39 research outputs found
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ABSTRACT. Objective. To investigate by high frequency grey-scale ultrasonography (US) and power Doppler sonography (PDS) the modality and frequency of involvement of the Achilles tendon and plantar fascia in chondrocalcinosis (CC), and to correlate these findings with clinical complaints and radiographic evidence. Methods. The heels of 57 consecutive patients with CC were evaluated by US, PDS, and radiography. One control group of 50 consecutive patients with osteoarthritis (OA) without signs of CC was studied in the same way. A second control group of 50 healthy subjects underwent only US/PDS examination. All subjects also underwent clinical assessment. Results. US revealed Achilles tendon calcifications in 57.9% of those with CC, but none in the control groups. Plantar fascia calcifications were observed in 15.8% of CC and in 2% of OA cases, but not in healthy controls. US showed no significant difference in postero-inferior and inferior calcaneal enthesophytosis between subjects with CC (59.6% and 61.4%, respectively) and those with OA (46% and 44%, respectively). Such alterations were also present, in lower percentages, in the healthy controls. Posterior and inferior calcaneal erosions were absent in all groups. Achilles enthesopathy was found in 22.8% of patients with CC (14.9% of heels, with vascular signals in 11.4% of heels on PDS). Deep retrocalcaneal bursitis was found in 10.5% of patients with CC (7% of heels, with vascular signals in 5.2% of heels on PDS). Plantar fasciitis was found in 40.3% of patients with CC (36% of heels, with vascular signals in 2.6% of heels on PDS) and in 14% of OA patients, but not in healthy controls. No significant correlation was found between talalgia or sex of patients and presence of calcifications. A significant correlation was observed between talalgia and Achilles enthesopathy (r = 0.78, p < 0.0001), deep retrocalcaneal bursitis (r = 0.7, p < 0.0001), and plantar fasciitis (r = 0.31, p < 0.001). A significant correlation between talalgia and vascular signals on PDS was observed in Achilles enthesopathy (r = 0.91, p < 0.0001) and deep retrocalcaneal bursitis (r = 0.65, p < 0.0001). The presence of vascular signals on PDS was significantly associated with the presence of tendinous and bursal grey-scale US alterations. Achilles tendon calcifications were 39% sensitive, 100% specific, and 77% accurate for the presence of CC, whereas plantar fascia calcifications were 15% sensitive, 98% specific, and 54% accurate. Excellent agreement was found between US and radiography in detecting Achilles tendon calcifications (k = 0.86), plantar fascia calcifications (k = 0.77), postero-inferior enthesophytosis (k = 0.90), and inferior enthesophytosis (k = 0.83). Chondrocalcinosis (CC) is an arthropathy generally caused by deposit of calcium pyrophosphate-dihydrate (CPPD) microcrystals in the joints and in the tendons 1,2 . In CPPD crystal deposition disease typical linear calcifications can be found in fibrocartilage, especially in the knee menisci, carpus triangular ligament, symphysis pubis, and in hyaline articular cartilage, especially in the knee 1,2 . Calcifications in tendons have been described in previous radiological reports 3-9 : Achilles tendon, gastrocnemius tendon, hip adductors, and quadriceps tendon were the sites primarily involved. Conclusio
Menstrual function among women exposed to polybrominated biphenyls: A follow-up prevalence study
BACKGROUND: Alteration in menstrual cycle function is suggested among rhesus monkeys and humans exposed to polybrominated biphenyls (PBBs) and structurally similar polychlorinated biphenyls (PCBs). The feedback system for menstrual cycle function potentially allows multiple pathways for disruption directly through the hypothalamic-pituitary-ovarian axis and indirectly through alternative neuroendocrine axes. METHODS: The Michigan Female Health Study was conducted during 1997–1998 among women in a cohort exposed to PBBs in 1973. This study included 337 women with self-reported menstrual cycles of 20–35 days (age range: 24–56 years). Current PBB levels were estimated by exponential decay modeling of serum PBB levels collected from 1976–1987 during enrollment in the Michigan PBB cohort. Linear regression models for menstrual cycle length and the logarithm of bleed length used estimated current PBB exposure or enrollment PBB exposure categorized in tertiles, and for the upper decile. All models were adjusted for serum PCB levels, age, body mass index, history of at least 10% weight loss in the past year, physical activity, smoking, education, and household income. RESULTS: Higher levels of physical activity were associated with shorter bleed length, and increasing age was associated with shorter cycle length. Although no overall association was found between PBB exposure and menstrual cycle characteristics, a significant interaction between PBB exposures with past year weight loss was found. Longer bleed length and shorter cycle length were associated with higher PBB exposure among women with past year weight loss. CONCLUSION: This study suggests that PBB exposure may impact ovarian function as indicated by menstrual cycle length and bleed length. However, these associations were found among the small number of women with recent weight loss suggesting either a chance finding or that mobilization of PBBs from lipid stores may be important. These results should be replicated with larger numbers of women exposed to similar lipophilic compounds
Influence of handaxe size and shape on cutting efficiency: a large-scale experiment and morphometric analysis
Handaxes represent one of the most temporally enduring and geographically widespread of Palaeolithic artifacts and thus comprised a key technological strategy of many hominin populations. Archaeologically observable variation in the size (i.e., mass) and shape properties of handaxes has been frequently noted. It is logical to ask whether some of this variability may have had functional implications. Here, we report the results of a large-scale (n = 500 handaxes) experiment designed to examine the influence of variation in handaxe size and shape on cutting efficiency rates during a laboratory task. We used a comprehensive dataset of morphometric (size-adjusted) shape variables and statistical methods (including multivariate methods) to address this issue. Our first set of analyses focused on handaxe mass/size variability. This analysis demonstrated that, at a broad-scale level of variation, handaxe mass may have been free to vary independently of functional (cutting) efficiency. Our analysis also, however, identified that there will be a task-specific threshold in terms of functional effectiveness at the lower end of handaxe mass variation. This implies that hominins may have targeted design forms to meet minimal (task-specific) thresholds, and may also have managed handaxe reduction and discard in respect to such factors. Our second set of analyses focused on handaxe shape variability. This analysis also indicated that considerable variation in handaxe shape may occur independently of any strong effect on cutting efficiency. We discuss how these results have several implications for considerations of handaxe variation in the archaeological record. At a general level, our results demonstrate that variability within and between handaxe assemblages in terms of their size and shape properties will not necessarily have had immediate or strong impact on their effectiveness when used for cutting, and that such variability may have been related to factors other than functional issues
Accuracy versus precision in boosted top tagging with the ATLAS detector
Abstract
The identification of top quark decays where the top quark has a large momentum transverse to the beam axis, known as top tagging, is a crucial component in many measurements of Standard Model processes and searches for beyond the Standard Model physics at the Large Hadron Collider.
Machine learning techniques have improved the performance of top tagging algorithms, but the size of the systematic uncertainties for all proposed algorithms has not been systematically studied.
This paper presents the performance of several machine learning based top tagging algorithms on a dataset constructed from simulated proton-proton collision events measured with the ATLAS detector at √
s
= 13 TeV.
The systematic uncertainties associated with these algorithms are estimated through an approximate procedure that is not meant to be used in a physics analysis, but is appropriate for the level of precision required for this study.
The most performant algorithms are found to have the largest uncertainties, motivating the development of methods to reduce these uncertainties without compromising performance.
To enable such efforts in the wider scientific community, the datasets used in this paper are made publicly available.</jats:p