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Sample records for neurovascular compressive sites

  1. Trigeminal Neuralgia: Evaluation of the Relationship Between the Region of Neuralgic Manifestation and the Site of Neurovascular Compression Under Endoscopy.

    Science.gov (United States)

    Zhang, Wenhao; Chen, Minjie; Zhang, Weijie; Chai, Ying

    2015-07-01

    This study aimed to evaluate the relationship among the pain region, branches of trigeminal nerve, and the neurovascular compression (NVC) location. A total of 123 consecutive patients with trigeminal neuralgia (TN) underwent endoscope-assisted microvascular decompression according to positive preoperative tomographic angiography. V2 alone was in 51 cases and V3 alone was in 64 cases. The location of NVC was classified into cranial, caudal, medial, or lateral sites. Some patients with multiple regions were recorded as medial + cranial, lateral + cranial, medial + caudal, and lateral + caudal. Twenty-eight (71.8%) of 39 patients with TN (V2) had their NVC at the medial site of the nerve. Twenty-seven (64.3%) of 42 patients with TN (V3) had their NVC at the lateral site of the nerve. There was a statistically significant difference (P = 0.0011  0.01). Evaluation of the relationship between the pain region and the NVC location by endoscopic images during microvascular decompression is more accurate. The second branch is mostly distributed in the medial area, and third branch is mainly distributed in the lateral area.

  2. Neurovascular Compression in Essential Hypertension: Cause, Consequence or Unrelated Finding?

    Czech Academy of Sciences Publication Activity Database

    Ceral, J.; Žižka, J.; Eliáš, P.; Solař, M.; Klzo, L.; Reissigová, Jindra

    2007-01-01

    Roč. 21, č. 2 (2007), s. 179-181 ISSN 0950-9240 R&D Projects: GA MZd NA6169 Institutional research plan: CEZ:AV0Z10300504 Keywords : neurovascular compression * rostral ventrolateral medulla oblongata * hypertension Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 2.244, year: 2007

  3. Neurovascular compression syndrome of the eighth cranial nerve

    International Nuclear Information System (INIS)

    Itoh, Akinori

    2010-01-01

    Neurovascular compression syndrome (NVCS) involves neuropathy due to intracranial blood vessels compressing the cranial nerves. NVCS of the eighth cranial nerve is less reportedly established as a clinical entity than that of the fifth and seventh cranial nerves. We report 17 cases of NVCS of the eighth cranial nerve and their clinical features. Clinical symptoms and test findings among our subjects indicated that most were aged more than 65 years, were unilateral, had intermittent tinnitus, suffered attacks lasting a few seconds dozens of times a day, experienced dizziness concomitantly with tinnitus, aggravated tinnitus and dizziness when tilting the head toward the affected side and looking downward (positional tinnitus, positional dizziness), heard specific tinnitus sounds such as crackling differing from those in cochlear tinnitus, had mild or no hearing loss, were diagnosed with retrocochlear hearing disturbance due to an interpeak latency delay between waves I and III of the auditory brainstem response (ABR), often had no nystagmus or canal paresis (CP), were found in constructive interference steady state magnetic resonance imaging (CISS MRI) to have compression of the eighth cranial nerve by the vertebral artery (VA) or the anterior inferior cerebellar artery (AICA), rarely had concomitant facial spasms, and had tinnitus and dizziness markedly suppressed by carbamazepine. With the number of elderly individuals continuing to increase, cases of NVCS due to arteriosclerotic changes in cerebral blood vessels are expected to increase, making it necessary to consider NVCS in elderly subjects with dizziness, tinnitus, and hearing loss. (author)

  4. Neurovascular compression syndrome of the eighth cranial nerve

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    Itoh, Akinori [Saitama Medical Univ., Faculty of Medicine, Moroyama, Saitama (Japan)

    2010-04-15

    Neurovascular compression syndrome (NVCS) involves neuropathy due to intracranial blood vessels compressing the cranial nerves. NVCS of the eighth cranial nerve is less reportedly established as a clinical entity than that of the fifth and seventh cranial nerves. We report 17 cases of NVCS of the eighth cranial nerve and their clinical features. Clinical symptoms and test findings among our subjects indicated that most were aged more than 65 years, were unilateral, had intermittent tinnitus, suffered attacks lasting a few seconds dozens of times a day, experienced dizziness concomitantly with tinnitus, aggravated tinnitus and dizziness when tilting the head toward the affected side and looking downward (positional tinnitus, positional dizziness), heard specific tinnitus sounds such as crackling differing from those in cochlear tinnitus, had mild or no hearing loss, were diagnosed with retrocochlear hearing disturbance due to an interpeak latency delay between waves I and III of the auditory brainstem response (ABR), often had no nystagmus or canal paresis (CP), were found in constructive interference steady state magnetic resonance imaging (CISS MRI) to have compression of the eighth cranial nerve by the vertebral artery (VA) or the anterior inferior cerebellar artery (AICA), rarely had concomitant facial spasms, and had tinnitus and dizziness markedly suppressed by carbamazepine. With the number of elderly individuals continuing to increase, cases of NVCS due to arteriosclerotic changes in cerebral blood vessels are expected to increase, making it necessary to consider NVCS in elderly subjects with dizziness, tinnitus, and hearing loss. (author)

  5. The Role of MRI in Diagnosing Neurovascular Compression of the Cochlear Nerve Resulting in Typewriter Tinnitus.

    Science.gov (United States)

