ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • SOLAR PHYSICS  (83)
  • Life and Medical Sciences  (59)
  • STRUCTURAL MECHANICS
  • 1980-1984  (189)
  • 1970-1974
  • 1984  (189)
Collection
Publisher
Years
  • 1980-1984  (189)
  • 1970-1974
Year
  • 1
    ISSN: 0148-7280
    Keywords: spermatozoa ; flow cytometry ; DNA staining ; nuclear morphology ; ultrastructure ; mammals ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The morphological and ultrastructural changes that occur during preparation of porcine, bovine, and murine spermatozoa for flow cytometric quantification of the relative DNA content of the X- and Y-chromosome-bearing sperm populations were examined. Ejaculated spermatozoa from the boar and bull were washed using a series of dimethyl sulfoxide (DMSO) solutions prior to fixation, whereas the epididymal mouse spermatozoa were washed only in phosphate-buffered saline (PBS). Spermatozoa from all three species were then fixed in ethanol and processed for fluorochrome staining by a treatment regimen consisting of sulfhydryl reduction and proteolysis. The processed sperm nuclei were stained for DNA with the fluorochrome, 4′-6-diamidino-2-phenylindole (DAPI) before quantification by flow cytometry. Scanning and transmission electron micrographs of sperm heads taken at various steps of the preparation and staining procedures show 1) that the rigorous washing procedure disrupted the plasma and outer acrosomal membranes, 2) that ethanol fixation resulted in removal of the outer membranes and disintegration of the nuclear envelope, and 3) that thiol and proteolysis treatment removed the remaining cellular organelles including the tail and rapidly induced partial decondensation of the tightly packed chromatin. Sequential micrographs showed that the nuclear matrix of all three species increased in thickness about twofold during the preparation and staining. Consequently, the harsh procedures currently used for quantitative staining of DNA for high-resolution flow cytometric analyses destroy most cellular organelles and thereby prevent simultaneous characterization of DNA content and other sperm cell constituents.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 180 (1984), S. 29-35 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study describes intercellular bridges in the ovaries of neonatal gerbils. Electron microscopy has revealed the presence of true intercellular bridges, connecting oogonia or oocytes, in ovaries of newborn gerbils. The cytoplasm of the intercellular channels is similar to that of the connected cells, with mitochondria, smooth and rough endoplasmic reticulum, and free ribosomes present. Lysosomes are also occasionally present in the intercellular bridges and they may be involved in early waves of oocyte atresia. An electrondense substance, 350-500 Å thick, is located immediately beneath the unit membrane of the intercellular bridges. Accumulation of electron-dense material increases the thickness of the walls of the intercellular bridges, supporting and maintaining the patency of the channels. It is suggested that the intercellular channels probably allow the interchange of nutrients, organelles, and possibly regulatory materials as well.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 180 (1984), S. 243-252 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A small short muscle frequently acts across a joint in parallel with a vastly larger and longer muscle; therefore it should play a minimal role in the mechanical control of that joint. This study provides evidence suggesting that the small member of such a “parallel muscle combination” (PMC) may serve an important sensory feedback role. The spindle densities of large and small members of PMCs in man and the dog were determined and compared. Epaxial PMCs controlling canine intervertebral joints were dissected and tissue samples were embedded in paraffin, sectioned transversely to the muscles' long axis and, stained with hematoxylin-periodic acid-Schiff (PAS). Representative tissue sections were projected on to stereological grids and the percentage volume of spindles was determined. Data existing in the literature were used to ascertain spindle densities in human PMCs controlling joints in the cervico-occipital region and the extremities. The spindle density for each muscle in a group of PMCs controlling a particular motion was listed, and the mean spindle densities were determined for both the large and the small members of the group. Student's unpaired t test was used to determine the significance of the differences between mean spindle densities. Linear regression was calculated and the data were plotted graphically.In all PMCs examined, the spindle density of the small muscles was significantly higher than that of their large counterparts. It is therefore proposed that the small muscles of PMCs may function as “kinesiological monitors” generating important proprioceptive feedback to the central nervous system.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 1 (1984), S. 299-309 
    ISSN: 0741-0581
    Keywords: Electron microscopy ; Ion microscopy ; Correlative microscopy ; Electron probe microanalysis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: In order to correctly interpret the chemical images obtained using ion microscopy (IM), it is useful to correlate them with the information provided by conventional light microscopy (LM), secondary electron imaging (SEI), backscattered electron imaging (BEI), and electron probe microanalysis (EPMA). Accordingly, we have devised a technique of specimen preparation which allows for the application of several different microanalytical techniques to a single histologic section mounted on the same substrate. Sections are cut onto polyester plastic coverslips (devoid of peaks for any element with atomic number 〉 9 using EPMA) and studied by LM. After a light rotary coating with carbon (to prevent charging), the section can then be examined by SEI, BEI, and EPMA. Specific areas can be marked for IM study either with an objective-mounted pin tissue microlocater, or by placing small pieces of metal foil, cut in specific geometric shapes, over features of interest. After sputter-coating the sample with platinum, metal-free shadows are visible using a low-power reflected light microscope available on a typical IM sample chamber as a guide for ion beam placement. The conductive coatings also minimize specimen charging during IM. Post-IM light microscopy, SEI, and BEI are used to confirm the location of specific areas probed in the IM experiments and to provide information on differential ion-sputtering artifacts and tissue contaminants. This new correlative technique should permit better understanding of the images obtained with these diverse instruments.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 5 (1984), S. 101-112 
    ISSN: 0197-8462
