Single String Research Articles

Ground-state Dirac monopole

We show theoretically that a monopole defect, analogous to the Dirac magnetic monopole, may exist as the ground state of a dilute spin-1 Bose-Einstein condensate. The ground-state monopole is not attached to a single semi-infinite Dirac string, but forms a point where the circulation of a single vortex line is reversed. Furthermore, the three-dimensional dynamics of this monopole defect are studied after the magnetic field pinning the monopole is removed and the emergence of antimonopoles is observed. Our scheme is experimentally realizable with the present-day state of the art.

Worst-case efficient single and multiple string matching on packed texts in the word-RAM model

In this paper, we explore worst-case solutions for the problems of single and multiple matching on strings in the word-RAM model with word length w. In the first problem, we have to build a data structure based on a pattern p of length m over an alphabet of size σ such that we can answer to the following query: given a text T of length n, where each character is encoded using logσ bits return the positions of all the occurrences of p in T (in the following we refer by occ to the number of reported occurrences). For the multi-pattern matching problem we have a set S of d patterns of total length m and a query on a text T consists in finding all positions of all occurrences in T of the patterns in S. As each character of the text is encoded using logσ bits and we can read w bits in constant time in the RAM model, we assume that we can read up to Θ(w/logσ) consecutive characters of the text in one time step. This implies that the fastest possible query time for both problems is O(nlogσw+occ). In this paper we present several different results for both problems which come close to that best possible query time. We first present two different linear space data structures for the first and second problem: the first one answers to single pattern matching queries in time O(n(1m+logσw)+occ) while the second one answers to multiple pattern matching queries to O(n(logd+logy+loglogmy+logσw)+occ) where y is the length of the shortest pattern. We then show how a simple application of the four Russian technique permits to get data structures with query times independent of the length of the shortest pattern (the length of the only pattern in case of single string matching) at the expense of using more space.

Vibration Reducing Analysis of Beam String Structure with Seismic Isolation Bearings

A vibration reducing system of seismic isolation bearings is introduced into beam string structures. The vibration control on seismic response of beam string structures (BSS) with seismic isolation bearings is discussed. Firstly finite element models for different analyses are established by using explicit dynamic analysis program LS-DYNA. Then the seismic response analyses are performed on a single beam string structure with and without seismic isolation bearings to investigate the effectiveness of the seismic isolation bearings in reducing vibration response of BSS. Furthermore, parametric analyses are conducted to examine the effects of lateral stiffness and damping of the seismic isolation bearings on seismic isolation. The analytical results indicate that the vibration reducing system can effectively reduce the vibration response of BSS against seismic force, and be applied in the vibration control of BSS.

Historical Linguistics and Evolutionary Genetics. Based on Symbol Frequencies in Tamil Texts and DNA Sequences

We have studied the rank frequency distribution (RFD) of letters of the alphabet in Tamil language texts. In a novel application of rank frequencies, we have defined a simple intuitive distance parameter between a pair of strings (text or DNA sequence of codons). This distance correlates well with age difference in historical linguistics and evolutionary genetics. Using a distance matrix of a set of strings, we derive evolutionary trees that are broadly in agreement with historical evidence. The method has potential for refinement and application in evolutionary studies to complement other approaches to evolution. The RFD in a single string conforms to a law called the CMPL (Cumulative Modified Power Law), which we had formulated and applied to RFD's of diverse symbol sets.

Tensor tilt from primordial B modes

A primordial cosmic microwave background B-mode is widely considered a "smoking gun" signature of an early period of inflationary expansion. However, competing theories of the origin of structure, including string gases and bouncing cosmologies, also produce primordial tensor perturbations that give rise to a B-mode. These models can be differentiated by the scale dependence of their tensor spectra: inflation predicts a red tilt ($n_T<0$), string gases and loop quantum cosmology predict a blue tilt ($n_T>0$), while a nonsingular matter bounce gives zero tilt ($n_T=0$). We perform a Bayesian analysis to determine how far $|n_T|$ must deviate from zero before a tilt can be detected with current and future B-mode experiments. We find that Planck in conjunction with QUIET (II) will decisively detect $n_T \neq 0$ if $|n_T| > 0.3$, too large to distinguish either single field inflation or string gases from the case $n_T=0$. While a future mission like CMBPol will offer improvement, only an ideal satellite mission will be capable of providing sufficient Bayesian evidence to distinguish between each model considered.

