Suppression of Richtmyer-Meshkov Instability via Special Pairs of Shocks and Phase Transitions.

The classical Richtmyer-Meshkov instability (RMI) is a hydrodynamic instability characterizing the evolution of an interface following shock loading. In contrast to other hydrodynamic instabilities such as Rayleigh-Taylor, it is known for being unconditionally unstable: regardless of the direction of shock passage, any deviations from a flat interface will be amplified. In this article, we show that for negative Atwood numbers, there exist special sequences of shocks which result in a nearly perfectly suppressed instability growth. We demonstrate this principle computationally and experimentally with stepped fliers and phase transition materials. A fascinating immediate corollary is that in specific instances, a phase-transitioning material may self-suppress RMI.

Do women benefit more than men from off-pump coronary artery bypass grafting?

OBJECTIVES: Outcomes after coronary artery bypass grafting (CABG) are worse in women than in men. This study aims to investigate whether off-pump coronary artery bypass (OPCAB) surgery improves the outcomes in women by comparing different outcome measures in both genders. METHODS: Patients who underwent isolated CABG, either on-pump (ONCAB) or OPCAB, between January 1998 and June 2017 were included. Primary endpoints were 30-day and 120-day mortality. Logistic regression models were constructed to evaluate the effect of the CABG technique on important outcomes such as mortality and the need for blood transfusion. RESULTS: The data of 17,052 patients were analysed, 3,684 of whom were women (414 OPCAB) and 13,368 men (1,483 OPCAB). The mean number of grafts was lower in the OPCAB group of both genders (p < 0.001). Postoperatively, both men and women undergoing OPCAB surgery received fewer red blood cell transfusions (p < 0.001) and had higher postoperative haemoglobin levels (p < 0.001) than those undergoing ONCAB. Early mortality occurred less frequently after OPCAB surgery in both genders, although the difference was not significant. However, 120-day mortality was significantly lower after OPCAB surgery in women, even after correction for preoperative risk factors [odds ratio (OR) = 0.356, 95% confidence interval (CI) 0.144-0.882, p = 0.026]. The difference in 120-day mortality was not significant in men (OR = 0.787, 95% CI 0.498-1.246, p = 0.307). CONCLUSIONS: Women undergoing CABG benefit more from OPCAB surgery than from ONCAB surgery in terms of 120-day mortality. This difference was not found in men in our patient population.

Towards a body hair atlas of women of caucasian ethnicity.

OBJECTIVE: A preliminary study was conducted in 17 female volunteers (mean age 29.8 years) to gain deeper insights into the characteristics of terminal Caucasian female body hair of different body parts. The focus on Caucasian women was driven by the high number of different scalp hair phenotypes in this ethnicity and intended to identify relevant differences between body areas to improve body hair removal approaches. METHODS: Multiple growth parameters and structural parameters were assessed for hair on the upper arm, forearm, upper leg, lower leg, axilla and intimate area and compared to scalp data. RESULTS: In particular, macroscopic and much less microscopic or hair surface properties differ strikingly in the investigated body areas. Hair density on the body is much lower than on scalp with the highest hair density in the axilla and intimate area. Multihair follicular units are described for scalp but were also found to a smaller proportion in the axilla and the intimate area. Substantial percentages of hair triplets are only found on the scalp and intimate area. Hair diameter is highest in the intimate area, followed by axillary and lower leg hair and correlates with a faster hair growth rate. The angle of emerging hair is smallest in the intimate area, axilla and on the lower leg. Hair shafts on the lower leg and in the axilla have most overlapping cuticle layers, but independent of body region, no significant differences in the mean thickness of cuticle layers were detectable. In addition, no differences were found in the mean distance between cuticle layer edges along the hair shaft and the hair surface roughness. Hair on the scalp, forearm, upper arm and upper leg had an almost round shape, whereas hair of the lower leg, intimate area and axilla had more elliptical shape. Hairs on the arm showed the highest luminance values and no visible medulla. The darkest hairs were in the axilla and intimate area containing the highest level of visible medulla in hair shafts. CONCLUSION: To our knowledge, this is the first systematic study comparing terminal hair properties in all cosmetically relevant body regions in Caucasian women.

