Mass Divergence Research Articles

Confinement-Higgs phase crossover as a lattice artifact in 1 + 1 dimensions

We examine the phase structure of massive Yang-Mills theory in 1+1 dimensions. This theory is equivalent to a gauged principal chiral sigma model. It has been previously shown that the gauged theory has only a confined phase, and no Higgs phase in the continuum, and at infinite volume. There are no massive gluons, but only hadron-like bound states of sigma-model particles. The reason is that the gluon mass diverges, being proportional to the two-point correlation function of the renormalized field of the sigma model at $x=0$. We use exact large-$N$ results to show that after introducing a lattice regularization and typical values of the coupling constants used in Monte Carlo simulations, the gluon mass becomes finite, and even sometimes small. A smooth crossover into a Higgs phase can then appear. For small volumes and large $N$, we find an analytic expression for the gluon mass, which depends on the coupling constants and the volume. We argue that this Higgs phase is qualitatively similar to the one observed in lattice computations at $N=2$.

Weak phase stiffness and nature of the quantum critical point in underdoped cuprates

Despite more than two decades of intensive investigations, the true nature of high temperature (high-$T_c$) superconductivity observed in the cuprates remains elusive to the researchers. In particular, in the so-called `underdoped' region, the overall behavior of superconductivity deviates $qualitatively$ from the standard theoretical description pioneered by Bardeen, Cooper and Schrieffer (BCS). Recently, the importance of phase fluctuation of the superconducting order parameter has gained significant support from various experiments. However, the microscopic mechanism responsible for the surprisingly soft phase remains one of the most important unsolved puzzles. Here, opposite to the standard BCS starting point, we propose a simple, solvable low-energy model in the strong coupling limit, which maps the superconductivity literally into a well-understood physics of superfluid in a special dilute bosonic system of local pairs of doped holes. In the prototypical material (La$_{1-\delta}$Sr$_\delta$)$_2$CuO$_4$, without use of any free parameter, a $d$-wave superconductivity is obtained for doping above $\sim 5.2\%$, below which unexpected incoherent $p$-wave pairs dominate. Throughout the whole underdoped region, very soft phases are found to originate from enormous mass enhancement of the pairs. Furthermore, a striking mass divergence is predicted that dictates the occurrence of the observed quantum critical point. Our model produces properties of the superfluid in good agreement with the experiments, and provides new insights into several current puzzles. Owing to its simplicity, this model offers a paradigm of great value in answering the long-standing challenges in underdoped cuprates.

Mirror moving in quantum vacuum of a massive scalar field

We present a mirror model moving in the quantum vacuum of a massive scalar field and study its motion under infinitely fluctuating quantum vacuum stress. The model is similar to the one in \cite{PhysRevD.89.085009}, but this time there is no divergent effective mass to weaken the effect of divergent vacuum energy density. We show that this kind of weakening is not necessary. The vacuum friction and strong anti-correlation property of the quantum vacuum are enough to confine the mirror's position fluctuations.

Divergent biochemical and enzymatic properties of oxalate oxidase isoforms encoded by four similar genes in rice

The biochemical and enzymatic properties of four highly similar rice oxalate oxidase proteins (OsOxO1–4) were compared after their purification from the leaves of transgenic plants each overexpressing the respective OsOxO1–4 genes. Although alignment of their amino acid sequences has revealed divergence mainly in the signal peptides and they catalyze the same enzymic (oxalate oxidase) reaction, divergence in apparent molecular mass, Km, optimum pH, stability and responses to inhibitors and activators was uncovered by biochemical characterization of the purified OsOxO1–4 proteins. The apparent molecular mass of oligomer OsOxO1 was found to be similar to that of OsOxO3 but lower than the other two. The molecular mass of the subunit of OsOxO1 was lower than that of OsOxO3. The Km value of OsOxO3 was higher than the other three which had similar Km. OsOxO1 and OsOxO4 possessed peak activity at pH 8.5 which was close to that at the optimum pH 4.0. The activity of OsOxO2 at pH 8.5 was only 65% of that at its optimum pH 3.5, while the activity of OsOxO3 did not vary much at pH 6–9 and was also much lower than that at its optimum pH 3. OsOxO2 and OsOxO3 still maintained all their activities after being heated at 70°C for 1h while OsOxO1 and OsOxO4 lost about 30% of their activities. Pyruvate and oxaloacetic acid inhibited the activity of OsOxO3 more strongly than the other three. Interestingly, glucose 6-phosphate, fructose 6-phosphate and fructose 1,6-biphosphate related to photosynthetic assimilation of triose phosphate greatly increased the activities of OsOxO3 and OsOxO4. In addition to the differences in the biochemical properties of the four OsOxO proteins, an intriguing finding is that the purified OsOxO1–4 exhibited substrate inhibition, which is a typical of the classical Michaelis–Menten enzyme kinetics exhibited by a majority of other enzymes.

