Split Rate Research Articles

Probability density function solutions to a Bessel type pantograph equation

We extend a cell growth model with a deterministic cell growth rate and asymmetric division to include dispersion. This extension yields a second order functional differential equation, the solution of which is required to be a probability density function for the size of a cell (as measured by DNA content). We study the equation for certain choice of non constant coeffcients that correspond to dispersion, growth and splitting rates. This choice of coeffcients leads to a Bessel type operator, and it is shown that there is a unique probability distribution function that solves the equation. The solution is constructed using the Mellin transform and is given in terms of an infinite series of modified Bessel functions.

Efficient hydrogen production by water-splitting over Pt-deposited C–HS–TiO2 hollow spheres under visible light

A Pt-deposited C–HS–TiO2 hollow sphere prepared through a simple template approach as well as their implementation as a photocatalyst for water splitting. The obtained Pt-deposited C–HS–TiO2 hollow spheres are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), UV–vis absorption spectrum (UV–vis), and transmission electron microscope (TEM). The results show that hollow spherical morphology was successfully synthesized. Compared with commercial P-25 TiO2 and C–TiO2 hollow sphere, Pt-deposited C–HS–TiO2 hollow spheres exhibit significant improvement in photoactivity under the visible light irradiation. It can be attributed to the enhanced visible light absorption by the deposited Pt. Furthermore, 1.0 wt% Pt/C–HS–TiO2 presents an ultra-high photocatalytic water splitting activity. The maximum production rate of hydrogen at a reaction temperature of 25 °C is measured as 2857 µmol/h. In addition, 1.0 wt% Pt/C–HS–TiO2 exhibits excellent long-term stability and durability of photocatalytic activity. The rate of visible light water splitting has no significant change. After 22 days of operation, an 8% loss of the initial activity occurs. Finally, the probable mechanism of hydrogen production by water splitting under visible light irradiation is proposed in this study.

Configuration splitting and gamma-decay transition rates in the two-group shell model

Expressions for reduced gamma-decay transition rates were obtained on the basis of the twogroup configuration model for the case of transitions between particles belonging to identical groups of nucleons. In practical applications, the present treatment is the most appropriate for describing decays for odd–odd nuclei in the vicinity of magic nuclei or for nuclei where the corresponding subshells stand out in energy. Also, a simple approximation is applicable to describing configuration splitting in those cases. The present calculations were performed for nuclei whose mass numbers are close to A ~ 90, including N = 51 odd—odd isotones.

Are Tax Avoidance Costs and Benefits Easily Quantified? Evidence from Credit Rating Disagreement

This study investigates the role of tax avoidance in the credit rating process and whether differences exist in how rating agencies account for the risk relevance of tax avoidance. Using a sample of initial credit ratings assigned to public debt issuances during the 1994-2013 period, our evidence is consistent with credit rating agencies assessing the costs and benefits associated with tax avoidance differently, resulting in more frequent and pronounced rating agency disagreement. Rating agency disagreement over tax avoidance is most prominent when it is accompanied by relatively high levels of uncertain tax positions, foreign activities, or research and development activities, as well as lower quality tax footnote disclosures. We also find evidence that changes in tax avoidance (tax footnote disclosures) are negatively (positively) associated with the convergence of split ratings, suggesting that firms can exacerbate or mitigate rating agency disagreement subsequent to bond issuance. Our study complements prior research by examining why sophisticated information intermediaries disagree about the risk relevance of tax avoidance and sheds light on how firms can impact rating agencies’ understanding of tax avoidance.

Revisiting Fungicide-Based Management Guidelines for Leaf Blotch Diseases in Soft Red Winter Wheat