    Bae, Y J; Jeon, Y J; Choi, B S; Koo, J-W; Song, J-J

    2017-06-01

    Typewriter tinnitus, a symptom characterized by paroxysmal attacks of staccato sounds, has been thought to be caused by neurovascular compression of the cochlear nerve, but the correlation between radiologic evidence of neurovascular compression of the cochlear nerve and symptom presentation has not been thoroughly investigated. The purpose of this study was to examine whether radiologic evidence of neurovascular compression of the cochlear nerve is pathognomonic in typewriter tinnitus. Fifteen carbamazepine-responding patients with typewriter tinnitus and 8 control subjects were evaluated with a 3D T2-weighted volume isotropic turbo spin-echo acquisition sequence. Groups 1 (16 symptomatic sides), 2 (14 asymptomatic sides), and 3 (16 control sides) were compared with regard to the anatomic relation between the vascular loop and the internal auditory canal and the presence of neurovascular compression of the cochlear nerve with/without angulation/indentation. The anatomic location of the vascular loop was not significantly different among the 3 groups (all, P > .05). Meanwhile, neurovascular compression of the cochlear nerve on MR imaging was significantly higher in group 1 than in group 3 ( P = .032). However, considerable false-positive (no symptoms with neurovascular compression of the cochlear nerve on MR imaging) and false-negative (typewriter tinnitus without demonstrable neurovascular compression of the cochlear nerve) findings were also observed. Neurovascular compression of the cochlear nerve was more frequently detected on the symptomatic side of patients with typewriter tinnitus compared with the asymptomatic side of these patients or on both sides of control subjects on MR imaging. However, considering false-positive and false-negative findings, meticulous history-taking and the response to the initial carbamazepine trial should be regarded as more reliable diagnostic clues than radiologic evidence of neurovascular compression of the cochlear nerve.

  6. Advanced and standardized evaluation of neurovascular compression syndromes

    Science.gov (United States)

    Hastreiter, Peter; Vega Higuera, Fernando; Tomandl, Bernd; Fahlbusch, Rudolf; Naraghi, Ramin

    2004-05-01

    Caused by a contact between vascular structures and the root entry or exit zone of cranial nerves neurovascular compression syndromes are combined with different neurological diseases (trigeminal neurolagia, hemifacial spasm, vertigo, glossopharyngeal neuralgia) and show a relation with essential arterial hypertension. As presented previously, the semi-automatic segmentation and 3D visualization of strongly T2 weighted MR volumes has proven to be an effective strategy for a better spatial understanding prior to operative microvascular decompression. After explicit segmentation of coarse structures, the tiny target nerves and vessels contained in the area of cerebrospinal fluid are segmented implicitly using direct volume rendering. However, based on this strategy the delineation of vessels in the vicinity of the brainstem and those at the border of the segmented CSF subvolume are critical. Therefore, we suggest registration with MR angiography and introduce consecutive fusion after semi-automatic labeling of the vascular information. Additionally, we present an approach of automatic 3D visualization and video generation based on predefined flight paths. Thereby, a standardized evaluation of the fused image data is supported and the visualization results are optimally prepared for intraoperative application. Overall, our new strategy contributes to a significantly improved 3D representation and evaluation of vascular compression syndromes. Its value for diagnosis and surgery is demonstrated with various clinical examples.

  7. Evaluation of trigeminal neurovascular compression in patients with trigeminal neuralgia with 3.0 T MRI

    International Nuclear Information System (INIS)

    Zhang Lirong; Wang Dehang; Wang Dongqing; Wu Min; Xu Guangming; Ma Cong

    2012-01-01

    Objective: To identify anatomical characteristics of neurovascular compression associated with trigeminal neuralgia (TN). Methods: Fifty patients with TN (23 of 50 patients underwent microvascular decompression) and 50 patients without facial pain underwent 3.0 T MRI scanning for analysis of 50 trigeminal nerves ipsilateral to TN symptoms, 50 contralateral to TN symptoms, and 100 in asymptomatic patients. MRI sequences included balanced fast-field echo and 3D MR angiography. Images were fused and reconstructed into virtual cisternoscopy images to determine the degree (severity of compression was defined as follows: 1=no compression; 2 =compressed by a vein; 3 =contacted by an artery; 4 =indented by an artery; and 5 =nerve displaced or distorted by an artery) and site of neurovascular compression (the point of each offending vascular structure: proximal was defined as located in 1/3 length of the cisternal segment of the trigeminal nerve near root entry zone; the place of superior was defined as above the cisternal segment of the trigeminal nerve). Reconstructed MPR images were used to measure nerve length and cross sectional area. The chi-square test was used for all 2 × 2 contingency tables. The t-test was used for dependent samples. The Logistic regression was used for prediction of occurrence of the event of TN. Results: Twenty-three of 50 patients with TN underwent microvascular decompression, which confirmed predicted neurovascular relationships in all cases, and 21 of 23 patients were pain free after the operation. The incidence of neurovascular compression on asymptomatic nerves (no. of level 1=79, level 2=5, level 3 =8, level 4 =8), on nerves contralateral to TN symptoms (no. of level 1=27, level 2 =6, level 3 =9, level 4 =8), and on nerves ipsilateral to TN symptoms (no. of level 1=4, level 2 =12, level 3 =12, level 4 =7, level 5 =15) was 21.0% (21/100), 46.0% (23/50), and 92.0% (46/50), respectively. The difference between symptomatic and asymptomatic

  8. Neurovascular compression of cranial nerves: CT and MRI findings

    International Nuclear Information System (INIS)

    Almeida Llanos, Julio; Sinner, Ricardo; Nagel, Jorge

    2002-01-01

    Purpose: The compression of a nervous structure by an aberrant vessel may be asymptomatic or produce an important symptoms, in these cases CT and MRI show relevant information. Materials and Methods: Between January 1998 and March 2001, we studied 27 patients: 8 with trigeminal neuralgia, 7 with hemi facial spasm, 4 vertigo and tinnitus, 2 hemianopsia, 1 with neuralgia of the amygdalin fossa, 1 with bitonal voice, 1 with tongue deviation with fascicular movements, 2 essential hypertension and 1 with severe headache. All of them had a neurologic evaluation from 2 specialists and 2 neuro radiologists interpreted the results. Results: The CT and RMI images with special sequences allowed to prove the compression of the entry segments of the V, VII, IX, X and XII cranial nerves, of the optic chiasma and the ventrolateral aspect of the medulla oblongata in close relation with the vasopressor centre. Also they demonstrate a rare vessel in the Silvio aqueduct avoiding the normal flow of the CSF. Of the total of patients that were studied, 37% had surgical confirmation. Conclusion: CT and RMI are sensitive and specific methods for the detection of vascular compressions of nervous structures. (author)

  9. Straightening the trigeminal nerve axis by complete dissection of arachnoidal adhesion and its neuroendoscopic confirmation for trigeminal neuralgia without neurovascular compression

    Directory of Open Access Journals (Sweden)

    Mami Ishikawa, MD, PhD

    2017-12-01

    Conclusions: Straightening the trigeminal nerve axis by complete dissection of the arachnoidal adhesion around the trigeminal nerve was effective for typical trigeminal neuralgia without neurovascular compression.

