Showing papers by "University of Bordeaux published in 1993"
TL;DR: Clinical, mechanographic and electromyographic results demonstrate that this technique can alleviate parkinsonian rigidity and bradykinesia without causing dyskinesIA or hemiballismus, and suggests that high‐frequency stimulation of the subthalamic nucleus could be included in treatment for parkinsonism.
Abstract: In Parkinson's disease the loss of dopaminergic neurons in the substantia nigra is associated with global disorganization of basal ganglia activity and, in particular, with increased activity of the excitatory glutamatergic neurons of the subthalamic nucleus. Recent experimental studies have shown that parkinsonian symptoms can be alleviated by selective lesioning of the subthalamic nucleus in monkeys treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). We measured the effect of high-frequency stimulation of the subthalamic nucleus in two unilaterally MPTP-treated monkeys in order to determine whether it was possible to obtain reversible, gradual and controllable functional impairment of this structure. Clinical, mechanographic and electromyographic results demonstrate that this technique can alleviate parkinsonian rigidity and bradykinesia without causing dyskinesia or hemiballismus. This study supports the hypothesis that the subthalamic nucleus and its excitatory projections have an important role in the mechanisms sustaining the expression of parkinsonian motor changes, and suggests that high-frequency stimulation of the subthalamic nucleus could be included in treatment for parkinsonism.
617 citations
TL;DR: The environmental (behavioral) factors that brought about the decline in postcranial robusticity in Homo are ultimately linked to increases in brain size and cultural-technological advances, although changes in robusticity lag behind changes in cognitive capabilities.
Abstract: Temporal trends in postcranial robusticity within the genus Homo are explored by comparing cross-sectional diaphyseal and articular properties of the femur, and to a more limited extent, the humerus, in samples of Recent and earlier Homo. Using both theoretical mechanical models and empirical observations within Recent humans, scaling relationships between structural properties and bone length are developed. The influence of body shape on these relationships is considered. These scaling factors are then used to standardize structural properties for comparisons with pre-Recent Homo (Homo sp. and H. erectus, archaic H. sapiens, and early modern H. sapiens). Results of the comparisons lead to the following conclusions: 1) There has been a consistent, exponentially increasing decline in diaphyseal robusticity within Homo that has continued from the early Pleistocene through living humans. Early modern H. sapiens are closer in shaft robusticity to archaic H. sapiens than they are to Recent humans. The increase in diaphyseal robusticity in earlier Homo is a result of both medullary contraction and periosteal expansion relative to Recent humans. 2) There has been no similar temporal decline in articular robusticity within Homo--relative femoral head size is similar in all groups and time periods. Thus, articular to shaft proportions are different in pre-Recent and Recent Homo. 3) These findings are most consistent with a mechanical explanation (declining mechanical loading of the postcranium), that acted primarily through developmental rather than genetic means. The environmental (behavioral) factors that brought about the decline in postcranial robusticity in Homo are ultimately linked to increases in brain size and cultural-technological advances, although changes in robusticity lag behind changes in cognitive capabilities.
544 citations
TL;DR: A new method is presented that allows the efficient computation of both the minimal cuts of a fault tree and the probability of its root event and results in a qualitative and quantitative improvement in safety analysis of industrial systems.
453 citations
TL;DR: It is shown that corticosterone has reinforcing properties, as evidenced by the development of intravenous self-administration, there are individual differences in cortic testosterone self-Administration, which are related to individual reactivity to novelty and sensitivity to drugs of abuse, behavioral features akin to certain traits of high-sensation seekers.
Abstract: In both humans and animals certain individuals seek stimuli or situations that are considered stressful and consequently avoided by others. A common feature of such situations is an activation of the hypothalamo-pituitary-adrenal axis leading to secretion of glucocorticoids. Since glucocorticoids have euphoric effects in some individuals and have been shown to potentiate the reinforcing properties of drugs of abuse in animals, we hypothesized that corticosterone secretion during stress-like situations may have reinforcing effects and that a higher sensitivity to the reinforcing effects of glucocorticoids might be a biological basis of sensation seeking. In this report we show that (i) corticosterone has reinforcing properties, as evidenced by the development of intravenous self-administration, (ii) self-administration of corticosterone is observed at plasma levels that are comparable to those induced by stress, and (iii) there are individual differences in corticosterone self-administration, which are related to individual reactivity to novelty and sensitivity to drugs of abuse, behavioral features akin to certain traits of high-sensation seekers. These findings provide insight into the physiological role of glucocorticoids and the biology of sensation seeking and may have clinical implications.