Association of the Endosomal Sorting Complex ESCRT-II with the Vps20 Subunit of ESCRT-III Generates a Curvature-sensitive Complex Capable of Nucleating ESCRT-III Filaments

The scission of membranes necessary for vesicle biogenesis and cytokinesis is mediated by cytoplasmic proteins, which include members of the ESCRT (endosomal sorting complex required for transport) machinery. During the formation of intralumenal vesicles that bud into multivesicular endosomes, the ESCRT-II complex initiates polymerization of ESCRT-III subunits essential for membrane fission. However, mechanisms underlying the spatial and temporal regulation of this process remain unclear. Here, we show that purified ESCRT-II binds to the ESCRT-III subunit Vps20 on chemically defined membranes in a curvature-dependent manner. Using a combination of liposome co-flotation assays, fluorescence-based liposome interaction studies, and high-resolution atomic force microscopy, we found that the interaction between ESCRT-II and Vps20 decreases the affinity of ESCRT-II for flat lipid bilayers. We additionally demonstrate that ESCRT-II and Vps20 nucleate flexible filaments of Vps32 that polymerize specifically along highly curved membranes as a single string of monomers. Strikingly, Vps32 filaments are shown to modulate membrane dynamics in vitro, a prerequisite for membrane scission events in cells. We propose that a curvature-dependent assembly pathway provides the spatial regulation of ESCRT-III to fuse juxtaposed bilayers of elevated curvature.

One-dimensional vertical dust strings in a glass box

The oscillation spectrum of a one-dimensional vertical dust string formed inside a glass box on top of the lower electrode in a gaseous electronics conference (GEC) reference cell was studied. A mechanism for creating a single vertical dust string is described. It is shown that the oscillation amplitudes, resonance frequencies, damping coefficients, and oscillation phases of the dust particles separate into two distinct groups. One group exhibits low damping coefficients, increasing amplitudes, and decreasing resonance frequencies for dust particles closer to the lower electrode. The other group shows high damping coefficients but anomalous resonance frequencies and amplitudes. At low oscillation frequencies, the two groups are also separated by a π phase difference. One possible cause for the difference in behavior between the two groups is discussed.

The Seismic Performance of Single Beam String Structure

The modal analysis is performed on the single beam string structure in a practical project in this paper. Then the response history analyses, under the four different earthquake-induced ground motions in the single direction, are implemented on the structure. The analysis results indicate that it is very necessary to install out-of-plane bracings for the single beam string structure. In the design of similar structures, the section dimensions of the struts can be appropriately reduced due to the average stresses of the struts being smaller, and cross beams near the middle of structures are be given attention. And the analysis results provide a reference for the seismic analysis and design of similar structures.

Effects of Some Design Parameters on the Static Performance of the Truss String Structure

The beam string structure，a new self-balancing system is a combination of a string (Cable), pole and beam-column (beam, arch). Because the beam string structure make full use of tensile properties of high-strength cord, force became more reasonable, transportation became more convenient and construction became more simple for the new self-balancing system. The beam string structure became a new structure with a good value and prospects. In this paper the effects of the static performance of the single truss string structure are researched through analyzing the influence of prestressed cable, pole pitch, blow-span ratio of cable and cross-sectional area of cable using of finite element theory. The results of the reasonable selection of string truss design parameters a valuable reference.