The Impact of Arctic Winter Infrared Radiation on Early Summer Sea Ice

Abstract The Arctic summer sea ice area has been rapidly decreasing in recent decades. In addition to this trend, substantial interannual variability is present, as is highlighted by the recovery in sea ice area in 2013 following the record minimum in 2012. This interannual variability of the Arctic summer sea ice area has been attributed to the springtime weather disturbances. Here, by utilizing reanalysis- and satellite-based sea ice data, this study shows that summers with unusually small sea ice area are preceded by winters with anomalously strong downward longwave radiation over the Eurasian sector of the Arctic Ocean. This anomalous wintertime radiative forcing at the surface is up to 10–15 W m−2, which is about twice as strong than that during the spring. During the same winters, the poleward moisture and warm-air intrusions into the Eurasian sector of the Arctic Ocean are anomalously strong and the resulting moisture convergence field closely resembles positive anomalies in column-integrated water vapor and tropospheric temperature. Climate model simulations support the above-mentioned findings and further show that the anomalously strong wintertime radiative forcing can decrease sea ice thickness over wide areas of the Arctic Ocean, especially over the Eurasian sector. During the winters preceding the anomalously small summer sea ice area, the upper ocean of the model is anomalously warm over the Barents Sea, indicating that the upper-ocean heat content contributes to winter sea ice thinning. Finally, mass divergence by ice drift in the preceding winter and spring contributes to the thinning of sea ice over the East Siberian and Chukchi Seas, where radiative forcing and upper-ocean heat content anomalies are relatively weak.

Heavy fermions, metal-to-insulator transition, and quantum criticality in La y Cu3Ru x Ti4−x O12

In this work we investigate the solid-solution series La y Cu3Ru x Ti4−x O12. The titanate La2/3Cu3Ti4O12 (x = 0) is an antiferromagnetic insulator exhibiting colossal dielectric constants, while the ruthenate LaCu3Ru4O12 (x = 4) is known as a rare d-electron derived heavy-fermion compound. Detailed structural investigations, AC- and DC-magnetization measurements, resistivity, specific-heat, and magnetic-resonance investigations have been performed for all polycrystalline compounds prepared by solid-state synthesis. These experiments have been accompanied by band-structure calculations. Close to the Ru concentration x = 2 we identify a quantum-critical point coinciding with a metal-to-insulator transition. The quantum-critical point separates an insulating spin glass from a paramagnetic metal. Interestingly, there is no evidence for a divergence of the effective mass upon reaching the quantum-critical point from the metallic side. In the paramagnetic metal, Ru behaves like a canonical Kondo ion. While the Ru oxidation state remains stable at + 4 for the whole concentration regime, the Cu valence seems to decrease from + 2 in the insulating antiferromagnet with localized copper spins to a significantly lower value in the metallic heavy-fermion compounds.

Effects of the STCC eddies on the Kuroshio based on the 20-year JCOPE2 reanalysis results

In this study, 20years of model reanalysis data are analyzed to study the effects of the subtropical countercurrent (STCC) eddies on the upstream Kuroshio, from east of Luzon to east of Taiwan. The effects are assessed from individual events to interannual time scales. The wind-driven Kuroshio is modified by the STCC eddies, with high spatiotemporal variations. The mass balance in the composite eddy events indicates that the strengthening and weakening of the Kuroshio transport are locally caused by the mass convergence and divergence produced by the eddies. The same analogy applies to the interannual time scale. In the eddy-rich years, the upstream Kuroshio is generally stronger because of wind forcing, yet the strengthening is nonuniform because of modification by the eddies. The larger number of warm eddies to the east of Taiwan and Luzon Island further strengthen the jet, whereas the larger number of cold eddies to the east of the Luzon Strait weaken the Kuroshio in the Luzon Strait. Drifter trajectories show larger Luzon Strait intrusion during the occurrence of cold eddies. The local weakening of the Kuroshio by cold eddies leads to a weaker potential vorticity jump, producing favorable conditions for the intrusion of a water mass into the South China Sea.

