Dynamic response mitigation of floating wind turbine platforms using tuned liquid column dampers.

In this paper, we experimentally study and compare the effects of three combinations of multiple tuned liquid column dampers (MTLCDs) on the dynamic performance of a model floating tension-leg platform (TLP) structure in a wave basin. The structural stability and safety of the floating structure during operation and maintenance is of concern for the performance of a renewable energy device that it might be supporting. The dynamic responses of the structure should thus be limited for these renewable energy devices to perform as intended. This issue is particularly important during the operation of a TLP in extreme weather conditions. Tuned liquid column dampers (TLCDs) can use the power of sloshing water to reduce surge motions of a floating TLP exposed to wind and waves. This paper demonstrates the potential of MTLCDs in reducing dynamic responses of a scaled TLP model through an experimental study. The potential of using output-only statistical markers for monitoring changes in structural conditions is also investigated through the application of a delay vector variance (DVV) marker for different conditions of control for the experiments.

New folds of plant lectins.

Among the crystal structures of lectins determined recently, three--snowdrop lectin, jacalin and amaranthin--represent new lectin families. Their polypeptide folds share remarkably similar features and consist exclusively of beta structure. Autonomously folded beta-sheet subdomains, inter-related by a pseudothreefold symmetry, assemble to form beta-prism or beta-barrel structures which are stabilized by a hydrophobic core.

Predicting forest floor and woody fuel consumption from prescribed burns in southern and western pine ecosystems of the United States.

We present pre-burn biomass and consumption data from 60 prescribed burns in the southeastern and western United States. The datasets include pre-burn biomass in Mg/ha by fuel category: herbaceous fuels, shrubs, 1-hr, 10-hr, 100-hr, 1000-hr, 10,000-hr, and > 10,000-hr downed wood, litter and duff. Pre-burn depth (cm) and reduction (cm) are provided for litter and duff layers. Day-of-burn fuel moistures and weather are also listed by site.

The 2.0 A structure of a cross-linked complex between snowdrop lectin and a branched mannopentaose: evidence for two unique binding modes.

BACKGROUND: Galanthus nivalis agglutinin (GNA), a mannose-specific lectin from snowdrop bulbs, is a tetrameric member of the family of Amaryllidaceae lectins that exhibit antiviral activity towards HIV. Its subunits are composed of three pseudo-symmetrically related beta sheet domains, each with a conserved mannose-binding site. Crystal structures of monosaccharide and disaccharide complexes of GNA have revealed that all 12 binding sites of the tetramer are functional, and that the degree of occupancy is dependent on the availability of subsidiary interactions from neighboring subunits. The complex of GNA with a branched mannopentaose ((Manalpha1,6-(alpha1, 3-Man)Man-alpha1,6-(alpha1,3-Man)Man) described here simulates a more biologically relevant complex. RESULTS: Two unique mannopentaose binding modes co-exist in the tetragonal structure (1 subunit/asymmetric unit) of the complex. In one, the conserved monosaccharide-binding pocket in domain 1 (CRD 1) is utilized for cross-linkage of twofold related GNA dimers by the outer 3,6 tri-Man arm, which alternates between two orientations consistent with crystal symmetry. Inter-linked dimers assemble helically along the 41 crystal axis forming a pore-like structure. In the second binding mode, the complete 3,6 tri-Man arm binds to an extended binding region in domain 3 (CRD 3) with subsites for each terminal Man and the internal Man positioned in the conserved monosaccharide pocket. The two remaining mannose residues are not visible in either binding mode. CONCLUSIONS: This structure provides insights into possible mechanisms of the cross-linkage that is known to occur when lectins interact with specific multivalent cell surface receptors during events such as agglutination and mitogenic stimulation. By virtue of the large number of sites available for mannose binding, GNA has multiple possibilities of forming unique lattice structures. The two distinctly different binding modes observed in this study confirm that high affinity mannose binding occurs only at the two domain sites located near dimer interfaces.

Refinement of the crystal structure of wheat germ agglutinin isolectin 2 at 1.8 A resolution.

