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ON THE TEMPORAL EVOLUTION OF THE DISK COUNTERPART OF TYPE II SPICULES IN THE QUIET SUN
The newly established type II spicule has been speculated to provide enough hot plasma to play an important role in the mass loading and heating of the solar corona. With the identification of rapid blueshifted excursions (RBEs) as the on-disk counterpart of type II spicules we have analyzed three different high-quality timeseries with the CRisp Imaging SpectroPolarimeter (CRISP) at the Swedish Solar Telescope on La Palma and subjected to an automated detection routine to detect a large number of RBEs for statistical purposes. Our observations are of a quiet-Sun region at disk center and we find lower Doppler velocities, 15-40 km s{sup -1}, and Doppler widths, 2-15 km s{sup -1}, of RBEs than in earlier coronal hole studies, 30-50 km s{sup -1} and 7-23 km s{sup -1}, respectively. In addition, we examine the spatial dependence of Doppler velocities and widths along the RBE axis and conclude that there is no clear trend to this over the field of view or in individual RBEs in the quiet Sun at disk center. These differences with previous coronal hole studies are attributed to the more varying magnetic field configuration in quiet-Sun conditions. Using an extremely high-cadence data set has allowed us to improve greatly on the determination of lifetimes of RBEs, which we find to range from 5 to 60 s with an average lifetime of 30 s, as well as the transverse motions in RBEs, with transverse velocities up to 55 km s{sup -1} and averaging 12 km s{sup -1}. Furthermore, our measurements of the recurrence rates of RBEs provide important new constraints on coronal heating by spicules. We also see many examples of a sinusoidal wave pattern in the transverse motion of RBEs with periods averaging 54 s and amplitudes from 21.5 to 129 km which agrees well with previous studies of wave motion in spicules at the limb. We interpret the appearance of RBEs over their full length within a few seconds as the result of a combination of three kinds of motions as is earlier reported for spicules. Finally, we look at the temporal connection between H{alpha} and Ca II 8542 RBEs and find that Ca II 8542 RBEs in addition to being located closer to the footpoint also appear before the H{alpha} RBEs. This connection between Ca II 8542 and H{alpha} supports the idea that heating is occurring in spicules and contributes more weight to the prominence of spicules as a source for heating and mass loading of the corona.
A dispersive treatment of K ι4 decays
K ι4 decays have several features of interest: they allow an accurate measurement of ππ-scattering lengths; the decay is the best source for the determination of some low-energy constants of chiral perturbation theory (χPT); one form factor of the decay is connected to the chiral anomaly. Here, we present the results of our dispersive analysis of K ι4 decays, which provides a resummation of ππ- and Kπ-rescattering effects. The free parameters of the dispersion relation are fitted to the data of the high-statistics experiments E865 and NA48/2. By matching to χPT at NLO and NNLO, we determine the low-energy constants and L r 1 , L r 2 , and L r 3 . In contrast to a pure chiral treatment, the dispersion relation describes the observed curvature of one of the K ι4 form factors, which we understand as an effect of rescattering beyond NNLO.
Spatiotemporal Crossover between Low- and High-Temperature Dynamical Regimes in the Quantum Heisenberg Magnet
The stranglehold of low temperatures on fascinating quantum phenomena in one-dimensional quantum magnets has been challenged recently by the discovery of anomalous spin transport at high temperatures. Whereas both regimes have been investigated separately, no study has attempted to reconcile them. For instance, the paradigmatic quantum Heisenberg spin-$1/2$ chain falls at low-temperature within the Tomonaga-Luttinger liquid framework, while its high-temperature dynamics is superdiffusive and relates to the Kardar-Parisi-Zhang universality class in $1+1$ dimensions. This work aims at reconciling the two regimes. Building on large-scale matrix product state simulations, we find that they are connected by a temperature-dependent spatiotemporal crossover. In this work, as the temperature $T$ is reduced, we show that the onset of superdiffusion takes place at longer length and time scales $\propto 1/T$. This prediction has direct consequences for experiments including nuclear magnetic resonance: it is consistent with earlier measurements on the nearly ideal Heisenberg $S=1/2$ chain compound Sr$_2$CuO$_3$ yet calls for new and dedicated experiments.
