Evolution of a curved vortex filament into a vortex ring

The deformation of a hairpin-shaped vortex filament under self-induction and in the presence of shear is studied numerically using the Biot-Savart law. It is shown that the tip region of an elongated hairpin vortex evolves into a vortex ring and that the presence of mean shear impedes the process. Evolution of a finite-thickness vortex sheet under self-induction is also investigated using the Navier-Stokes equations. The layer evolves into a hairpin vortex which in turn produces a vortex ring of high Reynolds stress content. These results indicate a mechanism for the generation of ring vortices in turbulent shear flows, and a link between the experimental and numerical observation of hairpin vortices and the observation of ring vortices in the outer regions of turbulent boundary layers

The Legal Status of “Dump & Sue”: Should Plaintiffs and their Attorneys be Prohibited from Trading the Stock of Companies they Sue? – a Law and Economics Approach

There is some evidence that plaintiffs and their attorneys are profitably short-selling the stock of the companies they intend to sue. The status of such short sales is undecided in the law. Lawsuits against companies can cause large drops in market value, and hence such an action by the plaintiff should cause concern. Plaintiffs, however, are not traditional insiders, and they do not owe the shareholders any fiduciary duties. They can therefore consent to their attorneys also short-selling the stock of the defendant corporation. The attorneys need to receive such permission to avoid misappropriating the information concerning their client’s decision to sue. A plaintiff’s decision to sue after short-selling does not constitute market manipulation in the traditional sense, since the decision to sue is a true fact that causes the drop in the share price as opposed to those who commit fraud by spreading false negative stories about the company. Plaintiffs need, therefore, to be legally deemed temporary insiders until they publicly reveal their intention to sue or actually sue. The reasons for deeming them insiders, and hence prohibiting them from short-selling, are threefold. First, allowing such activities would raise the same concerns regarding market integrity raised by those opposed to insider trading. Second, allowing such short-selling is a form of fraud by silence against those who purchase the shares. Third, allowing short-selling would give the plaintiffs double recovery for their lawsuit, as they could gain a large share of their claim against the company from the profitable short sales in addition to any verdict or settlement. Furthermore, proposals to extend Regulation FD to plaintiff’s attorneys would be ineffective in combating the harm from such short-selling. The law, therefore, through either developments by the courts, regulatory promulgations by the SEC, an act of Congress, or a combination of any of the preceding three mechanisms should be used to treat plaintiffs as insiders until they sue or announce their intention to sue

Eddies, streams, and convergence zones in turbulent flows

Recent studies of turbulent shear flows have shown that many of their important kinematical and dynamical properties can be more clearly understood by describing the flows in terms of individual events or streamline patterns. These events or flow regions are studied because they are associated with relatively large contributions to certain average properties of the flow, for example kinetic energy, Reynolds stress, or to particular processes in the flow, such as mixing and chemical reactions, which may be concentrated at locations where streamlines converge for fast chemical reactions (referred to as convergence or C regions), or in recirculating eddying regions for slow chemical reactions. The aim of this project was to use the numerical simulations to develop suitable criteria for defining these eddying or vortical zones. The C and streaming (S) zones were defined in order to define the whole flow field. It is concluded that homogeneous and sheared turbulent flow fields are made up of characteristic flow zones: eddy, C, and S zones. A set of objective criteria were found which describe regions in which the streamlines circulate, converge or diverge, and form high streams of high velocity flow

Distribution and Diversity of Archaeal and Bacterial Ammonia Oxidizers in Salt Marsh Sediments

Diversity and abundance of ammonia-oxidizing Betaproteobacteria (β-AOB) and archaea (AOA) were investigated in a New England salt marsh at sites dominated by short or tall Spartina alterniflora (SAS and SAT sites, respectively) or Spartina patens (SP site). AOA amoA gene richness was higher than β-AOB amoA richness at SAT and SP, but AOA and β-AOB richness were similar at SAS. β-AOB amoA clone libraries were composed exclusively of Nitrosospira-like amoA genes. AOA amoA genes at SAT and SP were equally distributed between the water column/sediment and soil/sediment clades, while AOA amoA sequences at SAS were primarily affiliated with the water column/sediment clade. At all three site types, AOA were always more abundant than β-AOB based on quantitative PCR of amoA genes. At some sites, we detected 109 AOA amoA gene copies g of sediment−1. Ratios of AOA to β-AOB varied over 2 orders of magnitude among sites and sampling dates. Nevertheless, abundances of AOA and β-AOB amoA genes were highly correlated. Abundance of 16S rRNA genes affiliated with Nitrosopumilus maritimus, Crenarchaeota group I.1b, and pSL12 were positively correlated with AOA amoA abundance, but ratios of amoA to 16S rRNA genes varied among sites. We also observed a significant effect of pH on AOA abundance and a significant salinity effect on both AOA and β-ΑΟΒ abundance. Our results expand the distribution of AOA to salt marshes, and the high numbers of AOA at some sites suggest that salt marsh sediments serve as an important habitat for AOA

Formulation of Sustained-Release Diltiazem Matrix Tablets Using Hydrophilic Gum Blends