Charged isotropic non-Abelian dyonic black branes

We construct black holes with a Ricci-flat horizon in Einstein–Yang–Mills theory with a negative cosmological constant, which approach asymptotically an AdSd spacetime background (with d≥4). These solutions are isotropic, i.e. all space directions in a hypersurface of constant radial and time coordinates are equivalent, and possess both electric and magnetic fields. We find that the basic properties of the non-Abelian solutions are similar to those of the dyonic isotropic branes in Einstein–Maxwell theory (which, however, exist in even spacetime dimensions only). These black branes possess a nonzero magnetic field strength on the flat boundary metric, which leads to a divergent mass of these solutions, as defined in the usual way. However, a different picture is found for odd spacetime dimensions, where a non-Abelian Chern–Simons term can be incorporated in the action. This allows for black brane solutions with a magnetic field which vanishes asymptotically.

Experimental and numerical investigation of propagation mechanism of gaseous detonations in channels with porous walls

In the present work the propagation of gaseous detonations in a channel with porous walls is investigated experimentally and numerically. The main goal of the study is to determine the role of diffusive turbulent mixing and transverse waves in controlling the detonation limits in channels with porous walls. Detonations in propane–oxygen and hydrogen–oxygen–argon mixtures, which are characterized by their irregular and regular cellular structures, are considered in the experimental and numerical investigations. Euler simulations are performed for parameters corresponding to both regular and irregular detonations. In the smooth wall region Schlieren photographs of hydrogen–oxygen–argon detonation show laminar reaction zones behind the main front. In addition, as the detonation propagates over the porous wall, due to the mass divergence into the damping section, the frontal wave curvature increases. The number of transverse waves decreases in the porous section which is caused by the attenuation of the detonation wave. In comparison to the stable argon diluted detonations, experiments for unstable propane–oxygen detonations illustrate lower wave curvature and high turbulence in the reaction zone in the porous section. The numerically obtained results for both regular and irregular detonations show that close to the porous wall the front curvature increases, a finding that is also observed in experiments. If the curvature extends to the whole channel width the detonation wave fails to propagate. Nevertheless, the numerical critical limit of W/λ for unstable detonations is found to be higher than that of stable detonations, which is in contradiction with the experimental results. This discrepancy can be explained by the effect of turbulent diffusive mixing in controlling the reaction rate in highly unstable detonations, which is not taken into account in the current numerical simulations.

Predictors of muscle protein synthesis after severe pediatric burns.

Following a major burn, skeletal muscle protein synthesis rate increases but is often insufficient to compensate for massively elevated muscle protein breakdown rates. Given the long-term nature of the pathophysiologic response to burn injury, we hypothesized that muscle protein synthesis rate would be chronically elevated in severely burned children. The objectives of this study were to characterize muscle protein synthesis rate of burned children over a period of 24 months after injury and to identify predictors that influence this response. A total of 87 children with 40% or greater total body surface area (TBSA) burned were included. Patients participated in stable isotope infusion studies at 1, 2, and approximately 4 weeks after burn and at 6, 12, and 24 months after injury to determine skeletal muscle protein fractional synthesis rate. Generalized estimating equations with log link normal distribution were applied to account for clustering of patients and control for patient characteristics. Patients (8 ± 6 years) had large (62, 51-72% TBSA) and deep (47% ± 21% TBSA third degree) burns. Muscle protein fractional synthesis rate was elevated throughout the first 12 months after burn compared with established values from healthy young adults. Muscle protein fractional synthesis rate was lower in boys, in children older than 3 years, and when burns were greater than 80% TBSA. Muscle protein synthesis is elevated for at least 1 year after injury, suggesting that greater muscle protein turnover is a component of the long-term pathophysiologic response to burn trauma. Muscle protein synthesis is highly affected by sex, age, and burn size in severely burned children. These findings may explain the divergence in net protein balance and lean body mass in different populations of burn patients. Prognostic study, level III.

