Developing a growth-transition matrix for the stock assessment of the green sea urchin (Strongylocentrotus droebachiensis) off Maine

The green sea urchin (Strongylocentrotus droebachiensis) is important to the economy of Maine. It is the state’s fourth largest fishery by value. The fishery has experienced a continuous decline in landings since 1992 because of decreasing stock abundance. Because determining the age of sea urchins is often difficult, a formal stock assessment demands the development of a size-structured population dynamic model. One of the most important components in a size-structured model is a growth-transition matrix. We developed an approach for estimating the growth-transition matrix using von Bertalanffy growth parameters estimated in previous studies of the green sea urchin off Maine. This approach explicitly considers size-specific variations associated with yearly growth increments for these urchins. The proposed growth-transition matrix can be updated readily with new information on growth, which is important because changes in stock abundance and the ecosystem will likely result in changes in sea urchin key life history parameters including growth. This growth-transition matrix can be readily incorporated into the size-structured stock assessment model that has been developed for assessing the green sea urchin stock off Maine

A Space-Filling, Nonregular Tetrahedron

This activity is an investigation of a special nonregular tetrahedron that can be arranged to fill space without leaving any internal gaps in the same way that certain planar figures tessellate the plane. These tetrahedra can be connected together with hinges to make fun and interesting puzzles. More background information can be found in the paper An Amazing, Space-Filling, Non-Regular Tetrahedron by Joyce Frost and Peg Cagle, published by the IAS/Park City Mathematics Institute (available at mathforum.org/pcmi/hstp/resources/dodeca/)

Developing a Sustainable Freight Transportation Framework with the Consideration of Improving Safety and Minimizing Carbon Emissions

Despite the difficulties of the American economy in recent years the transportation sector continues to expand. Freight transportation alone has been projected to increase enormously even if the economy as a whole only manages a very moderate growth. Not only does freight transportation use a large percentage of resources but it contributes significantly to America’s share of carbon emissions and affects the safety of the transportation system and all its users. These problems are only expected to increase as the volume of freight transportation is already reaching the limit of the American transportation infrastructure’s capacity and demand continues to increase. The primary objective of this research was to compile a list of technologies and practices that should be included in the sustainable freight transportation frameworks of government agencies and commercial fleets to reduce their carbon footprint and increase their safety by providing recommendations on promising legislation, research, technologies, and practices. Data was gathered through a literature review of available materials and a survey of the state Departments of Transportation. The success of this research project provides the needed knowledge for the development of a sustainable freight transportation framework

Intensive versus conventional glycaemic control for treating diabetic foot ulcers

Background  The estimated likelihood of lower limb amputation is 10 to 30 times higher amongst people with diabetes compared to those without diabetes. Of all non-traumatic amputations in people with diabetes, 85% are preceded by a foot ulcer. Foot ulceration associated with diabetes (diabetic foot ulcers) is caused by the interplay of several factors, most notably diabetic peripheral neuropathy (DPN), peripheral arterial disease (PAD) and changes in foot structure. These factors have been linked to chronic hyperglycaemia (high levels of glucose in the blood) and the altered metabolic state of diabetes. Control of hyperglycaemia may be important in the healing of ulcers.  Objectives  To assess the effects of intensive glycaemic control compared to conventional control on the outcome of foot ulcers in people with type 1 and type 2 diabetes.  Search methods  In December 2015 we searched: The Cochrane Wounds Specialised Register; The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library); Ovid MEDLINE; Ovid MEDLINE (In-Process & Other Non-Indexed Citations); Ovid EMBASE; EBSCO CINAHL; Elsevier SCOPUS; ISI Web of Knowledge Web of Science; BioMed Central and LILACS. We also searched clinical trial databases, pharmaceutical trial databases and current international and national clinical guidelines on diabetes foot management for relevant published, non-published, ongoing and terminated clinical trials. There were no restrictions based on language or date of publication or study setting.  Selection criteria  Published, unpublished and ongoing randomised controlled trials (RCTs) were considered for inclusion where they investigated the effects of intensive glycaemic control on the outcome of active foot ulcers in people with diabetes. Non randomised and quasi-randomised trials were excluded. In order to be included the trial had to have: 1) attempted to maintain or control blood glucose levels and measured changes in markers of glycaemic control (HbA1c or fasting, random, mean, home capillary or urine glucose), and 2) documented the effect of these interventions on active foot ulcer outcomes. Glycaemic interventions included subcutaneous insulin administration, continuous insulin infusion, oral anti-diabetes agents, lifestyle interventions or a combination of these interventions. The definition of the interventional (intensive) group was that it should have a lower glycaemic target than the comparison (conventional) group.  Data collection and analysis  All review authors independently evaluated the papers identified by the search strategy against the inclusion criteria. Two review authors then independently reviewed all potential full-text articles and trials registry results for inclusion.  Main results  We only identified one trial that met the inclusion criteria but this trial did not have any results so we could not perform the planned subgroup and sensitivity analyses in the absence of data. Two ongoing trials were identified which may provide data for analyses in a later version of this review. The completion date of these trials is currently unknown.  Authors’ conclusions  The current review failed to find any completed randomised clinical trials with results. Therefore we are unable to conclude whether intensive glycaemic control when compared to conventional glycaemic control has a positive or detrimental effect on the treatment of foot ulcers in people with diabetes. Previous evidence has however highlighted a reduction in risk of limb amputation (from various causes) in people with type 2 diabetes with intensive glycaemic control. Whether this applies to people with foot ulcers in particular is unknown. The exact role that intensive glycaemic control has in treating foot ulcers in multidisciplinary care (alongside other interventions targeted at treating foot ulcers) requires further investigation

Effects of poorly perfused peripheries on derived transit time parameters of the lower and upper limbs

A simple and non-intrusive approach termed the pulse transit time ratio (PTTR) has recently been shown to be a potential surrogate of the ankle-brachial index (ABI). PTTR is based on the principle of PTT, which is known to be temperature-sensitive. In this study, 23 healthy adults with normally perfused peripheries and 10 with poorly perfused peripheries were recruited. No significant change in PTTR was observed between those with cold (1.287±0.043) and normal (1.290±0.027) peripheries (p>0.05). A cold periphery may cause pulse waveform changes and indirectly affect PTT owing to poor skin microcirculation, but may have a limited effect on PTTR, which is useful as an ABI alternative. © 2008 by Walter de Gruyter