Learning from Correlated Events for Equipment Relation Inference in Buildings
Modern buildings produce thousands of data streams, and the ability to automatically infer the physical context of such data is the key to enabling building analytics at scale. As acquiring this contextual information is currently a time-consuming and error-prone manual process, in this study we make the first attempt at automatically inferring one important contextual aspect of the equipment in buildings — how each equipment is functionally connected with another. The main insight behind our solution is that functionally connected equipment is exposed to the same events in the physical world, creating correlated changes in the time series data of both equipment. Because events are of indeterminate length in time series, however, identifying them requires solving a non-polynomial combinatorial data segmentation problem. We present a solution that first extracts latent events from the sensory time series data, and then sifts out coincident events with a customized correlation procedure to identify the relationship between equipment.We evaluated our approach on data collected from over 1,000 pieces of equipment from 5 commercial buildings of various sizes located in different geographical regions in the US. Results show that this approach achieves 94.38% accuracy in relation inference, compared to 85.49% by the best baseline.
Nanosecond Gated CMOS Camera (NSGCC) ICD (Rev. 2.1)
The Ultra-Fast X-ray Imager (UXI) program is an ongoing effort at Sandia National Laboratories to create high speed, multi-frame, time-gated Read Out Integrated Circuits (ROICs), and a corresponding suite of photodetectors to image a wide variety of High Energy Density (HED) physics experiments on both Sandia’s Z-Machine and LLNL’s National Ignition Facility (NIF). Several cameras have been designed over the length of the program; one of the most recent is the Icarus, which is an improvement on past imagers (Furi and Hippogriff). A second sensor that can be connected is the Daedalus sensor. The Icarus is a 1024 × 512-pixel array with either 25 μm or 8 µm spatial resolution containing four frames of storage per pixel and has improved timing generation and distribution components while achieved 2 ns time gating. The Daedalus sensor is also a 1024 x 512-pixel array with 25 µm special resolution containing three frames of storage per pixel and has an increased set of features for a wider variety of applications from interlacing of rows in each frame to configurability of all shutters. See Section 14 for details regarding the Icarus implementation of the firmware and Section 15 for details regarding the Daedalus implementation. Due to the unique test environments UXI sensors are targeted for, full custom hardware was required to physically mount an Icarus or Daedalus sensor, manage its various functions, and read out pixel data for transfer to a host computer. Beyond experimental functionality, the hardware also needed to accommodate sensor characterization requirements. Lawrence Livermore National Laboratory’s ‘Version 4.0 Board’ was the result of these efforts. It mounts all the components required to fully utilize the Icarus and Daedalus sensors including analog to digital converters to convert pixel data and various system voltages to digital form for readout and analysis, DAC channels for remote configuration of critical bias voltages, static random-access memories to buffer pixel data, RS422 and Gigabit Ethernet communications for remote access, and an FPGA to tie these components together. This document describes the FPGA electrical interfaces in detail to allow the reader a greater understanding of the device, and to facilitate implementation of custom software to control and manage it. The Version 4.0 Board is a continuation of the Nano-second Gated CMOS hardware design that retains much of the functionality of the Version 1.0 Board while adding features including a DAC instead of digital potentiometers, as well as sensors for pressure and radiation. The Version 4.0 board is intended for applications requiring tight form-factor enclosures. It is composed of two stacking boards; one holds the FPGA and regulators to power the various components of the board while the other contains the mating connector to the sensor, image-readoff ADCs, the DAC, and other components.
Pinhole X-ray/coronagraph optical systems concept definition study
The Pinhole X-ray/Coronagraph Concept utilizes the long baselines possible in Earth orbit with the space transportation system (shuttle) to produce observations of solar X-ray emission features at extremely high spatial resolution (up to 0.1 arc second) and high energy (up to 100 keV), and also white light and UV observations of the inner and outer corona at high spatial and/or spectral resolution. An examination of various aspects of a preliminary version of the X-ray Pinhole/Coronagraph Concept is presented. For this preliminary version, the instrument package will be carried in the shuttle bay on a mounting platform, and will be connected to the occulter with a deployable boom such as an Astromast. Generally, the spatial resolution, stray light levels, and minimum limb observing angles improve as the boom length increases. However, the associated engineering problems also become more serious with greater boom lengths.
