Information Content in Data Sets for a Nucleated-Polymerization Model

We illustrate the use of tools (asymptotic theories of standard error quantification using appropriate statistical models, bootstrapping, model comparison techniques) in addition to sensitivity that may be employed to determine the information content in data sets. We do this in the context of recent models [23] for nucleated polymerization in proteins, about which very little is known regarding the underlying mechanisms; thus the methodology we develop here may be of great help to experimentalists

Computer program to assess impact of fatigue and fracture criteria on weight and cost of transport aircraft

A preliminary design analysis tool for rapidly performing trade-off studies involving fatigue, fracture, static strength, weight, and cost is presented. Analysis subprograms were developed for fatigue life, crack growth life, and residual strength; and linked to a structural synthesis module which in turn was integrated into a computer program. The part definition module of a cost and weight analysis program was expanded to be compatible with the upgraded structural synthesis capability. The resultant vehicle design and evaluation program is named VDEP-2. It is an accurate and useful tool for estimating purposes at the preliminary design stage of airframe development. A sample case along with an explanation of program applications and input preparation is presented

Shape mode analysis exposes movement patterns in biology: flagella and flatworms as case studies

We illustrate shape mode analysis as a simple, yet powerful technique to concisely describe complex biological shapes and their dynamics. We characterize undulatory bending waves of beating flagella and reconstruct a limit cycle of flagellar oscillations, paying particular attention to the periodicity of angular data. As a second example, we analyze non-convex boundary outlines of gliding flatworms, which allows us to expose stereotypic body postures that can be related to two different locomotion mechanisms. Further, shape mode analysis based on principal component analysis allows to discriminate different flatworm species, despite large motion-associated shape variability. Thus, complex shape dynamics is characterized by a small number of shape scores that change in time. We present this method using descriptive examples, explaining abstract mathematics in a graphic way.Comment: 20 pages, 6 figures, accepted for publication in PLoS On

Trace metal accumulation in hair and skin of the harbour seal, Phoca vitulina

Skin and hair samples of harbour seals (Phoca vitulina) found dead along the west coast of northern Germany in 1988 were analysed for total mercury, cadmium and lead. Cadmium and lead concentrations were below the detection limit in most skin samples. The mercury content of the hair (median: 23.1 μg g−1 wet wt) was several magnitudes higher than the mercury content of the skin (0.27 μg g−1 wet wt). Mercury concentrations in hair samples were significantly higher than lead concentrations (0.54 μg g−1 wet wt), which significantly exceeded cadmium levels (0.09 μg g−1 wet wt). Female seals revealed lower cadmium concentrations in the hair than male seals. Accumulations of metals with age were observed for cadmium and lead in hair samples and for mercury in skin samples of male seals. A connection between metal accumulation and pigmentation or rather moult was clearly recognizable

Perforatationstrauma im Gesichtsschädel. Eine ungewöhnliche Verletzung beim Skifahren

Facial perforation injuries are very rare. We describe a case of a 48-year-old man who sustained a perforation trauma from an 11 cm long wooden tree branch in the middle of the face in a skiing accident. He suffered from additional injuries, such as fractures of the ribs and hand, but was neurologically without pathologic findings and was cardiopulmonary stable.The branch penetrated the head from the sinus maxillaris through the maxilla just missing the internal and external carotid arteries and ending just short of the cervical vertebra. The patient was transported to a center for oral and maxillofacial surgery and underwent several operations.He could return to his normal social and professional life 8 months after the accident

Synchrony Dynamics During Initiation, Failure, and Rescue of the Segmentation Clock

The “segmentation clock” is thought to coordinate sequential segmentation of the body axis in vertebrate embryos. This clock comprises a multicellular genetic network of synchronized oscillators, coupled by intercellular Delta-Notch signaling. How this synchrony is established and how its loss determines the position of segmentation defects in Delta and Notch mutants are unknown. We analyzed the clock's synchrony dynamics by varying strength and timing of Notch coupling in zebra-fish embryos with techniques for quantitative perturbation of gene function. We developed a physical theory based on coupled phase oscillators explaining the observed onset and rescue of segmentation defects, the clock's robustness against developmental noise, and a critical point beyond which synchrony decays. We conclude that synchrony among these genetic oscillators can be established by simultaneous initiation and self-organization and that the segmentation defect position is determined by the difference between coupling strength and noise

Significance of HbA1c levels in diabetic retinopathy extremes in South Africa

Background. Diabetic retinopathy (DR) is one of the leading causes of blindness in sub-Saharan Africa and globally, placing a huge disease burden on patients and the public health system. DR varies in severity from non-proliferative to proliferative DR (PDR).Objectives. Using a monitor of medium- to long-term blood glucose control, to determine the association between glycated haemoglobin (HbA1c) levels in patients with PDR and those with no DR.Methods. A prospective, cross-sectional study was conducted at McCord Provincial Eye Hospital in Durban, South Africa. We studied only patients diagnosed with diabetes mellitus (DM) for >1 year who had either PDR or no DR, and compared their HbA1c levels. Patients with non-proliferative DR were not included.Results. Patients with PDR had significantly higher HbA1c levels than those with no DR. Patients with type 1 DM had higher HbA1c levels than patients with type 2 DM in both the PDR and no-DR groups. Older patients (>70 years) had lower HbA1c levels than younger patients. Gender, race and duration of diabetes had no influence on HbA1c levels.Conclusions. PDR was associated with higher HbA1c in type 2 DM in all races and age groups and was independent of duration of disease. The trend was the same for type 1 DM, but significance could not be reached, probably because of small numbers in this subset of patients

Significance of HbA1c levels in diabetic retinopathy extremes in South Africa

Background. Diabetic retinopathy (DR) is one of the leading causes of blindness in sub-Saharan Africa and globally, placing a huge disease burden on patients and the public health system. DR varies in severity from non-proliferative to proliferative DR (PDR). Objectives. Using a monitor of medium-to long-term blood glucose control, to determine the association between glycated haemoglobin (HbA1c) levels in patients with PDR and those with no DR. Methods. A prospective, cross-sectional study was conducted at McCord Provincial Eye Hospital in Durban, South Africa. We studied only patients diagnosed with diabetes mellitus (DM) for >1 year who had either PDR or no DR, and compared their HbA1c levels. Patients with non-proliferative DR were not included. Results. Patients with PDR had significantly higher HbA1c levels than those with no DR. Patients with type 1 DM had higher HbA1c levels than patients with type 2 DM in both the PDR and no-DR groups. Older patients (>70 years) had lower HbA1c levels than younger patients. Gender, race and duration of diabetes had no influence on HbA1c levels. Conclusions. PDR was associated with higher HbA1c in type 2 DM in all races and age groups and was independent of duration of disease. The trend was the same for type 1 DM, but significance could not be reached, probably because of small numbers in this subset of patients