Precise Agreement Research Articles

Perturbative tests of non-perturbative counting

We observe that a class of quarter-BPS dyons in $ \mathcal{N} = 4 $ theories with charge vector (Q, P) and with nontrivial values of the arithmetic duality invariant I := gcd(Q∧P) are nonperturbative in one frame but perturbative in another frame. This observation suggests a test of the recently computed nonperturbative partition functions for dyons with nontrivial values of the arithmetic invariant. For all values of I, we show that the nonperturbative counting yields vanishing indexed degeneracy for this class of states everywhere in the moduli space in precise agreement with the perturbative result.

AdS7/CFT6, Gauss-Bonnet gravity, and viscosity bound

We study the relation between the causality and the positivity of energy bounds in Gauss-Bonnet gravity in AdS_7 background and find a precise agreement. Requiring the group velocity of metastable states to be bounded by the speed of light places a bound on the value of Gauss-Bonnet coupling. To find the positivity of energy constraints we compute the parameters which determine the angular distribution of the energy flux in terms of three independent coefficients specifying the three-point function of the stress-energy tensor. We then relate the latter to the Weyl anomaly of the six-dimensional CFT and compute the anomaly holographically. The resulting upper bound on the Gauss-Bonnet coupling coincides with that from causality and results in a new bound on viscosity/entropy ratio.

A General Framework for Symbol Error Probability Analysis of Wireless Systems and Its Application in Amplify-and-Forward Multihop Relaying

New exact single-integral expressions for the evaluation of the average error probability of a wireless communication system are derived for a variety of modulation schemes in terms of the moment-generating function (MGF) of the reciprocal of the instantaneous received signal-to-noise ratio (SNR). The expressions obtained form a framework for performance evaluation of wireless communication systems for which the well-known MGF-based performance analysis method cannot be used, that is, systems for which the MGF of the instantaneous received SNR is not known or cannot be derived in closed-form. Using the framework obtained, the error probability performance in general fading of an amplify-and-forward (AF) multihop relaying system with both variable-gain and fixed-gain relays is then evaluated. In particular, a new expression for the MGF of the reciprocal of the instantaneous received SNR of an AF multihop system with fixed-gain relays is derived. Numerical examples show precise agreement between simulation results and theoretical results.

Transcriptional Control of Photosynthesis Genes: The Evolutionarily Conserved Regulatory Mechanism in Plastid Genome Function

Chloroplast sensor kinase (CSK) is a bacterial-type sensor histidine kinase found in chloroplasts—photosynthetic plastids—in eukaryotic plants and algae. Using a yeast two-hybrid screen, we demonstrate recognition and interactions between: CSK, plastid transcription kinase (PTK), and a bacterial-type RNA polymerase sigma factor-1 (SIG-1). CSK interacts with itself, with SIG-1, and with PTK. PTK also interacts directly with SIG-1. PTK has previously been shown to catalyze phosphorylation of plastid-encoded RNA polymerase (PEP), suppressing plastid transcription nonspecifically. Phospho-PTK is inactive as a PEP kinase. Here, we propose that phospho-CSK acts as a PTK kinase, releasing PTK repression of chloroplast transcription, while CSK also acts as a SIG-1 kinase, blocking transcription specifically at the gene promoter of chloroplast photosystem I. Oxidation of the photosynthetic electron carrier plastoquinone triggers phosphorylation of CSK, inducing chloroplast photosystem II while suppressing photosystem I. CSK places photosystem gene transcription under the control of photosynthetic electron transport. This redox signaling pathway has its origin in cyanobacteria, photosynthetic prokaryotes from which chloroplasts evolved. The persistence of this mechanism in cytoplasmic organelles of photosynthetic eukaryotes is in precise agreement with the CoRR hypothesis for the function of organellar genomes: the plastid genome and its primary gene products are Co-located for Redox Regulation. Genes are retained in plastids primarily in order for their expression to be subject to this rapid and robust redox regulatory transcriptional control mechanism, whereas plastid genes also encode genetic system components, such as some ribosomal proteins and RNAs, that exist in order to support this primary, redox regulatory control of photosynthesis genes. Plastid genome function permits adaptation of the photosynthetic apparatus to changing environmental conditions of light quantity and quality.