Standard foliar fungicide applications in wheat are usually made between flag leaf emergence (Feekes [FK] 8) and heading (FK10.5) to minimize damage to the flag leaf. However, over the last few years, new fungicide programs such as applications prior to FK8 and split half-rate applications have been implemented, although there are few data pertaining to the efficacy of these programs. Eight experiments were conducted in Illinois, Indiana, Ohio, and Wisconsin from 2010 to 2012 to compare new programs to standard FK8 and FK10 programs in terms of disease control and yield response. The programs evaluated consisted of single full-rate applications of 19% tebuconazole + 19% prothioconazole (Prosaro) or 23.6% pyraclostrobin (Headline) at FK5 (pseudostem strongly erected), FK8, or FK10, or split half rates at FK5 and 8 (FK5+8), plus an untreated check (CK). Leaf blotch (LB) severity and yield data were collected and random effects meta-analytical models fitted to estimate the overall log odds ratio of disease reaching the flag leaf ( ) and mean yield increase ( ) for each fungicide program relative to CK. For all programs, was significantly different from zero (P < 0.05). Based on estimated odds ratios (OR = exp[ ]), the two FK8 programs reduced the risk of LB reaching the flag leaf by 55 and 75%, compared with 62 and 69% and 67 and 70% for the two FK10 and FK5+8 programs, respectively, and only 32 and 37% for the two FK5 programs. was significantly different from zero (P ≤ 0.003) for all FK8, FK10, and FK5+8 programs, with values of 233 and 245, 175 and 220, and 175 and 187 kg ha-1 for the FK10, FK5+8, and FK8 programs, respectively. Differences in mean yield response between Headline and Prosaro were not statistically significant (P > 0.05). The probability of profitability was estimated for each program for a range of grain prices and fungicide application costs. All FK8, FK10, and FK5+8 programs had more than an 80% chance of resulting in a positive yield response, compared with 63 and 67% for the two FK5 programs. The chance of obtaining a yield increase of 200 kg ha-1, required to offset an application cost of $36 ha-1 at a grain price of $0.18 kg-1, ranged from 44 to 60% for FK8, FK10 and FK5+8 programs compared with 22 and 25% for the two FK5 programs. These findings could be used to help inform fungicide application decisions for LB diseases in soft red winter wheat.

Silicon nanowires grown on metal substrates via self-catalyst mechanism

Low Pressure Chemical Vapor Deposition (LPCVD) was applied to grow Silicon Nanowires (SiNWs) without any heteroatom catalyst or special pretreatment of substrates used. Silane (SiH4) as a precursor was pyrolyzed at 500°C in an oven at molybdenum or iron substrates. NWs were several microns long, about 100nm thick and possessed a core–jacket structure. The thin core was composed of crystalline silicon oriented in 〈110〉 direction whereas the jacket was formed by amorphous silicon. Unlike other approaches, this method avoids contamination caused by metal heteroatom seeds and/or applying special procedures for substrate pretreatment to initialize/support NW growth. The photocatalytical activity revealed that SiNW layers could be accredited with a relatively high rate of photocatalytical splitting of water into H2/O2.

Third-Nearest-Neighbors Tight-Binding Description of Optical Response of Carbon Nanotubes: Effects of Chirality and Diameter

We have applied a third nearest-neighbor tight binding model to investigate the optical properties of CNTs in terms of radius, chirality and magnetic field. The optical spectrum of CNTs depends strongly on the radius and chirality in the infrared region in contrast to the middle energy region. The dependence of E22/E11 on the radius and chirality from optical peak positions and band structure is similar. In the infrared region, by applying the magnetic field, the optical peak splitting rates show well-expressed radius and chirality dependence and family behaviors.

The Information Environment and Borrowing Costs in International Bond Markets

We examine whether and how a firm's information environment – as characterized by earnings quality, analyst forecast dispersion, and the probability of informed trading – affects its borrowing costs in international bond markets. Using a sample of Eurobonds issued by firms across 38 countries, we find that bonds issued by firms with poor information environments are associated with higher costs of debt, lower credit ratings, greater probability of split bond ratings, and higher underwriting fees. Thus, we demonstrate that the information environment plays a crucial role in determining borrowing costs in international bond markets.

Energetics of contraction.

Muscles convert energy from ATP into useful work, which can be used to move limbs and to transport ions across membranes. The energy not converted into work appears as heat. At the start of contraction heat is also produced when Ca(2+) binds to troponin-C and to parvalbumin. Muscles use ATP throughout an isometric contraction at a rate that depends on duration of stimulation, muscle type, temperature and muscle length. Between 30% and 40% of the ATP used during isometric contraction fuels the pumping Ca(2+) and Na(+) out of the myoplasm. When shortening, muscles produce less force than in an isometric contraction but use ATP at a higher rate and when lengthening force output is higher than the isometric force but rate of ATP splitting is lower. Efficiency quantifies the fraction of the energy provided by ATP that is converted into external work. Each ATP molecule provides 100 zJ of energy that can potentially be converted into work. The mechanics of the myosin cross-bridge are such that at most 50 zJ of work can be done in one ATP consuming cycle; that is, the maximum efficiency of a cross-bridge is ∼50%. Cross-bridges in tortoise muscle approach this limit, producing over 90% of the possible work per cycle. Other muscles are less efficient but contract more rapidly and produce more power.

