Imaging quantum fluctuations near criticality.

A quantum phase transition (QPT) occurs between two competing phases of matter at zero temperature, driven by quantum fluctuations. Though the presence of these fluctuations is well established, they have not been locally imaged in space and their local dynamics has not been studied so far. We use a scanning superconducting quantum interference device to image quantum fluctuations in the vicinity of the QPT from a superconductor to an insulator. We find fluctuations of the diamagnetic response in both space and time that survive well below the transition temperature, demonstrating their quantum nature. The fluctuations appear as telegraph-like noise with a range of characteristic times and a non-monotonic temperature dependence, revealing unexpected quantum granularity. The lateral dimension of these fluctuations grows towards criticality, offering a new measurable length scale. Our results provide physical insight about the reorganization of phases across a QPT, with implications for any theoretical description. This paves a new route for future quantum information applications.

The roots of ego-control in young adulthood: links with parenting in early childhood.

This study examined the early parenting correlates of ego-control, the modal threshold for the expression or containment of impulse. Fifty-three female and 50 male participants were followed between 3 and 23 years of age. Ego-control was measured in early childhood (ages 3 and 4) and, independently, in early adulthood (ages 18 and 23) using a Q-sort prototype based on observer ratings. Parenting during early childhood was indexed using a self-report inventory of child-rearing orientations at age 3 and observer ratings of parent-child interactions at age 5. Correlations between early parenting and later ego-control, after partialing out early ego-control to control for parents' reactions to their children, revealed meaningful and convergent relations between independently measured data sets. The patterns of results, which differed between male and female participants, are discussed in terms of gender differences in socialization outcomes.

Depressive tendencies and susceptibility to anxiety: differential personality correlates.

Although the constructs of depression and anxiety are conceptually and clinically separable, they have been difficult to separate psychometrically. The present study is an attempt to statistically disentangle the two constructs and to evaluate their differential correlates. A common factor analysis of the items in a depression and an anxiety inventory was conducted using data collected from two samples-208 college students and eighty-seven 18-years-old participating in the Block Longitudinal Study. In both samples two factors, interpreted as depressive tendencies and susceptibility to anxiety, were found; the factor loadings on each factor were highly correlated across the two samples. No sex differences were found in these factor structures. Factor-based scores comprised of well-differentiating items were computed for participants in the Block sample. Using partial correlation analyses, observer-measured as well as self-report-based personality correlates of the specific variance associated with depressive tendencies and with susceptibility to anxiety, respectively, were contrasted. The results indicated that a strong interpersonal component discernible in depression was less noticeable in anxiety.

IQ and ego-resiliency: conceptual and empirical connections and separateness.

The constructs of intelligence and ego-resiliency are discussed. The personality implications of "pure intelligence" and "pure ego-resilience" were identified. Intelligence (IQ) was indexed by the Wechsler Adult Intelligence Scale-Revised and ego-resiliency by an inventory scale. Residual scores measuring "pure intelligence" and "pure ego-resilience" were correlated with the items of the observer-based California Q-sort, used to describe participants. Persons relatively high on ego-resilience tend to be more competent and comfortable in the "fuzzier" interpersonal world; persons defined primary by raw IQ tend to be effective in the "clearer" world of structured work but tend also to be uneasy with affect and less able to realize satisfying human connections. Gender differences exist in the relations of ego-resilience and intelligence and in their adaptive relevance.

Ribosomes as molecular energy machines.

The idea that ribosomes operate as biological molecular energy machines offers an alternative description to that based on the assumption that the functionally important motions in ribosomes are only coupled to thermal degrees of freedom. The alternative model assumes that the energy gained in GTP cleavage generates in the ribosomal complex a localized metastable region temporarily not interacting with thermal motions. The metastable region may move along a definite pathway and in distinct sites promote irreversible logical operations involved in polypeptide biosynthesis. The new alternative represents a more complex and advanced algorithm offering advantages in speed, accuracy, more sophisticated control, and better resistance to various kinds of noise.

Critical analysis of objections against the biological molecular energy machines.

In the past, two important objections against McClare's idea of biological molecular energy machines were raised. One of the criticisms was concerned with the origin of energy gained in ATP cleavage and with an interpretation of McClare's "excited vibrational state." The former argument reveals a failure of the critics to comprehend McClare's approach. As to the excited vibrational state, it can be identified with nonequilibrium conformational states of the unit rather than with a single vibrational mode. The other criticism based on Brillouin's energy cost of measurement argued that reversible operation of biological molecular energy machines would be virtually impossible. Using propagation velocities of deformations of the unit's structure (instead of velocity of light), the objections against reversibility are invalidated even in the framework of the critic's approach. McClare's idea and relevant definitions are thus physically correct.

Plausible view on the biological molecular energy machines.