  10. Virtual endoscopic images by 3D FASE cisternography for neurovascular compression

    International Nuclear Information System (INIS)

    Ishimori, Takashi; Nakano, Satoru; Kagawa, Masahiro

    2003-01-01

    Three-dimensional fast asymmetric spin echo (3D FASE) cisternography provides high spatial resolution and excellent contrast as a water image acquisition technique. It is also useful for the evaluation of various anatomical regions. This study investigated the usefulness and limitations of virtual endoscopic images obtained by 3D FASE MR cisternography in the preoperative evaluation of patients with neurovascular compression. The study included 12 patients with neurovascular compression: 10 with hemifacial spasm and two with trigeminal neuralgia. The diagnosis was surgically confirmed in all patients. The virtual endoscopic images obtained were judged to be of acceptable quality for interpretation in all cases. The areas of compression identified in preoperative diagnosis with virtual endoscopic images showed good agreement with those observed from surgery, except in one case in which the common trunk of the anterior inferior cerebellar artery and posterior inferior cerebellar artery (AICA-PICA) bifurcated near the root exit zone of the facial nerve. The veins are displayed in some cases but not in others. The main advantage of generating virtual endoscopic images is that such images can be used for surgical simulation, allowing the neurosurgeon to perform surgical procedures with greater confidence. (author)

  11. [Neurovascular compression of the medulla oblongata: a rare cause of secondary hypertension].

    Science.gov (United States)

    Nádas, Judit; Czirják, Sándor; Igaz, Péter; Vörös, Erika; Jermendy, György; Rácz, Károly; Tóth, Miklós

    2014-05-25

    Compression of the rostral ventrolateral medulla oblongata is one of the rarely identified causes of refractory hypertension. In patients with severe, intractable hypertension caused by neurovascular compression, neurosurgical decompression should be considered. The authors present the history of a 20-year-old man with severe hypertension. After excluding other possible causes of secondary hypertension, the underlying cause of his high blood pressure was identified by the demonstration of neurovascular compression shown by magnetic resonance angiography and an increased sympathetic activity (sinus tachycardia) during the high blood pressure episodes. Due to frequent episodes of hypertensive crises, surgical decompression was recommended, which was performed with the placement of an isograft between the brainstem and the left vertebral artery. In the first six months after the operation, the patient's blood pressure could be kept in the normal range with significantly reduced doses of antihypertensive medication. Repeat magnetic resonance angiography confirmed the cessation of brainstem compression. After six months, increased blood pressure returned periodically, but to a smaller extent and less frequently. Based on the result of magnetic resonance angiography performed 22 months after surgery, re-operation was considered. According to previous literature data long-term success can only be achieved in one third of patients after surgical decompression. In the majority of patients surgery results in a significant decrease of blood pressure, an increased efficiency of antihypertensive therapy as well as a decrease in the frequency of highly increased blood pressure episodes. Thus, a significant improvement of the patient's quality of life can be achieved. The case of this patient is an example of the latter scenario.

  12. Assessment of neurovascular compression in patients with trigeminal neuralgia with a boundary fusion three-dimensional magnetic resonance cisternogram/angiogram

    International Nuclear Information System (INIS)

    Satoh, Toru; Omi, Megumi; Ohsako, Chika; Onoda, Keisuke; Date, Isao

    2007-01-01

    Precise assessment of the complex nerve-vessel relationship at the root entry zone (REZ) of the trigeminal nerve is useful for the planning of the microvascular decompression (MVD) in patients with trigeminal neuralgia. We have applied a boundary imaging of fusion three-dimensional (3D) magnetic resonance (MR) cisternogram/angiogram. The boundary imaging allows virtual assessment of the spatial relationship of the neurovascular compression at the REZ of the trigeminal nerve. The boundary images depicted complex anatomical relationship of the offending vessels to the trigeminal nerve REZ. The presence of offending vessels, compressive site, and degree of neurovascular compression were assessed from various viewpoints in the cistern and virtually through the brainstem and trigeminal nerve per se. The 3D visualization of the nerve-vessel relationship with fusion images was consistent with the intraoperative findings. The boundary fusion 3D MR cisternogram/angiogram may prove a useful adjunct for the diagnosis and decision-marking process to execute the MVD in patients with trigeminal neuralgia. (author)

  13. Neurovascular compression of cranial nerves: CT and MRI findings; Evaluacion de las compresiones neurovasculares intracraneales: hallazgos en TC y RM

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    Almeida Llanos, Julio; Sinner, Ricardo; Nagel, Jorge [Instituto Gamma, Rosario (Argentina)

    2002-07-01

    Purpose: The compression of a nervous structure by an aberrant vessel may be asymptomatic or produce an important symptoms, in these cases CT and MRI show relevant information. Materials and Methods: Between January 1998 and March 2001, we studied 27 patients: 8 with trigeminal neuralgia, 7 with hemi facial spasm, 4 vertigo and tinnitus, 2 hemianopsia, 1 with neuralgia of the amygdalin fossa, 1 with bitonal voice, 1 with tongue deviation with fascicular movements, 2 essential hypertension and 1 with severe headache. All of them had a neurologic evaluation from 2 specialists and 2 neuro radiologists interpreted the results. Results: The CT and RMI images with special sequences allowed to prove the compression of the entry segments of the V, VII, IX, X and XII cranial nerves, of the optic chiasma and the ventrolateral aspect of the medulla oblongata in close relation with the vasopressor centre. Also they demonstrate a rare vessel in the Silvio aqueduct avoiding the normal flow of the CSF. Of the total of patients that were studied, 37% had surgical confirmation. Conclusion: CT and RMI are sensitive and specific methods for the detection of vascular compressions of nervous structures. (author)