The two-dimensional structure of diffuse ions associated with the earth's bow shock
The lateral distribution of upstream, diffuse energetic ions resulting from shock acceleration at an idealized model bow shock is investigated, where the model consists of a uniform planar shock along which steady source ion injection takes place over a finite region of the shock. The solution exhibits growth toward a peak ion concentration whose location beneath the point of initial magnetic connection with the shock is sensitive to the model parameters. It is found that a plateau forms if the source size is large in comparison to the scale length of ion distribution function's growth, and that cross-field diffusion strongly enhances the diffuse ion concentration near the leading edge of the source.
Sensitivity to the external temperature of some GPS time receivers
It has been assumed until recently that GPS time receiver units (recever+cables+antenna) have good stability and do not affect time transfer by more than 1 ns. Differences of a few nanoseconds sometimes observed during calibration campaigns have been attributed to external causes, such as multipath propagation, rather than to variations within the hardware. The characteristic feature of most comparisons of GPS time receivers is their short duration. Normally the comparison takes place, at most, over one week. To observe the behavior of GPS time receivers over a period of several months, an experiment has been organized involving three receivers of two types. All three were connected to the same atomic clock. An unexpected sensitivity to external temperature was found in one type of receiver. This effect proved to be a function of the length and type of the antenna cable. In the most unfavorable case the sensitivity was 1.8 ns/C.
The Measurement of Pressure Through Tubes in Pressure Distribution Tests
The tests described in this report were made to determine the error caused by using small tubes to connect orifices on the surface of aircraft to central pressure capsules in making pressure distribution tests. Aluminum tubes of 3/16-inch inside diameter were used to determine this error. Lengths from 20 feet to 226 feet and pressures whose maxima varied from 2 inches to 140 inches of water were used. Single-pressure impulses for which the time of rise of pressure from zero to a maximum varied from 0.25 second to 3 seconds were investigated. The results show that the pressure recorded at the capsule on the far end of the tube lags behind the pressure at the orifice end and experiences also a change in magnitude. For the values used in these tests the time lag and pressure change vary principally with the time of rise of pressure from zero to a maximum and the tube length. Curves are constructed showing the time lag and pressure change. Empirical formulas are also given for computing the time lag. Analysis of pressure distribution tests made on airplanes in flight shows that the recorded pressures are slightly higher than the pressures at the orifice and that the time lag is negligible. The apparent increase in pressure is usually within the experimental error, but in the case of the modern pursuit type of airplane the pressure increase may be 5 per cent. For pressure-distribution tests on airships the analysis shows that the time lag and pressure change may be neglected.
Tunable thermal link
Disclosed is a device whereby the thermal conductance of a multiwalled nanostructure such as a multiwalled carbon nanotube (MWCNT) can be controllably and reversibly tuned by sliding one or more outer shells with respect to the inner core. As one example, the thermal conductance of an MWCNT dropped to 15% of the original value after extending the length of the MWCNT by 190 nm. The thermal conductivity returned when the tube was contracted. The device may comprise numbers of multiwalled nanotubes or other graphitic layers connected to a heat source and a heat drain and various means for tuning the overall thermal conductance for applications in structure heat management, heat flow in nanoscale or microscale devices and thermal logic devices.
Crystal structure of (2Z)-(3,3-dimethyl-3,4-dihydroisoquinolin- 1(2H)-ylidene)nitrosoacetonitrile
The crystal structure of (2Z)-(3,3-dimethyl-3,4-dihydroisoquinolin-1(2Н)-ylidene)nitrosoacetonitrile is determined (T = 150 K, R1 = 0.0435). The compound crystallizes as the E-cis and Z-cis isomers of the nitroso tautomer. Two independent molecules differ in the rotation of the nitroso group about the С–С bond between the dihydroisoquinoline group and the substituent. Analysis of bond lengths reveals their conjugation and prevailing contribution of the zwitter-ionic structures with the positive charge located on the isoquinoline fragment and the negative charge located on the substituent. Molecules having E and Z conformations are connected by the N–H···O hydrogen bond (N···O 2.922(3) Å) into dimers. The N–H group of the other molecule forms the intramolecular N–H···O hydrogen bond (N···O 2.544(3) Å) which closes a sixmembered cycle. Electronic absorption spectra are studied, and quantum-chemical modeling of the compound is performed.