A near-uniform fluctuation of ocean bottom pressure and sea level across the deep ocean basins of the Arctic Ocean and the Nordic Seas

Across the Arctic Ocean and the Nordic Seas, a basin-wide mode of ocean bottom pressure and sea level fluctuation is identified using satellite and in situ observations in conjunction with a global ocean circulation model and its adjoint. The variation extends across the interconnected deep ocean basins of these semi-enclosed Arctic seas, collectively called the Arctic Mediterranean, with spatially near-uniform amplitude and phase. The basin-wide fluctuation is barotropic and dominates the region’s large-scale variability from sub-monthly to interannual timescales. The fluctuation results from bifurcating coastally trapped waves generated by winds along the continental slopes of the Arctic Mediterranean and its neighboring seas, including the North Atlantic Ocean. The winds drive Ekman transport across the large bathymetric gradients, forcing mass divergence between the shallow coastal area and the deep ocean basins and creating ocean bottom pressure anomalies of opposite signs in the two regions. The anomalies rapidly propagate away as barotropic coastally trapped waves with the coast and continental slope as respective boundaries. The waves subsequently bifurcate at the shallow straits connecting the Arctic Mediterranean with the rest of the globe. The straits transmit the shallow anomalies but not the deep variations, thereby inhibiting the anomalies’ mutual cancelation by geographically separating the two. Anomalies that enter the deep Arctic basins equilibrate uniformly across the domain characterized by a homogeneous depth-integrated planetary potential vorticity distribution. The potential vorticity’s steep gradient that borders the basins shields the region from neighboring shallow variations, giving rise to the observed spatially confined fluctuation. Compensating anomalies outside the Arctic adjust similarly across the rest of the globe but are comparatively negligible in amplitude because of the global ocean’s larger area relative to that of the deep Arctic Mediterranean. The study, from a technical perspective, illustrates the utility of a model’s adjoint in identifying causal mechanisms underlying a complex system.

Cubic-quintic nonlinearity in superfluid Bose-Bose mixtures in optical lattices: Heavy solitary waves, barrier-induced criticality, and current-phase relations

We study superfluid (SF) states of strongly interacting Bose-Bose mixtures with equal mass and intra-component interaction in optical lattices both in the presence and absence of a barrier potential (BP). We show that the SF order parameters obey the two-component nonlinear Schroedinger equation (NLSE) with not only cubic but also quintic nonlinearity in the vicinity of the first-order transitions to the Mott insulators with even fillings. In the case of no BP, we analyze solitary-wave (SW) solutions of the cubic-quintic NLSE. When the SF state changes from a ground state to a metastable one, a standard dark SW turns into a bubble-like dark SW, which has a non-vanishing density dip and no pi phase kink even in the case of a standing SW. It is shown that the former and latter SW are dynamically unstable against an out-of-phase fluctuation and an in-phase fluctuation, respectively, and the dynamical instabilities are weakened when one approaches the transition point. We find that the size and the inertial mass of the SW diverge at the first-order transition point. We suggest that the divergence of the inertial mass may be detected through measurement of the relation between the velocity and the phase jump of the SW. In the presence of BP, we reveal that when the barrier strength exceeds a certain critical value, the SF state that was metastable without the barrier is destabilized towards complete disjunction of the SF. The presence of the critical BP strength indicates that the strong BP qualitatively changes the criticality near the metastability limit of the SF state. We derive critical behaviors of the density, the compressibility, and the critical current near the metastability limit induced by the BP. It is also found that the relation between the supercurrent and the phase jump across the BP exhibits a peculiar behavior, owing to the non-topological nature of the bubble-like SW.

Mobile impurities and orthogonality catastrophe in two-dimensional vortex lattices

We investigate the properties of a neutral impurity atom coupled with the Tkachenko modes of a two-dimensional vortex lattice in a Bose-Einstein condensate. In contrast with polarons in homogeneous condensates, the marginal impurity-boson interaction in the vortex lattice leads to infrared singularities in perturbation theory and to the breakdown of the quasiparticle picture in the low-energy limit. These infrared singularities are interpreted in terms of a renormalization of the coupling constant, quasiparticle weight, and effective impurity mass. The divergence of the effective mass in the low-energy limit gives rise to a power-law singularity in the impurity spectral function and provides an example of an emergent orthogonality catastrophe in a bosonic system.