Radix-8 Booth Encoded Modulo $2 ^{n} -1$ Multipliers With Adaptive Delay for High Dynamic Range Residue Number System

A special moduli set Residue Number System (RNS) of high dynamic range (DR) can speed up the execution of very-large word-length repetitive multiplications found in applications like public key cryptography. The modulo 2n-1 multiplier is usually the noncritical datapath among all modulo multipliers in such high-DR RNS multiplier. This timing slack can be exploited to reduce the system area and power consumption without compromising the system performance. With this precept, a family of radix-8 Booth encoded modulo 2n-1 multipliers, with delay adaptable to the RNS multiplier delay, is proposed. The modulo 2n-1 multiplier delay is made scalable by controlling the word-length of the ripple carry adder, k employed for radix-8 hard multiple generation. Formal criteria for the selection of the adder word-length are established by analyzing the effect of varying k on the timing of multiplier components. It is proven that for a given n, there exist a number of feasible values of k such that the total bias incurred from the partially-redundant partial products can be counteracted by only a single constant binary string. This compensation constant for different valid combinations of n and k can be precomputed at design time using number theoretic properties of modulo 2n-1 arithmetic and hardwired as a partial product to be accumulated in the carry save adder tree. The adaptive delay of the proposed family of multipliers is corroborated by CMOS implementations. In an RNS multiplier, when the critical modulo multiplier delay is significantly greater than the noncritical modulo 2n-1 multiplier delay, k = n and k = n /3 are recommended for n not divisible by three and divisible by three, respectively. Conversely, when this difference diminishes, k is better selected as n /4 and n /6 for n not divisible by three and divisible by three, respectively. Our synthesis results show that the proposed radix-8 Booth encoded modulo 2n-1 multiplier saves substantial area and power consumption over the radix-4 Booth encoded multiplier in medium to large word-length RNS multiplication.

Availability Analysis and Design Optimization of Photovoltaic Systems

In this paper, the importance of including random inverter failures in the photovoltaic (PV) system reliability and life-cycle cost calculations is demonstrated. A new performance-adjusting reliability coefficient, which accounts for system downtime, is proposed, and a Monte Carlo simulation for determining the values of the coefficient for various inverter configurations is presented. Several commonly used inverter configurations are considered, including a single inverter, string inverters and parallel inverters. The parallel configuration is found to yield maximal energy over the lifetime of the system. In addition, an inverter control strategy in a system with parallel inverters that further improves the total energy yield is proposed. The strategy is designed to selectively shut down one or more inverters during the periods of low insolation, thus enabling the remaining inverters to operate at higher conversion efficiency.

Detection of cosmic superstrings by geodesic test particle motion

$(p,q)$-strings are bound states of $p$ F-strings and $q$ D-strings and are predicted to form at the end of brane inflation. As such, these cosmic superstrings should be detectable in the Universe. In this paper we argue that they can be detected by the way that massive and massless test particles move in the space-time of these cosmic superstrings. In particular, we study solutions to the geodesic equation in the space-time of field theoretical $(p,q)$-strings. The geodesics can be classified according to the test particles' energy, angular momentum and momentum in the direction of the string axis. We discuss how the change of the magnetic fluxes, the ratio between the symmetry-breaking scale and the Planck mass, the Higgs-to-gauge-boson mass ratios and the binding between the F- and D-strings, respectively, influence the motion of the test particles. While massless test particles can move only on escape orbits, a new feature as compared to the infinitely thin string limit is the existence of bound orbits for massive test particles. In particular, we observe that---in contrast to the space-time of a single Abelian-Higgs string---bound orbits for massive test particles in $(p,q)$-string space-times are possible if the Higgs boson mass is larger than the gauge boson mass. We also compute the effect of the binding between the $p$- and the $q$-string on observables such as the light deflection and the perihelion shift. While light deflection can also be caused by other matter distributions, the possibility of a negative perihelion shift seems to be a feature of finite width cosmic strings that could lead to the unmistakable identification of such objects. In Melvin space-times, which are asymptotically nonconical, massive test particles have to move on bound orbits, while massless test particles can escape to infinity only if their angular momentum vanishes.