A qualitative picture of operation modes of biological molecular energy machines is presented. It is suggested that there is mutual control between the flow of molecular energy stored in a biological molecular energy machine and the sequence of nonequilibrium conformational states through which the machine passes in doing work. If the structure of the conformational space is favorable, the set of trajectories in this space decomposes into two families, each of which accomplishes another task. This divergence of trajectories enables to distinguish molecular objects according to differences in interaction between the machine and the object, i.e., to perform a measurement on a molecular object and process the object according to the result of that measurement.

Reconstruction of the left innominate vein in a patient with invasive thymoma undergoing coronary artery bypass surgery.

This is a report of a case in which a patient undergoing coronary artery bypass surgery was found to have a thymoma invading the left innominate vein without obstructing it. The tumor was removed, the left innominate vein reconstructed with ringed PTFE graft and the coronary revascularization performed successfully. The surgical treatment adopted the considerations involving this particular patient and the literature of similar cases is reviewed and briefly discussed.

The Dacron EXS graft: patency in femoropopliteal and femorotibial surgery.

Choice of the most suitable synthetic graft for use in peripheral vascular surgery in the lower extremity is controversial. The knitted Dacron Velour Externally Supported (EXS) graft is a recently developed vascular prosthesis which promises to be effective and durable for use in femoropopliteal and femorotibial bypass surgery. Between 11/80 and 7/83, 56 grafts were implanted in 49 patients. Eight patients were lost to follow-up, leaving 46 grafts for which patency data was determined. The distribution of sites of distal anastomosis was as follows: 25% were to the popliteal artery above the knee, 50% were to the popliteal artery below the knee, and 25% were to the tibial or peroneal arteries. Graft occlusion was determined by loss of Doppler pulses, return of ischemic symptoms, or failure to visualize flow in angiograms. Overall cumulative patency rates, calculated by the life table method, were as follows: 81% at 6 months; 76% at 1 year; 68% at 2 and 2 and 1/2 years. There was no statistical difference in patency between above-knee and below-knee popliteal artery bypasses. Moreover, patency rates were similar for diabetics vs. non-diabetics, for patients operated on for claudication vs. limb salvage; and for patients who had sympathectomy vs. no sympathectomy. Patency rates for bypass to the tibial and peroneal vessels in this series were better than recently reported in the literature for other synthetic prostheses; i.e. 75% at 4 months and 1 year; 56% at 2 and 2 and 1/2 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Logical elements in living cells.

Recognition processes with enhanced accuracy (as performed by structures like enzymes or ribosomes) are investigated using elementary ideas of statistical mechanics and related concepts of thermodynamics. The analysis starts from a formal definition of recognition and provides a correspondence with appropriate physical properties of the macromolecular logical elements. Transitions of the recognizing system between different modifications are a necessary feature of a more exacting recognition process. Rearrangement steps provide the process with higher accuracy by performing two physical operations: (1) rearranging the phase space of the system so that the "correct" states be better separated from the "wrong" states and the probability of occupation of the "correct" states be enhanced, (2) directing the process toward the more favourable modifications thus formed. Both operations are related to changes in the physical properties of the recognizing system. These changes can be expressed as differences of macromolecular Gibbs energy levels; if ligand binding or release participate in a step, directivity of the step depends also on the actual chemical potentials of the ligands in solution. The two operations just mentioned resemble two basic operations known to be necessary in electronic digital networks: directivity of control and signal standardization. An analysis of the entire reaction catalysed by a macromolecular logical element takes into account the requirements imposed by the logical functions as well as the need that the chemical potential of the product be not restricted to very low values. To satisfy these conditions, the reaction must be supported by a so-called non-specific reaction, usually implemented by the cleavage reaction of a nucleoside triphosphate.

Information-theoretic significance of Gibbs energy supply to editing mechanisms.

If a branched multistep editing mechanism is implemented by an enzyme with a single site for the specific substrates, there is no reason to believe that the number of testing steps is fixed and cannot be controlled by some external factors. The paper considers the mechanisms of single- or multistep editing done in response to various factors, particularly to the value of displacement from the reaction equilibrium. To avoid a complicated analysis of a fully specified case, which would be likely to obscure the general significant features, the operating modes of those mechanisms are estimated using the method of minimizing associated information gains. It turns out that sufficiently far from equilibrium the variable mechanisms can essentially operate just as well as the fixed multistep mechanisms.

Regulation and biosynthesis of secondary metabolites. XVIII. Adenylate level and chlorotetracycline production in Streptomyces aureofaciens.

The relationship was studied between the energy metabolism of the actinomycete Streptomyces aureofaciens and the biosynthesis of chlorotetracycline by this organism. The energy charge values in a culture of low-production strain were almost identical with those of a production variant but the total sum of adenylates was about 10 times higher. In the stationary growth phase both strains evinced a drop in energy charge values followed by a rise to the original level. An increase in the concentration of inorganic phosphate in fermentation medium caused a suppression of antibiotic formation in the lowproduction strain and further rise in the total adenylate level. The expression of the energy charge in Streptomyces aureofaciens acquires a complex character owing to the participation, apart from the adenylate system, of high-molecular polyphosphates as energy donors and the probable lack of a regulating mechanism such as the adenylate kinase reaction.