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At least 235 records · Page 13Linked to original sources
PubMed1997

[Changes in individual profiles of cerebral hemispheric asymmetry during somatosensory stimulation due to wearing of G-suits by healthy adults and children].

Presented are results of the investigations of individual profiles of the brain interhemispheric asymmetry (IPIHA) in healthy grown-ups and children prior to, during, and immediately after somatosensory stimulation. The somatosensory stimulation was performed by one-time wearing of space g-loading suit PENGUIN and its modification ADELIE. IPIHA was studied by the main functional asymmetries including motor hand asymmetry, sensory asymmetry of the visual hemispheres, body mass center asymmetry (BMA) using a computerized stabilimeter indirectly measuring the muscle tone of contralateral extensor. Results demonstrate differences in IPIHA of grown-ups and children, persons with right- and left-hand motor asymmetry. It was shown that peculiar features of standing posture acquisition with and without visual control are original IPIHA and age dependent. Initial stability was higher in grown-ups than children and right-handed grown-ups and left-handed children. IPIHA and stability of the vertical posture can be modified even during single somatosensory stimulation. Unequal effects of the somatosensory stimulation on IPIHA in right- and left-handed subjects of varying age dictate the necessity to allow for these differences when assessing effects of the somatosensory stimulation in grown-ups and developing criteria of effective therapy of patients with CNS pathology, specifically, infantile cerebral paralysis.

Adolescent↗
PubMed2002

Fourier analysis reveals increased trabecular spacing in sickle cell anemia.

Sickle cell anemia may expand marrow spaces in the jaws. Fourier analysis is well-suited to the analysis of trabecular spacing in radiographs. We hypothesize that individuals with sickle cell anemia demonstrate increased intertrabecular spacing. Periapical radiographs of 18 African Americans with sickle cell disease and 18 controls were examined by one-dimensional discrete Fourier analyses in both jaws for measurement of the spatial frequency distribution of repeating trabecular structures. A strut analysis of trabeculae was also performed and the results compared. Trabecular structures in individuals with sickle cell anemia revealed increased intertrabecular distance compared with controls. Strut analysis revealed significant reductions in trabecular complexity. Fourier analysis allows for the classification of subjects with 94% sensitivity and specificity. Fourier analysis of dental radiographs is a more effective method of identifying individuals with sickle cell anemia than strut analysis.

Adult↗
PubMed1990

Effectiveness of the Space Shuttle anti-exposure system in a cold water environment.

The purpose of this study was to evaluate the National Aeronautics and Space Administration (NASA) Space Shuttle Launch Entry Suit (LES) and raft for 24 h of protection against cold water immersion. Two configurations, the LES and the LES with raft (Navy LRU-18/U with NASA spray shield) were evaluated for anti-exposure protection. Conditions were selected to simulate worst case water and air temperatures along projected Space Shuttle ground tracks; i.e., water temperatures = 4.4 degrees C (40 degrees F), air temperature = 5.6 degrees C (42 degrees F), 1 foot waves (chop), and constant spray. Four males, 31-44 years of age, and one 32-year-old female, were studied once in each configuration. Trials with and without a raft were scheduled for up to 24 and 6 h, respectively. Mean LES trial durations were 150 +/- 9 min and final rectal temperature (Tre, f) = 36.5 +/- 0.3 degrees C. Mean LES with raft (LES/r) trial durations were 398 +/- 126 min and final rectal temperature (Tre, f) = 35.6 +/- 0.4 degrees C. LES and LES/r trials were terminated for reaching Tre = 35.0 degrees C or subject-requested termination due to discomfort. The longest LES and LES/r trials were terminated due to subject discomfort. Although not achieving the desired durations, the LES and LES/r did prove capable of protecting individuals, respectively, for up to 3 and 13.5 h. Since the longest LES and LES/r runs were terminated due to subjective tolerance and not physical incapacitation, actual survival times greater than 3 and 13.5 h, respectively, could be expected for individuals in these ensembles.

Adult↗
PubMed1981

Brain space for a learned task.

