihydrofolic acid (H2PteGlu), have not been shown to have any specific biological function, both can be reduced to the tetrahydro form in biological systems. In addition, the one-carbon units that are sub stituted at the 5 and 10 nitrogens can vary in oxidation state from the formate oxidation state of 5-formyl

The ternary complex method for the determination of folylpolyglutamates was combined with procedures for interconverting folate derivatives to measure 28 different folate derivatives in the subcellular fractions of rat liver. Folates in the homogenate showed a typical distribution with nearly equal quantities of penta- and hexaglutamates and pteridine derivatives in decreasing order as follows : 1) methyl substituted folates [5-methyltetrahydropteroylglutamates], 2) unsubstituted folates [tetrahydropteroylglutamates + 5,10-methylenetetrahydropteroylglutamates], 3) formyl substituted folates [5-formyltetrahydropteroylglutamates + 10-formyltetrahydropteroylglutamates + 5,10-methenyl-tetrahydropteroylglutamates], and 4) oxidized folates [di-hydropteroylglutamates]. In the homogenate the methyl substituted folates exhibited a higher hexa :pentaglutamate ratio than did the other pteridine derivatives. As the fractionation proceeded toward purer subcellular components, the methyl substituted folates were found almost exclusively in the soluble fraction, and this fraction also contained the higher hexa :pentaglutamate ratio characteristic of the methyl substituted folates. The plasma membrane, the microsomal and the nuclear fractions did not contain appreciable folate. The mitochondrial fraction contained primarily formyl substituted and unsubstituted folates, and these folates exhibited the lower hexa :pentaglutamate ratios. These data support the hypothesis that folate-dependent one-carbon metabolism is compartmentalized in the eukaryotic cell. J. Nutr. 125 : 2096-2103, 1995.

Prior to weaning, medium-chain fatty acids constitute an important energy source in the developing rat. Fatty acid oxidation rates increase with age in most developing tissues, but the pattern of this increase may vary according to the role of the particular organ. In skeletal muscle, heart, and liver of developing rats, we measured mitochondrial activities of long- and short-chain enoyl-CoA hydratase, 3-hydroxyacyl-CoA dehydrogenase, and long- and short-chain acyl-CoA thiolase. In skeletal muscle, the pattern of development in fatty acid oxidation enzymes favored utilization of long-chain rather than medium-chain fatty acids. In liver, enzyme activities for medium-chain fatty acids were highest prior to weaning. Heart occupied a position intermediate between skeletal muscle and liver.

γ 1 -heavy chain disease protein (HCD) BAZ has a molecular weight of 60,000 daltons and contains a substantial quantity of carbohydrate (14%) in comparison to normal γ-chains which is distributed as follows: sialic acid (5%), fucose (1.7%), hexoses (3.5%), glucosamine (1.7%), and galactosamine (2.0%). Dansylation of the protein indicates that it has a blocked N -terminal amino acid, whereas treatment of the protein with hydrazine liberates glycine as the C-terminal amino acid. Thus, both amino and carboxy terminal residues appeared to be homologous to normal γ-chains. The amino acid composition of the protein also shows a markedly lower half-cystine content in comparison to other γ 1 -chains, indicating that the protein lacks interchain disulfide bridges connecting the heavy chains due to a deletion encompassing the hinge region. Amino acid sequence analysis of the C-terminal octadecapeptide of protein BAZ demonstrated a previously unrecognized amino acid substitution in the constant region. It contains a substitution of glycine for alanine at position 431. This exchange may conceivably represent another allotypic variant of IgGl proteins.

An electrophoretic and enzyme-substrate staining technique for acyl-CoA dehydrogenase (ACD) enzymes was developed for use with small (less than 100 mg) tissue samples. Based on their electrophoretic mobility and substrate staining specificity, at least two and perhaps three chain-length specific enzymes for dehydrogenation of saturated fatty acids were found in human skeletal muscle. ACD enzymes staining with octanoyl-CoA or palmitoyl-CoA were identified by this technique in human skeletal muscle, heart, and liver, but the ACD enzyme staining with butyryl-CoA was difficult to detect and was definitely visualized only in skeletal muscle.

The physicochemical and antigenic properties of a γ1 heavy chain disease protein (γl HCD BAZ) are described. Protein BAZ is positive for the Glm(1) determinant and gives a reaction of identity with Fc fragment, whether derived from Cohn Fraction II or from an IgG1 myeloma protein. It also gives a reaction of complete identity with the γHCD proteins CRA and ZUC. The mol. wt of the native protein was determined from (1) sedimentation-diffusion, (2) sedimentation-viscosity, and (3) sedimentation-equilibrium measurements to be approx 60,000 daltons. The mol. wt of the unreduced protein in 6 M guanidine hydrochloride was found to be 30,000 daltons, which was identical to that of the reduced-alkylated form in 6 M guanidine. These results established that γ1 HCD BAZ is a noncovalently linked dimer and suggested the possibility of a missing hinge region.

The performance of float-sink coal cleaning devices customarily is characterized by a distribution curve, in which the percent of feed reporting to clean coal is plotted against specific gravity. For a given vessel and a given feed a family of distribution curves can be obtained, each having its own specific gravity of separation. This paper presents a method for combining these distribution curves at different specific gravities of separation, for a given coal cleaning vessel and a given feed, into a single, generalized distribution curve which is independent of the specific gravity of separation. This curve can be expressed in tabular form or it can be represented mathematically by an exponential type equation, known as a Weibull function. A different generalized distribution curve will be obtained for each of several different size fractions. A method is presented for utilizing these curves with feeds which encompass a broad spectrum of sizes. The well-known concepts of error area and probable error are extended to the generalized distribution curve. It is shown that the conventional probable error, and — under certain conditions — the conventional error area, are directly proportional to the specific gravity of separation for a given vessel and a given feed size.

This article presents a historical account of the various steps taken by Missouri librarians to achieve a distribution system for Missouri state documents. Planning, development, passage, and implementation of Missouri documents depository legislation are addressed. This article will serve as a useful framework for state documents librarians wishing to implement or upgrade their state documents depository programs.