The crystal structure of wheat germ agglutinin isolectin 2 has been refined by the restrained least-squares method of Hendrickson & Konnert (1980). The asymmetric unit of the C2 crystals contains two chemically identical promoters related by a non-crystallographic 2-fold screw operation. A total of 2290 protein atoms and 186 ordered water sites refined to a final R-factor of 0.179 and an average B-value of 21.6 A2, using 54% (15,601) of the total possible number of reflections in the resolution range 8 to 1.8 A with Fo greater than 3 sigma (Fo). The final model conforms to stereochemically correct bond distances and angles with root-mean-square (r.m.s.) values of 0.018 A and 3.3 degrees, respectively. Accuracy of this model is estimated to be 0.20 A on the basis of a Luzzati plot. Main-chain atomic positions in the two independent promoters, designated I and II, agree with an r.m.s. deviation of 0.30 A (0.58 A for all atoms), indicating identical backbone conformation. The largest discrepancies are seen at flexible surface residues. One error was detected in the amino acid sequence at position 41 (Ser), which refined satisfactorily as a Trp. Loss of electron density for residue A171 during the course of refinement suggests either disorder or absence of this C-terminal residue. The conformation of the polypeptide chain, which is folded into four homologous 43-residue domains (A, B, C and D), was analyzed in terms of dihedral angles, backbone hydrogen bond lengths and CA-atom positions. The four domains were found to be very similar according to all these criteria and superposition of their CA-atoms yielded r.m.s. distances ranging from 0.36 to 0.72 A for the six possible comparisons [corrected]. Large deviations (greater than 1.0 A) are only seen in the five-residue segments that link adjacent domains and at the N and C termini. Refinement has also allowed critical examination of each of the two unique sugar binding sites, referred to as "primary" and "secondary" sites, in different lattice environments. While the essential tyrosyl side-chain in each of these sites (Y73, Y159) assumes precise orientation for optimum hydrophobic contact with the N-acetyl methyl group of the sugar ligand, side-chains involved in hydrogen bonds (S62, E115; and S148, D29) were found to be relatively flexible and able to adapt their conformation to changes in environment. Ordered water structure present in these binding sites is not completely analogous in the different environments.(ABSTRACT TRUNCATED AT 400 WORDS)

Comparison of the refined crystal structures of two wheat germ isolectins.

The crystal structures of two closely related members of the multigene family of wheat lectins (isolectins 1 and 2) have been compared. These isolectins differ at five sequence positions, one being located in the saccharide binding site modulating ligand affinity. Crystals of the two isolectins are closely isomorphous (space group C2). The atomic models are based on structure refinement at 1.8 A resolution in the case of isolectin 2 (WGA2) and 2.0 A resolution in the case of isolectin 1 (WGA1). Refinement results for WGA1, recently completed with a crystallographic R-factor of 16.5% (Fo greater than 3 sigma (Fo)), are presented. Examination of a difference Fourier map, [FWGA2-FWGA1], at 2.0 A resolution and direct superposition of the two models indicated an overall close match of the two structures. Local differences are observed in the region of residues 44 to 69, where three sequence differences occur, and at highly mobile external residues on the surface. The average positional discrepancy (root-mean-square delta r) for corresponding protein atoms in the two crystal structures is 0.64 A for independent protomer I and 0.61 A for protomer II (0.29 A and 0.30 A for main-chain atoms). The mean atomic temperature factors are very similar 20.9 versus 22.0 A2). Regions of high flexibility coincide in the two isolectin structures. Of the 210 water sites identified in WGA1, 144 have corresponding positions in WGA2. A set of 51 well-ordered sites was found to be identical in the two independent environments in both structures, and was considered to be important for structure stabilization. Both of the unique sugar binding sites superimpose very closely, exhibiting root-mean-square positional differences ranging from 0.29 A to 0.42 A. The side-chains of the critical tyrosine residues, Tyr73 (P-site) and Tyr159 (S-site), superimpose best, while other highly flexible aromatic groups (Tyr64 and Trp150) and several water sites display large differences in position (0.5 to 1.0 A) and high temperature factors. The aromatic side-chains of Tyr66 in WGA1 and His66 in WGA2 are oriented similarly.

Structural comparison of the two distinct sugar binding sites in wheat germ agglutinin isolectin II.