316 citations
TL;DR: The ultimate aim of these investigations on plasticity would be to correlate the observed structural and functional changes and to understand the way these changes are brought about by use and disuse.
282 citations
TL;DR: An in vitro technique based on rainbow trout hepatocytes incubated in a basic medium free of any additional growth factors or estrogenic chemicals and uses the production of vitellogenin as a marker for the estrogenic potency of the compounds tested can provide complementary results about the activity of chemicals which need an hepatic metabolization to be estrogenic.
281 citations
TL;DR: In this article, a single molecule was detected by tuning a single-frequency laser in the inhomogeneously broadened fluorescence excitation band of a dilute dispersion of pentacene in a host crystal of p-terphenyl.
Abstract: MAGNETIC resonance spectroscopy1 is a powerful tool for molecular characterization and structure determination. The sensitivity of conventional approaches is limited to about 1010 electron spins or 1016 nuclear spins; this sensitivity can be improved to about 105 spins by polarizing the spins via optical pumping and detecting optical rather than microwave photons2. Recently, fluorescence from single molecules was detected by tuning a single-frequency laser in the inhomogeneously broadened fluorescence excitation band of a dilute dispersion of pentacene in a host crystal of p-terphenyl3,4. Here we report that, by combining single-molecule fluorescence spectroscopy with optically detected magnetic resonance for the pentacene-doped p-terphenyl system, we can detect magnetic resonance in a single pentacene molecule. We observe two of the three possible transitions between sublevels of the metastable triplet state. The spectral lineshapes indicate that the proton nuclear spin states change during the measurement, leading to spectral diffusion within the magnetic resonance line.
277 citations
TL;DR: The LiNiO2LiCoO2 system exhibits a complete solid solution as discussed by the authors and the highest specific energy (close to 500 W h/kg) is obtained in the LixNi0.7Co0.3O 2 system.
272 citations
TL;DR: Regression analysis showed that stress-induced changes in DA levels accounted for 75% of the variance observed in the locomotor response to a novel environment, suggesting that this biochemical modification may be one neurobiological substrate of the predisposition to acquire psychostimulant self-administration.
263 citations
TL;DR: A yeast strain with a weak SCD activity has been selected and its use in vinification should eliminate the appearance of the phenolic taint in white wines coming from grapes rich in decarboxylable hydroxycinnamic acids.
Abstract: Vinylphenols (4-vinylphenol and 4-vinylguaiacol) are natural constituents of wine and can play a role in wine aroma. However, only white wines contain important quantities of these volatile substances which, beyond a certain concentration (limit threshold = 725 μg litre−1 of 4-vinylguaiacol+4-vinylphenol (1:1)), can be responsible for a depreciating ‘phenolic’ or ‘pharmaceutic’ characteristic, Saccharomyces cerevisiae possesses a type-(E) enzymic activity, substituted cinnamate carboxy-lyase (SCD), which is capable of transforming, by non-oxidative decarboxylation, the phenolic acids in the must, (E) p-coumaric and (E) ferulic acids, into corresponding vinylphenols. This endocellular activity is constitutive, it is only expressed during alcoholic fermentation and with a variable intensity depending on the yeast strain. Furthermore, the enzyme is rapidly inhibited by catechic tannins, which explains why, in comparison with white wines, red and rose wines contain low levels of vinylphenols despite having more precursors. A yeast strain with a weak SCD activity has been selected and its use in vinification should eliminate the appearance of the phenolic taint in white wines coming from grapes rich in decarboxylable hydroxycinnamic acids.
238 citations
TL;DR: Although the reservoir is well known, the routes of infection are still poorly understood: Are they oral-oral or fecal-oral?
TL;DR: The combination of HIV-1-infected cells in breastmilk and a defective IgM response was the strongest predictor of infection, and IgM and IgA anti-HIV-1 in Breastmilk may protect against postnatal transmission of the virus.
TL;DR: It is concluded that TENS should be used as a short‐term analgesic procedure in a multidisciplinary program for low back pain rather than as an exclusive or long‐term treatment.