Shocks, Stocks, and Socks: Smoothing Consumption Over a Temporary Income Loss

We investigate how households in temporarily straitened circumstances due to an unemploy-ment spell cut back on expenditures and how they spend marginal dollars of unemployment insurance (UI) benefit. Our theoretical and empirical analyses emphasize the importance of allowing for the fact that households buy durable as well as non-durable goods. The theoretical analysis shows that in the short run households can cut back significantly on total expenditures without a significant fall in welfare if they concentrate their budget reductions on durables. We then present an empirical analysis based on a Canadian survey of workers who experienced a job separation. Exploiting changes in the unemployment insurance system over our sample period we show that cuts in UI benefits lead to reductions in total expenditure with a stronger impact on clothing than on food expenditures. Our empirical strategy allows that these expenditures may be non-separable from employment status. The effects we find are particularly strong for households with no liquid assets before the spell started. These qualitative findings are in precise agreement with the theoretical predictions. (JEL: D11, D12, D91, J65). © 2009 by the European Economic Association.

Evidence for biodegradation products in the interstellar medium

AbstractThe interstellar absorption band centred on 2175 Å that is conventionally attributed to monodisperse graphite spheres of radii 0.02 μm is more plausibly explained as arising from biologically derived aromatic molecules. On the basis of panspermia models, interstellar dust includes a substantial fraction of biomaterial in various stages of degradation. We have modeled such an ensemble of degraded biomaterial with laboratory spectroscopy of algae, grass pigments, bituminous coal and anthracite. The average ulrtraviolet absorption profile for these materials is centred at 2175 Å with a full width at half maximum of 250 Å, in precise agreement with the interstellar extinction observations. Mid-infrared spectra also display general concordance with the unidentified interstellar absorption features found in a wide variety of astronomoical sources.

The Multiple Zeta Value data mine

We provide a data mine of proven results for Multiple Zeta Values (MZVs) of the form ζ ( s 1 , s 2 , … , s k ) = ∑ n 1 > n 2 > ⋯ > n k > 0 ∞ { 1 / ( n 1 s 1 ⋯ n k s k ) } with weight w = ∑ i = 1 k s i and depth k and for Euler sums of the form ∑ n 1 > n 2 > ⋯ > n k > 0 ∞ { ( ϵ 1 n 1 ⋯ ϵ 1 n k ) / ( n 1 s 1 ⋯ n k s k ) } with signs ϵ i = ± 1 . Notably, we achieve explicit proven reductions of all MZVs with weights w ⩽ 22 , and all Euler sums with weights w ⩽ 12 , to bases whose dimensions, bigraded by weight and depth, have sizes in precise agreement with the Broadhurst–Kreimer and Broadhurst conjectures. Moreover, we lend further support to these conjectures by studying even greater weights ( w ⩽ 30 ), using modular arithmetic. To obtain these results we derive a new type of relation for Euler sums, the Generalized Doubling Relations. We elucidate the “pushdown” mechanism, whereby the ornate enumeration of primitive MZVs, by weight and depth, is reconciled with the far simpler enumeration of primitive Euler sums. There is some evidence that this pushdown mechanism finds its origin in doubling relations. We hope that our data mine, obtained by exploiting the unique power of the computer algebra language form, will enable the study of many more such consequences of the double-shuffle algebra of MZVs, and their Euler cousins, which are already the subject of keen interest, to practitioners of Quantum Field Theory, and to mathematicians alike.

Domain wall flow equations and [formula omitted] structure compactifications

We study supersymmetric domain wall solutions in four dimensions arising from the compactification of type II supergravity on an SU ( 3 ) × SU ( 3 ) structure manifold. Using a pure spinor approach, we show that the supersymmetry variations can be reinterpreted as a generalisation of the Hitchin flow equations and describe the embedding of an SU ( 3 ) × SU ( 3 ) structure manifold into a G 2 × G 2 structure manifold. We find a precise agreement between the four- and ten-dimensional supergravity results. The flow equations derived here should have applications in constructing the gravity duals of Chern–Simons-matter conformal field theories.