Forty-six adult male and female canaries were sacrificed, their brains were weighed and the volume of several brain nuclei reconstructed from the cresyl violet-stained material. Two forebrain vocal control nuclei, hyperstriatum ventrale, pars caudale (HVc) and nucleus robustus archistriatalis (RA), were approximately 4 and 3 times larger, respectively, in males than in females, confirming previous findings. There was no consistent right-left asymmetry in the volume of these nuclei in males and females. Twenty-five male birds in this study had their song repertoire recorded during the peak of the singing season. They were sacrificed 3 to 4 months later. The size of the song repertoire, measured as number of different syllable types, showed a positive and significant correlation with the size of HVc and RA. There was no significant correlation between size of the syllable repertoire and age, brain weight or the volume of two brain nuclei not involved in song control. This is the first time that the amount of brain allotted to a specific learned skill has been shown to correlate positively with the amount of that skill that is learned. Interestingly, too, there was a positive and significant correlation between testis weight at the end of the breeding season and the volume of RA at that time, suggesting a hormone-mediated seasonal modulation of part of the brain space occupied by song control pathways. This material seems well suited for studying the relation between space and learning, and the manner in which this relation is influenced by gonadal hormones.

Animals↗
PubMed1999

Color spaces of color-normal and color-abnormal observers reconstructed from response times and dissimilarity ratings.

With multidimensional scaling analysis, color spaces were reconstructed from reaction times (RTs) required to make same-different judgements of pairs of 15 equiluminant colors and from dissimilarity ratings between them. In addition to normal trichromats, observers with red-green color deficiency were tested. Two main purposes were served by this study: (1) to compare spatial representations of colors derived from discriminative RTs with those derived from dissimilarity measures and (2) to examine whether the task may selectively affect the dimension reflecting, in color-abnormal spaces, the deficient red-green mechanism. Contradicting our hypothesis of lower dimensionality of RT spaces, as compared with rating spaces, no consistent differences in solution dimensionality were found. However, configurations derived from the two measures diverged. The rating procedure yielded the most logical results for recovering color space. The RT configuration revealed contraction in the tritanopic direction, indicating longer color processing when the short-wavelength mechanism is involved, and in addition, for color-abnormal observers, clustering in the protanopic and deuteranopic directions, indicating even longer processing by the deficient red-green mechanism. This finding implies that RTs are suitable for detecting temporal differences in color processing but, for that very same reason, rather ill-suited for reconstructing color spaces.

Adult↗
PubMedDate not supplied

[Human calorimetry in sealed hermetic enclosures].

The paper gives the results of an experimental assessment of personal biocalorimeter and calorimetric garment. The paper is addressed to biologists, physiologists and physicians investigating heat exchange and thermal regulation of the human body as well as to thephysicists developing calorimetric theories and methods. It presents theoretical concepts underlying direct calorimetry of a suited man and contains a block-diagram of the biocalorimeter that was used to examine energy parameters of the human body, including metabolic rate, heat production, heat release and heat balance. The data obtained were statistically treated and heat effects were characterized by empiric expressions. It was for the first time in medical practice that the personal calorimeter and calorimetric garment made it possible to accumulate information on the thermal state of the human body. This information helps to diagnose the health condition of man, to standardise environmental parameters in aviation, space and such like suits and to automatize their maintenance in experimental and real life situations.

Body Temperature Regulation↗
PubMed2001

Simulated shuttle egress: role of helmet visor position during approach and landing.

BACKGROUND: We previously reported that carbon dioxide (CO2) rapidly accumulates in the helmet of the NASA Launch and Entry Suit (LES) during a simulated egress from the Space Shuttle following 6 min of visor-closed seated rest to simulate approach and landing. The purpose of this study was to determine if CO2 accumulation and walking time in the LES would be improved by helmet visor-open rather than visor-closed seated rest prior to the performance of the simulated egress. METHODS: Wearing the LES, 12 male subjects performed 4 laboratory egress simulations consisting of 6-min seated rest, 2-min stand, and 5-min walk at 1.56 m x s(-1) (3.5 mph). During seated rest, subjects sat either with the visor open, breathing room air until the visor was closed on standing, or with the visor closed for the duration of the simulation. For all visor-closed operations 100%, O2 was supplied. The G-suit was either deflated (0.0 psi) or inflated to 1.5 psi. Inspired CO2 and walking time were measured. Data were analyzed at the end of seated rest, standing, and after 5 min of walking at 0.0 psi or after 2 min of walking at 1.5 psi (>90% of data available). RESULTS: Walk time was not different following visor-open (0.0 psi: 5.0 +/- 0.0; 1.5 psi: 3.4 +/- 0.3 min) or visor-closed (0.0 psi: 4.8 +/- 0.2; 1.5 psi: 3.5 +/- 0.4 min) seated rest at either G-suit pressure. Inspired CO2 levels were not different between the two conditions during walking at 5 min at 0.0 psi (p = 0.50; Open: 4.39 +/- 0.14; Closed: 4.48 +/- 0.18%) or at 2 min at 1.5 psi (p = 0.53; Open: 3.59 +/- 0.12; Closed: 3.65 + 0.21%). CONCLUSIONS: Visor position during seated rest immediately preceding the egress walk had no effect on inspired CO2 or walking time.