    Keywords: 60-Hz electric fields ; rats ; behavior ; teratology ; growth ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: A series of three experiments was performed to determine the effects of 30-day exposures to uniform 60-Hz electric fields (100 kV/m) on reproduction and on growth and development in the fetuses and offspring of rats. In the first experiment, exposure of females for 6 days prior to and during the mating period did not affect their reproductive performance, and continued exposure through 20 days of gestation (dg) did not affect the viability, size, or morphology of their fetuses. In the second experiment, exposure of the pregnant rat was begun on 0 dg and continued until the resulting offspring reached 8 days of age. In the third experiment, exposure began at 17 dg and continued through 25 days of postnatal life. In the second and third experiments, no statistically significant differences suggesting impairment of the growth or survival of exposed offspring were detected. In the second experiment, a significantly greater percentage of the exposed offspring showed movement, standing, and grooming at 14 days of age than among-sham-exposed offspring. There was a significant decrease at 14 days in the percentage of exposed offspring displaying the righting reflex in the second experiment and negative geotropism in the third experiment. These differences were all transient and were not found when the animals were tested again at 21 days of age. Evaluation of the reproductive integrity of the offspring of the second experiment did not disclose any deficits.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Publication Date: 2011-08-19
    Description: Low-noise (S/N greater than 100), high spectral resolution observations of two pure rotation transitions of OH from the solar photosphere are used to make inferences concerning the thermal structure and inhomogeneity of the upper photosphere. It is found that the v = O R22(24.5)e line strengthens at the solar limb, in contradiction to the predictions of current one-dimensional photospheric models. The results for this line support a two-dimensional model in which horizontal thermal fluctuations in the upper photosphere are of the order plus or minus 800 K. This thermal bifurcation may be maintained by the presence of magnetic flux tubes and may be related to the solar limb extensions observed in the 30-200-micron region.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 94; 57-74
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Publication Date: 2011-08-18
    Description: An analysis is made of interplanetary tangential and rotational solar wind discontinuities (TD and RD) and comparisons are made between the features of RDs and TDs. An ISEE 3 field and positive ion data set from 1978 includes high time resolution magnetometer data and is used for the comparisons, as are data from a positive ion analyzer. The field magnitude of RDs remains constant as the field rotates, while that of a TD passes through a local minimum. First and second adiabatic invariants for protons and He abundances are usually also conserved for RDs but not for TDs. The velocity change for an RD across a discontinuity is smaller than that predicted by MHD theory. Finally, plasma conditions at a discontinuity more closely resemble RDs than TDs.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 89; 5395-540
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Publication Date: 2019-01-25
    Description: Transient vibration test criteria, developed for spacecraft hardware, provide a test rationale to verify the capability of the hardware to withstand the low and mid frequency transient vibration environments induced by launch vehicle events. A test method, consisting of a series of discrete frequency, limited cycle, modulated sine wave pulses, was developed to avoid the slow swept sine drawbacks, yet provide a repeatable test that would excite all frequencies. The shape of the waveform is that of the classic response of the mass of a one degree of freedom system when it is base-excited by an exponentially decayed sine wave transient. Criteria were developed to define pulse amplitudes, shapes, and center frequencies from spacecraft loads analyses. Test tolerance criteria were also developed and specified. The transient vibration test criteria were implemented on spacecraft flight hardware and provided a more realistic test simulation (i.e., less conservative) for qualification of spacecraft hardware without risk of undertest.
    Keywords: STRUCTURAL MECHANICS
    Type: Shock and Vibration Information Center The Shock and Vibration Bull. 54, Pt. 3; p 99-110
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Publication Date: 2019-06-28
    Description: The decomposition of solar oscillations into their constituent normal modes requires a knowledge of both the spatial and temporal variation of the perturbation to the Sun's surface. The task is especially difficult when only limited spatial information is available. Observations of the limb darkening function, for example, are probably sensitive to too large a number of modes to permit most of the modes to be identified in a power spectrum of measurements at only a few points on the limb, unless the results are combined with other data. A procedure was considered by which the contributions from quite small groups of modes to spatially well resolved data obtained at any instant can be extracted from the remaining modes. Combining these results with frequency information then permits the modes to be identified, at least if their frequencies are low enough to ensure that modes of high degree do not contribute substantially to the signal.
    Keywords: SOLAR PHYSICS
    Type: NASA-CR-173667 , NAS 1.26:173667
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Publication Date: 2019-06-28
    Description: Low energy electron measurements collected by ISEE 1 reveal the frequent presence of field-aligned fluxes of few hundred eV electrons in he geomagnetic tail lobes. In the northern tail lobe these electrons are most prominent when the interplanetary magnetic field is directed away from the Sun. This characteristic helps identify the electrons as polar rain electrons. By mapping the tail lobe velocity distribution function into the solar wind, previous suggestions that the polar rain is indeed of solar wind origin and is due to the access of electrons to the magnetotail lobe were confirmed. It was demonstrated that the moe energetic component of the polar rain is composed of electrons from the solar wind strahl - a field-aligned component of the solar wind which is difficult to measure but which is thought to be caused by the collisionless transit of hundred eV electrons from the inner solar corona to 1 AU.
    Keywords: SOLAR PHYSICS
    Type: NASA-TM-86150 , NAS 1.15:86150
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...