Sustenance of phytoplankton in the subpolar North Atlantic during the winter through patchiness

This study investigates the influence of two factors that change the mixed layer depth and can potentially contribute to the phytoplankton sustenance over winter: 1) variability of air-sea fluxes and 2) three-dimensional processes arising from strong fronts. To study the role of these factors, we perform several three-dimensional numerical simulations forced with air-sea fluxes at different temporal averaging frequencies as well as different spatial resolutions. Results show that in the winter, when the average mixed layer is much deeper than the euphotic layer and the days are short, phytoplankton production is relatively insensitive to the high-frequency variability in air-sea fluxes. The duration of upper ocean stratification due to high-frequency variability in air-sea fluxes is short and hence has a small impact on phytoplankton production. On the other hand, slumping of fronts creates patchy, stratified, shallow regions that persist considerably longer than stratification caused by changes in air-sea fluxes. Simulations show that before spring warming, the average MLD with fronts is about 700 m shallower than the average MLD without fronts. Therefore, fronts increase the residence time of phytoplankton in the euphotic layer and contribute to phytoplankton growth. Results show that before the spring warming, the depth-integrated phytoplankton concentration is about twice as large as phytoplankton concentration when there are no fronts. Hence, fronts are important for setting the MLD and sustaining phytoplankton in the winter. Model results also show that higher numerical resolution leads to stronger restratification, shallower mixed layers, greater variability in the MLD and higher production of phytoplankton

Effective factors on the determination of audit fees in Iran

One of the issues that most companies and the independent auditors encounter refers to determining the amount of audit fees to the conclusion of contract for the annual financial statement audit of companies. The auditor should naturally consider the probability of audit duration more than anything. Since the determination of the exact time to do work (before starting work) is not possible, auditors only rely on providing an estimate of fee. This estimate is generally determined by some effective factors in the extent of audit work. This study aims to investigate the effective factors on determination of the company's audit fee and data of accepted companies in the stock exchange in 2000 to 2007 is used.‎ Among the 1380 companies, the 30 industries existed in stock exchange are used. Multivariate regression model to analyze the data and the t-student test to test the meaningfulness of hypotheses are used. The results indicate that the factors of company size, the ratio of debt and the auditor type on audit fees are effective in determining audit fees and inherent risk has no influence on determining audit fees

Individual and joint inversion of surface wave tomography for near-surface applications

L'abstract è presente nell'allegato / the abstract is in the attachmen

Effective factors on the determination of audit fees in Iran

One of the issues that most companies and the independent auditors encounter refers to determining the amount of audit fees to the conclusion of contract for the annual financial statement audit of companies. The auditor should naturally consider the probability of audit duration more than anything. Since the determination of the exact time to do work (before starting work) is not possible, auditors only rely on providing an estimate of fee. This estimate is generally determined by some effective factors in the extent of audit work. This study aims to investigate the effective factors on determination of the company's audit fee and data of accepted companies in the stock exchange in 2000 to 2007 is used.‎ Among the 1380 companies, the 30 industries existed in stock exchange are used. Multivariate regression model to analyze the data and the t-student test to test the meaningfulness of hypotheses are used. The results indicate that the factors of company size, the ratio of debt and the auditor type on audit fees are effective in determining audit fees and inherent risk has no influence on determining audit fees

An Experimental and Computational Study of Windborne Debris in Severe Storms

Abstract This research focuses on an experimental and theoretical investigation of windborne debris emanating from loose gravel on built-up roofs. During severe storms, windborne debris can cause considerable physical harm and property damage. One of the major sources of flying debris in large commercial areas is loose gravel on built-up roofs. Such loose gravel can be responsible loss of life and significant property damage. Despite the high risk of windborne debris, their flight mechanics are poorly understood. To better understand windborne debris flight, a series of experiments were conducted in the Clemson University Boundary Layer Wind Tunnel. These experiments were designed to quantify the conditions under which gravel became airborne, the rate at which it was removed, and the resulting flight distance of the debris. In order to conduct experiments in the Boundary Layer Wind Tunnel it is important to understand how to model the atmospheric boundary layer (ABL). A new curve fitting method is presented for calculating the ABL logarithmic velocity profile parameters i.e. shear velocity, surface roughness and zero plane displacement. The new method uses only the time averaged velocity profile and requires no iteration. Comparison with existing methods shows that the new approach has equal or better accuracy than existing curve fitting and geometric approaches with fewer calculation steps. Debris flight is a highly stochastic process with uncertainty and variability in the debris particle the turbulent wind field. However, current models are almost entirely deterministic. A series of Monte Carlo simulations based on existing debris flight equations were run to quantify the impact if input uncertainty on flight outcome (flight distance and impact kinetic energy). Results indicate that failure to account for parameter variability will result in under predicting the mean flight distance and kinetic energy, and ignoring outcome variability / uncertainty. A full quantification of the relationship between input variability and outcome variability is presented for roof gravel blow-off. A series of new experimental methods have been developed to measure the conditions under which blow-off occurs, the rate of gravel removal, and the downwind flight distance for two-dimensional buildings. The critical condition for blow off is parameterized in terms of the particle densimetric Froude number, particle Reynolds number and building geometry. A series of non-dimensional plots of the critical Froude number versus Reynolds number for different parapet heights are presented. The results indicate that the current approach for scaling result from laboratory to full scale is flawed and that full scale experiments are required to fully understand this process. The rate of removal, or mass flux, varies over time. The removal process exhibits an initial high mass flux regime followed by a period of reduced blow-off rate. Dimensionless plots of both regimes mass flux versus Particle Froude number for different parapet heights are presented. The results show that increasing the parapet height usually decreases the mass loss rate, though this is not the case for very small parapets. Further, the transition time from the initial to secondary blow-off regimes is independent of the building geometry. Finally, the initial mass flux is approximately four times that of the secondary loss rate, and that this ratio is independent of both the building geometry and the Froude number. Experimental results indicate that the wake behind the building dominates the downwind transport of debris. The flight distance is a function of the building height, particle Froude number (written in terms of a Tachikawa number), and the parapet geometry. A full characterization of the down-wind debris field requires a detailed analysis of the wake behind the building that is beyond the experimental capability of the current facility. Further, scaling of the results to full scale is again problematic, and therefore full scale testing is recommended

Effective factors on the determination of audit fees in Iran

One of the issues that most companies and the independent auditors encounter refers to determining the amount of audit fees to the conclusion of contract for the annual financial statement audit of companies. The auditor should naturally consider the probability of audit duration more than anything. Since the determination of the exact time to do work (before starting work) is not possible, auditors only rely on providing an estimate of fee. This estimate is generally determined by some effective factors in the extent of audit work. This study aims to investigate the effective factors on determination of the company's audit fee and data of accepted companies in the stock exchange in 2000 to 2007 is used.‎ Among the 1380 companies, the 30 industries existed in stock exchange are used. Multivariate regression model to analyze the data and the t-student test to test the meaningfulness of hypotheses are used. The results indicate that the factors of company size, the ratio of debt and the auditor type on audit fees are effective in determining audit fees and inherent risk has no influence on determining audit fees

The investigation of effective factors on implementation of Value Added Tax (VAT) in Final Distribution Chain

It is important to survey factors that have effects on establishing added value tax system in limit supply chain. This guides us to knowing the limitations and provides best solutions for them and we can perform these laws in retailers supply chain. This survey is descriptive. In this survey we use spearman survey test and our purpose society are experts, text experts and authority of tax office of Tehran province. Result show that there is a meaningful relationship between enabling necessary substructures in tax gain and performing added relationships between economic transactions and correct broadcasting of this law in supply chain.