The two unique sugar binding sites in wheat germ agglutinin, located in the subunit/subunit interface of the dimer molecule and termed primary and secondary binding sites, are compared in the light of the newly obtained chemical amino acid sequence and a high-resolution electron density map (1.8 A). Homology was found in the three amino acid residues directly involved in sugar binding: Tyr73II, Ser62II, Glu115I in the primary site, and Tyr159I, Ser148I, Asp29II in the secondary site (subscripts refer to promoters I and II). Thirteen corresponding side-chain atoms of these three homologous residues in the two sites could be superimposed with a root-mean-square difference of 1.39 A. The three sugar binding residues are located in subsite 1 of each extended binding location and contribute to binding of the terminal, non-reducing N-acetyl-D-glucosamine and N-acetyl-D-neuraminic acid residues only, and they provide three hydrogen bonds for complex stabilization. Two hydrogen bonds are made with the carbonyl and amido portions of the N-acetyl group and the third with the C-3 OH group of the sugar ring. It is suggested that small differences in the sugar binding affinities at these two unique sites exist, due to the different numbers of van der Waals' interactions made at these sites, which contribute to stabilizing, for instance, the wheat germ agglutinin/N,N'-diacetyl-chitobiose complex. The single tryptophan residue is located at a distance of approximately 13 A from the primary site and is thought to have no affect on sugar binding. In addition, the disposition of the four saccharide binding sites of the dimer with respect to three local, pseudo 2-fold symmetry axes, relating domains of opposite protomers, is discussed.

2.2 A resolution structure analysis of two refined N-acetylneuraminyl-lactose--wheat germ agglutinin isolectin complexes.

The crystal structures of complexes of isolectins 1 and 2 of wheat germ agglutinin (WGA1 and WGA2) with N-acetylneuraminyl-lactose (NeuNAc-alpha(2-3)-Gal-beta(1-4)-Glc) have been refined on the basis of data in the 8 to 2.2 A resolution range to final crystallographic R-factors of 17.2% and 15.3% (Fo greater than 1 sigma), respectively. Specific binding interactions and water association, as well as changes in conformation and mobility of the structure upon ligand binding, were compared in the two complexes. The temperature factors (B = 16.3 A2 and 18.4 A2) were found to be much lower compared with those of their respective native structures (19 to 22 A2). Residues involved in sugar binding, dimerization and in lattice contacts exhibit the largest decreases in B-value, suggesting that sugar binding reduces the overall mobility of the protein molecules in the crystal lattice. The binding mode of this sialyl-trisaccharide, an important cell receptor analogue, has been compared in the two isolectins. Only one of the two unique binding sites (4 per dimer), located in the subunit/subunit interface, is occupied in the crystals. This site, termed the "primary" binding site, contains one of the five amino acid substitutions that differentiate WGA1 and WGA2. Superposition of the refined models in each of the independent crystallographic environments indicates a close match only of the terminal non-reducing NeuNAc residue (root-mean-square delta r of 0.5 to 0.6 A). The Gal-Glc portion was found to superimpose poorly, lack electron density, and possess high atomic thermal factors. In both complexes NeuNAc is stabilized through contact with six amino acid side-chains (Ser114 and Glu115 of subunit 1 and Ser62, Tyr64, Tyr(His)66 and Tyr73 of subunit 2), involving all NeuNAc ring substituents. Refinement has allowed accurate assessment of the contact distances for four hydrogen bonds, a strong buried non-polar contact with the acetamido CH3 group and a large number of van der Waals' interactions with the three aromatic side-chains. The higher affinity of N-acetylneuraminyl-lactose observed by nuclear magnetic resonance studies for WGA1 can be explained by the more favorable binding interactions that occur when residue 66 is a Tyr. The tyrosyl side-chain provides a larger surface for van der Waals' stacking against the NeuNAc pyranose ring than His66 and a hydrogen bond contact with Gal (C2-OH), not possible in WGA2.(ABSTRACT TRUNCATED AT 400 WORDS)

Preliminary X-ray diffraction results on co-crystals of wheat germ agglutinin with a sialoglycopeptide from the red cell receptor glycophorin A.

Diffraction-quality crystals have been obtained for complexes of each of the major wheat germ agglutinin (WGA) isolectins with the tryptic sialoglycopeptide T-5 from the WGA red cell receptor glycophorin A. This octa-glycopeptide possesses a Thr-linked carbohydrate moiety (GalNAc(NeuNAc)-Gal-NeuNAc) with specificity for the WGA binding site. The crystals belong to the orthorhombic space group P2(1)2(1)2 and have unit cell dimensions: a = 112.2 A, b = 51.0 A, c = 63.5 A (isolectin 1); a = 109.0 A, b = 52.3 A, c = 62.4 A (isolectin 2). There are two monomer complexes in each asymmetric unit.

The mannose-specific bulb lectin from Galanthus nivalis (snowdrop) binds mono- and dimannosides at distinct sites. Structure analysis of refined complexes at 2.3 A and 3.0 A resolution.