The phase structure of supersymmetric Sp(2Nc) gauge theories with an adjoint

We study the phase structure of = 1 supersymmetric Sp(2Nc) gauge theories with 2Nf fundamentals, an adjoint, and vanishing superpotential. Using a-maximization, we derive analytic expressions for the values of Nf below which the first several gauge-invariant operators in the chiral ring violate the unitarity bound and become free fields. In doing so we are able to explicitly check previous conjectures about the behavior of this theory made by Luty, Schmaltz, and Terning. We then compare this to an analysis of the first two 'deconfined' dual descriptions based on the gauge groups Sp(2Nf+2) × SO(2Nc+5) and Sp(2Nf+2) × SO(4Nf+4) × Sp(2Nc+2), finding precise agreement. In particular, we find no evidence for non-obvious accidental symmetries or the appearance of a mixed phase in which one of the dual gauge groups becomes free.

Probing the momentum relaxation time of charge carriers in ultrathin layers with terahertz radiation

We report on the development of a terahertz time-domain technique for measuring the momentum relaxation time of charge carriers in ultrathin semiconductor layers. Making use of the Drude model, our phase sensitive modulation technique directly provides the relaxation time. Time-resolved THz experiments were performed on n-doped GaAs and show precise agreement with data obtained by electrical characterization. The technique is well suited for studying novel materials where parameters such as the charge carriers' effective mass or the carrier density are not known a priori.

In-vivo imaging of retinal nerve fiber layer vasculature: imaging - histology comparison

BackgroundAlthough it has been suggested that alterations of nerve fiber layer vasculature may be involved in the etiology of eye diseases, including glaucoma, it has not been possible to examine this vasculature in-vivo. This report describes a novel imaging method, fluorescence adaptive optics (FAO) scanning laser ophthalmoscopy (SLO), that makes possible for the first time in-vivo imaging of this vasculature in the living macaque, comparing in-vivo and ex-vivo imaging of this vascular bed.MethodsWe injected sodium fluorescein intravenously in two macaque monkeys while imaging the retina with an FAO-SLO. An argon laser provided the 488 nm excitation source for fluorescence imaging. Reflectance images, obtained simultaneously with near infrared light, permitted precise surface registration of individual frames of the fluorescence imaging. In-vivo imaging was then compared to ex-vivo confocal microscopy of the same tissue.ResultsSuperficial focus (innermost retina) at all depths within the NFL revealed a vasculature with extremely long capillaries, thin walls, little variation in caliber and parallel-linked structure oriented parallel to the NFL axons, typical of the radial peripapillary capillaries (RPCs). However, at a deeper focus beneath the NFL, (toward outer retina) the polygonal pattern typical of the ganglion cell layer (inner) and outer retinal vasculature was seen. These distinguishing patterns were also seen on histological examination of the same retinas. Furthermore, the thickness of the RPC beds and the caliber of individual RPCs determined by imaging closely matched that measured in histological sections.ConclusionThis robust method demonstrates in-vivo, high-resolution, confocal imaging of the vasculature through the full thickness of the NFL in the living macaque, in precise agreement with histology. FAO provides a new tool to examine possible primary or secondary role of the nerve fiber layer vasculature in retinal vascular disorders and other eye diseases, such as glaucoma.

Structure of pressure-induced amorphous form ofSnI4at high pressure

The structure of pressure-induced amorphous form of ${\text{SnI}}_{4}$ has been studied by synchrotron x-ray diffraction measurements using diamond-anvil cell. The structure factor, the reduced radial distribution function, and the density were obtained between 25 and 55 GPa. Comparison of measured structure factor with that calculated for a randomly oriented dimerized molecules model shows no similarity between them. Experimentally obtained radial distribution function provides clear evidence for the absence of both distances between tin and iodine atoms and between iodine atoms within the ${\text{SnI}}_{4}$ tetrahedral molecule. Characteristic features of the structure factor for amorphous ${\text{SnI}}_{4}$ show a marked resemblance to those for elemental metallic glasses which are successfully reproduced by a model of dense random packing of equal-sized spheres. Indeed, various quantities such as positions of peaks in measured structure factors and in experimental radial distribution functions, the coordination number are in precise agreement with those derived from the dense random-packing model. We conclude that the structure of the high-pressure amorphous form of ${\text{SnI}}_{4}$ is the relatively rigid packing of tetrahedra composed of iodine and substitutional tin atoms.

SNOMED CT’s Ontological Commitment

AbstractSNOMED CT is a clinical terminology that describes the meaning of terms by logical axioms. This requires an ontological commitment, i.e. precise agreements about the ontological nature of the entities referred to. We provide evidence that SNOMED implicitly supports at least three different kinds of commitments, viz. (i) independently existing entities, (ii) representational artifacts, and (iii) clinical situations. Our analysis shows how the truth-value of a sentence changes according to one of these perspectives. We argue that a clear understanding of to what kind of entities SNOMED CT concepts extend is crucial for the proper use and maintenance of SNOMED CT.

