Functional Analysis of Anuran Pelvic and Thigh Anatomy Using Musculoskeletal Modelling of Phlyctimantis maculatus

Using their abundant musculature, frogs are able to exhibit outstanding behavioural versatility. However, understanding the dynamic motion of their 30 + hindlimb muscles, with multi-joint action, and curved pathways, is challenging. This is particularly true in walking, a relatively understudied, but complex frog gait. Building on prior musculoskeletal modelling work we construct and analyse a 3D musculoskeletal model of the spine, pelvis, and hindlimb of Phlyctimantis maculatus (previously known as Kassina maculata) to simulate the natural motion of muscle pathways as joints rotate during locomotion. Combining experimental kinematics and DICE-CT scan data we use several simulations conducted in MuJoCo to decouple femur and pelvic motions, generating new insights into the functional mechanics of walking in frogs. Outputs demonstrate pelvic lateral rotation about the iliosacral joint influences moment arm magnitude in the majority of hindlimb muscles. The extent of pelvic influence depends on femoral angle which changes muscle function in some instances. The workflow presented here can be used to help experimentalists predict which muscles to probe with in vivo techniques towards a better understanding of how anuran musculoskeletal mechanics enable multiple behaviours.

Constraining the External Capture to the ^{16}O Ground State and the E2 S Factor of the ^{12}C(α,γ)^{16}O Reaction

The ^{12}C(α,γ)^{16}O reaction is one of the most crucial reactions in nuclear astrophysics. The E2 external capture to the ^{16}O ground state (GS) has not been emphasized in previous analyses but may make a significant contribution to the ^{12}C(α,γ)^{16}O cross section depending on the value of the GS asymptotic normalization coefficient (ANC). In the present work, we determine this ANC to be 337±45  fm^{-1/2} through the ^{12}C(^{11}B,^{7}Li)^{16}O reaction using a high-precision magnetic spectrograph. This sheds light on the existing large discrepancy of more than 2 orders of magnitude between the previously reported ANC values. Based on the new ANC, we experimentally constrain the GS external capture and show that through interference with the high energy tail of the 2^{+} subthreshold state, a substantial enhancement in the GS S_{E2}(300) factor can be obtained (70±7  keV b) compared to that of a recent review (45 keV b), resulting in an increase of the total S factor from 140 to 162 keV b, which is now in good agreement with the value obtained by reproducing supernova nucleosynthesis calculations with the solar-system abundances. This work emphasizes that the external capture contribution for the ground state transition cannot be neglected in future analyses of the ^{12}C(α,γ)^{16}O reaction.

Efficient atmospheric cleansing of oxidized organic trace gases by vegetation

The biosphere is the major source and sink of nonmethane volatile organic compounds (VOCs) in the atmosphere. Gas-phase chemical reactions initiate the removal of these compounds from the atmosphere, which ultimately proceeds via deposition at the surface or direct oxidation to carbon monoxide or carbon dioxide. We performed ecosystem-scale flux measurements that show that the removal of oxygenated VOC via dry deposition is substantially larger than is currently assumed for deciduous ecosystems. Laboratory experiments indicate efficient enzymatic conversion and potential up-regulation of various stress-related genes, leading to enhanced uptake rates as a response to ozone and methyl vinyl ketone exposure or mechanical wounding. A revised scheme for the uptake of oxygenated VOCs, incorporated into a global chemistry-transport model, predicts appreciable regional changes in annual dry deposition fluxes.

Ontogenetic scaling of foot musculoskeletal anatomy in elephants

This study quantifies the shape change in elephant manus and pes anatomy with increasing body mass, using computed tomographic scanning. Most manus and pes bones, and manus tendons, maintain their shape, or become more gracile, through ontogeny. Contrary to this, tendons of the pes become significantly more robust, suggesting functional adaptation to increasingly high loads. Ankle tendon cross-sectional area (CSA) scales the highest in the long digital extensor, proportional to body mass(1.08+/-0.21), significantly greater than the highest-scaling wrist tendon (extensor carpi ulnaris, body mass(0.69+/-0.09)). These patterns of shape change relate to the marked anatomical differences between the pillar-like manus and tripod-like pes, consistent with differences in fore- and hindlimb locomotor function. The cartilaginous predigits (prepollux and prehallux) of the manus and pes also become relatively more robust through ontogeny, and their pattern of shape change does not resemble that seen in any of the 10 metacarpals and metatarsals. Their CSAs scale above isometry proportional to body mass(0.73+/-0.09) and body mass(0.82+/-0.07) respectively. We infer a supportive function for these structures, preventing collapse of the foot pad during locomotion.