Exact correlators on the Wilson loop in $$ \mathcal{N}=4 $$ SYM: localization, defect CFT, and integrability
We compute a set of correlation functions of operator insertions on the 1/8 BPS Wilson loop in N=4 SYM by employing supersymmetric localization, OPE and the Gram-Schmidt orthogonalization. These correlators exhibit a simple determinant structure, are position-independent and form a topological subsector, but depend nontrivially on the ’t Hooft coupling and the rank of the gauge group. When applied to the 1/2 BPS circular (or straight) Wilson loop, our results provide an infinite family of exact defect CFT data, including the structure constants of protected defect primaries of arbitrary length inserted on the loop. At strong coupling, we show precise agreement with a direct calculation using perturbation theory around the AdS 2 string worldsheet. We also explain the connection of our results to the “generalized Bremsstrahlung functions” previously computed from integrability techniques, reproducing the known results in the planar limit as well as obtaining their finite N generalization. Furthermore, we show that the correlators at large N can be recast as simple integrals of products of polynomials (known as Q-functions) that appear in the Quantum Spectral Curve approach. This suggests an interesting interplay between localization, defect CFT and integrability.
Understanding the Twisted Structure of Amyloid Fibrils via Molecular Simulations
According to the article, accumulation and aggregation of amyloid are associated with the pathogenesis of many human diseases, such as Alzheimer’s disease and Type 2 diabetes mellitus. Therefore, a quantitative understanding of the molecular mechanisms causing different aggregated structures and biomechanical properties of amyloid fibrils could shed some light into the progression of these diseases. In this work, we develop coarse-grained molecular dynamics (CGMD) models to simulate the dynamic self-assembly of two types of amyloids (amylin and amyloid β (Aβ)). We investigate the structural and mechanical properties of different types of aggregated amyloid fibrils. Our simulations demonstrate that amyloid fibrils could result from longitudinal growth of protofilament bundles, confirming one of the hypotheses on the fibril formation. In addition, we find that the persistence length of amylin fibrils increases concurrently with their pitch length, suggesting that the bending stiffness of amylin fibrils becomes larger when the amylin fibrils are less twisted. Similar results are observed for Aβ fibrils. These findings quantify the connection between the structural and the biomechanical properties of the fibrils. The CGMD models developed in this work can be potentially used to examine efficacy of anti-aggregation drugs, which could help in developing new treatments.
Dependence of occurrence rates of solar flares and coronal mass ejections on the solar cycle phase and the importance of large-scale connectivity
We investigate the dependence of the occurrence rates of major solar flares (M- and X-class) and front-side halo coronal mass ejections (FHCMEs), observed from 1996 to 2013, on the solar cycle (SC) phase for six active McIntosh sunspot group classes: Fkc, Ekc, Dkc, Fki, Eki, and Dki. We classify SC phases as follows: (1) ascending phase of SC 23 (1996–1999), (2) maximum phase of SC 23 (2000–2002), (3) descending phase of SC 23 (2003–2008), and (4) ascending phase of SC 24 (2009–2013). We find that the occurrence rates of major flares and FHCMEs during the descending phase are noticeably higher than those during the other phases for most sunspot group classes. For the most active sunspot group class, Fkc, the occurrence rate of FHCMEs during the descending phase of SC 23 is three times as high as that during the ascending phase of SC 23. The potential of each McIntosh sunspot group class to produce major flares or FHCMEs is found to depend on the SC phase. The occurrence rates (R) of major flares and FHCMEs are strongly anti-correlated with the annual average latitude of the sunspot groups (L): R∼L{sup −2.07} for major flares and R∼L{sup −2.42} for FHCMEs. This finding indicates the possible role of large-scale coronal connectivity, e.g., trans-equatorial loops, in powerful energy releases. Interestingly, this relationship is very similar to that between the volumetric coronal heating rate and X-ray loop lengths, indicating common energy release mechanisms.
