Personalised statistical modelling of soft tissue structures in the ankle.

BACKGROUND AND OBJECTIVE: Revealing the complexity behind subject-specific ankle joint mechanics requires simultaneous analysis of three-dimensional bony and soft-tissue structures. 3D musculoskeletal models have become pivotal in orthopedic treatment planning and biomechanical research. Since manual segmentation of these models is time-consuming and subject to manual errors, (semi-) automatic methods could improve the accuracy and enlarge the sample size of personalised 'in silico' biomechanical experiments and computer-assisted treatment planning. Therefore, our aim was to automatically predict ligament paths, cartilage topography and thickness in the ankle joint based on statistical shape modelling. METHODS: A personalised cartilage and ligamentous prediction algorithm was established using geometric morphometrics, based on an 'in-house' generated lower limb skeletal model (N = 542), tibiotalar cartilage (N = 60) and ankle ligament segmentations (N = 10). For cartilage, a population-averaged thickness map was determined by use of partial least-squares regression. Ligaments were wrapped around bony contours based on iterative shortest path calculation. Accuracy of ligament path and cartilage thickness prediction was quantified using leave-one-out experiments. The novel personalised thickness prediction was compared with a constant cartilage thickness of 1.50 mm by use of a paired sample T-test. RESULTS: Mean distance error of cartilage and ligament prediction was 0.12 mm (SD 0.04 mm) and 0.54 mm (SD 0.05 mm), respectively. No significant differences were found between the personalised thickness cartilage and segmented cartilage of the tibia (p = 0.73, CI [-1.60 .10-17, 1.13 .10-17]) and talus (p = 0.95, CI[ -1.35 .10-17, 1.28 .10-17]). For the constant thickness cartilage, a statistically significant difference was found in 89% and 92% of the tibial (p < 0.001, CI [0.51, 0.58]) and talar (p < 0.001, CI [0.33, 0.40]) cartilage area. CONCLUSIONS: In this study, we described a personalised prediction algorithm of cartilage and ligaments in the ankle joint. We were able to predict cartilage and main ankle ligaments with submillimeter accuracy. The proposed method has a high potential for generating large (virtual) sample sizes in biomechanical research and mitigates technological advances in computer-assisted orthopaedic surgery.

Time scales of autonomic information flow in near-term fetal sheep.

Autonomic information flow (AIF) characterizes fetal heart rate (FHR) variability (fHRV) in the time scale dependent complexity domain and discriminates sleep states [high voltage/low frequency (HV/LF) and low voltage/high frequency (LV/HF) electrocortical activity (ECoG)]. However, the physiologic relationship of AIF time scales to the underlying sympathetic and vagal rhythms is not known. Understanding this relationship will enhance the benefits derived from using fHRV to monitor fetal health non-invasively. We analyzed AIF measured as Kullback-Leibler entropy (KLE) in fetal sheep in late gestation as function of vagal and sympathetic modulation of fHRV, using atropine and propranolol, respectively (n = 6), and also analyzed changes in fHRV during sleep states (n = 12). Atropine blockade resulted in complexity decrease at 2.5 Hz compared to baseline HV/LF and LV/HF states and at 1.6 Hz compared to LV/HF. Propranolol blockade resulted in complexity increase in the 0.8-1 Hz range compared to LV/HF and in no changes when compared to HV/LF. During LV/HF state activity, fHRV complexity was lower at 2.5 Hz and higher at 0.15-0.19 Hz than during HV/LF. Our findings show that in mature fetuses near term vagal activity contributes to fHRV complexity on a wider range of time scales than sympathetic activity. Related to sleep, during LV/HF we found lower complexity at short-term time scale where complexity is also decreased due to vagal blockade. We conclude that vagal and sympathetic modulations of fHRV show sleep state-dependent and time scale-dependent complexity patterns captured by AIF analysis of fHRV. Specifically, we observed a vagally mediated and sleep state-dependent change in these patterns at a time scale around 2.5 Hz (0.2 s). A paradigm of state-dependent non-linear sympathovagal modulation of fHRV is discussed.

Stochastic and deterministic models for agricultural production networks.

An approach to modeling the impact of disturbances in an agricultural production network is presented. A stochastic model and its approximate deterministic model for averages over sample paths of the stochastic system are developed. Simulations, sensitivity and generalized sensitivity analyses are given. Finally, it is shown how diseases may be introduced into the network and corresponding simulations are discussed.

Knowledge discovery in time series databases.

Adding the dimension of time to databases produces time series databases (TSDB) and introduces new aspects and difficulties to data mining and knowledge discovery. In this correspondence, we introduce a general methodology for knowledge discovery in TSDB. The process of knowledge discovery in TSDR includes cleaning and filtering of time series data, identifying the most important predicting attributes, and extracting a set of association rules that can be used to predict the time series behavior in the future. Our method is based on signal processing techniques and the information-theoretic fuzzy approach to knowledge discovery. The computational theory of perception (CTP) is used to reduce the set of extracted rules by fuzzification and aggregation. We demonstrate our approach on two types of time series: stock-market data and weather data.