Abstract: Although high-frequency low-intensity transcutaneous electric nerve stimulation (TENS) has been extensively used to relieve low back pain, experimental studies of its effectiveness have yielded contradictory findings mainly due to methodological problems in pain evaluation and placebo control. In the present study, separate visual analog scales (VAS) were used to measure the sensory-discriminative and motivational-affective components of low back pain. Forty-two subjects were randomly assigned to 1 of 3 groups: TENS, placebo-TENS, and no treatment (control). In order to measure the short-term effect of TENS, VAS pain ratings were taken before and after each treatment session. Also, to measure long-term effects, patients rated their pain at home every 2 h throughout a 3-day period before and 1 week, 3 months and 6 months after the treatment sessions. In comparing the pain evaluations made immediately before and after each treatment session, TENS and placebo-TENS significantly reduced both the intensity and unpleasantness of chronic low back pain. TENS was significantly more efficient than placebo-TENS in reducing pain intensity but not pain unpleasantness. TENS also produced a significant additive effect over repetitive treatment sessions for pain intensity and relative pain unpleasantness. This additive effect was not found for placebo-TENS. When evaluated at home, pain intensity was significantly reduced more by TENS than placebo-TENS 1 week after the end of treatment, but not 3 months and 6 months later. At home evaluation of pain unpleasantness in the TENS group was never different from the placebo-TENS group.(ABSTRACT TRUNCATED AT 250 WORDS)
Abstract: The structural preferences of peptides (and depsipeptides) from the achiral MeAib and Hib residues, and the chiral Iva, (alpha Me) Val, (alpha Me) Leu, and (alpha Me) Phe residues, as determined by conformational energy computations, x-ray diffraction analyses, and 1H-nmr and spectroscopic studies, are reviewed and compared with literature data on Aib-containing peptides. The results obtained indicate that helical structures are preferentially adopted by peptides rich in these alpha-amino acids methylated at the alpha-carbon. Intriguing experimental findings on the impact of the chirality of Iva, (alpha Me) Val, and (alpha Me) Phe residues on helix screw sense are illustrated.
TL;DR: In this paper, the self-diffusion coefficients for fused H 3 PO 4 have been measured by the PFG-NMR technique and the results are discussed together with conductivity, self-dissociation and QNS data.
TL;DR: A novel strategy has been developed for identifying yeast strain employing polymerase chain reaction technology using customised oligonucleotides, some regions of the yeast genome between δ elements are amplified to give an 'amplified' sequence polymorphisml characteristic of the strains.
Abstract: Commonly used techniques for the identification of industrial yeast strains are usually time-consuming and cumbersome. Moreover, some of these methods may give ambiguous results. A novel strategy has been developed for identifying yeast strain employing polymerase chain reaction technology. Using customised oligonucleotides, some regions of the yeast genome between δ elements are amplified to give an ‘amplified’ sequence polymorphisml (Skolnick and Wallace 1988) characteristic of the strains. With this technique it is possible to identify individual strains of Saccharomyces cerevisiae.
TL;DR: The first cases occurring in patients, most were associated with left‐sided placement of the ports, with catheter tips lying against the external wall in the upper half of the superior vena cava, suggesting vessel injury.
Abstract: Background. Thrombosis of the central veins is one of the most frequent complications of implanted venous access devices. Among the first cases occurring in our patients, most were associated with left-sided placement of the ports, with catheter tips lying against the external wall in the upper half of the superior vena cava. Some chest radiographs showed lateromediastinal opacities centered on the catheter tip, suggesting a vessel injury. This position allows a narrow contact between the catheter tip and the vessel wall, thus endothelial injuries might result from mechanical and chemical attack.
Methods. To assess the role of catheter position, we reviewed the routine chest radiographs of 379 patients who received chemotherapy through venous access devices and were followed up at our department between December 1985 and December 1990. Four groups (upper left, upper right, lower left, and lower right) were defined according to the level of the catheter tip (innominate veins or upper half of the vena cava versus lower half of the vena cava or auricula) and to the side of port implantation.
Results. Ten patients developed symptomatic venous thrombosis (superior vena cava in 9 patient, left subclavian vein in 1 patient). A strong correlation existed between catheter position and incidence of thrombosis: upper left, 8/28 (28.6%); upper right, 1/33 (3%); lower right, 1/68 (1.5%); and lower left, 0/250. Since 1988, we have insisted on replacement of malpositioned catheters, and we have observed fewer thromboses (2/191 versus 8/188).