  14. Correlation of MR tomographic findings and microvascular decompression treatment of the neurovascular compressions of the cranial nerves

    International Nuclear Information System (INIS)

    Liu Zengsheng; Chen Xiangmin; Sun Yiyan; Fang Ming; Wang Ping; Guan Yong; Sun Miao

    2010-01-01

    Objective: To explore the correlation of the operation effects of the miorovascular decompression (MVD) and the findings on magnetic resonance tomographie angiography (MRTA) in patients of neurovascular compression of the cranial nerves. Methods: Two hundred and twenty three patients treated with the microvascular decompression were analyzed retrospectively. They were grouped and graded according to the vessel compression on the cranial nerves. The compression were grouped as none, moderate and severe, and the operation effects were graded as I (complete relief), II (partial relief) and III ( no relief). The operation effects grades were correlated according to the compression groups by Kruskal-Wallis test and the operation effects between each two of the groups were compared using Nemenyi test. P 2 =16.84 and P<0.05. The mean rank of the non-compression, the moderate and the severe group was 134.21,102.37 and 110.4, respectively. The difference of the mean ranks between the non-compression group and the moderate group was 31.84, and between the non-compression and the severe group was 24.17, respectively, where P<0.05 both. Conclusions: There was close relationship between the findings on magnetic resonance tomographic angiography and the operation effects of the MVD. The operation effects of patients with moderate and severe vessel compression were much better than the non-compression group. MRTA is helpful for MVD surgical indication and its prognosis. (authors)

  15. Atrophic changes in the trigeminal nerves of patients with trigeminal neuralgia due to neurovascular compression and their association with the severity of compression and clinical outcomes.

    Science.gov (United States)

    Leal, Paulo Roberto Lacerda; Barbier, Charlotte; Hermier, Marc; Souza, Miguel Angelo; Cristino-Filho, Gerardo; Sindou, Marc

    2014-06-01

    The aim of this study was to prospectively evaluate atrophic changes in trigeminal nerves (TGNs) using measurements of volume (V) and cross-sectional area (CSA) from high-resolution 3-T MR images obtained in patients with unilateral trigeminal neuralgia (TN), and to correlate these data with patient and neurovascular compression (NVC) characteristics and with clinical outcomes. Anatomical TGN parameters (V and CSA) were obtained in 50 patients (30 women and 20 men; mean age 56.42 years, range 22-79 years) with classic TN before treatment with microvascular decompression (MVD). Parameters were compared between the symptomatic (ipsilateralTN) and asymptomatic (contralateralTN) sides of the face. Twenty normal control subjects were also included. Two independent observers blinded to the side of pain separately analyzed the images. Measurements of V (from the pons to the entrance of the nerve into Meckel's cave) and CSA (at 5 mm from the entry of the TGN into the pons) for each TGN were performed using imaging software and axial and coronal projections, respectively. These data were correlated with patient characteristics (age, duration of symptoms before MVD, side of pain, sex, and area of pain distribution), NVC characteristics (type of vessel involved in NVC, location of compression along the nerve, site of compression around the circumference of the root, and degree of compression), and clinical outcomes at the 2-year follow-up after surgery. Comparisons were made using Bonferroni's test. Interobserver variability was assessed using the Pearson correlation coefficient. The mean V of the TGN on the ipsilateralTN (60.35 ± 21.74 mm(3)) was significantly smaller (p controls (78.62 ± 24.62 mm(3) and 89.09 ± 14.72 mm(3), respectively). The mean CSA of the TGN on the ipsilateralTN (4.17 ± 1.74 mm(2)) was significantly smaller than those for the contralateralTN and controls (5.41 ± 1.89 mm(2) and 5.64 ± 0.85 mm(2), respectively). The ipsilateralTN with NVC Grade III

  16. Experimental study of essential hypertension related to neurovascular compression established by fixation of balloon at the left lateral medulla

    International Nuclear Information System (INIS)

    Shen Jialin; Xu Jianrong; Luo Qizhong; Zhang Xiaohua; Li Shanquan; Chen Kemin

    2002-01-01

    Objective: To explore the possible mechanisms of neurogenic hypertension. Methods: With the guide of modern imaging, the hypertensive animal model of pulsatile neurovascular compression was established by fixation of balloon at the entry zone of the ninth and tenth cranial nerves of the left ventrolateral medulla oblongata. Blood pressure and heart rate data were collected at preoperation and one hour, 2 weeks, 4 weeks, and 6 weeks of postoperation. Results: The results showed that SBP at postoperation rose by 27.3%, 26.1%, 25.4% and 27.4%, respectively; DBP rose by 18.8%, 20.8%, 20.0% and 20.2%, respectively; MAP rose by 24.2%, 24.1%, 23.2% and 24.8%, respectively; HR rose by 34.9%, 26.7%, 26.9% and 26.1% respectively. Statistically, SBP, DAP, MAP and HR of postoperation significantly increased compared with that of preoperation in hypertension group (F = 9.044, 12,679, 11.306, 16.536, P 0.05). Conclusion: Essential hypertension may by caused by neurovascular compression of ninth and tenth cranial nerves of the left ventrolateral medulla oblongata at the REZ

  17. Three-dimensional short-range MR angiography and multiplanar reconstruction images in the evaluation of neurovascular compression in hemifacial spasm

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    Choi, Woo Suk; Kim, Eui Jong; Lee, Jae Gue; Rhee, Bong Arm [Kyunghee Univ. Hospital, Seoul (Korea, Republic of)