Galanthus nivalis agglutinin (GNA, a 50 kDa tetramer) is a mannose-specific lectin of the Amaryllidaceae family of bulb lectins. Crystal structures of GNA complexed with methyl-alpha-D-mannose (MeMan) and mannose-alpha 1,3-D-mannose-alpha-OMe (MeMan-2) have been determined and analyzed in terms of internal structural symmetry and saccharide binding. The final model of the 2.29 A orthorhombic methyl-alpha-Man complex refined with an R-factor of 0.167 (all data) includes 12 bound sugar ligands and 327 water molecules. The four independent subunits (A, B, C and D) of the 222 tetramer and the three four-stranded beta-sheets (I,II and III) that constitute each subunit compare closely (r.m.s. delta = < 1.0 A). The 12 bound methyl-alpha-Man molecules refined with B-factors < 22 A2 and occupancies in the range of 0.5 to 1.0. The highest occupied site is located in beta-sheet I (site 1), where interactions from the dimer-related subunit contribute to complex stabilization. These subunit pairs (A-D and B-C) associate tightly with a buried surface area of 1738 A2 and 33 interchain hydrogen bonds resulting from C-terminal strand exchange. In comparison, the A-B and C-D subunit pairs have narrow interfaces (476 A2) and no direct H-bond contacts. The 3.0 A structure of the cubic Man-alpha 1,3-Man-OMe complex, determined by molecular replacement and refined with X-PLOR using NCS constraints and density modification methods, is less well ordered due to a high crystal solvent content (68%). Complexed disaccharide is responsible for the most crucial lattice contacts, which involve only one of the two independent subunits (A). The second subunit (C) shows a high degree of flexibility (Bav = 41.7 A2). The complete disaccharide molecule is visible in both subunits at site 3, which is the only extended site. The ligand is oriented with its reducing end positioned in the specificity pocket. The non-reducing manose is in contact through hydrogen bonding with a charged subsite (D37-K38) on the 2-fold-related subunit (A-B or C-D interfaces). Bound Man-alpha 1,3-MeMan is also well defined in site 2 of subunit A, as a result of favorable lattice contacts, while only the mannose residue bound in the specificity pocket is visible at site 2 of subunit C and site 1 of both subunits. Together these results suggest that strong binding correlates with the presence of subsidiary contacts coming either from a dimer-related subunit or from lattice interactions. Site 1 is most specific for terminal non-reducing or reducing mannose, while site 3 is extended and complementary to alpha-1,3 linked mannose oligosaccharides.

Crystallographic refinement and structure analysis of the complex of wheat germ agglutinin with a bivalent sialoglycopeptide from glycophorin A.

Wheat germ agglutinin (WGA) elicits a number of biological effects in erythrocytes as a result of specific binding to the transmembrane protein glycophorin A. The structure of co-crystals of WGA (isolectin 1: WGA1) with a bivalent sialoglycopeptide fragment of glycophorin A (T5), determined at 2.0 A resolution, has been further refined and analyzed with respect to ligand-induced changes in the tertiary structure, mobility, solvation, saccharide conformation and protein/saccharide interactions at three independent N-acetyl-D-neuraminic (NeuNAc) binding sites. The final model, which includes the two independent WGA1 monomers (composed of domains A, B, C and D), two positions for bound T5 sialo-tetrasaccharide (NeuNAc-alpha 2,3-Gal-beta 1,3-(alpha 2,6-NeuNAc)GalNAc) and 386 water molecules, refined to a crystallographic R-factor of 17.1% (Fo > 1.0 sigma) and an average temperature factor of 31.99 A2. Comparisons between the tertiary structures of the liganded and unliganded WGA1 dimers indicate that the largest deviations from 2-fold symmetry are localized in domains engaged in sugar binding (B1 and C2) and at the C-terminal domain of monomer II (D2), forming a strong lattice contact. Interactions of the tetrasaccharide with amino acid ligands in the three binding sites and with water were carefully analyzed and compared. Bound conformations of terminal NeuNAc match to within a root-mean-square delta r of 0.3 A. The specificity-determining N-acetyl group superimposes best in comparison with other substituents of the sugar ring. Of the five domain binding sites that are not occupied in this dimeric crosslinked complex, only one is accessible to the NeuNAc monosaccharide as determined from a difference Fourier map at 3.0 A resolution.

Crystal structure of human GM2-activator protein with a novel beta-cup topology.