Conclusions. The current study suggests that patients with left-sided ports and catheter tips lying in the upper part of the vena cava are at high risk for severe thrombotic complications.
TL;DR: A xylem-limited bacterium resemblingXylella fastidiosa has been shown previously by electron mmcroscopy to be associated with citrus variegated chlorosis (CVC), a new disease of sweet organe tress in Brazil and ELISA indicates that the CVC bacterium is a strain ofX.
Abstract: A xylem-limited bacterium resemblingXylella fastidiosa has been shown previously by electron mmcroscopy to be associated with citrus variegated chlorosis (CVC), a new disease of sweet organe tress in Brazil. A bacterium was consistently cultured from plant tissues from CVC twigs of sweet orange trees but not from tissues of healthy trees on several cell-free media known to support the growth ofXylella fastidiosa. Bacterial colonies typical ofX. fastidiosa became visible on PW, CS20, and PD2 agar media after 5 and 7–10 days of incubation, respectively. The cells of the CVC bacterium were rod-shaped, 1.4–3 μm in length, and 0.2–0.4 μm in diameter, with rippled walls. An antiserum against an isolate (8.1.b) of the bacterium gave strong positive reactions to double-antibody-sandwich (DAS), enzyme-linked immunosorbent assay (ELISA) with other cultured isolates from CVC citrus, as well as with several type strains ofX. fastidiosa. This result indicates that the CVC bacterium is a strain ofX. fastidiosa. ELISA was also highly positive with all leaves tested from CVC-affected shoots. Leaves from symptomless tress reacted negatively. Sweet organe seedlings inoculated with a pure culture of the CVC bacterium supported multiplication of the bacterium, which became systemic with 6 months after inoculation and could be reisolated from the inoculated seedlings. Symptoms characteristic of CVC developed 9 months post inoculation.
TL;DR: In this article, a common temporal framework for comparing phase relationships between atmospheric records (from ice cores) and oceanographic records constructed from deep-sea cores has been proposed for comparing the Vostok and marine chronologies.
Abstract: The object of the present study is to introduce a means of comparing the Vostok and marine chronologies. Our strategy has been to use the δ18O of atmospheric O2 (denoted δ18Oatm) from the Vostok ice core as a proxy for the δ18O of seawater (denoted δ18Osw). Our underlying premise in using δ18Oatm as a proxy for δ18Osw is that past variations in δ18Osw (an indicator of continental ice volume) have been transmitted to the atmospheric O2 reservoir by photosynthesizing organisms in the surface waters of the world's oceans. We compare our record of δ18Oatm to the δ18Osw record which has been developed from studies of the isotopic composition of biogenic calcite (δ18Oforam) in deep-sea cores. We have tied our δ18Oatm record from Vostok to the SPECMAP timescale throughout the last 135 kyr by correlating δ18Oatm with a δ18Osw record from V19-30. Results of the correlation indicate that 77% of the variance is shared between these two records. We observed differences between the δ18Oatm and the δ18Osw records during the coldest periods, which indicate that there have been subtle changes in the factors which regulate δ18Oatm other than δ18Osw. Our use of δ18Oatm as a proxy for δ18Osw must therefore be considered tentative, especially during these periods. By correlating δ18Oatm with δ18Osw, we provide a common temporal framework for comparing phase relationships between atmospheric records (from ice cores) and oceanographic records constructed from deep-sea cores. Our correlated age-depth relation for the Vostok core should not be considered an absolute Vostok timescale. We consider it to be the preferred timescale for comparing Vostok climate records with marine climate records which have been placed on the SPECMAP timescale. We have examined the fidelity of this common temporal framework by comparing sea surface temperature (SST) records from sediment cores with an Antarctic temperature record from the Vostok ice core. We have demonstrated that when the southern ocean SST and Antarctic temperature records are compared on this common temporal framework, they show a high degree of similarity. We interpret this result as supporting our use of the common temporal framework for comparing other climate records from the Vostok ice core with any climate record that has been correlated into the SPECMAP chronology.
TL;DR: In this paper, the S = 1 Heisenberg model was used to fit the magnetic susceptibility of Y 2 BaNiO 5 to the crystal structure of NiO 5 and the best fit for J/k ≈ −285 K (T max ≈ 410 K).