Control of Rubisco function via homeostatic equilibration of CO2 supply.

Rubisco is the most abundant protein on Earth that serves as the primary engine of carbon assimilation. It is characterized by a slow rate and low specificity for CO2 leading to photorespiration. We analyze here the challenges of operation of this enzyme as the main carbon fixation engine. The high concentration of Rubisco exceeds that of its substrate CO2 by 2–3 orders of magnitude; however, the total pool of available carbon in chloroplast, i.e., mainly bicarbonate, is comparable to the concentration of Rubisco active sites. This makes the reactant stationary assumption (RSA), which is essential as a condition of satisfying the Michaelis–Menten (MM) kinetics, valid if we assume that the delivery of CO2 from this pool is not limiting. The RSA is supported by active carbonic anhydrases (CA) that quickly equilibrate bicarbonate and CO2 pools and supply CO2 to Rubisco. While the operation of stromal CA is independent of light reactions, the thylakoidal CA associated with PSII and pumping CO2 from the thylakoid lumen is coordinated with the rate of electron transport, water splitting and proton gradient across the thylakoid membrane. At high CO2 concentrations, CA becomes less efficient (the equilibrium becomes unfavorable), so a deviation from the MM kinetics is observed, consistent with Rubisco reaching its Vmax at approximately 50% lower level than expected from the classical MM curve. Previously, this deviation was controversially explained by the limitation of RuBP regeneration. At low ambient CO2 and correspondingly limited capacity of the bicarbonate pool, its depletion at Rubisco sites is relieved in that the enzyme utilizes O2 instead of CO2, i.e., by photorespiration. In this process, CO2 is supplied back to Rubisco, and the chloroplastic redox state and energy level are maintained. It is concluded that the optimal performance of photosynthesis is achieved via the provision of continuous CO2 supply to Rubisco by carbonic anhydrases and photorespiration.

The credit signals that matter most for sovereign bond spreads with split rating

We investigate how split ratings influence the information content of credit rating events on the sovereign bond markets during 2000–2012. We find that market reactions are far stronger for negative events on the inferior ratings and for positive events on the superior ratings. Such evidence suggests aversion of market participants to the ambiguity inherent in split ratings. Sovereign credit spreads are particularly responsive to negative events by S&P (the more conservative agency in the sample). Moody's positive events have a significant impact only when Moody's assigns superior pre-event ratings compared with S&P. There is little evidence that split ratings involving Fitch have any market implication.

Innovative use of membrane contactor as condenser for heat recovery in carbon capture.

The gas-liquid membrane contactor generally used as a nonselective gas absorption enhancement device is innovatively proposed as a condenser for heat recovery in liquid-absorbent-based carbon capture. The membrane condenser is used as a heat exchanger to recover the latent heat of the exiting vapor from the desorber, and it can help achieve significant energy savings when proper membranes with high heat-transfer coefficients are used. Theoretical thermodynamic analysis of mass and heat transfer in the membrane condensation system shows that heat recovery increases dramatically as inlet gas temperature rises and outlet gas temperature falls. The optimal split mass flow rate is determined by the inlet gas temperature and the overall heat-transfer coefficient in the condensation system. The required membrane area is also strongly dependent on the overall heat-transfer coefficient, particularly at higher inlet gas temperatures. Mass transfer across the membrane has an insignificant effect on heat transfer and heat recovery, suggesting that membrane wetting may not be an issue when a membrane condenser is used for heat recovery. Our analysis provides important insights into the energy recovery performance of the membrane condensation system as well as selection of operational parameters, such as split mass flow rate and membrane area, thickness, and thermal conductivity.