Photodarkening in Yb-doped aluminosilicate fibers induced by 488 nm irradiation

Photodarkening of Yb-doped aluminosilicate fibers by continuous wave 488 nm irradiation was investigated. The irradiation induced significant excess loss in the UV-visible spectroscopy (VIS) region in Yb-doped aluminosilicate fibers while pure aluminosilicate fibers showed negligible induced loss. Ultraviolet-VIS-near-infrared spectroscopy revealed an absorption peak at 220 nm in unexposed Yb-doped aluminosilicate fiber preforms. The observed peak was attributed to Yb-associated oxygen deficiency centers (ODCs) and proposed as a precursor of the photodarkening. The proposed model was supported by measurements on oxygen-loaded Yb-doped aluminosilicate fibers. In these, the photodarkening could be significantly reduced, which we attribute to a smaller number of ODCs following oxygen loading.

Nanostructures of bismuth sulphide: synthesis and electrical properties

Bismuth ammonium citrate complex (C24H20Bi4O28 x 6NH3 x 10H2O) interacted with sodium sulphide (Na2S) in presence of beta-cyclodextrin (beta-CD) yielding Bi2S3 nanospheres. Solvothermal treatment of the bismuth complex and dimethyl sulphoxide (DMSO) produced Bi2S3 nanorods. Reaction conditions were optimized to investigate the morphology evolution of the product. Electrical properties of the nanorods were monitored in details.

Morphological modifications of selenium by recrystallization of its aqueous complex solutions

Recrystallization of elemental selenium (Se) from aqueous solution in presence of sodium sulphite (Na2SO3) and sodium sulphide (Na2S) acting as complexing agents has resulted in the formation of nano and microstructures of Se having five different morphological modifications. (1) An aqueous solution of sodium selenosulphate (Na2SO3Se) obtained by dissolving Se in Na2SO3 under refluxing condition yields hemispherical microcrystals. (2) The filtrate of the above reaction mixture on aging produces hexagonal prismatic microrods of Se. Addition of Na2SO3Se solution to formalin (HCHO) at room temperature and refluxing conditions generates (3) Se nanorods, and (4) spherical microcrystals, respectively. (5) Recrystallization of Se from aqueous solution of Na2S develops flower shaped microcrystals.

Nanorods of tellurium: synthesis and self-assembly

A simple solution phase approach is described to prepare tellurium nanorods which undergo morphological modifications to yield different microstructures under varied experimental conditions. The morphology of the prepared products is drastically altered in presence of a few oxidizing agents such as sodium oxychloride (NaOCl), hydrogen peroxide (H2O2) etc. The effects of poly (sodium 4-styrene sulphonate) (PSS) and Isooctyl phenoxy poly oxyethanol (TritonX-100) on the size and shape of the products in presence of air/NaOCl have also been monitored.

Pathogenicity of Xanthomonas translucens from Annual Bluegrass on Golf Course Putting Greens

Bacterial wilt of Poa annua has been seen increasingly in the Northeast and mid-Atlantic United States in the past few years. The disease causes severe injury to putting greens and can kill large stands of turfgrass. For some time, however, both the bacterial origin of the disease and the causal agent were in doubt. In order to investigate the identity of the causal agent, isolation of the pathogen was undertaken and pathogenicity was confirmed using Koch's postulates on P. annua. Additional pathogenicity trials then were undertaken to determine the host range of the causal bacterium. Ability of the bacterium to cause disease was restricted to P. annua var. annua and P. attenuata. However, the bacterium was able to survive asymptomatically in vascular systems of P. annua var. reptans and P. trivialis. Experiments to determine the optimal growth temperature of the organism demonstrated that the bacterial growth peaked between 30 and 35°C. Fatty acid analysis suggested that the bacterium might be a species of Xanthomonas but was inconclusive. Ribosomal RNA analysis demonstrated significant similarity to the American Type Culture Collection isolate of Xanthomonas translucens pv. poae at 99.8%. Comparison of the host range to previously reported data agrees with our molecular findings and indicates that the likely casual organism of bacterial wilt of annual bluegrass is X. translucens pv. poae.