Primary placement technique of jejunostomy using the entristar™ skin-level gastrostomy tube in patients with esophageal cancer

BackgroundWe developed a skin-level jejunostomy tube (SLJT) procedure for patients undergoing esophagectomy using a skin-level gastrostomy tube (G-tube) (Entristar™; Tyco Healthcare, Mansfield, Mass), in order to improve their nutrition status and quality of life (QOL). We describe the procedure and the adverse effects of SLJT in patients with esophageal cancer (EC).MethodsOver a 24-month period (March 2008 to March 2010), there were 16 patients (mean age: 61.8 years; age range: 49-75 years; 15 men, 1 woman) who had Stage II or III EC. Primary jejunostomy was performed under general anesthesia during esophagectomy. The technical success and the immediate and delayed complications of the procedure were recorded.Jejunostomy techniquesSLJT placement using the G-tube (20Fr) was performed 20 cm from the Treitz ligament on the side opposing the jejunal mesenterium. The internal retention bolster was exteriorized through an incision in the abdominal wall. A single purse string suture using a 4-0 absorbable suture was performed. The internal retention bolster was then inserted into the jejunal lumen via the small incision. The intestine adjacent to the tube was anchored to the peritoneum using a single stitch.ResultsThe SLJT was successfully inserted in all 16 patients. No early complications were documented. Follow-up for a median of 107 days (range, 26-320 days) revealed leakage to the skin in four patients, including superficial wound infections in two patients. There were no cases of obstruction of the tube or procedure-related death.ConclusionsThis SLJT placement technique using the G-tube is a safe procedure in patients with EC and allows the creation of a long-term feeding jejunostomy.

Percolation of color sources and the equation of state of QGP in central Au–Au collisions at $\sqrt{s_{\mathit{NN}}}=200$ GeV

The Color String Percolation Model (CSPM) is used to determine the equation of state (EOS) of the QGP produced in central Au-Au collisions at $\sqrt{s_{NN}}$ = 200 A GeV using STAR data at RHIC. When the initial density of interacting colored strings exceeds the 2D percolation threshold a cluster is formed, which defines the onset of color deconfinement. These interactions also produce fluctuations in the string tension which transforms the Schwinger particle (gluon) production mechanism into a maximum entropy thermal distribution. The single string tension is determined by identifying the known value of the universal hadron limiting temperature $T_{c}$ = 167.7 $\pm$ 2.6 MeV with the CSPM percolation temperature at the critical threshold $\xi_{c}$ =1.2. At mid-rapidity the initial Bjorken energy density and the initial temperature determine the number of degrees of freedom consistent with the formation of a $\sim$ 2+1 flavor QGP. An analytic expression for the equation of state, the sound velocity $C_{s}^{2}(\xi)$ is obtained in CSPM. The CSPM $C_{s}^{2}(\xi)$ and the bulk thermodynamic values $\varepsilon /T^{4}$ and $s /T^{3}$ are in excellent agreement in the phase transition region with recent lattice QCD simulations (LQCD) by the HotQCD Collaboration.

Practical and commercial issues in the design and manufacture of vanadium flow batteries

The vanadium flow battery has emerged as one of the most favourable types of flow batteries for a number of reasons, including the lack of cross-contamination that troubled many earlier systems such as the Fe/Cr flow battery. Because the vanadium flow battery employs the same metal ion in both electrolytes, albeit in different oxidation states, there is no cumulative loss in performance, just an effective reversible self-discharge current.The self discharge that occurs in the vanadium flow batteries is limited to the electrolyte volume in the cells. However it can become substantial under low load conditions. The pumps also use power from the battery and may be considered as another source of self discharge. Taking these and maintenance considerations into account the layout of a 10kW, 100kWh, 48V vanadium flow battery was designed as a “Multi-Stage-Operation” system to provide maximum performance at all levels of load, ease of use and optimum maintenance conditions. ExperimentalA complete energy storage system with 10kW in power and 100kWh in energy was designed. It consists of a vanadium flow battery with smart controller and configurable power electronics housed in a weatherproof housing. The battery can be charged and discharged at up to 10kW and provides up to 100kWh of energy. The smart controller ensures that the battery operates at maximum efficiency at all times and allows remote observation of various battery parameters, including a reliable state of charge (SOC) measurement. The option of different arrangements of power electronics gives almost complete freedom in specification of electrical output (dc, single or three-phase ac). The battery can also be connected to photovoltaic, wind turbine, diesel/petrol/gas/biogas generators, fuel cells and water turbines to form discrete autonomous power supplies or to be part of a micro-, mini- or smart-grid. The FB10/100 battery for “Multi-Stage-Operation” is comprised of 5 strings of 36–40 cells each in 3 separate fluid circuits. The first fluid circuit, containing a single string, is always actively pumped with electrolyte and electrically connected to the charger and load. The second and third fluid circuits contain 2 strings each and are only actively pumped and electrically connected when the voltage reaches preset limits. When the circuits are in “standby”, i.e. not actively pumped and electrically connected, the self discharge is limited to the small volume of electrolyte in the cells. There is also a significant saving of pumping energy, because 3 pairs of small pumps are used in place of 1 pair of more powerful pumps. ResultsIn “Multi-Stage-Operation” mode, the overall battery performance is improved significantly. This is very important in off-grid installations, where loads are typically small compared to the power levels necessary for charging; i.e. a solar powered telemetric station may use 500W continuous power but requires fast charging due to the narrow time window when solar energy is available. In example, at a 1kW load the battery provides 25% more energy when operated in “Multi-Stage-Operation” mode compared to all stacks in operation.Since 2008, several power station have been equipped with FB10/100 storage units and put into operation. Within the presentation a report on the latest results including technical performance and cost issues will be given.