Short-term effects of soil amendment with meadowfoam seed meal on soil microbial composition and function

Meadowfoam (Limnanthes alba Hartw. ex Benth) seed meal (MSM), a by-product of meadowfoam oil extraction, has a secondary metabolite known as glucosinolate glucolimnanthin. MSM applied as a soil amendment has been reported to have herbicidal and fertilizer properties. Experiments were conducted over 28 days to evaluate short-term effects of a MSM application on soil microbial communities. MSM was applied to soil as either a full or a split application. In addition to MSM and untreated control treatments, urea was used as a N source to account for the fertilizer effect of the seed meal. Urea was applied either as a full or a split rate on the same schedule as MSM. Soil microbial activities were not different between the full and the split rate applications of MSM. After day 7 following MSM application, carbon-source utilization of microbial communities of MSM was different from the urea and control treatments. Microbial communities in MSM treatments utilized complex carbon sources to a relatively greater degree than microbial communities in urea or control treatments. The C and N inputs from MSM increased the gross metabolic activity of the mixed microbial population. Basal respiration was stimulated and microbes reallocated carbon input to biomass and enzyme production. Within 7 and 14 days after MSM application, the reallocation occurred quickly and microbial biomass increased by at least 80% for C and 95% for N compared to the untreated control. In the short-term, MSM treatments affected nutrient dynamics, and the soil microbial structure and function. The effects of MSM application on the composition of bacterial and fungal communities warrant additional study.

Ancestral state reconstruction, rate heterogeneity, and the evolution of reptile viviparity.

Virtually all models for reconstructing ancestral states for discrete characters make the crucial assumption that the trait of interest evolves at a uniform rate across the entire tree. However, this assumption is unlikely to hold in many situations, particularly as ancestral state reconstructions are being performed on increasingly large phylogenies. Here, we show how failure to account for such variable evolutionary rates can cause highly anomalous (and likely incorrect) results, while three methods that accommodate rate variability yield the opposite, more plausible, and more robust reconstructions. The random local clock method, implemented in BEAST, estimates the position and magnitude of rate changes on the tree; split BiSSE estimates separate rate parameters for pre-specified clades; and the hidden rates model partitions each character state into a number of rate categories. Simulations show the inadequacy of traditional models when characters evolve with both asymmetry (different rates of change between states within a character) and heterotachy (different rates of character evolution across different clades). The importance of accounting for rate heterogeneity in ancestral state reconstruction is highlighted empirically with a new analysis of the evolution of viviparity in squamate reptiles, which reveal a predominance of forward (oviparous-viviparous) transitions and very few reversals.

Magnetic Field-Induced Splitting of Optical Spectra in Silicon Nanotubes: Tight Binding Calculations

The splitting of band structure and absorption spectra, for silicon nanotubes (SiNTs) under axial magnetic field, are studied using the tight binding approximation. It is found that band splitting is approximately proportional to the magnitude of magnetic field as \(\frac {\Delta E}{E_{g}}=\nu _{ii} \frac {\Phi }{{\Phi }_{0}}\) where ν i i is the splitting rate. For Si g-NTs, we calculated the splitting rate of the two first bands nearest to the Fermi level in the Γ point and found that it can be fitted with a two degree polynomial as \(\nu _{ii}={\sum }_{j=0}^{2}{a^{i}_{j}}x^{j}\) where \(x=\frac {1}{n^{2}}\) and for sufficiently large diameter Si g-NTs, the ν i i can be fitted by a linear function. For semiconductor Si h-NTs the ν 11 = 6 but ν 22 and ν 33 show radial dependence. Also we found that applying magnetic field leads to splitting for all peaks in the low energy ranges for all zigzag Si h-NTs and Si g-NTs. The first peak of group (I) of Si g-NTs does not show any splitting in the magnetic field and for all metallic Si h-NTs, the magnetic field leads to creating a peak in the energy range less than 0.2 eV where this peak arises from energy gap created around Fermi energy.

Catalytic reduction of polar substrates without metals: A thermodynamic and kinetic study of heterolytic activation of hydrogen by vacancies in frustrated Lewis pairs