Adult↗
PubMed1996

Crystallographic Analysis of Antigen-Antibody Complexes: End-on Insertion of Ligands in Antibodies-CDR3 Loops as Arbiters

As the dominant constituents of the active sites, complementarity-determining regions (CDRs) and particularly the CDR3 loops strongly influence the size and shape of this interdomain space. Six sets of CDR3 loops were extracted from our collection of crystal structures and examined for their modes of association. The CDR3 loops of the NC6.8 Fab face each other across a small crevice that is expanded further by end-on insertion of its high-affinity ligand (a trisubstituted guanidine sweet-tasting compound). This wedging event triggers a series of extensive local and transmitted conformational changes. In the 4-4-20 Fab, the CDR3 loops provide scaffolding for the high-affinity binding of fluorescein and shield the ligand from bulk solvent in the interdomain space above and below the very compact binding slot. Constituents of the CDR2 and CDR3 loops of the BV04-01 Fab interact to form "false floors" over potential cavity-type sites and thereby eliminate end-on insertion. Instead, fragments of single-stranded DNA are bound with low affinity in a groove whose course is altered on complex formation by global movements of VH relative to VL and by local shifts of HCDR3. Trafficking of even small peptide ligands between the V domains of the Pot Fv is prevented by the collapse of the large HCDR3 segment into the residual interdomain space. This protein is better suited to polyreactive binding of a variety of large protein antigens on its external surfaces. By comparison, the space available between the CDR3 loops of the Mcg light-chain dimer is very large. It has proved to be accessible for end-on insertion of peptides and other ligands ranging over seven orders of magnitude in affinity. Recently, an insect neuropeptide hormone, with pGlu as its penetrating agent, has been found to pierce the entire V dimer interface from the entrance of the traditional active site to the solvent pool between the V and C domains. In an Mcg x Hud heterodimer, the Hud CDR3 plays a role similar to that of the Pot H chain and blocks access to the interdomain space by close interactions with the CDR3 of Mcg.

Journal Article↗
PubMed2004

Fizeau interferometer for global astrometry in space.

We discuss the design and the performance of a Fizeau interferometer with a long focal length and a large field of view that is well suited for a global astrometry space mission. Our work focuses on the geometric optimization and minimization of aberration of such an astrometric interferometer, which is able to observe astronomical targets down to the visual magnitude (mag) mv = 20 mag, with an accuracy in the measurements of 10 micro-arcseconds at mv = 15 mag. We assume a mission profile similar to that of the Global Astrometric Interferometer for Astrophysics mission of the European Space Agency. In this framework, data acquisition is performed by an array of CCDs working in time-delay integration mode. Optical aberrations, particularly distortion and coma, play a crucial role in the efficiency of this technique. We present a design solution that meets the requirements for the best possible exploitation of the time-delay integration mode over a field of view of 0.7 degrees x 0.7 degrees.

Journal Article↗
PubMed2004

A modular suite of hardware enabling spaceflight cell culture research.