    1998-08-01

    To evaluate the diagnostic efficacy of three-dimensional(3D) short-range MR angiography(MRA) and multiplanar reconstruction(MPR) imaging in hemifacial spasm(HS). Materials and Methods : Two hundreds patients with HS were studied using a 1.5T MRI system with a 3D time-of-flight(TOF) MRA sequence. To reconstruct short-range MRA, 6-10 source images near the 7-8th cranial nerve complex were processed using a maximum-intensity projection technique. In addition, an MPR technique was used to investigate neurovascular compression. We observed the relationship between the root-exit zone(REZ) of the 7th cranial nerve and compressive vessel, and identified the compressive vessels on symptomatic sides. To investigate neurovascular contact, asymptomatic contralateral sides were also evaluated. Results : MRI showed that in 197 of 200 patients there was vascular compression or contact with the facial nerve REZ on symptomatic sides. One of the three remaining patients was suffering from acoustic neurinoma on the symptomatic side, while in two patients there were no definite abnormal findings.Compressive vessels were demonstrated in all 197 patients; 80 cases involved the anterior inferior cerebellar artery(AICA), 74 the posterior cerebellar artery(PICA), 13 the vertebral artery(VA), 16 the VA and AICA, eight the VA and PICA, and six the AICA and PICA. In all 197 patients, compressive vessels were reconstructed on one 3D short-range MRA image without discontinuation from vertebral or basilar arteries. 3D MPR studies provided additional information such as the direction of compression and course of the compressive vessel. In 31 patients there was neurovascular contact on the contralateral side at the 7-8th cranial nerve complex. Conclusion : Inpatients with HS, 3D short-range MRA and MPR images are excellent and very helpful for the investigation of neurovascular compression and the identification of compressive vessels.

  18. Three-dimensional short-range MR angiography and multiplanar reconstruction images in the evaluation of neurovascular compression in hemifacial spasm

    International Nuclear Information System (INIS)

    Choi, Woo Suk; Kim, Eui Jong; Lee, Jae Gue; Rhee, Bong Arm

    1998-01-01

    To evaluate the diagnostic efficacy of three-dimensional(3D) short-range MR angiography(MRA) and multiplanar reconstruction(MPR) imaging in hemifacial spasm(HS). Materials and Methods : Two hundreds patients with HS were studied using a 1.5T MRI system with a 3D time-of-flight(TOF) MRA sequence. To reconstruct short-range MRA, 6-10 source images near the 7-8th cranial nerve complex were processed using a maximum-intensity projection technique. In addition, an MPR technique was used to investigate neurovascular compression. We observed the relationship between the root-exit zone(REZ) of the 7th cranial nerve and compressive vessel, and identified the compressive vessels on symptomatic sides. To investigate neurovascular contact, asymptomatic contralateral sides were also evaluated. Results : MRI showed that in 197 of 200 patients there was vascular compression or contact with the facial nerve REZ on symptomatic sides. One of the three remaining patients was suffering from acoustic neurinoma on the symptomatic side, while in two patients there were no definite abnormal findings.Compressive vessels were demonstrated in all 197 patients; 80 cases involved the anterior inferior cerebellar artery(AICA), 74 the posterior cerebellar artery(PICA), 13 the vertebral artery(VA), 16 the VA and AICA, eight the VA and PICA, and six the AICA and PICA. In all 197 patients, compressive vessels were reconstructed on one 3D short-range MRA image without discontinuation from vertebral or basilar arteries. 3D MPR studies provided additional information such as the direction of compression and course of the compressive vessel. In 31 patients there was neurovascular contact on the contralateral side at the 7-8th cranial nerve complex. Conclusion : Inpatients with HS, 3D short-range MRA and MPR images are excellent and very helpful for the investigation of neurovascular compression and the identification of compressive vessels

  19. Unusual Branching Pattern of the Lateral Cord of the Brachial Plexus Associated with Neurovascular Compression; Case report

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    Hitendra K. Loh

    2017-03-01

    Full Text Available The brachial plexus consists of a network of nerves that innervates the upper limbs and its musculature. We report a rare formation of the lateral cord of the brachial plexus observed during the dissection of a 47-year-old male cadaver at the Department of Anatomy, Vardhman Mahavir Medical College, New Delhi, India, in 2016. The lateral cord was exceptionally long with twin lateral pectoral nerves and twin lateral roots of the median nerve. The proximal lateral root of the median nerve was thin in comparison to the medial root of the median nerve. The distal lateral root of the median nerve was thicker and followed an unusual course through the coracobrachialis muscle. In the lower third of the arm, the median nerve and the brachial artery—along with its vena comitans—spanned through the brachialis muscle. Surgeons, anaesthesiologists, radiologists and anatomists should be aware of such anatomical variations as they may result in neurovascular compression.

  20. Patterns of neurovascular compression in patients with classic trigeminal neuralgia: A high-resolution MRI-based study

    International Nuclear Information System (INIS)

    Lorenzoni, José; David, Philippe; Levivier, Marc

    2012-01-01

    Purpose: To describe the anatomical characteristics and patterns of neurovascular compression in patients suffering classic trigeminal neuralgia (CTN), using high-resolution magnetic resonance imaging (MRI). Materials and methods: The analysis of the anatomy of the trigeminal nerve, brain stem and the vascular structures related to this nerve was made in 100 consecutive patients treated with a Gamma Knife radiosurgery for CTN between December 1999 and September 2004. MRI studies (T1, T1 enhanced and T2-SPIR) with axial, coronal and sagital simultaneous visualization were dynamically assessed using the software GammaPlan™. Three-dimensional reconstructions were also developed in some representative cases. Results: In 93 patients (93%), there were one or several vascular structures in contact, either, with the trigeminal nerve, or close to its origin in the pons. The superior cerebellar artery was involved in 71 cases (76%). Other vessels identified were the antero-inferior cerebellar artery, the basilar artery, the vertebral artery, and some venous structures. Vascular compression was found anywhere along the trigeminal nerve. The mean distance between the nerve compression and the origin of the nerve in the brainstem was 3.76 ± 2.9 mm (range 0–9.8 mm). In 39 patients (42%), the vascular compression was located proximally and in 42 (45%) the compression was located distally. Nerve dislocation or distortion by the vessel was observed in 30 cases (32%). Conclusions: The findings of this study are similar to those reported in surgical and autopsy series. This non-invasive MRI-based approach could be useful for diagnostic and therapeutic decisions in CTN, and it could help to understand its pathogenesis.