Knowledge of signs, treatment and need for urgent management in patients presenting with an acute ischaemic stroke or transient ischaemic attack: a prospective study.

OBJECTIVE: To assess stroke awareness among patients presenting to the emergency department with an acute ischaemic stroke or transient ischaemic attack (TIA). METHODS: A consecutive cohort of patients presenting with a cerebrovascular event was prospectively enrolled over a 15-month period and questionnaires were administered. If the patient was unable to respond to the questions or answer the questionnaire, it was administered to the primary caregiver. Comprehension of having a cerebrovascular event, reason for delay in presentation, mode of arrival and knowledge of treatment modalities were determined. RESULTS: Only 42% of 400 patients thought they were having a stroke or TIA. The median time to presentation was 3.4 h. Delayed presentation was almost equal in men and women. When asked about onset, 19.4% thought that a stroke came on gradually and only 51.9% thought immediate presentation was crucial. 20.8% of patients had heard of thrombolysis. CONCLUSION: Community knowledge of ischaemic stroke needs to be enhanced so that individuals present earlier, leading to timely management.

Kinetics of populating and depopulating of the components of the photoinduced triplet state of the photosynthetic bacteria Rhodospirillum rubrum, Rhodopseudomonas spheroides (wild type), and its mutant R-26 as measured by ESR in zero-field.

Optically detected ESR spectra in zero magnetic field of the triplet state of three photosynthetic bacteria are presented. The zero field splitting parameters [D] and [E] and the widths of the resonances show small but significant differences for the three bacteria. The resonance lines are inhomogeneously broadened as demonstrated by hole-burning experiments. The populating probabilities and depopulating rates for the triplet sublevels have been measured. The populating kinetics are very similar for the three bacteria. The depopulating rates are more than one order faster than those of chlorophyll a and chlorophyll b and of porphyrin model systems. The populating probability of the lowest level is about 6 times less, and the depopulating rate about 6 times slower, than for the upper levels, identifying this level as the level connected to the molecular z-axis perpendicular to the plane of the molecule. The relative populations of the triplet sublevels are almost equal in zero magnetic field.

Transfer of light-induced electron-spin polarization from the intermediary acceptor to the prereduced primary acceptor in the reaction center of photosynthetic bacteria.

In reaction centers and chromatophores of photosynthetic bacteria strong light-induced emissive ESR signals have been found, not only after a flash but also under continuous illumination. The signal, with g = 2.0048 and delta Hpp = 7.6 G, is only present under reducing conditions in material in which the primary acceptor, ubiquinone, U and its associated high-spin ferrous ion are magnetically uncoupled. its amplitude under continuous illumination is strongly dependent on light intensity and on microwave power. The emissive signal is attributed to the prereduced primary acceptor, U-, which becomes polarized through transfer of spin polarization by a magnetic exchange interaction with the photoreduced, spin polarized intermediary acceptor, I-. A kinetic model is presented which explains the observed dependence of emissivity on light intensity and microwave power. Applying this analysis to the light saturation data, a value of the exchange rate between I- and U- of 4.10(8) s-1 is derived, corresponding to an exchange interaction of 3--5 G.

Magnetic field-induced increase of the yield of (bacterio)chlorophyll emission of some photosynthetic bacteria and of Chlorella vulgaris.

In photosynthetic bacteria, in which the iron-ubiquinone complex X is prereduced, a magnetic field induces an increase of the emmission yield, which is correlated with the decrease in reaction center triplet yield reported previously (Hoff, A.J., Rademaker, H., van Grondelle, R. and Duysens, L.N.M. (1977) Biochim. Biophys. Acta 460, 547--554). Our results support the hypothesis that under these conditions charge recombination of the oxidized primary donor and the reduced primary acceptor predominantly generates the excited singlet state of the reaction center bacteriochlorophyll. In Chlorella vulgaris and spinach chloroplasts, at 120 K, the magnetic field has an effect similar to that found in bacteria, which suggests that an intermediary electron acceptor between P-680 and Q is present in Photosystem II also.