BioServe Space Technologies, a NASA Research Partnership Center (RPC), has developed and operated various middeck payloads launched on 23 shuttle missions since 1991 in support of commercial space biotechnology projects. Modular cell culture systems are contained within the Commercial Generic Bioprocessing Apparatus (CGBA) suite of flight-qualified hardware, compatible with Space Shuttle, SPACEHAB, Spacelab and International Space Station (ISS) EXPRESS Rack interfaces. As part of the CGBA family, the Isothermal Containment Module (ICM) incubator provides thermal control, data acquisition and experiment manipulation capabilities, including accelerometer launch detection for automated activation and thermal profiling for culture incubation and sample preservation. The ICM can accommodate up to 8 individually controlled temperature zones. Command and telemetry capabilities allow real-time downlink of data and video permitting remote payload operation and ground control synchronization. Individual cell culture experiments can be accommodated in a variety of devices ranging from 'microgravity test tubes' or standard 100 mm Petri dishes, to complex, fed-batch bioreactors with automated culture feeding, waste removal and multiple sample draws. Up to 3 levels of containment can be achieved for chemical fixative addition, and passive gas exchange can be provided through hydrophobic membranes. Many additional options exist for designing customized hardware depending on specific science requirements.

Bioreactors↗
PubMed1996

Cryopreservation of anchorage-dependent mammalian cells fixed to structured glass and silicon substrates.

This paper describes a procedure for the cryopreservation of anchorage-dependent cells in a predefined position on microstructured glass or silicon substrates. During freezing and thawing, cells retain their location on the substrate, and an individual comparison and identification of cells before and after preservation are possible. To utilize this advantage, a good adherence and a high survival rate are important. It can be shown that adhesion of mouse fibroblasts (NIH-3T3) to substrate strongly influences the survival rate: 94% of cells grown for 16 h before freezing were judged to be alive after thawing. Widely spaced cells are best suited to cryopreservation on substrates. The different patterns of adhesion of cells to substrates when incubated for 1, 3, 6, and 16 h, were visualized by total internal reflection microscopy (TIRM).

3T3 Cells↗
PubMed2002

SnapDRAGON: a method to delineate protein structural domains from sequence data.

We describe a method to identify protein domain boundaries from sequence information alone based on the assumption that hydrophobic residues cluster together in space. SnapDRAGON is a suite of programs developed to predict domain boundaries based on the consistency observed in a set of alternative ab initio three-dimensional (3D) models generated for a given protein multiple sequence alignment. This is achieved by running a distance geometry-based folding technique in conjunction with a 3D-domain assignment algorithm. The overall accuracy of our method in predicting the number of domains for a non-redundant data set of 414 multiple alignments, representing 185 single and 231 multiple-domain proteins, is 72.4 %. Using domain linker regions observed in the tertiary structures associated with each query alignment as the standard of truth, inter-domain boundary positions are delineated with an accuracy of 63.9 % for proteins comprising continuous domains only, and 35.4 % for proteins with discontinuous domains. Overall, domain boundaries are delineated with an accuracy of 51.8 %. The prediction accuracy values are independent of the pair-wise sequence similarities within each of the alignments. These results demonstrate the capability of our method to delineate domains in protein sequences associated with a wide variety of structural domain organisation.

Algorithms↗
PubMed2006

Multiresolution phase retrieval in the fresnel region by use of wavelet transform.

A multiresolution (multiscale) analysis based on wavelet transform is applied to the problem of optical phase retrieval from the intensity measured in the in-line geometry (lens-free). The transport-of-intensity equation and the Fresnel diffraction integral are approximated in terms of a wavelet basis. A solution to the phase retrieval problem can be efficiently found in both cases using the multiresolution concept. Due to the hierarchical nature of wavelet spaces, wavelets are well suited to multiresolution methods that contain multigrid algorithms. Appropriate wavelet bases for the best solution approximation are discussed. The proposed approach reduces the computational complexity and accelerates the convergence of the solution. It is robust and reliable, and successful on both simulated and experimental images obtained with hard x rays.

Algorithms↗
PubMed2002

Planning library spaces to encourage collaboration.

Most librarians can give examples from their own experience in which a library's physical space was either ill suited to the work to be performed or, in some unfortunate cases, a genuine barrier to productivity. In an effort to correct or avoid these situations, planners of library renovations or new construction make pre-design studies of individual workers' tasks and workflow at the work-unit level. In this article, the authors discuss how a pre-design review of library and institutional values influenced the course of a library renovation. The identification of collaboration as the major theme of the library and the institution's strategic directions drove renovation decisions and resulted in a facility that supports and promotes this concept.

Cooperative Behavior↗