Synthesis and studies on spectroscopic as well as electron donating properties of the two alkoxy benzo[b]thiophenes

Synthesis, characterization, steady state and time resolved, using time correlated single photon counting as well as laser flash photolysis techniques, spectroscopic investigations were made for two alkoxy benzo[b]thiophene molecules: 5-methoxy benzo[b]thiophene (5MBT) and 5-methoxymethyl benzo[b]thiophene (5MMBT). In both non-polar n-heptane (NH) and polar acetonitrile (ACN) solvents and at ambient temperature the electronic absorption spectra of these thiophenes exhibit different band systems whose assignments were made from the measurements of the steady state excitation polarization spectra. Steady state fluorescence spectra of these molecules in the different polarity solvents show the presence of non-specific interactions. From the redox properties of the benzothiophenes, measured by cyclic voltammetry, their electron donating properties were observed in the presence of the well-known electron acceptor 9cyanoanthracene (9CNA). Further, detailed studies by laser flash photolysis techniques show that ion-recombination mechanism predominates after the initial excitation of the acceptor moiety using the third harmonic of Nd:YAG laser. This recombination together with the external heavy atom effect (the donor containing 'sulphur' atom) appears to be responsible for the formation of the triplet of the monomeric acceptor 9CNA. From the steady state experiments it is shown that both in non-polar NH and highly polar ACN the quenching in the fluorescence emission of 9CNA in the presence of the benzothiophene donors is brought about primarily by the external heavy atom effect and in ACN, although the presence of the photoinduced ET reaction is confirmed, this process seems, from the observed bimolecular dynamic quenching rate, kq to be significantly masked by the external heavy atom effect.

Abundance of siderophages in sputum: indicator of an adverse lung reaction to air pollution

OBJECTIVE

To investigate the lung response to traffic-related air pollution by enumerating hemosiderin-laden alveolar macrophages (AM) in sputum.

STUDY DESIGN

Sputum samples were collected from 103 urban adult males from Calcutta chronically exposed to automobile exhaust. Forty-nine rural individuals served as controls. AM were identified by nonspecific esterase staining. Perl's Prussian blue technique was employed for the detection of hemosiderin-laden AM (siderophages).

RESULTS

The urban group, consisting of 31 traffic officers, 25 automobile service station workers and 47 street hawkers, had seven times more AM in their sputum than did the matched controls. Besides, a remarkable rise (27-fold) in the number of siderophages in sputum was observed in urban individuals. Smoking further elevated the AM count and number of siderophages.

CONCLUSION

Abundant siderophages in the urban group may indicate the toxic effect of airborne pollutants on the lung, leading to phagocytosis of destroyed cells, including erythrocytes, and accumulation of iron in AM. Enumeration of siderophages in sputum appears to be a simple, noninvasive, inexpensive cytochemical technique well suited to preliminary assessment of the adverse effects of air pollution on the lungs in large, population-based studies, especially in developing countries.

Technical Paper Recommendation: A Study in Combining Multiple Information Sources

The growing need to manage and exploit the proliferation of online data sources is opening up new opportunities for bringing people closer to the resources they need. For instance, consider a recommendation service through which researchers can receive daily pointers to journal papers in their fields of interest. We survey some of the known approaches to the problem of technical paper recommendation and ask how they can be extended to deal with multiple information sources. More specifically, we focus on a variant of this problem -- recommending conference paper submissions to reviewing committee members -- which offers us a testbed to try different approaches. Using WHIRL -- an information integration system -- we are able to implement different recommendation algorithms derived from information retrieval principles. We also use a novel autonomous procedure for gathering reviewer interest information from the Web. We evaluate our approach and compare it to other methods using preference data provided by members of the AAAI-98 conference reviewing committee along with data about the actual submissions.

Air pollution in Calcutta elicits adverse pulmonary reaction in children

BACKGROUND & OBJECTIVE

Pulmonary responses of children chronically exposed to ambient air pollution in Calcutta have been investigated.

METHODS

A total number of 153 children from Calcutta and 116 from rural West Bengal in the age group of 6-17 yr were included in this study. Respiratory symptom complex, sputum cytology and micronucleus (MN) count of buccal epithelial cells were evaluated. Blood smears were examined for WBC differential count and RBC morphology.

RESULTS

Marked rise in respiratory symptoms (43% in urban vs 14% in rural) and sputum alveolar macrophage (AM) number was observed in urban children compared to their rural counterparts (14.2 +/- 1.4 AM/hpf vs 6.7 +/- 1.4 AM/hpf, mean +/- SE, P < 0.001). The urban group also demonstrated increased numbers of neutrophils, eosinophils and iron-laden AM in their sputum. Besides, buccal epithelial cells of urban children exhibited higher MN frequency than their rural counterparts (0.22 vs 0.17%, P < 0.05). While sputum neutrophilia and eosinophilia suggest inflammatory and allergic lung reactions, elevated MN count is indicative of greater genotoxic effect on the exposed tissues of urban children. Hypochromic red cells in peripheral blood smear was a common finding in both urban and rural groups, but eosinophils and monocytes were present in elevated frequencies in the rural children.