  1. High-resolution STIR for 3-T MRI of the posterior fossa: visualization of the lower cranial nerves and arteriovenous structures related to neurovascular compression.

    Science.gov (United States)

    Hiwatashi, Akio; Yoshiura, Takashi; Yamashita, Koji; Kamano, Hironori; Honda, Hiroshi

    2012-09-01

    Preoperative evaluation of small vessels without contrast material is sometimes difficult in patients with neurovascular compression disease. The purpose of this retrospective study was to evaluate whether 3D STIR MRI could simultaneously depict the lower cranial nerves--fifth through twelfth--and the blood vessels in the posterior fossa. The posterior fossae of 47 adults (26 women, 21 men) without gross pathologic changes were imaged with 3D STIR and turbo spin-echo heavily T2-weighted MRI sequences and with contrast-enhanced turbo field-echo MR angiography (MRA). Visualization of the cranial nerves on STIR images was graded on a 4-point scale and compared with visualization on T2-weighted images. Visualization of the arteries on STIR images was evaluated according to the segments in each artery and compared with that on MRA images. Visualization of the veins on STIR images was also compared with that on MRA images. Statistical analysis was performed with the Mann-Whitney U test. There were no significant differences between STIR and T2-weighted images with respect to visualization of the cranial nerves (p > 0.05). Identified on STIR and MRA images were 94 superior cerebellar arteries, 81 anteroinferior cerebellar arteries, and 79 posteroinferior cerebellar arteries. All veins evaluated were seen on STIR and MRA images. There were no significant differences between STIR and MRA images with respect to visualization of arteries and veins (p > 0.05). High-resolution STIR is a feasible method for simultaneous evaluation of the lower cranial nerves and the vessels in the posterior fossa without the use of contrast material.

  2. Neurovascular pharmacology of migraine

    NARCIS (Netherlands)

    MaassenVanDenBrink, Antoinette; Chan, Kayi Y.

    2008-01-01

    Migraine is a paroxysmal neurovascular disorder, which affects a significant proportion of the population. Since dilation of cranial blood vessels is likely to be responsible for the headache experienced in migraine, many experimental models for the study of migraine have focussed on this feature.

  3. CLASSIFICATION OF THE MGR SITE COMPRESSED AIR SYSTEM

    International Nuclear Information System (INIS)

    J.A. Ziegler

    1999-01-01

    The purpose of this analysis is to document the Quality Assurance (QA) classification of the Monitored Geologic Repository (MGR) site compressed air system structures, systems and components (SSCs) performed by the MGR Safety Assurance Department. This analysis also provides the basis for revision of YMP/90-55Q, Q-List (YMP 1998). The Q-List identifies those MGR SSCs subject to the requirements of DOE/RW-0333P, ''Quality Assurance Requirements and Description'' (QARD) (DOE 1998)

  4. Neurovascular conflict in oculomotor imbalance

    Directory of Open Access Journals (Sweden)

    Natalya Agafonovna Totolyan

    2015-12-01

    Full Text Available This article, based on the data of Russian and foreign literature, considers modern approaches to the understanding of neurovascular conflict (NVC term, different causes of its development and realization mechanisms; statistical data are presented on its occurrence in different medical specialties; modern approaches to early diagnosis of neurovascular conflicts are covered. Special attention is drawn to oculomotor imbalances being one of neurovascular conflict manifestations. Based on global experience, approaches to most exact and early diagnosis are described, differences in notion terminology of neurovascular contact and neurovascular conflict are shown. As most effective method for NVC diagnosis, the use of neurovisualization method, that is high-resolution magnetic resonance imaging (MRI (high field MRI, is positioned.

  5. 磁共振断层血管成像在颅神经血管压迫综合征的应用%Magnetic resonance tomographic angiography in cranial neurovascular compression syndrome

    Institute of Scientific and Technical Information of China (English)

    胡兴荣; 李顺振; 邓民强; 陈华东; 邱妮妮

    2010-01-01

    Objective To investigate the clinical diagnostic value of magnetic resonance tomographic angiography (MRTA) on cranial neurovascular compression syndrome,and evaluate the ability of 3D-FIESTA and 3D-TOF-SPGR sequences in demonstrating the relation of three-dimensional space between cranial nerves and blood vessels.Methods The data of 41 patients with cranial neurovascular compression syndrome,admitted to our hospital from May 2007 to May 2009,were analyzed.These patients were planed to perform micro vasular decompression (MVD).Before the operation,MRTA,3D-FIESTA and 3D-TOF-SPGR sequence scanning were performed to observe the relation of three-dimensional space between cranial nerves and blood vessels;these results were compared with the intraoperative results to evaluate the advantages and disadvantages of 3D-FIESTA and 3D-TOF-SPGR sequence scanning.Results MRTA could demonstrate such cranial nerves as trigeminal nerve,facial nerve and glossopharyngeal nerve,and responsible blood vessels clearly and simultaneously.The 3D-FIESTA imaging showed high signal in the cerebrospinal fluid and moderate signal in the nerves and blood vessels.The 3D-TOF-SPGR imaging showed low signal in the cerebrospinai fluid,moderate signal in the nerves and brain parenchyma,and high signal in the blood vessels.Closed relation between the nerves and the blood vessels in the lesion side were found in 34 patients (82.9%) by 3D-FIESTA sequence scanning,and that was found in 35 patients by 3D-TOF-SPGR sequence scanning; no significant difference between 3D-FIESTA and 3D-TOF-SPGR sequence scanning was found in displaying the relation of nerves and blood vessels (P>0.05).Conclusion MRTA technology may clearly show the relation of cranial nerves and responsible blood vessels;combined application of 3D-FIESTA and 3D-TOF-SPGR sequence scanning can help making the preoperative diagnosis and determining the surgical indications in patients with cranial neurovaseular compression syndrome.%目的 探