Electron spin resonance in zero magnetic field of the reaction center triplet of photosynthetic bacteria.

The decay rates kx, ky, kz of the individual spin levels of the light-induced triplet state have been accurately measured by the zero-field resonance technique under conditions of very low light intensity and a microwave sweep rate of 2.5 MHz/microseconds, which is in excess of that commonly used in optical detection magnetic resonance experiments. The rates ku found correspond well with those previously determined under somewhat different conditions (Hoff, A.J. (1976) Biochim. Biophys. Acta 440, 765--771) and with those inferred from the decay at 4.2 degrees K of the triplet-triplet absorption after picosecond excitation (Parson, W.W. and Monger, T.G. (1977) Brookhaven Symp. Biology 28, 195--212). Thus there seems no reason to doubt that PR corresponds to the triplet state detected by ESR. In a recent publication Clarke and Connors (Clarke, R.H. and Conners, R.E. (1976) Chem. Phys. Lett. 42, 69--72) published values of the rates ku which differ substantially from ours and which lead to a mean lifetime in excess of that of PR. We show that erroneous rates are obtained when the microwave sweep rate is not made fast relative to the decay of the individual spin levels. Zero-field splitting parameters for a member of photosynthetic bacteria have been measured with an accuracy of better than 0.4% for D and 1% for E. The enhanced precision as compared to conventional ESR allows one to discriminate between species of one family. Deuteration reduces the ku values by a factor of about 2, with little spin selectivity. This effect is much larger than previously observed for chlorophyll a. The present results explain the decrease in fluorescence intensity observed on microwave saturation in zero-field optical detection magnetic resonance experiments, and they also show that the simple exciton model is inadequate to derive the geometry of the reaction center dimer from the observed zerofield splitting and decay rates.

Zero field resonance and spin alignment of the triplet state of chloroplasts at 2 degrees K.

Microwave induced transitions in zero magnetic field have been observed in the photoinduced triplet of chloroplasts treated with dithionite by monitoring changes in the intensity of the 735 nm fluorescence band at 2 degrees K. Similar results were obtained with chloroplasts treated with hydroxylamine plus 3-(3,4-dichlorophenyl)-1,1-dimethylurea and preillumination. The zero field parameters are D = 0.02794 +/- 0.00007 cm-1, E = 0.00382 +/- 0.00007 cm-1, i.e. equal to those of monomeric chlorophyll a to within the experimental error. The photoinduced triplet appears to be linked to Photosystem II. This indicates that the low temperatures 735 nm fluorescence band of chloroplasts is at least partly due to Photosystem II.

Electron spin echo studies on chloroplasts. Spectral characteristics of electron transport components and light-induced transients.

Electron-spin resonance echoes are used to study the complex overlapping ESR spectra of whole chloroplasts. By varying the repetition rate of the microwave pulse sequence, delay time, and pulse width, signals with different longitudinal and transverse relaxation times were extracted. We have identified the echo signals due to plastocyanin and ferredoxins. In addition, we have found a strong signal at g = 4.3, that possibly arises from distorted cytochrome, and weak signals in the region g = 6-9. The strong echo signal at g = 2.0047 (Signal II), is made up of at least three "dark" components that differ in their relaxation times. Upon illumination at 1.2 K several of the echo signals including Signal II show reversible light-induced components. The kinetics of these transients depend on the addition of 3(3,4-dichlorophenyl)-1,1-dimethyl urea. Part of the transients are believed to arise from cyclic electron flow around Photosystem I.

Carotenoid triplet yields in normal and deuterated Rhodospirillum rubrum.