Orbital-attitude coupling effects on the motion of a dumbbell space tether

The effects of the divergence between the centre of mass and centre of gravity on the orbital motion of a dumbbell space tether, treated as a satellite of finite size, are investigated. For a radially aligned dumbbell tether with the angular speed required for a circular orbit of its centre of mass; the centre of mass of the system will traverse a trajectory from orbital apogee to perigee. This is found to be a direct result of this mass and gravity centre divergence and the system only undertakes a circular orbit when it has the angular speed required for a circular orbit of a particle at its centre of orbit. The coupling between the orbital and attitude motion for a radially aligned dumbbell tether is investigated and it is shown that for small deviations from the angular speed required for a circular orbit a libration of the tether spans is generated. This can progress to spin if the angular speed is increased further. Furthermore, it is shown that tether spans with a small initial speed relative to the centre of mass result in significant variations in orbital motion of the system. Finally, the exchange of energy between the orbital and attitude motion is investigated.

When Information Does Not Translate into Knowledge. Ebola and Hemorrhagic Fevers Knowledge among Primary Care Physicians and Nurses

After the first secondarily-transmitted ebola case in Spain, a wave of divergent opinions flooded mass and sanitary media. Very few of these opinions, however, came from experts on epidemiology or hemorrhagic fevers. This observational study aimed to assess the specific knowledge of Primary Care physicians and nurses about ebola and hemorrhagic fevers by means of analyzing the results obtained from a 5-item self-reported questionnaire dealing on hemorrhagic fevers basic knowledge. Validity and reliability of questionnaire were confirmed by a pilot study. The participants were 138 family doctors and nurses from the 64 public Primary Care centers sited in the North Metropolitan Area of Barcelona (1,400,000 inhab; Catalonia, Spain) taking part in training-the-trainers ebola workshops. Overall, there were 117 (84.8%) respondents out from 138 workshop participants; of them were physicians 61 (51.2%). The main age was 46.7 (8.8) years; stating previous specific knowledge on hemorrhagic fevers 39 (33.3%). On the whole, up to 92 (78.6%) of respondents shown a poor knowledge. Previous specific formation was significantly and independently associated with having proper knowledge (p < 0.001); OR = 8.6 (CI 95%: 3.199 - 23.623). In summary, confusion that accompanied the single secondary-transmitted ebola case in Spain could probably be explained by the existence of a serious gap on hemorrhagic fevers knowledge. More accurate, scientific and formally-presented information should be provided to Primary Care physicians and nurses.

Moisture budget analysis of SST-driven decadal Sahel precipitation variability in the twentieth century

It is well known that the Sahel region of Africa is impacted by decadal scale variability in precipitation, driven by global sea surface temperatures. This work demonstrates that the National Center for Atmospheric Research’s Community Atmosphere Model, version 4 is capable of reproducing relationships between Sahelian precipitation variability and Indian and Atlantic Ocean sea surface temperature variations on such timescales. Further analysis then constructs a moisture budget breakdown using model output and shows that the change in precipitation minus evaporation in the region is dominated by column integrated moisture convergence due to the mean flow, with the convergence of mass in the atmospheric column mainly responsible. It is concluded that the oceanic forcing of atmospheric mass convergence and divergence to a first order explains the moisture balance patterns in the region. In particular, the anomalous circulation patterns, including net moisture divergence by the mean and transient flows combined with negative moisture advection, together explain the drying of the Sahel during the second half of the twentieth century. Diagnosis of moisture budget and circulation components within the main rainbelt and along the monsoon margins show that changes to the mass convergence are related to the magnitude of precipitation that falls in the region, while the advection of dry air is associated with the maximum latitudinal extent of precipitation.

Mirror as polaron with internal degrees of freedom

We consider the model suggested by Wang and Unruh \cite{WangUnruh2013} for the $1+1$ D mirror moving in the quantum vacuum. We consider the relation of this model to the problem of polaron -- the electron moving in the vacuum of the quantum field of phonons. We introduce the field - theoretical model of such a mirror. It contains the multi - component spinor field interacting with the scalar field. We discuss the source of the logarithmic divergence in the mirror mass and its relation to the problem of the divergencies in vacuum energy.