  6. A 6-year study of mammographic compression force: Practitioner variability within and between screening sites

    International Nuclear Information System (INIS)

    Mercer, Claire E.; Szczepura, Katy; Kelly, Judith; Millington, Sara R.; Denton, Erika R.E.; Borgen, Rita; Hilton, Beverley; Hogg, Peter

    2015-01-01

    Background: The application of compression force in mammography is more heavily influenced by the practitioner rather than the client. This can affect client experience, radiation dose and image quality. This research investigates practitioner compression force variation over a six year screening cycle in three different screening units. Methods: Data were collected from three consecutive screening events in three breast screening sites. Recorded data included: practitioner code, applied compression force (N), breast thickness (mm), BI-RADS ® density category. Exclusion criteria included: previous breast surgery, previous/ongoing assessment and breast implants. 975 clients (2925 client visits, 11,700 mammogram images) met inclusion criteria across three sites. Data analysis assessed practitioner and site variation of compression force and breast thickness. Results: Practitioners across three breast screening sites behave differently in the application of compression force. Two of the three sites demonstrate variability within themselves though they demonstrated no significant difference in mean, first and third quartile compression force and breast thickness values CC (p > 0.5), MLO (p > 0.1) between themselves. However, in the third site, where mandate dictates a minimum compression force is applied, greater consistency was demonstrated between practitioners and clients; a significant difference in mean, first and third quartile compression force and breast thickness values (p < 0.001) was demonstrated between this site and the other two sites. Conclusion: Variability within these two sites and between the three sites could result in variations. Stabilisation of these variations may have a positive impact on image quality, radiation dose reduction, re-attendance levels and potentially cancer detection. The large variation in compression forces could negatively impact on client experience between the units and within a unit. Further research is required to

  7. The humeral origin of the brachioradialis muscle: an unusual site of high radial nerve compression.

    Science.gov (United States)

    Cherchel, A; Zirak, C; De Mey, A

    2013-11-01

    Radial nerve compression is seldom encountered in the upper arm, and most commonly described compression syndromes have their anatomical cause in the forearm. The teres major, the triceps muscle, the intermuscular septum region and the space between the brachialis and brachioradialis muscles have all been identified as radial nerve compression sites above the elbow. We describe the case of a 38-year-old male patient who presented with dorso-lateral forearm pain and paraesthesias without neurological deficit. Surgical exploration revealed radial nerve compression at the humeral origin of the brachioradialis muscle. Liberation of the nerve at this site was successful at relieving the symptoms. To our knowledge, this compression site has not been described in the literature. Copyright © 2013 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

  8. Novel Use of a Pneumatic Compression Device for Haemostasis of Haemodialysis Fistula Access Catheterisation Sites

    Energy Technology Data Exchange (ETDEWEB)

    O’Reilly, Michael K., E-mail: moreilly1@mater.ie; Ryan, David; Sugrue, Gavin; Geoghegan, Tony; Lawler, Leo P.; Farrelly, Cormac T. [Mater Misericordiae University Hospital, Department of Interventional Radiology (Ireland)

    2016-12-15

    PurposeTransradial pneumatic compression devices can be used to achieve haemostasis following radial artery puncture. This article describes a novel technique for acquiring haemostasis of arterio-venous haemodialysis fistula access sites without the need for suture placement using one such compression device.Materials and MethodsA retrospective review of fistulograms with or without angioplasty/thrombectomy in a single institution was performed. 20 procedures performed on 12 patients who underwent percutaneous intervention of failing or thrombosed arterio-venous fistulas (AVF) had 27 puncture sites. Haemostasis was achieved using a pneumatic compression device at all access sites. Procedure details including size of access sheath, heparin administration and complications were recorded.ResultsTwo diagnostic fistulograms, 14 fistulograms and angioplasties and four thrombectomies were performed via access sheaths with an average size (±SD) of 6 Fr (±1.12). IV unfractionated heparin was administered in 11 of 20 procedures. Haemostasis was achieved in 26 of 27 access sites following 15–20 min of compression using the pneumatic compression device. One case experienced limited bleeding from an inflow access site that was successfully treated with reinflation of the device for a further 5 min. No other complication was recorded.ConclusionsHaemostasis of arterio-venous haemodialysis fistula access sites can be safely and effectively achieved using a pneumatic compression device. This is a technically simple, safe and sutureless technique for acquiring haemostasis after AVF intervention.

  9. 磁共振断层血管成像对颅神经血管压迫综合征的诊断价值%Diagnostic Value of Magnetic Resonance Tomographic Angiography in the Diagnosis of Cranial Neurovascular Compression Syndrome

    Institute of Scientific and Technical Information of China (English)

    胡兴荣; 邱妮妮; 向海波; 陈华东; 张丽君

    2017-01-01

    Objective To explore the clinical value of magnetic resonance tomography angiography (MRTA) in the etiological diagnosis of cranial neurovascular compression syndrome.Methods A total of 158 patients with cranial neurovascular compression syndrome were selected (involving 107 primary trigeminal neuralgia,46 facial spasm and 5 glossopharyngeal neuralgia).The imaging data of MRAT (including 3D-FIESTA,3D-TOF and 3D-CE-TOF sequence),surgical results were retrospectively analyzed and compared,and the spatial relationship between cranial nerve and its peripheral vessel in preoperative were evaluated.Results Compared with the results of microvasular decompression (MVD),the ability for showing relationship of cranial nerve and corresponding vessels among 3D-FIESTA,3D-TOF and 3D-CE-TOF sequence was significatly different (P<0.05).3D-CE-TOF sequence only did best showing cranial nerve and compression vessels (positive rate 95.57%).3D-FIESTA and 3D-TOF sequence combination improved positive detection rate of corresponding vessels for cranial nerves compression (positive rate 93.04%).There was no significant difference between single 3D-CE-TOF sequence and 3D-FIESTA combing with 3D-TOF sequence in positive detection rate of corresponding vessels (P>0.05).Conclusion MRTA can definitely display cranial nerves and its corresponding vessels.Single 3D-CETOF,3D-FIESTA combing with 3D-TOF show the best clinical values among these MRTA sequences.%目的 探讨磁共振断层血管成像(magnetic resonance tomographic angiography,MRTA)对颅神经血管压迫综合征病因诊断的临床应用价值.方法 收集颅神经血管压迫综合征患者158例,其中原发性三叉神经痛107例,面肌痉挛46例,舌咽神经痛5例,回顾性分析MRTA检查中3D-FIESTA、3D-TOF及3D-CE-TOF序列图像资料并与手术结果进行对照,评价MRTA检查中不同序列在术前观察颅神经与周围血管的空间关系.结果 与微血管减压术(microvasular decompression,MVD