INTERPRETATION & CONCLUSION

The study demonstrated that children inhaling grossly polluted air of Calcutta suffer from adverse lung reactions and genetic abnormality in the exposed tissues.

The 3-D monitor and head-mounted display. A quantitative evaluation of advanced laparoscopic viewing technologies

BACKGROUND

Stereoscopic (3-D) monitors and head-mounted displays have promised to facilitate laparoscopic surgery by increasing positional accuracy and decreasing operative time. To test this hypothesis, we evaluated the performance of subjects using these displays to perform standardized laparoscopic dexterity drills.

METHODS

Fifty laparoscopic novices worked within an abdominal cavity simulator using four videoscopic display configurations: (1) standard (2-D) monitor; (2) 3-D monitor; (3) 2-D head-mounted display; and (4) 3-D head-mounted display. Subjects repeated 3 standardized training exercises 2 times. We measured time to complete each drill and number of errors committed.

RESULTS

Mean total times to complete all 3 drills were 455, 459, 485, and 449 sec for configurations 1-4, respectively. Mean total errors committed numbered 11.3, 10.4, 12.3, and 10.8, respectively. Neither comparison reached statistical significance (p < 0.05). When 3-D configurations were compared to 2-D configurations overall, a small but statistically significant reduction in errors was noted for 1 drill only (4.3 vs 5.0, p = 0.018).

CONCLUSIONS

Three-dimensional imaging slightly reduced the number of errors committed by laparoscopic novices during one test drill; this improvement, however, was not clinically significant. Neither the 3-D monitor nor the head-mounted display decreased task performance time. Widespread adoption of this technology awaits future improvement in display resolution and ease of use.

Light chain contribution to specificity in anti-DNA antibodies

We studied mice expressing one of two H chain transgenes. Both transgenes expressed the same 3H9 anti-DNA VDJ, but differed in their constant domains. The IgM transgene efficiently induced tolerance and selected for a subset of endogenous L chains that prevented dsDNA binding. In contrast, the IgG2b secreted-only H chain allowed expression of a broad range of L chains, most of which yielded anti-dsDNA Ab. To deduce the features of L chains that affect DNA binding, we derived hybridomas from LPS-stimulated splenic B cells from the two transgene lines and compared the V kappa sequences of Ab they secreted. Identification of L chains with related sequences but different binding to ssDNA, dsDNA, and cardiolipin allowed us to pinpoint L chain residues that correlate with enhanced or reduced binding. Arginines at the junction of V kappa 1 or V kappa 8 regions and J kappa 1, and arginines or asparagines in CDR1 or CDR2 enhanced DNA binding. Negatively charged residues at the same positions were found to interfere with binding. Thus, we predict that appropriate amino acids at these positions may form contacts with DNA. The likely locations of contact residues in the combining site were evaluated by inspection of previously determined Ab structures. Our results indicate that L chains in anti-DNA Ab are able to modulate DNA binding and contribute contact sites for additional determinants on a complex autoantigen.

Light chain contribution to specificity in anti-DNA antibodies

We studied mice expressing one of two H chain transgenes. Both transgenes expressed the same 3H9 anti-DNA VDJ, but differed in their constant domains. The IgM transgene efficiently induced tolerance and selected for a subset of endogenous L chains that prevented dsDNA binding. In contrast, the IgG2b secreted-only H chain allowed expression of a broad range of L chains, most of which yielded anti-dsDNA Ab. To deduce the features of L chains that affect DNA binding, we derived hybridomas from LPS-stimulated splenic B cells from the two transgene lines and compared the V kappa sequences of Ab they secreted. Identification of L chains with related sequences but different binding to ssDNA, dsDNA, and cardiolipin allowed us to pinpoint L chain residues that correlate with enhanced or reduced binding. Arginines at the junction of V kappa 1 or V kappa 8 regions and J kappa 1, and arginines or asparagines in CDR1 or CDR2 enhanced DNA binding. Negatively charged residues at the same positions were found to interfere with binding. Thus, we predict that appropriate amino acids at these positions may form contacts with DNA. The likely locations of contact residues in the combining site were evaluated by inspection of previously determined Ab structures. Our results indicate that L chains in anti-DNA Ab are able to modulate DNA binding and contribute contact sites for additional determinants on a complex autoantigen.