TL;DR: The gene RVS167, which shows reduced viability and abnormal cell morphology upon carbon and nitrogen starvation, could be implicated in cytoskeletal reorganization in response to environmental stresses and could act in the budding site selection mechanism.
Abstract: Mutations in genes necessary for survival in stationary phase were isolated to understand the ability of wild-type Saccharomyces cerevisiae to remain viable during prolonged periods of nutritional deprivation. Here we report results concerning one of these mutants, rvs167, which shows reduced viability and abnormal cell morphology upon carbon and nitrogen starvation. The mutant exhibits the same response when cells are grown in high salt concentrations and other unfavorable growth conditions. The RVS167 gene product displays significant homology with the Rvs161 protein and contains a SH3 domain at the C-terminal end. Abnormal actin distribution is associated with the mutant phenotype. In addition, while the budding pattern of haploid strains remains axial in standard growth conditions, the budding pattern of diploid mutant strains is random. The gene RVS167 therefore could be implicated in cytoskeletal reorganization in response to environmental stresses and could act in the budding site selection mechanism.
TL;DR: The polyphenoloxidase from Helianthus annuus was purified by a combination of SP-Sephadex G-50 chromatography, DEAE-cellulose chromatography and Sepha.
TL;DR: A common methodology was developed and can now be applied to all studies with sufficient follow-up and comparisons made between transmission rates, essential for assessing determinants of transmission and for the development of a common approach for the evaluation of interventions aimed at reducing or interrupting MTCT of HIV.
Abstract: PURPOSE: In the last 8 years, numerous cohort studies have been conducted to estimate the rate of mother-to-child transmission (MTCT) of HIV. Many of these have faced problems in data collection and analysis, making it difficult to compare transmission rates between studies. This workshop on methodological aspects of the study of MTCT of HIV-1 was held in Ghent (Belgium) in February 1992. STUDY SELECTION AND DATA EXTRACTION: Fourteen teams of investigators participated, representing studies from Central (five) and Eastern Africa (three), Europe (two), Haiti (one) and the United States (three). A critical evaluation of the projects was carried out, under four headings: (1) enrollment and follow-up procedures, (2) diagnostic criteria and case definitions, (3) measurement and comparison of MTCT rates and (4) determinants of transmission. RESULTS OF DATA ANALYSIS: Reported transmission rates ranged from 13 to 32% in industrialized countries and from 25 to 48% in developing countries. However, no direct comparisons could be made because methods of calculation differed from study to study. Based on this review, a common methodology was developed. Agreement was reached on definitions of HIV-related signs/symptoms, paediatric AIDS and HIV-related deaths. A classification system of children born to HIV-1-infected mothers according to their probable HIV infection status during the first 15 months of life, allowed the elaboration of a direct method of computation of the transmission rate and of an indirect method for studies with a comparison group of children born to HIV-seronegative mothers. This standardized approach was subsequently applied to selected data sets. CONCLUSIONS: The methodology can now be applied to all studies with sufficient follow-up and comparisons made between transmission rates. This step is essential for assessing determinants of transmission and for the development of a common approach for the evaluation of interventions aimed at reducing or interrupting MTCT of HIV.
TL;DR: These four IADLs could be useful for screening subjects at high risk of incident dementia, according to their performance on a four Instrumental Activities of Daily Living (IADL) score.
Abstract: The purpose of the study was to estimate the risk of one-year incident dementia in elderly community dwellers, according to their performance on a four Instrumental Activities of Daily Living (IADL) score. From a random sample of 2792 French elderly community dwellers included in the PAQUID study, 1804 non-demented subjects were interviewed by specifically trained psychologists about their performance on telephone use, use of transport, responsibility for medication intake, and budget management, and then followed up. One year later 21 of these subjects had a diagnosis of incident dementia, according to DSM-IIIR criteria and confirmed by a neurologist. The odds ratio for incident dementia, adjusted for age, increased from 10.6 for subjects dependent in one IADL to 318.4 for those dependent in the four IADLs (p < 0.0001), compared with independent subjects. These four IADLs could be useful for screening subjects at high risk of incident dementia.
TL;DR: Results suggest that corticosterone secretion may be one of the mechanisms by which food restriction amplifies the behavioral responses to amphetamine and morphine, and point to a role for glucocorticoids in the susceptibility to drug abuse.
TL;DR: In this paper, a new method for preparing fully stoichiometric SrCoO3 has been proposed using electrochemical oxidation, which can be found in the form of a perovskite at a potential of 500 mV for 180 hours at room temperature in alkaline media (1 M KOH).