Distributed multiport memory architecture
A multiport memory architecture is diclosed for each of a plurality of task centers connected to a command and data bus. Each task center, includes a memory and a plurality of devices which request direct memory access as needed. The memory includes an internal data bus and an internal address bus to which the devices are connected, and direct timing and control logic comprised of a 10-state ring counter for allocating memory devices by enabling AND gates connected to the request signal lines of the devices. The outputs of AND gates connected to the same device are combined by OR gates to form an acknowledgement signal that enables the devices to address the memory during the next clock period. The length of the ring counter may be effectively lengthened to any multiple of ten to allow for more direct memory access intervals in one repetitive sequence. One device is a network bus adapter which serially shifts onto the command and data bus, a data word (8 bits plus control and parity bits) during the next ten direct memory access intervals after it has been granted access. The NBA is therefore allocated only one access in every ten intervals, which is a predetermined interval for all centers. The ring counters of all centers are periodically synchronized by DMA SYNC signal to assure that all NBAs be able to function in synchronism for data transfer from one center to another.
The 2x2 quasi-optical power combiner array at 20 GHz
Investigation of a power combiner made of two FET oscillators for an active array are reported. As an approach by a quasi-optical method, a two-dimensional planar array of strongly coupled oscillators by direct connection through a microstrip line is used. In-phase condition between the oscillators as well as in-phase condition of each radiation wave was accomplished by regulating length of feed microstrip lines. The radiation elements of 1 lambda-slot are embedded in a circuit ground plane. At an operation frequency of 20 GHz, in both H- and E-planes, reasonable sigma radiation patterns were obtained which have good agreement with theoretical patterns.
Diagnostics Adapted for Heat-Treating Furnace Environment
Diagnostics developed for the in situ monitoring of rocket combustion environments were adapted for use in heat-treating furnaces. Simultaneous, in situ monitoring of the carbon monoxide, carbon dioxide, methane, water, and hydrogen concentrations in the endothermic gas of a heat-treating furnace were demonstrated under a Space Act Agreement between the NASA Lewis Research Center, the Heat Treating Network, and Akron Steel Treating Company. This endothermic gas, or "endogas," is produced in a catalytic process, where natural gas is "cracked" in the presence of air. Variations in the composition of the natural gas supplied lead to variations in the composition of the endothermic gas. These variations could lead to an unacceptable quality of steel products that are hardened through the carborization process that uses this gas. Conventional methods of monitoring the endogas include measuring the dew point of the gas and the oxygen concentration. From these data, the carbon monoxide content of the gas can be calculated. This carbon monoxide concentration creates the carbon potential needed for carburization. Several weak links are present in this approach. The oxygen monitor deteriorates over time, and the measurement might be inaccurate by 50 percent. Also, the chemistry equations, which are based on several assumptions, such as secondary species concentrations, provide only an approximate estimate of the carbon monoxide concentration. To address these weaknesses, we investigated a new method based on ordinary Raman spectroscopy, in which the carbon monoxide concentration is measured directly and in situ. This method measures the laser light scattered from the molecules. Each species interacts with the light and scatters the light at a different frequency. Spectral monitoring of the scattered light intensity at each molecular frequency of interest provides the species concentrations. One advantage over the conventional method is that several species can be monitored simultaneously. A second advantage is that the measurement is direct; there is no need to make assumptions, to filter the gas, or to calibrate the instrument. An instrument was designed consisting of a laser and a detection system within an enclosure, connected to an optical probe by fibers. For determining carbon monoxide concentration, the probe is mounted on the endothermic gas line, close to the generator. Optical fibers with a length of 150 ft have been used to transmit laser light from the instrument to the probe. There, the light is focused into the gas, and the scattered light is collected and transmitted back to the instrument where it is analyzed with a photomultiplier and lock-in amplifier. Laboratory tests have shown that with the current system the concentration of carbon monoxide, water, nitrogen, oxygen, and hydrogen in the air can be monitored with an accuracy of 1 percent. The concentration of carbon dioxide in the air can be monitored with an accuracy of 0.5 percent, and the concentration of methane with an accuracy of 0.2 percent. This instrument was taken to the Akron Steel Treating Plant, where field tests are in progress to verify the system capabilities. Planned developments are improving the accuracy, monitoring multiple locations, and reducing instrument size and cost.