Quantum yields of carotenoid triplet formation in Rhodospirillum rubrum wild type and fully deuterated cells and chromatophores were determined in weak laser flashes for excitation wavelength lambda i = 530 nm (mainly absorbed by the carotenoid spirilloxanthin) and for lambda i = 608 nm (mainly absorbed by bacteriochlorophyll) in the presence and absence of magnetic fields. All experiments were performed at room temperature and in the absence of oxygen. The quantum yield of reaction center bacteriochlorophyll oxidation in wild type preparations, in which all reaction centers are in state PIX, at lambda i = 608 nm is close to unity, whereas the quantum yield of antenna carotenoid triplet formation is low (about 5%); P is the primary electron donor, a bacteriochlorophyll dimer, I the primary acceptor, a bacteriopheophytin, and X the secondary acceptor, an iron-ubiquinone complex. In cells in which the reaction centers are in the state P+IX(-), the antenna carotenoid triplet yield is about 0.2. In contrast, at lambda i = 530 nm, the quantum yield of P+ formation is relatively low (0.3) and the yield of the antenna carotenoid triplet state in state PIX unusually high (0.3). At increasing light intensities of 530 nm only about 3 carotenoids per reaction center of the 15 carotenoids present are efficiently photoconverted into the triplet state, which indicates that there are two different pools of carotenoids, one with a low efficiency for transfer of electronic excitation to bacteriochlorophyll and a high yield for triplet formation, the other with a high transfer efficiency and a low triplet yield. The absorption difference spectrum of the antenna carotenoid triplet, excited by 608 or 530 nm light in the state P+IX(-) does not show the peak at 430 nm, that is present in the difference spectrum of the reaction center carotenoid triplet, mainly observed at lambda i = 608 nm with weak flashes. The yield of the reaction center carotenoid triplet, generated in chromatophores in the state PIX(-), is decreased by about 10% by a magnetic field of 0.6 T. In a magnetic field of 0.6 T the yield of the carotenoid triplet, formed by 530 nm excitation in chromatophores at ambient redox potential, is decreased by about 45%. The high quantum yield of formation and the pronounced magnetic field effect for the carotenoid triplet generated by direct excitation at 530 nm can be explained by assuming that this triplet is not formed by intersystem crossing, but by fission of the singlet excitation into two triplet excitations and subsequent annihilation (triplet pair mechanism), or by charge separation and subsequent recombination (radical pair mechanism). Fully deuterated bacteria give essentially the same triplet yields, both in the reaction center and in the antenna carotenoids and show the same magnetic field effects as non-deuterated samples. This indicates that hyperfine interactions do not play a major role in the dephasing of the spins in the radical pair P+I- nor in the formation of the antenna carotenoid triplet.

Influence of KF, DCMU and removal of Ca+ on the high-spin EPR signal of the cytochrome b-559 heme Fe(III) ligated by OH- in chloroplasts.

An EPR signal at g = 6.8 attributed to the cytochrome (Cyt) b-559 heme Fe(III) ligated by OH- (Fiege, R., Schrieber, U., Lubitz, W., Renger, G. and Shuvalov, V.A. (1995) FEBS Lett. 377, 325-329) was studied. This signal is observed in intact chloroplasts when oxidized by 10 mM 2,3-dicyano,5,6-dichloro-p-benzoquinone (DDQ), but not when 5 mM p-benzoquinone is added. Addition of KF (100 mM) or removal of Ca 21 for blocking the water-oxidizing complex considerably decreases the heme Fe(III)-OH- EPR signal. In contrast, DCMU does not decrease this signal and does not influence its photochemical changes at 140 K. Thus, the EPR spectrum of Cyt b-559 Fe(III) ligated by OH- is not affected by changes at the acceptor side of Photosystem 11, and its photochemical decrease is probably not due to reduction via the acceptor side. Comparison of the effect of KF on the model heme Fe(III) in myoglobin (Mb) at pH 10.5 shows that F- replaces OH- as a ligand at the sixth coordination position of the heme Fe(III) in both Mb and chloroplasts Cyt b-559. This replacement is accompanied by changes of the symmetry of the molecular field causing a disappearance of the EPR signals at g = 6.8 and 5.0. Our results provide further evidence for a possible participation of the Cyt b-559 heme Fe ligated by OH- in photosynthetic water oxidation.