GM2 activator protein (GM2-AP) belongs to a small group of non- enzymatic lysosomal proteins that act as cofactors in the sequential degradation of gangliosides. It has been postulated that GM2-AP extracts single GM2 molecules from membranes and presents them in soluble form to beta-hexosaminidase A for cleavage of N-acetyl-d-galactosamine and conversion to GM3. The high affinity of GM2-AP for GM2 is based on specfic recognition of the oligosaccharide moiety as well as the ceramide lipid tail. Genetic defects in GM2-AP result in an atypical form of Tay-Sachs disease known as variant AB GM2 gangliosidosis. The 2.0 A resolution crystal structure of GM2-AP reported here reveals a previously unobserved fold whose main feature is an eight-stranded cup-shaped anti-parallel beta-pleated sheet. The striking feature of the GM2-AP structure is that it possesses an accessible central hydrophobic cavity rather than a buried hydrophobic core. The dimensions of this cavity (12 Ax14 Ax22 A) are suitable for binding 18-carbon lipid acyl chains. Flexible surface loops and a short alpha-helix decorate the mouth of the beta-cup and may control lipid entry to the cavity.

Crystallization and preliminary X-ray diffraction studies of recombinant barley lectin and pro-barley lectin.

Barley lectin (BL) and its precursor form (proBL), synthesized and over-expressed in Escherichia coli, have been crystallized under conditions identical to those used for the closely related lectin wheat germ agglutinin. These lectins are members of the Gramineae family and possess a unique disulfide-rich domain structure. The pro-lectin polypeptides are extended by 15 amino acid residues at the carboxy terminus. This pro-peptide, which is proteolytically removed as the mature lectin is deposited in the vacuoles, is thought to function as a targeting signal for molecular sorting. Crystals of BL and proBL are well ordered and belong to space groups C222(1) and P2(1)2(1)2(1). The unit cell dimensions for BL and proBL are a = 51.9 A, b = 73.7 A, c = 89.3 A (one monomer per asymmetric unit), and a = 45.2 A, b = 70.5 A, c = 111.6 A (two monomers per asymmetric unit), respectively. Diffraction patterns on precession photographs of BL crystals are closely similar to those of mature wheat germ agglutinin crystals, suggesting similar crystal packing and correct conformation of this recombinant protein in terms of the four structural domains and 16 disulfide bridges.

Differences in hydropathic properties of ligand binding at four independent sites in wheat germ agglutinin-oligosaccharide crystal complexes.

The binding interactions of N-acetyl-D-neuraminic acid and N,N' diacetyl-chitobiose (GlcNAc-beta-1,4-GlcNAc), observed in crystal complexes of wheat germ agglutinin (WGA) at four independent sites/monomer, were analyzed and compared with the modeling program HINT (Hydropathic INTeractions). This empirical method allows assessment of relative ligand binding strength and is particularly applicable to cases of weak binding where experimental data is absent. Although the four WGA binding sites are interrelated by a fourfold sequence repeat (eight sites/dimer), similarity extends only to the presence of an aromatic amino acid-rich pocket and a conserved serine. Strong binding requires additional interactions from a contacting domain in the second subunit. Ligand positions were either derived from crystal structures and further optimized by modeling and molecular mechanics, or from comparative modeling. Analysis of the overall HINT binding scores for the two types of ligands are consistent with the presence of two high-affinity and two low-affinity sites per monomer. Identity of these sites correlates well with crystal structure occupancies. The high-affinity sites are roughly equivalent, as predicted from solution binding studies. Binding scores for the low-affinity sites are weaker by at least a factor of two. Quantitative estimates for polar, nonpolar, and ionic interactions revealed that H-bonding makes the largest contribution to complex stabilization in the seven bound configurations, consistent with published thermodynamic data. Although the observed nonpolar interactions are small, they may play a critical role in orienting the ligand optimally.

Compliance of Dunedin school playground equipment with the New Zealand playground standard.

OBJECTIVE: Injuries resulting from falls from playground equipment are a public health concern in New Zealand. Like many other countries, New Zealand has a safety standard aimed at reducing the incidence and severity of these injuries by limiting the height from which children can fall from playground equipment and requiring the provision of impact-absorbing surfaces beneath equipment from which falls are possible. The purpose of this study was to examine progress towards achieving compliance with these requirements in Dunedin school playgrounds. METHODS: Sixty-two schools were audited over the summer of 1997/98 and information recorded on equipment type, maximum fall height, surface type, and depth of loose-fill surface materials. Comparisons were made with audits conducted in 1989 and 1981. RESULTS: Substantial increases in the amount of playground equipment and in the provision of impact-absorbing surfaces were observed. A small increase in compliance with the requirement that the maximum fall height of equipment not exceed 2.5 metres was also observed. CONCLUSIONS: Any gains in safety achieved through increased compliance with the height and surface requirements of the New Zealand Standard have been counteracted by the substantial increase in the amount of equipment available in playgrounds. IMPLICATIONS: A more drastic measure is needed to achieve a meaningful reduction in the incidence of injury following falls from playground equipment.

