Time and Spacetime: The Crystallizing Block Universe

The nature of the future is completely different from the nature of the past. When quantum effects are significant, the future shows all the signs of quantum weirdness, including duality, uncertainty, and entanglement. With the passage of time, after the time-irreversible process of state-vector reduction has taken place, the past emerges, with the previous quantum uncertainty replaced by the classical certainty of definite particle identities and states. The present time is where this transition largely takes place, but the process does not take place uniformly: Evidence from delayed choice and related experiments shows that isolated patches of quantum indeterminacy remain, and that their transition from probability to certainty only takes place later. Thus, when quantum effects are significant, the picture of a classical Evolving Block Universe (`EBU') cedes place to one of a Crystallizing Block Universe (`CBU'), which reflects this quantum transition from indeterminacy to certainty, while nevertheless resembling the EBU on large enough scales.Comment: 25 Pages. 3 figure

“I\u27ll do whatever as long as you keep telling me that I’m important”: A case study illustrating the link between adolescent dating violence and sex trafficking victimization

Background: Approximately 10% of U.S. high school-attending youth are physically abused by a dating partner each year. Many sequelae of dating violence have been documented, but the dating violence literature is lacking information about commercial sexual exploitation as a possible outcome of an abusive dating relationship. Conversely, scholarship on sex trafficking victimization has documented that some girls are enticed into sex work by exploitative partners who initially pretend to be dating partners, but the research lacks specificity about why and how the girls become vulnerable to these destructive relationships. This case series chronicles the experiences of four women who were commercially sexually exploited in the U.S. as minors, identifies common themes cross their narratives, and organizes these themes into a proposed framework for understanding a possible pathway from safety to unsafe dating to sex trafficking victimization. Methods: We conducted in-depth qualitative interviews with four adult women who had firsthand experience as victims of domestic minor sex trafficking. Participants were recruited through an organization that serves sex trafficking survivors. A constructivist grounded approach was used for data analysis. Participants’ narratives are presented, as well as illustrative quotes that typify each of the primary themes identified. Results: There were six primary themes that emerged from the cases’ narratives. Factors that made girls vulnerable to entering into abusive dating relationships and subsequently to experiences as sex trafficked minors included: (1) feeling physically unattractive and unimportant; (2) lacking examples of healthy relationships; (3) experiencing sexual abuse that caused subsequent dissociation and emotional debilitation; (4) being flattered by romantic gestures early in an abusive dating relationship and becoming emotionally attached; (5) gaining confidence from dating someone with higher social status; and (6) experiencing short-term satisfaction from out-earning other sex workers. Secondary themes that merit further investigation included having conflicts with guardians, engaging in criminal behavior at the request of their dating partner, and developing substance dependence that made it difficult to exit sex work. Discussion: Findings support the conclusions that one pathway into commercial sexual exploitation for minors is via dating partners, and that some minors are motivated to engage in sex work out of devotion to their dating partners rather than fear of violent retribution. A proposed framework for understanding how youth become vulnerable to sexual exploitation by a dating partner includes pre-dating, early phase dating, and late phase dating factors. Some pre-dating factors, for example, include feeling insecure, being bullied by peers, and having conflict with a guardian. Early phase dating factors include being impressed by the high social status of a new love interest and romantic gestures. Late phase dating factors include engaging in criminal activity to please the dating partner, and being physically, sexually, financially and emotionally abused. Additional empirical research that replicates and expands the proposed framework is encouraged, with the long-term objective of improving both dating violence and sexual exploitation prevention initiative

Development of improved low-strain creep strength in Cabot alloy R-41 sheet

The feasibility of improving the low-strain creep properties of a thin gauge nickel base sheet alloy through modified heat treatment or through development of a preferred crystal-lographic texture was investigated. The basic approach taken to improve the creep strength of the material by heat treatment was to increase grain size by raising the solution treatment temperature for the alloy to the range of 1420 K to 1475 K (2100 F to 2200 F). The key technical issue involved was maintenance of adequate tensile ductility following the solutioning of M6C primary carbides during the higher temperature solution treatment. The approach to improve creep properties by developing a sheet texture involved varying both annealing temperatures and the amount of prior cold work. Results identified a heat treatment for alloy R-14 sheet which yields a substantial creep-life advantage at temperatures above 1090 K (1500 F) when compared with material given the standard heat treatment. At the same time, this treatment provides reasonable tensile ductility over the entire temperature range of interest. The mechanical properties of the material given the new heat treatment are compared with those for material given the standard heat treatment. Attempts to improve creep strength by developing a sheet texture were unsuccessful

Two-dimensional hydrodynamic lattice-gas simulations of binary immiscible and ternary amphiphilic fluid flow through porous media