Healing the social wounds of war.

The healing of those hurt by war can take different forms, ranging from violence and vengeance to psychotherapy and humanitarian aid imposed from outside. This healing has been widely and critically discussed in the literature. Instead, the focus here is more on the way communities try to heal themselves long after the outside world has lost interest. In this context, resisting the oppressor becomes less important than recovery, and the past can matter less than the future.

40 years of the British Medical Association film competition.

Since its inception in 1957 the BMA's annual film competition has fulfilled three roles--promoting the effective use of film and video in medical education, encouraging the production of high quality audiovisual material, and helping to increase the holdings of its film library. The BMA awards recognise programmes for their clinical accuracy, educational value and creative use of the medium.

Putting children first.

Save the Children Fund in 1923 and UNICEF in 1990 both declared that children must come first in receiving relief. Whereas SCF's call was a corporate credo for the world, for use whenever disaster struck, UNICEF's was offered as a strategic policy document applicable at all times. In contrast, the 1989 UN Convention on the Rights of the Child, as a legally-binding document in the field of human rights, omitted all reference to giving such priority to children. The reason for transforming the original credo is that the principle of 'children first', if it includes every child and is to be applied literally in the field, is not only impracticable but unacceptable in many cultures. The social value of a particular child's life--or of human life generally--is simply not an absolute, in all circumstances, in all cultures.

Oxygen deficit and blood lactate in prepubertal boys during exercise above the anaerobic threshold.

Recent studies have shown that in boys a steady-state of blood lactate is maintained at exercise levels above the anaerobic threshold. Therefore, the explanation hitherto provided for the steeper increase in blood lactate beyond the anaerobic threshold, i.e. the onset of anaerobic metabolism, needs modification. Investigations were carried out in ten boys, aged 11-12 years, during treadmill running. Maximal oxygen uptake (VO2max) and maximal blood lactate were determined during incremental exercise. Subsequently each boy performed four runs at different high constant speeds of 16 min duration, in order to determine maximal steady-state blood lactate. The underlying data also served to estimate roughly the lactate anaerobic threshold. Oxygen uptaken (VO2) was measured at 0.5 min intervals during the initial 7.5 min of each constant-speed run. Maximal steady-state blood lactate was 5.6 mmol/l corresponding to 92% of VO2max. The mean blood lactate at which the anaerobic threshold was reached or just exceeded was 2.7 mmol/l corresponding to 82% of VO2max. Oxygen transport transient kinetics were computed from the mean 0.5 min VO2-values during the constant-speed runs near the maximal steady-state blood lactate and from runs near the anaerobic threshold. Half-times of VO2 response were shorter than values previously reported for adults due to a faster increase in VO2 at the onset of exercise. Half-times increased with increasing work rates as did the oxygen deficit, due to a slower increase in VO2 along with a longer time required to attain a steady-state at higher work rates.(ABSTRACT TRUNCATED AT 250 WORDS)

An update on the acquired immunodeficiency syndrome (AIDS). Associated disorders of the alimentary tract.

The pandemic, acquired immunodeficiency syndrome (AIDS) has been described in 40 nations throughout the world. This paper describes the wide spectrum of gastrointestinal tract manifestations seen in this syndrome, with particular attention to the epidemiology, etiology, and measurement of these problems. Discussion of candidiasis, herpes simplex, "hairy" leukoplakia, Kaposi's sarcoma, cytomegalovirus, anal warts and carcinoma, chlamydial proctitis (LGV), coccidiosis, and mycobacterial diarrhea, as well as "gay bowel syndrome," demonstrates the complex management problems associated with this condition.

Conservative management of paraileostomy ulcers in patients with Crohn's disease.

Paraileostomy ulcers (PSU) are uncommon after construction of an ileostomy and are difficult to manage. Seventeen patients with Crohn's disease developed 28 parastomal ulcers at least 1.5 cm in diameter from two weeks to seven years after ileostomy construction (mean 45.6 weeks, median 8 weeks). Some patients had multiple episodes of parastomal ulceration. The etiology and clinical features of PSU are discussed. Conservative management included debridement, curettage, unroofing of the ulcer complex, pouching of the stoma with Telfa strips placed in the ulcer base and a conventional appliance or a Perry Model #51 device. Most of the ulcers healed between two and 32 weeks (mean 12.7 weeks, median 8 weeks). In the six patients in whom the ulcers did not heal, Crohn's disease or another ileostomy complication necessitated ileostomy relocation. This conservative management allowed most patients to be treated on an outpatient basis, carrying out their daily tasks and delaying or obviating the need for ileostomy relocations. When required, relocations were done electively.

Major hemorrhage and perforation due to a solitary cecal ulcer in a patient with end-stage renal failure.

A case of solitary cecal ulcer with major hemorrhage followed by perforation after treatment with intra-arterial vasopressin in a patient with end-stage renal failure is presented. Though vasopressin has been used with success in the treatment of colonic hemorrhage, caution should be applied in patients with a bleeding cecal ulcer as the vasoconstriction produced by vasopressin may cause perforation in an area whose blood supply is already compromised.