SNOMED CT’s Ontological Commitment

SNOMED CT is a clinical terminology that describes the meaning of terms by logical axioms. This requires an ontological commitment, i.e. precise agreements about the ontological nature of the entities referred to. We provide evidence that SNOMED implicitly supports at least three different kinds of commitments, viz. (i) independently existing entities, (ii) representational artifacts, and (iii) clinical situations. Our analysis shows how the truth-value of a sentence changes according to one of these perspectives. We argue that a clear understanding of to what kind of entities SNOMED CT concepts extend is crucial for the proper use and maintenance of SNOMED CT.

Planar dynamics of a rigid body system with frictional impacts. II. Qualitative analysis and numerical simulations

The objective of this paper is to implement and test the theory presented in a companion paper for the non-smooth dynamics exhibited in a bouncing dimer. Our approach revolves around the use of rigid body dynamics theory combined with constraint equations from the Coulomb's frictional law and the complementarity condition to identify the contact status of each contacting point. A set of impulsive differential equations based on Darboux–Keller shock dynamics is established that can deal with the complex behaviours involved in multiple collisions, such as the frictional effects, the local dissipation of energy at each contact point, and the dispersion of energy among various contact points. The paper will revisit the experimental phenomena found in Dorbolo et al . ( Dorbolo et al . 2005 Phys. Rev. Lett. 95 , 044101), and then present a qualitative analysis based on the theory proposed in part I. The value of the static coefficient of friction between the plate and the dimer is successfully estimated, and found to be responsible for the formation of the drift motion of the bouncing dimer. Plenty of numerical simulations are carried out, and precise agreements are obtained by the comparisons with the experimental results.

Analytic formulas for above-threshold ionization or detachment plateau spectra

Closed-form analytic formulas are derived in the tunneling limit for both above-threshold detachment (ATD) of negative ions and above-threshold ionization (ATI) of neutral atoms. These formulas are shown to give precise agreement with essentially exact single-active-electron numerical results for detached or ionized electron energies corresponding to the high-energy end of the ATD and ATI plateaus (with only a small constant shift of electron energies being required in the case of ATI). These formulas for ATI and ATD rates thus provide an analytic explanation for the well-known oscillatory patterns of ATI and ATD rates as functions of electron energy and of the parameters of the laser field. They also provide an analytic explanation for the dependence of these rates on the initial orbital angular momentum of the active electron. Most significantly, these formulas provide a fully quantum justification of the well-known classical three-step scenario for strong-field ionization and detachment spectra in the high-energy region of the ATI or ATD plateau.

Agreement between Task-Based Estimates of the Full-Shift Noise Exposure and the Full-Shift Noise Dosimetry

Noise assessments have been conducted using full-shift dosimetry and short-term task-based measurements. Advantages of the task-based method include the opportunity to directly identify high-noise exposure tasks and to target control measures, as well as obtain estimates of task-based full-shift exposures; however, there is little empirical evidence comparing the two methods. National Institute for Occupational Safety and Health assessed noise exposures at three industrial facilities using dosimetry and task-based methods with the objective of comparing the two strategies and assessing the degree of agreement and causes of disagreement. Eight indices of task-based full-shift exposures were created from task-based sampling using three methods to assess time-at-task (direct observation by industrial hygienist, end-of-shift worker estimates and supervisor estimates) and three methods to assign noise levels to tasks [direct measurement, arithmetic mean (AM) and geometric mean (GM)]. We assessed aspects of agreement (precision, bias and absolute agreement) using Bland-Altman plots and concordance correlation coefficient (CCC). Overall, the task-based methods worked fairly well, with mean biases less than +/-2.8 dBA and precision ranges of 3.3-4.4 dBA. By all measures, task-based full-shift estimates based on supervisor assessment of time-at-task agreed most poorly with the dosimetry data. The task-based full-shift estimates based on worker estimates of time-at-task generally agreed as well as those based on direct observation. For task noise level, task-based full-shift estimates based on directly measured task agreed the best with dosimetry data, while agreement for task-based indices based on task AM or GM was variable. Overall, the task-based full-shift estimates based on direct observation task and direct measured task noise level achieved the best agreement with the dosimetry data (CCC 0.84) with 95% of their differences being within 7.4 dBA and 56% of the differences <3 dBA. For this index, a high degree of accuracy was observed (accuracy coefficient = 0.96) with major cause of disagreement arising from a lack of precision (precision coefficient = 0.88). When the measurements were classified by job characteristics, significant improvements in the degree of agreement were observed in the low job mobility, low job complexity and low job variability categories. Our data suggest that a high degree of absolute agreement can be achieved between the task-based and dosimetry-based estimates of full-shift exposures. The task-based approach that uses worker reports combined with task AM or GM levels is similar to the more time-intensive direct observation method to estimate full-shift exposures.