Effective field theory and keV lines from dark matter

We survey operators that can lead to a keV photon line from dark matter decay or annihilation. We are motivated in part by recent claims of an unexplained 3.5 keV line in galaxy clusters and in Andromeda, but our results could apply to any hypothetical line observed in this energy range. We find that given the amount of flux that is observable, explanations in terms of decay are more plausible than annihilation, at least if the annihilation is directly to Standard Model states rather than intermediate particles. The decay case can be explained by a scalar or pseudoscalar field coupling to photons suppressed by a scale not far below the reduced Planck mass, which can be taken as a tantalizing hint of high-scale physics. The scalar case is particularly interesting from the effective field theory viewpoint, and we discuss it at some length. Because of a quartically divergent mass correction, naturalness strongly suggests the theory should be cut off at or below the 1000 TeV scale. The most plausible such natural UV completion would involve supersymmetry. These bottom-up arguments reproduce expectations from top-down considerations of the physics of moduli. A keV line could also arise from the decay of a sterile neutrino, in which case a renormalizable UV completion exists and no direct inference about high-scale physics is possible.

Effects of porous walled tubes on detonation transmission into unconfined space

Experiments were carried out to investigate the failure mechanisms in the critical tube diameter phenomenon for stable and unstable mixtures. It was previously postulated that in unstable mixtures where the detonation structure is highly irregular, the failure during the diffraction is caused by the suppression of the instability responsible for the generation of local explosion centers. In stable mixtures, typically with high argon dilution and where the detonation is characterized by very regular cells, the failure is driven by the excessive global front curvature above which a detonation cannot propagate. To discern these two failure mechanisms, porous walled tubes are used to attenuate the transverse instability before the detonation emerges into the unconfined space. Porous sections with length L/D from 0 to 3.0 are used with two confined tube diameters D=12.7 and 15.5mm. The present results show that when porous walled tubes are used, the critical pressure for unstable C2H2+2.5O2 and C2H2+5N2O mixtures increases significantly. In contrast, for stable argon diluted C2H2+2.5O2+70% mixtures, the results with porous wall tubes exhibit little variation up to L/D=2.5. For L/D>2.5 a noticeable increase in critical pressure for argon diluted mixtures is also observed. This is dominantly caused by the slow mass divergence through the porous material inducing a curvature on the detonation front even before it emerges into the open area. The present experiment again demonstrates the importance of the transverse wave instability for typical hydrocarbon mixtures in critical situations such as the critical tube diameter experiment. For special cases such as highly argon diluted mixtures, the instability does not play a significant role in the failure and the propagation is controlled dominantly by the global curvature effect and the shock-ignition mechanism.

Causes of Increasing Aridification of the Mediterranean Region in Response to Rising Greenhouse Gases*

Abstract The hydrological cycle in the Mediterranean region, as well as its change over the coming decades, is investigated using the Interim European Centre for Medium-Range Weather Forecasts Re-Analysis (ERA-Interim) and phase 5 of the Coupled Model Intercomparison Project (CMIP5) historical simulations and projections of the coming decades. The Mediterranean land regions have positive precipitation minus evaporation, P − E, in winter and negative P − E in summer. According to ERA-Interim, positive P − E over land in winter is sustained by transient eddy moisture convergence and opposed by mean flow moisture divergence. Dry mean flow advection is important for opposing the transient eddy moisture flux convergence in the winter half year and the mass divergent mean flow is a prime cause of negative P − E in the summer half year. These features are well reproduced in the CMIP5 ensemble. The models predict reduced P − E over the Mediterranean region in the future year-round. For both land and sea, a common cause of drying is increased mean flow moisture divergence. Changes in transient eddy moisture fluxes largely act diffusively and cause drying over the sea and moistening over many land areas to the north in winter and drying over western land areas and moistening over the eastern sea in summer. Increased mean flow moisture divergence is caused by both the increase in atmospheric humidity in a region of mean flow divergence and strengthening of the mass divergence. Increased mass divergence is related to increased high pressure over the central Mediterranean in winter and over the Atlantic and northern Europe in summer, which favors subsidence and low-level divergence over the Mediterranean region.