The Design and Implementation of an Automated System for Logging Clinical Experiences Using an Anesthesia Information Management System

Residents in anesthesia training programs throughout the world are required to document their clinical cases to help ensure that they receive adequate training. Current systems involve self-reporting, are subject to delayed updates and misreported data, and do not provide a practicable method of validation. Anesthesia information management systems (AIMS) are being used increasingly in training programs and are a logical source for verifiable documentation. We hypothesized that case logs generated automatically from an AIMS would be sufficiently accurate to replace the current manual process. We based our analysis on the data reporting requirements of the American College of Graduate Medical Education (ACGME). We conducted a systematic review of ACGME requirements and our AIMS record, and made modifications after identifying data element and attribution issues. We studied 2 methods (parsing of free text procedure descriptions and CPT4 procedure code mapping) to automatically determine ACGME case categories and generated AIMS-based case logs and compared these to assignments made by manual inspection of the anesthesia records. We also assessed under- and overreporting of cases entered manually by our residents into the ACGME website. The parsing and mapping methods assigned cases to a majority of the ACGME categories with accuracies of 95% and 97%, respectively, as compared with determinations made by 2 residents and 1 attending who manually reviewed all procedure descriptions. Comparison of AIMS-based case logs with reports from the ACGME Resident Case Log System website showed that >50% of residents either underreported or overreported their total case counts by at least 5%. The AIMS database is a source of contemporaneous documentation of resident experience that can be queried to generate valid, verifiable case logs. The extent of AIMS adoption by academic anesthesia departments should encourage accreditation organizations to support uploading of AIMS-based case log files to improve accuracy and to decrease the clerical burden on anesthesia residents.

Mechanical Properties of a One-Way Beam String Structure with the Cooperation of the Supporting Structure

In this paper, taking a practical project for the study, using the finite element analysis software ANSYS, static analyses under different load conditions are performed on a single beam string structure (BSS) and a one-way beam string structure with the cooperation of the supporting structure, respectively. Moreover, influence of factors on mechanical properties of the one-way BSS with the cooperation of the supporting structure is investigated. The factors include grouting, support form, corrosion. The results can provide a reference for design and construction of the same type of structure.

High-level modeling of resistor string based digital-to-analog converters

To obtain a high performance CMOS resistor string digital-to-analog converter (DAC), one of the key design issues is the mismatch in the resistor ratio. This mismatch causes nonlinearity errors such as integral nonlinearity (INL) and differential nonlinearity (DNL), degrading the performances of the converter. Usually these matching properties are taken into account during the design phase by using time consuming and computational intensive transistor-level Monte Carlo simulations for the process technology corner. Recent research aims at reducing the design time by exploiting high-level modeling of converters as a trade-off between simulation time and modelling accuracy. In this work an analytical model for resistor mismatch in DACs is presented and implemented in MATLABTM environment. The model utilizes geometrical size of resistors and statistical data of the technology process. Starting from random process variations on geometries it was possible to estimate DNL and INL with very short time simulations. The proposed model is valid both for single stage resistor string DACs or segmented ones. The model can be used to speed up the design of resistor-string based DACs, or as a starting point to develop more accurate models by taking into account high-order effects. The model was successfully used to design a 10bit resistor string DAC in a 0.18 μm BCD technology with DNL and INL lower than 1 LSB (in absolute value). Since the complexity of the DAC is dominated by the resistor string, its optimization since the early design steps, enabled by the proposed high-level model, allowed to minimize area versus state of the art.