On the magnetic field dependence of the yield of the triplet state in reaction centers of photosynthetic bacteria.

The yield of the triplet state in reaction centers of Rhodopseudomonas sphaeroides is dependent on the strength of an applied magnetic field. Reaction centers of the wild type that lack a functional iron complexed to the primary acceptor ubiquinone show a dependence similar to that of reaction centers of the mutant R-26 in which the iron-ubiquinone complex is intact. Apparently, the iron of the iron-ubiquinone complex is not essential to the effect, but it does exert an influence on its extent. Inchromatophores, the effect is about 2-fold decreased; the value of the magnetic field at which half the effect is found is about 500 G, in contrast to this value for reaction centers, which is 50--100 G. The magnetodependence of the triplet yield is discussed in terms of the Chemically Induced Dynamic Electron Polarization mechanism (CIDEP).

Light-induced structural changes in photosynthetic reaction centres studied by ESEEM of spin-correlated D+QA- radical pairs.

Zn-substituted Rhodobacter sphaeroides R26 reaction centres (RCs) frozen in the dark and under illumination exhibit quite different recombination kinetics of the D+QA- radical pairs [Kleinfeld et al., Biochemistry, 23 (1984) 5780]. We have applied electron spin echo envelope modulation (ESEEM) of the spin-correlated D+QA- radical pairs to assess a possible light-induced change in the distance between the D and QA cofactors. The recombination kinetics and the field-swept spin-polarized EPR signal for the two preparations have been monitored by time-resolved EPR spectroscopy. For the samples frozen under illumination, a slight increase in the distance, 0.4+/-0.2 A, has been detected.

Towards a vibrational analysis of spheroidene. Resonance Raman spectroscopy of 13C-labelled spheroidenes in petroleum ether and in the Rhodobacter sphaeroides reaction centre.

We report resonance Raman spectra of the carotenoid spheroidene and its 14'-13C and 15'-13C substituted analogues in petroleum ether and bound to the reaction centre of Rhodobacter sphaeroides R26. The spectra in petroleum ether correspond to planar all-trans spheroidene while those of the reaction centres are consistent with a nonplanar 15,15'-cis spheroidene. The effect of 13C labelling is largest in the carbon-carbon double-bond stretching region. The 15'-13C substitution of the reaction centre bound spheroidene, however, hardly changes the C=C band as compared to that for the natural abundance spheroidene apart from a new weak band at 1508 cm(-1). This observation has been interpreted as a decoupling of the C15=C15' stretch from the other double-bond stretches in combination with a small intrinsic Raman intensity of this local mode for 15,15'-cis spheroidene.

Structural magnetic resonance imaging abnormalities in men with severe chronic schizophrenia and an early age at clinical onset.

BACKGROUND: Early age at onset of schizophrenia often signifies a more severe form of the illness. However, the relationship between age at onset and brain abnormalities has not been established. We assessed temporal-limbic morphometry in severely ill men with chronic schizophrenia who had a relatively early onset of illness and examined the relationships among regional brain volumes, clinical symptoms, and age at illness onset. METHOD: Temporal lobe, superior temporal gyrus, hippocampus, temporal horn, lateral ventricles, third ventricle, and frontoparietal volumes were measured on magnetic resonance imaging data from 56 schizophrenic men (mean [SD] age at illness onset, 16.6 [4.2] years) recruited from a state hospital and 52 age- and range-matched healthy control men. RESULTS: Patients had significantly smaller gray matter volumes in the temporal lobe, superior temporal gyrus, and frontoparietal regions; smaller temporal lobe white matter volumes; and larger cerebrospinal fluid volumes for temporal lobe sulci and the 3 ventricular measures. There were no group differences in hippocampal volumes. Psychotic symptom subscores from the Brief Psychiatric Rating Scale were selectively correlated with smaller left posterior superior temporal gyrus gray matter volumes. None of the brain measurements were significantly correlated with age at illness onset. CONCLUSIONS: Data from this unique sample of severely ill schizophrenic men emphasize a pattern of structural abnormalities involving the cortex, but not the hippocampus, in schizophrenia. Furthermore, these data support theories suggesting that superior temporal gyrus abnormalities contribute selectively to psychotic symptoms and that the extent of structural abnormalities is unrelated to age of clinical symptom onset.