Abstract: A nearly stoichiometric SrCoO3 phase had been prepared up to now only using high oxygen pressure. A new method for preparing fully stoichiometric SrCoO3 has been proposed using electrochemical oxidation. Brownmillerite-type SrCoO2.50 is oxidized into a completely stoichiometric perovskite at a potential of 500 mV for 180 hours at room temperature in alkaline media (1 M KOH). The oxidized phase has a cubic unit cell (a=383.5 pm). It is metallic and, at temperatures below T=280 K, it shows ferromagnetic behavior. The magnetic moment at 0 K is 2.1 μB. The physical properties of SrCoO3.00 have been explained in terms of partial occupancy of a σ*e band.
Synthese und Charakterisierung der vollig formelreinen Verbindung SrCoO3 durch elektrochemische Oxidation.
Fast formelreines SrCoO3 ist bisher nur unter Anwendung hohen Sauerstoffdrucks dargestellt worden. Es wird ein neues Verfahren zur Herstellung vollig formelreinem SrCoO3 durch elektrochemische Oxidation vorgeschlagen. SrCoO2,50 vom Brownmillerite-Typ wird zu einem vollkommen stochiometrischen Perowskit oxidiert bei einem Potential von 500 mV in 180 h bei Raumtemperatur in alkalischem Medium (1 M KOH). Die oxidierte Phase hat eine kubische Einheitszelle (a=383,5 pm); sie ist metallisch und zeigt bei Temperaturen unter 280 K ferromagnetisches Verhalten. Das magnetische Moment bei 0 K betragt 2, 1 μB. Die physikalischen Eigenschaften des SrCoO3,00 werden durch die teilweise Besetzung des σ*e-Bands erklart.
TL;DR: It is demonstrated that a moderate increase in maternal corticosterone during lactation influences the activity of HPA axis and improves spatial learning ability of the adult offspring.
TL;DR: Based on many examples of bottom current deposits, from the Atlantic and from other oceans, the authors recognize three major types of contourite accumulation: (1) giant elongate drifts, (2) contours, and (3) channel-related drifts.
TL;DR: Genetic and molecular data showed that the chimeric plasmid containing the transgene is inherited as a Mendelian trait, and the production and frequency of semifertile or male-sterile transgenic plants conform to the proposed hypothesis.
Abstract: Cytoplasmic male sterility in plants is associated with mitochondrial dysfunction. We have proposed that a nuclear-encoded chimeric peptide formed by mitochondrial sequences when imported into the mitochondria may impair organelle function and induce male sterility in plants. A model developed to test this hypothesis is reported here. Assuming that the editing process in higher plant mitochondria reflects a requirement for producing active proteins, we have used edited and unedited coding sequences of wheat ATP synthase subunit 9 (atp9) fused to the coding sequence of a yeast coxIV transit peptide. Transgenic plants containing unedited atp9 exhibited either fertile, semifertile, or male-sterile phenotypes; controls containing edited atp9 or only the selectable marker gave fertile plants. Pollen fertility ranged from 31% to 75% in fertile plants, 10% to 20% in semifertile plants, and < 2% in male-sterile plants. Genetic and molecular data showed that the chimeric plasmid containing the transgene is inherited as a Mendelian trait. The transgenic protein is imported into the mitochondria. The production and frequency of semifertile or male-sterile transgenic plants conform to the proposed hypothesis.
TL;DR: This new method proves that while some TLS's may be stable for several hours others are modified by transitions of their neighbors, and three types of TLS-phonon coupling are revealed, of which one is new.
Abstract: We have measured the autocorrelation of the fluorescence of single aromatic molecules in polyethylene at T\ensuremath{\approxeq}2 K. Assuming intensity fluctuations to be caused by frequency jumps when two-level systems (TLS's) change states, we show that individual TLS's can be probed, allowing direct measurement of some of their properties, with minimal recourse to theory and no assumptions about the distribution of TLS parameters. Besides providing a simple confirmation of the tunneling theory of TLS's, this new method, by eliminating statistical uncertainties, proves that while some TLS's may be stable for several hours others are modified by transitions of their neighbors. Tunneling times of individual TLS's are measured directly, as are their temperature dependences, revealing three types of TLS-phonon coupling, of which one is new.