The behaviour of two dimensional binary and ternary amphiphilic fluids under flow conditions is investigated using a hydrodynamic lattice gas model. After the validation of the model in simple cases (Poiseuille flow, Darcy's law for single component fluids), attention is focussed on the properties of binary immiscible fluids in porous media. An extension of Darcy's law which explicitly admits a viscous coupling between the fluids is verified, and evidence of capillary effects are described. The influence of a third component, namely surfactant, is studied in the same context. Invasion simulations have also been performed. The effect of the applied force on the invasion process is reported. As the forcing level increases, the invasion process becomes faster and the residual oil saturation decreases. The introduction of surfactant in the invading phase during imbibition produces new phenomena, including emulsification and micellisation. At very low fluid forcing levels, this leads to the production of a low-resistance gel, which then slows down the progress of the invading fluid. At long times (beyond the water percolation threshold), the concentration of remaining oil within the porous medium is lowered by the action of surfactant, thus enhancing oil recovery. On the other hand, the introduction of surfactant in the invading phase during drainage simulations slows down the invasion process -- the invading fluid takes a more tortuous path to invade the porous medium -- and reduces the oil recovery (the residual oil saturation increases).Comment: 48 pages, 26 figures. Phys. Rev. E (in press

Kinetic barriers to SNAREpin assembly in the regulation of membrane docking/priming and fusion

Neurotransmission is achieved by soluble NSF attachment protein receptor (SNARE)-driven fusion of readily releasable vesicles that are docked and primed at the presynaptic plasma membrane. After neurotransmission, the readily releasable pool of vesicles must be refilled in less than 100 ms for subsequent release. Here we show that the initial association of SNARE complexes, SNAREpins, is far too slow to support this rapid refilling owing to an inherently high activation energy barrier. Our data suggest that acceleration of this process, i.e., lowering of the barrier, is physiologically necessary and can be achieved by molecular factors. Furthermore, under zero force, a low second energy barrier transiently traps SNAREpins in a half-zippered state similar to the partial assembly that engages calcium-sensitive regulatory machinery. This result suggests that the barrier must be actively raised in vivo to generate a sufficient pause in the zippering process for the regulators to set in place. We show that the heights of the activation energy barriers can be selectively changed by molecular factors. Thus, it is possible to modify, both in vitro and in vivo, the lifespan of each metastable state. This controllability provides a simple model in which vesicle docking/priming, an intrinsically slow process, can be substantially accelerated. It also explains how the machinery that regulates vesicle fusion can be set in place while SNAREpins are trapped in a half-zippered state

Low energy cost for optimal speed and control of membrane fusion

Membrane fusion is the cell’s delivery process, enabling its many compartments to receive cargo and machinery for cell growth and intercellular communication. The overall activation energy of the process must be large enough to prevent frequent and nonspecific spontaneous fusion events, yet must be low enough to allow it to be overcome upon demand by specific fusion proteins [such as soluble N-ethylmaleimide–sensitive factor attachment protein receptors (SNAREs)]. Remarkably, to the best of our knowledge, the activation energy for spontaneous bilayer fusion has never been measured. Multiple models have been developed and refined to estimate the overall activation energy and its component parts, and they span a very broad range from 20 kBT to 150 kBT, depending on the assumptions. In this study, using a bulk lipid-mixing assay at various temperatures, we report that the activation energy of complete membrane fusion is at the lowest range of these theoretical values. Typical lipid vesicles were found to slowly and spontaneously fully fuse with activation energies of ∼30 kBT. Our data demonstrate that the merging of membranes is not nearly as energy consuming as anticipated by many models and is ideally positioned to minimize spontaneous fusion while enabling rapid, SNARE-dependent fusion upon demand

Hypothesis - buttressed rings assemble, clamp, and release SNAREpins for synaptic transmission

Neural networks are optimized to detect temporal coincidence on the millisecond timescale. Here, we offer a synthetic hypothesis based on recent structural insights into SNAREs and the C2 domain proteins to explain how synaptic transmission can keep this pace. We suggest that an outer ring of up to six curved Munc13 ‘MUN’ domains transiently anchored to the plasma membrane via its flanking domains surrounds a stable inner ring comprised of synaptotagmin C2 domains to serve as a work-bench on which SNAREpins are templated. This ‘buttressed-ring hypothesis’ affords straightforward answers to many principal and long-standing questions concerning how SNAREpins can be assembled, clamped, and then released synchronously with an action potential

Effects of interdot dipole coupling in mesoscopic epitaxial Fe(100) dot arrays

The domain structure and the coercivity of epitaxial Fe(100) circular dot arrays of different diameters and separations have been studied using magnetic force microscopy (MFM) and focused magneto-optical Kerr effect (MOKE). The MFM images of the 1 µm diameter single domain dot arrays show direct evidence of strong interdot dipole coupling when the separation is reduced down to 0.1 µm. The coercivity of the dots is also found to be dependent on the separation, indicating the effect of the interdot dipole coupling on the magnetization reversal process