Purpose: To develop sustained release matrix tablets of diltiazem hydrochloride (DTZ) using karaya gum (K) alone or in combination with locust bean gum (LB) and hydroxypropyl methylcellulose (H).Methods: Matrix tablets of DTZ were prepared at different ratios of drug:gum (1:1, 1:2, and 1:4) and of the gum blends (K, K/LB, K/H and K/LB/H) by direct compression. The matrix tablets were evaluated for hardness, friability, in vitro release and drug content. The formulations were also characterised by scanning electron microscopy (SEM), Fourier transform infra-red spectroscopy (FTIR) and differential scanning calorimetry (DSC). A commercial diltiazem hydrochloride product Dilzem SR, was used as a reference for comparison Results: Tablets with only K or K/H had the highest mean dissolution time (MDT), the least dissolution efficiency (DE, 12 %), and released drug by swelling, diffusion and erosion mechanisms. Karaya gum or combinations with locust bean gum sufficiently controlled drug release, while combinations of KH and KLBH exhibited high and low drug release efficiency, respectively. SEM images of the tablets before and after dissolution showed morphological changes on the tablet surface while FTIR and DSC studies indicate that there was no chemical interaction between the drug and the polymers. Three of the formulations compared well with the reference (p < 0.05) in terms of release characteristics. Conclusion: The results of the study demonstrate that karaya gum alone or in suitable combination with locust bean gum and hydroxypropyl methylcellulose is suitable for formulating sustained-release matrix tablets of diltiazem.Key words: Karaya gum, Locust bean gum, Diltiazem hydrochloride, Sustained release, Hydroxypropyl methylcellulos

International Water Law and Fresh Water Dispute Resolution: A Cosean Perspective

International Water Law has developed a set of rules for resolving interstate fresh water disputes that govern both the substance of these disputes and the conduct of the disputing states. Equitable and reasonable utilization is commonly considered as the leading substantive rule, no significant harm as subsidiary to it, and the duty to cooperate as the central procedural rule. The purpose of this Article is to analyze the merits of these substantive and procedural rules under the lens of the celebrated Coase theorem. The normative part of the Coase theorem observes that if transaction costs are high, then the legal rule governing the resolution of a dispute between two parties should minimize these costs. Such a legal rule will ensure an optimal and efficient allocation of resources. International fresh water disputes usually involve high transaction costs such as unequal and asymmetric access to information, enforcement uncertainty, and unclear political goals of the parties. We argue that a legal rule such as equitable and reasonable utilization only increases uncertainty and transaction costs, whereas a rule such as no significant harm is better-suited to achieving efficient dispute resolution. Moreover, when a so-called procedural rule such as the duty to cooperate is imposed on the parties and gives rise to its own set of obligations, this ensures a better negotiation environment, which in turn leads to more efficient dispute resolution

Does a Judge\u27s Party of Appointment or Gender Matter to Case outcomes?: An Empirical Study of the Court of Appeal for Ontario

A recent study by Cass Sunstein identified ideological differences in the votes cast by judges on the United States Courts of Appeals in certain types of cases. He found that these patterns varied depending on the ideology of an appellate judge\u27s co-panelists. In this study, we undertake a similar examination of the busiest appellate court in Canada, the Court of Appeal for Ontario. This study collects data on the votes cast by individual judges in every reported decision between 1990 and 2003. Each case was cod6d by type, for example criminal law, constitutional law, or private law. In addition, the votes cast by individual judges in each category were tracked based on variables such as the type of litigant, the political party that appointed the judge, and the judge\u27s gender. This study reveals that at least in certain categories of cases, both party of appointment and gender are statistically significant in explaining case outcomes. Between these two variables, gender actually appears to be the stronger determinant of outcome in certain types of cases. While these findings are cause for concern, this study also points toward a simple solution. Diversity in the composition of appeal panels both from the standpoint of gender and party of appointment dampened the statistical influence of either variable. In other words, in the case of gender, a single judge on a panel who is of the opposite sex from the others, or in the case of political party, a single judge appointed by a different political party, is sufficient to eliminate the potential distorting influence of either variable. This finding suggests a need to reform how appeal panels are currently assembled in order to ensure political and gender diversity and minimize concerns about the potential for bias

Does a Judge\u27s Party of Appointment or Gender Matter to Case outcomes?: An Empirical Study of the Court of Appeal for Ontario

A recent study by Cass Sunstein identified ideological differences in the votes cast by judges on the United States Courts of Appeals in certain types of cases. He found that these patterns varied depending on the ideology of an appellate judge\u27s co-panelists. In this study, we undertake a similar examination of the busiest appellate court in Canada, the Court of Appeal for Ontario. This study collects data on the votes cast by individual judges in every reported decision between 1990 and 2003. Each case was cod6d by type, for example criminal law, constitutional law, or private law. In addition, the votes cast by individual judges in each category were tracked based on variables such as the type of litigant, the political party that appointed the judge, and the judge\u27s gender. This study reveals that at least in certain categories of cases, both party of appointment and gender are statistically significant in explaining case outcomes. Between these two variables, gender actually appears to be the stronger determinant of outcome in certain types of cases. While these findings are cause for concern, this study also points toward a simple solution. Diversity in the composition of appeal panels both from the standpoint of gender and party of appointment dampened the statistical influence of either variable. In other words, in the case of gender, a single judge on a panel who is of the opposite sex from the others, or in the case of political party, a single judge appointed by a different political party, is sufficient to eliminate the potential distorting influence of either variable. This finding suggests a need to reform how appeal panels are currently assembled in order to ensure political and gender diversity and minimize concerns about the potential for bias