Pubertal development: correspondence between hormonal and physical development.

Puberty is advanced by sex hormones, yet it is not clear how it is best measured. The interrelation of multiple indices of puberty was examined, including the Pubertal Development Scale (PDS), a picture-based interview about puberty (PBIP), and a physical exam. These physical pubertal measures were then associated with basal hormones responsible for advancing puberty. Participants included 160 early adolescents (82 boys). Puberty indices were highly correlated with each other. The physical exam stages correlated well with boys' and girls' testosterone and dehydroepiandrosterone and less so with girls' estradiol. The PDS and PBIP were similarly related to basal hormones. Self-report may be adequate when precise agreement is unnecessary. Multiple measures of puberty are viable options, each with respective strengths.

CaV1.4 C-tail Segment (ICDI) Inhibits CaV Channel Inactivation by Competing with Calmodulin–Resolution by Holochannels and Calmodulin FRET Sensors

An intriguing variation on calmodulin/CaV channel inactivation (CDI) is the action of a C-tail segment from CaV1.4 channels (ICDI) to eliminate CDI. Introducing ICDI into CaV1.2 or CaV1.3 channels nearly abolishes strong baseline CDI, and a like effect is observed when ICDI is present within CaV1.4 itself. In retina, the effect in CaV1.4 helps sustain Ca2+ influx despite maintained depolarization. Contrasting with clear-cut function, the underlying ICDI mechanism remains controversial. One group proposes that ICDI allosterically inhibits CDI (Wahl-Schott et al PNAS 2006), while another suggests direct competition between calmodulin and ICDI for the channel (Singh et al Nature Neurosci 2006). The discussion hinges on differing calmodulin versus channel peptide assays. Here, we perform functional interaction assays using holochannels within live cells. As baseline, we electrophysiologically characterized CaV1.3 channels fused to an ICDI-containing segment (α1D-ABI-F). These α1D-ABI-F channels exhibited little CDI compared to wild-type CaV1.3. Critically, variations in the ambient calmodulin concentration would only affect competitive versus allosteric mechanisms. Indeed, when calmodulin was depleted by a ‘calmodulin sponge,’ residual CDI in α1D-ABI-F, was totally eliminated. More telling, when calmodulin was over-expressed with α1D-ABI-F, we observed a resurgence of CDI to wild-type CaV1.3 levels. To test for precise agreement with a competitive mechanism, we co-expressed α1D-ABI-F channels with BSCaMIQ, a FRET biosensor of calmodulin (Black et al Biochemistry 2006). Accordingly, both CDI and calmodulin concentrations could be measured within single cells; and pooling data from cells exhibiting variable calmodulin levels permitted explicit resolution of an in situ calmodulin binding curve, in strict agreement with a competitive mechanism. In all, ICDI suppresses CDI by competing with calmodulin for the channel, raising the possibility that natural variations in calmodulin might customize CDI through this mechanism.

Spin and orbital Hall effects for diffracting optical beams in gradient-index media

We examine the evolution of paraxial beams carrying intrinsic spin and orbital angular momenta (AM) in gradient-index media. A parabolic-type equation is derived which describes the beam diffraction in curvilinear coordinates accompanying the central ray. The center of gravity of the beam experiences transverse AM-dependent deflections---the spin and orbital Hall effects. The spin Hall effect generates a transverse translation of the beam as a whole, in precise agreement with recent geometrical optics predictions. At the same time, the orbital Hall effect is significantly affected by the diffraction in the inhomogeneous medium and is accompanied by changes in the intrinsic orbital AM and deformations of the beam.