Laparoscopic sterilization with spring-loaded clips: double-puncture technique.

The application of a spring-loaded clip to each fallopian tube using a second-incision clip applicator is a safe and effective method of laparoscopic sterilization. The operation is quick and easy to perform and is suitable for use with local anesthesia. The method avoids the dangers of hemorrhage, for the clip only alters 3 mm of the fallopian tube and does not transect the tube or mesosalpinx. No pregnancies have followed the sterilization procedure. An intrauterine pregnancy has occurred after a reversal procedure in one patient.

PIP: 533 women undergoing laparoscopic sterilization were studied in an effort to determine the feasibility and safety of a second-puncture clip applicator. The operation was done on an outpatient or overnight basis and a choice of general or local anesthesia was offered. Results indicated that 97.7% of the cases were uncomplicated while 1.2% resulted in bowel perforation; .4% in hematoma and .7% in tubal ligation. None of the complications were due to clip or applicator design. 85% of the cases had no complaints while 5% of the patients experienced abdominal discomfort lasting 48 to 72 hours. This was the only side effect related to the procedure with a spring-loaded clip. No pregnancies occurred at the 6-month follow-up and 1 reanastomosis occurred supporting existing evidence about successful reversal after sterilization with a spring-loaded clip.

Inhibition of erythropoiesis by plasma component(s) from sheep, goats, and rabbits.

Plasma from hypertransfused and normal sheep and experimentally induced anemic and normal goats was fractionated by ultrafiltration. Fractions obtained were assayed for erythropoiesis stimulatory factor (ESF) or erythropoiesis inhibitory factor (EIF) activity (or both) in the posthypoxic polycythemic mouse assay. The most potent sheep plasma-inhibitor fraction was found in the retentate on a membrane with a cutoff at mol wt 50,000. The most potent EIF fraction from anemic goats passed into the ultrafiltrate, but the comparable EIF from normal goats remained in the retentate on a membrane with a cutoff at mol wt 500. The yield of the most potent EIF fraction was higher from anemic goats than was the yield from normal goats. During thin-layer chromatography, EIF extracted from goat plasma fractions had the same mobility as did prostaglandin F2 alpha. Cohn rabbit plasma fraction IV-4 had an inhibitory factor, and a benzene extract of the fraction contained a component that had the same mobility as did prostaglandin F2 alpha. Cohn rabbit plasma fraction V contained a component that potentiated an erythropoietin-generating factor.

Response in mice to an erythropoietin-generating factor.

The bioassay for erythropoietin-stimulating factor (ESF) was compared in 3 strains of mice. One strain was made polycythemic by hypertransfusion and the other 2 by hypoxia. An erythropoiesis-generating factor (EGF) measured in the 3 strains generated approximately the same amounts of ESF, determined with log dose-log response curves for the respective techniques, after incubation with normal rabbit serum (NRS). The amount of ESF generated by EGF without prior incubation with NRS was also approximately the same in the 3 strains of mice.

Compound dislocations of four metacarpophalangeal joints.

A case of compound dorsal dislocation of four metacarpophalangeal joints is presented. The use of early joint motion and extension block splinting resulted in an excellent range of motion in this uncommon injury.

Identifying possible contingencies during descriptive analyses of severe behavior disorders.

Contingencies of reinforcement involve, in part, relations between behavior and subsequent environmental events. In this study we observed 11 individuals with developmental disabilities and severe behavior problems while they interacted with their primary care providers in simulated environments (hospital therapy rooms). We compared the probability of obtaining attention, escape from instructional demands, or access to materials following instances of problem behavior with the background probability of those events. However, the focus of our analysis was the evaluation of comparative probabilities ("contingency values") in the context of relevant establishing operations such as diverted attention, instructional demands, and restricted access to materials. Results showed that the method was useful in identifying relations between behavior and subsequent environmental events. Implications for linking descriptive and functional analyses are discussed, and difficulties in identifying naturally occurring contingencies are considered.