Calcium-induced activation of a mutant G-protein-coupled receptor causes in vitro transformation of NIH/3T3 cells.

The calcium-sensing receptor (CaR) is a G-protein-coupled receptor that is widely expressed, has tissue-specific functions, and regulates cell growth. Activating mutations of this receptor cause autosomal dominant hypocalcemia, a syndrome characterized by hypocalcemia and hypercalciuria. The identification of a family with an activating mutation of the CaR (Thr151Met) in which hypocalcemia cosegregates with several unusual neoplasms led us to examine the transforming effects of this mutant receptor. Transfection of NIH/3T3 cells with the mutant but not the normal receptor supported colony formation in soft agar at subphysiologic calcium concentrations. The mutant CaR causes a calcium-dependent activation of the extracellular signal-regulated protein kinase (ERK) 1/2 and Jun-N-terminal kinase/stress-activated (JNK/ SAPK) pathways, but not P38 MAP kinase. These findings contribute to a growing body of information suggesting that this receptor plays a role in the regulation of cellular proliferation, and that aberrant activation of the mutant receptor in this family may play a role in the unusual neoplastic manifestations.

Gender differences in corpus callosum size in first-episode schizophrenics.

Previous studies indicate differences between schizophrenics and normals in thickness and overall size of the corpus callosum, particularly in female subjects. The present study compares the area of the corpus callosum as measured by magnetic resonance imaging (MRI) in men and women experiencing first-episode cases of schizophrenia. The corpus callosum area is also correlated with measures of neuropsychological function. The results of this study suggest that women who are first-episode schizophrenic patients have a smaller total corpus callosum area than female controls, with no difference noted for men. In normal controls, a larger corpus callosum was associated with better cognitive function, whereas in schizophrenics, no such relationship emerged.

Brain morphology in first-episode schizophrenic-like psychotic patients: a quantitative magnetic resonance imaging study.

Brain morphology was examined using magnetic resonance imaging in 30 first-episode patients with a schizophreniclike psychosis, 15 chronic schizophrenics, and 20 neurological controls. Statistical analyses of computer-generated measurements of regions of interest were controlled for gender, age, social class, and total brain volume. Lateral ventricular size was increased in both first-episode and chronic schizophrenic patients, with greater significance on the left than on the right side. Only the chronic patients, however, had reduced temporal lobe size, which also was greater on the left side. No major correlations of regional brain morphological measurements with cognitive functioning were found, although some measurements of verbal memory were correlated with parahippocampal size. This is a report of a preliminary study that suggests that some morphological brain changes may be present at the time of first treatment for a psychotic illness, whereas others may occur later in the course of illness. Future prospective studies may determine the clinical significance of these changes and whether they progress with the development of illness chronicity.

A prospective follow-up study of brain morphology and cognition in first-episode schizophrenic patients: preliminary findings.

Brain morphological abnormalities have been reported in several independent investigations of chronic schizophrenic patients. The present study is a prospective 4-year follow-up of first-episode schizophrenic patients to determine whether some of these abnormalities may be a consequence of regional brain structural change over time after the onset of a first psychotic episode. Whole hemisphere, temporal lobes, superior temporal gyrus, hippocampus, caudate, corpus callosum, and lateral ventricles were measured in a series of MRI scans taken over a 4-year period in 20 patients and five controls. Total volume reduction was noted in both hemispheres to a greater degree in patients than controls. When adjusted for total brain size, left ventricular enlargement occurred in patients, but not controls, over time. These preliminary data suggest that subtle cortical atrophy may be occurring over time after the onset of illness.