Tunable Helmholtz Resonators Using Multiple Necks.

One of the uses of Helmholtz resonators is as sound absorbers for room acoustic applications, especially for the low frequency range. Their efficiency is centered around their resonance frequency which mainly depends on elements of their geometry such as the resonator volume and neck dimensions. Incorporating additional necks on the body of a Helmholtz resonator (depending on whether they are open or closed) has been found to alter the resulting resonance frequency. For this study, tunable Helmholtz resonators to multiple resonance frequencies, are proposed and investigated utilizing additional necks. The resonance frequencies of various multi-neck Helmholtz resonators are first modeled with the use of the finite element method (FEM), then calculated with the use of an analytical approach and the results of the two approaches are finally compared. The results of this study show that Helmholtz resonators with multiple resonances at desired frequencies are achievable with the use of additional necks, while FEM and analytical methods can be used for the estimation of the resonance frequencies. Analytical and FEM approach results show a good agreement in cases of small number of additional necks, while the increasing differences in cases of higher neck additions, were attributed to the change in effective length of the necks as demonstrated by FEM. The proposed approach can be useful for tunable sound absorbers for room acoustics applications according to the needs of a space. Also, this approach can be applied in cases of additional tunable air resonances of acoustic instruments (e.g., string instruments).

Employing body-fixed sensors and machine learning to predict physical activity in military personnel.

INTRODUCTION: This was a feasibility pilot study aiming to develop and validate an activity recognition system based on a custom-made body-fixed sensor and driven by an algorithm for recognising basic kinetic movements in military personnel. The findings of this study are deemed essential in informing our development process and contributing to our ultimate aim which is to develop a low-cost and easy-to-use body-fixed sensor for military applications. METHODS: Fifty military participants performed a series of trials involving walking, running and jumping under laboratory conditions in order to determine the optimal, among five machine learning (ML), classifiers. Thereafter, the accuracy of the classifier was tested towards the prediction of these movements (15 183 measurements) and in relation to participants' gender and fitness level. RESULTS: Random forest classifier showed the highest training and validation accuracy (98.5% and 92.9%, respectively) and classified participants with differences in type of activity, gender and fitness level with an accuracy level of 83.6%, 70.0% and 62.2%, respectively. CONCLUSIONS: The study showed that accurate prediction of various dynamic activities can be achieved with high sensitivity using a low-cost easy-to-use sensor and a specific ML model. While this technique is in a development stage, our findings demonstrate that our body-fixed sensor prototype alongside a fully trained validated algorithm can strategically support military operations and offer valuable information to commanders controlling operations remotely. Further stages of our developments include the validation of our refined technique on a larger range of military activities and groups by combining activity data with physiological variables to predict phenomena relating to the onset of fatigue and performance decline.

Dupuytren's disease: limited fasciectomy, night splinting, and hand exercises-long-term results.

BACKGROUND: Dupuytren's contracture (DC) is a fibroproliferative disorder of palmar fascia that causes flexion contractures of one or more digits. There is currently no gold standard operative and postoperative protocol for reducing recurrence rates. We propose a combination of surgical intervention, night splinting, and home hand exercises as a treatment protocol. METHODS: Thirty patients were included in our study, diagnosed with DC Tubiana grade II-IV. Our treatment protocol was limited fasciectomy followed by a 24-week night splint application, combined with home hand exercises for eight weeks. The outcomes were recurrence, QuickDASH score, extension or flexion deficit, and grip strength. The mean follow-up was 4.9 years (range 2-11 years). RESULTS: Recurrence of DC occurred in two patients (7%), who had discontinued the use of the splint within two months postoperatively. All other patients had complied with the postoperative protocol. The mean QuickDASH score improved from 61.5 (SD 2.1) to 8.6 (SD 2) postoperatively (p < 0.001). Grip strength did not differ significantly in the operated hands (37.9 kg, SD 1.3) when compared to the healthy hands (40.2 kg, SD 1.3, p = 0.035). The recurrence was not significantly correlated either with the Tubiana grade (p = 0.7), or with the patients' age (p = 0.27). CONCLUSIONS: This study shows that limited fasciectomy followed by a 24-week night splint application, combined with home hand exercises for at least eight weeks, is a viable protocol which reduces the rates of recurrence of DC.

Suprascapular Nerve Pathology: A Review of the Literature.

BACKGROUND: Suprascapular nerve pathology is a rare diagnosis that is increasingly gaining popularity among the conditions that cause shoulder pain and dysfunction. The suprascapular nerve passes through several osseoligamentous structures and can be compressed in several locations. METHODS: A thorough literature search was performed using online available databases in order to carefully define the pathophysiology and to guide diagnosis and treatment. RESULTS: Suprascapular neuropathy diagnosis is based on a careful history and a thorough clinical and radiological examination. Although the incidence and prevalence of the condition remain unknown, it is highly diagnosed in specific groups (overhead athletes, patients with a massive rotator cuff tear) probably due to higher interest. The location and the etiology of the compression are those that define the treatment modality. CONCLUSION: Suprascapular neuropathy diagnosis is based on a careful history and a thorough clinical and radiological examination. The purpose of this article is to describe the anatomy of the suprascapular nerve, to define the pathophysiology of suprascapular neuropathy and to present methodically the current diagnostic and treatment strategies.