Time-resolved reaction calorimetry provides a measure of the turnover frequency (TOF), ca. 1.1min−1, and enthalpic driving force, ca. −73kJ/mol, for the metal-free catalytic reduction of an organic imine, tert-butylbenzaldimine, (tBu-IM) with a frustrated Lewis acid-base pair, [2-(dimesitylphosphino)ethyl] bis(pentafluorophenyl)borane (PBCat), at 298K and 13.8bar hydrogen (H2) pressure. Lowering the H2 pressure by a factor of two decreases the TOF (0.6min−1), which is consistent with a pseudo first-order reaction in H2. In the absence of imine, the heat flux measured in the calorimeter provides a measure of the enthalpy for heterolytic splitting of H2, PBcat+H2 --> PBCatH2, ΔH ca. −43(4)kJ/mol. Solution phase 19F nuclear magnetic resonance spectroscopy was used to determine the rate of heterolytic splitting of H2 by PBCat, k=0.7(.3)M−1s−1 and the equilibrium constant for PBCat+H2(soln) ⇔ PBCatH2, Keq(295)=2.2(.5)×105M, providing an estimate of the free energy for heterolytic splitting of H2, ΔG ca. −29.8(1.3)kJ/mol at 295K in toluene. Deconvolution of the instrument time constant from the heat flux using the Tian equation shows the concentration of imine decreases linearly in time (i.e., the substrate imine is not involved in the rate limiting step, suggesting that H2 activation by the Lewis acid-base pair is rate limiting).

Split ratings and debt-signaling in bond markets: A note

Split ratings occur when national and international credit rating agencies assign different ratings to the same firm. Employing various proxies for asymmetric information and data from advanced and emerging bond markets, we review the evidence that split ratings are caused by asymmetric information between firms and credit rating agencies. We then apply the debt-signaling model to the split ratings problem, by testing for a systematic relationship between the debt-to-equity ratio and the magnitude of split ratings across countries. We finally test for the existence of an optimal debt-signal, which implies that higher debt-to-equity ratios will reduce the ratings split to an optimal minimum, after which accumulating more debt widens the ratings split. Our results suggest that firms in emerging markets can use the debt-signal up to a maximal point, after which it becomes inefficient.

The fragmentation process of an infinite recursive tree and Ornstein-Uhlenbeck type processes

We consider a natural destruction process of an infinite recursive tree by removing each edge after an independent exponential time. The destruction up to time $t$ is encoded by a partition $\Pi(t)$ of $\mathbb{N}$ into blocks of connected vertices. Despite the lack of exchangeability, just like for an exchangeable fragmentation process, the process $\Pi$ is Markovian with transitions determined by a splitting rates measure ${\bf r}$. However, somewhat surprisingly, ${\bf r}$ fails to fulfill the usual integrability condition for the dislocation measure of exchangeable fragmentations. We further observe that a time-dependent normalization enables us to define the weights of the blocks of $\Pi(t)$. We study the process of these weights and point at connections with Ornstein-Uhlenbeck type processes.

Experimental study on diesel fuel injection characteristics under cold start conditions with single and split injection strategies

Studies on fuel flow characteristics under both room temperature (25°C) and low temperature (−18°C) were carried out under a wide range of injection pressures and back pressures using a long tube real-time fuel flow rate measuring instrument. Both single and split injection strategies were employed. Several modified correlations were proposed to analyze fuel injection characteristics. It was found that low fuel temperature caused longer injection delay, shorter injection duration, lower mass flow rate and less injected fuel mass. The injector discharge coefficient was affected more by fuel viscosity changes due to low temperature than by the geometric structure of the injector. Cold start conditions effectively limited the inception of cavitation as seen in the flow rate/pressure dependence and accelerated the transition of flow regime from cavitation to turbulent and laminar flow with the decrease of injection pressure. This contributed to increased chances for the existence of laminar flow and thus to reduction of the discharge coefficient. Besides, low fuel temperature significantly weakened the degree of interaction between individual parts of split injection and split mass flow rate shapes became much less continuous than those under room temperature. These findings are of great importance for engine cold start studies.

Electrowetting on dielectric device with crescent electrodes for reliable and low-voltage droplet manipulation.

Digital microfluidics based on electrowetting on dielectric is an emerging popular technology that manipulates single droplets at the microliter or even the nanoliter level. It has the unique advantages of rapid response, low reagent consumption, and high integration and is mainly applied in the field of biochemical analysis. However, currently, this technology still has a few problems, such as high control voltage, low droplet velocity, and continuity in flow, limiting its application. In this paper, through theoretical analysis and numerical simulation, it is deduced that a drive electrode with a crescent configuration can reduce the driving voltage. The experimental results not only validate this deduction but also indicate that crescent electrode can improve the droplet motion continuity and the success in split rate.