Single Pellet String Reactor for Intensification of Catalyst Testing in Gas/Liquid/Solid Configuration

Catalyst improvement is a key route toward process improvement in terms of yield, energy efficiency and selectivity optimization. The catalyst development strategy includes catalyst testing on a model or real feedstock. This key step has been the focus of many studies during the last decades concerning reactor design, analytical tool development and operating procedures. Most studies aim to determine catalytic grain activity in isothermal conditions so as to be able to understand and predict the kinetics. With catalyst improvement, in the lab-scale reactors available, the mass transfer rate can become the limiting step compared with the reaction rate, especially for fast exothermic reactions. A new reactor geometry is proposed to intensify the mass transfer and to accelerate the fluid superficial velocities: the single pellet string reactor. To characterize this new geometry, a hydrodynamic study was carried out in a horizontal single pellet string reactor with a 4.0 × 4.0 mm<sup>2<sup/> square section, filled with spherical particles of diameter varying between 2.0 and 4.0 mm. In this hydrodynamic study, visual observations of the flow patterns were performed, as well as pressure drop measurements and residence time distribution analysis in single liquid phase flow and two-phase flows. In every configuration tested, two main regimes were identified: the “isolated bubbles” regime and the “stratified” regime. Peclet number and liquid hold-up were deduced from the residence time distribution analysis. The measured liquid hold-ups are always higher than 0.6, which indicates, in addition to the visual observations and colorimetric tests, that the catalyst is always fully wetted by the liquid film. The axial dispersion measurements showed that the single liquid phase flow cannot be interpreted by a classical axial dispersion model. However, when a gas phase is added, the flow becomes closer to plug flow, with Peclet numbers always higher than 40. It has been shown that the pressure drop is controlled by the liquid/solid friction surface and that the pressure drop is not a limiting parameter in the reactor’s operation (values always lower than 0.1 bar). So, from a hydrodynamic point of view, this new reactor exhibits characteristics suitable for its use in catalytic tests. Finally, this reactor was implemented under reaction conditions to study hydrogenation reactions with a real industrial catalyst. The selective hydrogenation of allene was studied. The string reactor was shown to run isothermal kinetic tests with a very small amount of industrial-sized catalyst particles (less than 2 cc) and to explore kinetics of fast reaction at high space velocities impossible to achieve in standard fixed bed units with appropriate hydrodynamic conditions. For constant residence time, the allene conversion does not vary with pressure and feed flow rate, which confirms that the string reactor allows one to perform catalytic tests with such a fast reaction without external mass transfer resistance.

The eggs and hatchlings of the octopusRobsonella fontaniana(Cephalopoda: Octopodidae)

Very little is known about the life history ofRobsonella fontaniana. In particular, there are no descriptions of the early life stages that enable correct identification of samples taken from the wild. In this work, eggs and hatchlings are described from egg clutches obtained in the field with brooding females and incubated until hatching. Individual eggs exhibited marked differences in stages of embryonic development within egg clutches or even within a single egg string. For one clutch collected at early stages of embryonic development, embryogenesis took 91 days at 11.5 °C and for a second clutch at intermediate developmental stages it took 68 days at 11 °C and 39 days at 14 °C. For the later clutch the hatching period lasts 25 days at 14 °C. The eggs and paralarvae were small, with an egg length of 3.9–5.2 mm, a dorsal mantle length of 2–3 mm and a total paralarvae length of 3.4–6.0 mm. Chromatophore shape and distribution presented a very distinctive pattern. Characteristics of the eggs, egg strings and paralarvae make it possible to distinguish the early stagesof R. fontanianafrom those of other octopodid species found off the Atlantic coast of Patagonia.