A Misguiding Osteoid Osteoma in the Bicipital Tuberosity of the Radius.

Osteoid osteoma is a benign bone tumor that appears most frequently in young patients. It is more common in males and it concerns mostly the long bones of the lower limb. A 20-year-old young woman presented to our outpatient department with pain in her left elbow. The symptoms began four years ago. At first, her symptoms were attributed to ulnar neuritis, confirmed by nerve conduction studies. In the following two years, she had undergone two surgical operations for decompression of the ulnar nerve. As a result, she reported poor results, which forced her to take frequently anti-inflammatory drugs for some years. When the patient presented to us, we planned a three-phase bone scan and an elbow MRI, which revealed the lesion. Based on the image findings of osteoid osteoma, we proceeded to the surgical removal of the tumor. Since then, the patient is pain-free and has a full range of motion of the affected elbow. Osteoid osteoma usually mimics multiple pathologies in the upper limb especially joint disease posing a challenge for the physician. The diagnosis requires high index of suspicion and a prompt diagnostic and surgical management.

Cervical, uterine corpus, and ovarian cancer mortality in Greece during 1980 to 2005: a trend analysis.

INTRODUCTION: The aim of the present study was to analyze cervical, uterine corpus, and ovarian cancer mortality, between 1980 and 2005, in Greece. METHODS: Mortality data and population age distribution were provided by the National Statistical Service of Greece. Time trends of mortality were calculated for each tumor type per 100,000 women in the whole female population of Greece, and 2 different age groups, that is, women aged 49 years and younger and those 50 years and older. Joinpoint regression was used for further analysis of mortality trends. RESULTS: Overall, cervical and uterine corpus cancer mortality in the whole female population of Greece had a slightly decreasing trend between 1980 and 2005, whereas ovarian cancer mortality rates increased steadily throughout the period studied. Subgroup analyses according to age showed that cervical cancer mortality decreased very slightly only in women older than 50 years, whereas it remained steady in younger women. Uterine corpus cancer mortality decreased slightly in both age groups, but increased during the last years of the study period in the older age group. Ovarian cancer mortality increased in women older than 50 years, whereas it remained steady in the younger age group. Joinpoint regression analysis showed that only the increase after 1997 in the mortality trend for uterine corpus cancer in women 50 years and older was statistically significant (P = 0.0044). CONCLUSIONS: Although our findings regarding cervical cancer mortality in Greece are encouraging, still more efforts are needed, particularly in preventing cervical cancer in younger women. The increasing trend of uterine corpus and ovarian cancer mortality in older women suggests that development of well-organized tertiary centers for the implementation of modern therapeutic modalities is urgently needed.

Integration of functional MRI and white matter tractography in stereotactic radiosurgery clinical practice.

PURPOSE: To study the efficacy of the integration of functional magnetic resonance imaging (fMRI) and diffusion tensor imaging tractography data into stereotactic radiosurgery clinical practice. METHODS AND MATERIALS: fMRI and tractography data sets were acquired and fused with corresponding anatomical MR and computed tomography images of patients with arteriovenous malformation (AVM), astrocytoma, brain metastasis, or hemangioma and referred for stereotactic radiosurgery. The acquired data sets were imported into a CyberKnife stereotactic radiosurgery system and used to delineate the target, organs at risk, and nearby functional structures and fiber tracts. Treatment plans with and without the incorporation of the functional structures and the fiber tracts into the optimization process were developed and compared. RESULTS: The nearby functional structures and fiber tracts could receive doses of >50% of the maximum dose if they were excluded from the planning process. In the AVM case, the doses received by the Broadmann-17 structure and the optic tract were reduced to 700 cGy from 1,400 cGy and to 1,200 cGy from 2,000 cGy, respectively, upon inclusion into the optimization process. In the metastasis case, the motor cortex received 850 cGy instead of 1,400 cGy; and in the hemangioma case, the pyramidal tracts received 780 cGy instead of 990 cGy. In the astrocytoma case, the dose to the motor cortex bordering the lesion was reduced to 1,900 cGy from 2,100 cGy, and therefore, the biologically equivalent dose in three fractions was delivered instead. CONCLUSIONS: Functional structures and fiber tracts could receive high doses if they were not considered during treatment planning. With the aid of fMRI and tractography images, they can be delineated and spared.

Is psychopathology related to children's unintentional injury?

This research aimed to study children's psychopathology and unintentional accidents in Thrace, northern Greece. We examined whether there was a correlation between each risk factor of the research and the dependent variables: 1) minor accidents, 2) serious accidents that required Emergency Room attendance (ER accidents), 3) serious accidents that led to hospital admission (admission accidents). High school children (n = 1,516) completed an anonymous questionnaire regarding the cause of their accident, as well as the "Strengths and difficulties questionnaire" (SDQ) by Goodman. The results indicate that sex, conduct disorders, hyperactivity, and abnormal score in SDQ were important risk factors for minor injuries and continued to be important risk factors for ER accidents. Sex, conduct disorders, hyperactivity, peer-problems, and abnormal score in SDQ were important risk factors for the most serious accidents (admission accidents). Because major accidents can result in serious health problems or disability, attention should be paid to the risk factors found.