  10. Fractional dynamical model for neurovascular coupling

    KAUST Repository

    Belkhatir, Zehor; Laleg-Kirati, Taous-Meriem

    2014-01-01

    The neurovascular coupling is a key mechanism linking the neural activity to the hemodynamic behavior. Modeling of this coupling is very important to understand the brain function but it is at the same time very complex due to the complexity

  11. Neurovascular Unit in Chronic Pain

    Directory of Open Access Journals (Sweden)

    Beatrice Mihaela Radu

    2013-01-01

    Full Text Available Chronic pain is a debilitating condition with major socioeconomic impact, whose neurobiological basis is still not clear. An involvement of the neurovascular unit (NVU has been recently proposed. In particular, the blood-brain barrier (BBB and blood-spinal cord barrier (BSCB, two NVU key players, may be affected during the development of chronic pain; in particular, transient permeabilization of the barrier is suggested by several inflammatory- and nerve-injury-based pain models, and we argue that the clarification of molecular BBB/BSCB permeabilization events will shed new light in understanding chronic pain mechanisms. Possible biases in experiments supporting this theory and its translational potentials are discussed. Moving beyond an exclusive focus on the role of the endothelium, we propose that our understanding of the mechanisms subserving chronic pain will benefit from the extension of research efforts to the NVU as a whole. In this view, the available evidence on the interaction between analgesic drugs and the NVU is here reviewed. Chronic pain comorbidities, such as neuroinflammatory and neurodegenerative diseases, are also discussed in view of NVU changes, together with innovative pharmacological solutions targeting NVU components in chronic pain treatment.

  12. NEURO-VASCULAR CONFLICT AS CAUSATIVE FACTOR IN IDI-OPATHIC TRIGEMINAL NEURALGIA

    Directory of Open Access Journals (Sweden)

    Mumtaz Ali

    2010-12-01

    Full Text Available Introduction Trigeminal neuralgia is one of the most unbearable pain syndromes in one or more branches of trigeminal nerve. The basic pathology is still poorly understood 1. Two divergent view points, central versus peripheral have been presented to explain the possible mechanism 2. In spite of numerous favorable reports, the neurovascular conflict theory remains contra-vertical 3. Nevertheless, whether or not, neurovascular compression is accessory or predominant in the mechanism of trigeminal neuralgia is not yet determined. Although neurovascular compression and global atrophy of the root, a focal arachnoid thickening and angulated root on crossing over the petrous ridge have been observed. Yet, neurovascular conflict has made responsible as the main cause of this neuralgia 4. This lead to focal demylination of the nerve due to its pulsatile compression. Demylination result in short circuiting of neuronal flow and hence trigeminal neuralgia 5.      Present study was therefore designed as to appreciate neurovascular conflict as causative agent in idiopathic trigeminal neuralgia. Material and Methods This prospective observational study was conducted in department of Neurosurgery Government Lady Reading Hospital Peshawar where microvascular decompression is performed as a primary procedure of choice for patients with trigeminal neuralgia. The duration of this study was from May 2003 – to June 2007. Total number of patients operated was 86. Drug resistant cases of trigeminal neuralgia that were   willing for operation was selected and proper clinical record was documented. MRI was done in all patients to exclude secondary causes of trigeminal Neuralgia. Under general Anesthesia in lateral position, small 2.5x2.5cm retro-mastoid craniotomy was performed. All these cases were operated by one surgeon with a team of associate’s doctors. Microscopic per-operative anatomical findings were recorded. Any possible per-operative complications

  13. Siting-selection study for the Soyland Power Cooperative, Inc. , compressed-air energy-storage system (CAES)

    Energy Technology Data Exchange (ETDEWEB)

    1982-01-01

    A method used for siting a compressed air energy storage (CAES) system using geotechnical and environmental criteria is explained using the siting of a proposed 220 MW water-compensated CAES plant in Illinois as an example. Information is included on the identification and comparative ranking of 28 geotechnically and environmental sites in Illinois, the examination of fatal flaws, e.g., mitigation, intensive studies, costly studies, permit denials, at 7 sites; and the selection of 3 sites for further geological surveying. (LCL)

  14. Investigation of Nonlinear Site Response and Seismic Compression from Case History Analysis and Laboratory Testing

    Science.gov (United States)

    Yee, Eric

    In this thesis I address a series of issues related to ground failure and ground motions during earthquakes. A major component is the evaluation of cyclic volumetric strain behavior of unsaturated soils, more commonly known as seismic compression, from advanced laboratory testing. Another major component is the application of nonlinear and equivalent linear ground response analyses to large-strain problems involving highly nonlinear dynamic soil behavior. These two components are merged in the analysis of a truly unique and crucial field case history of nonlinear site response and seismic compression. My first topic concerns dynamic soil testing for relatively small strain dynamic soil properties such as threshold strains, gammatv. Such testing is often conducted using specialized devices such as dual-specimen simple-shear, as devices configured for large strain testing produce noisy signals in the small strain range. Working with a simple shear device originally developed for large-strain testing, I extend its low-strain capabilities by characterizing noisy signals and utilizing several statistical methods to extract meaningful responses in the small strain range. I utilize linear regression of a transformed variable to estimate the cyclic shear strain from a noisy signal and the confidence interval on its amplitude. I utilize Kernel regression with the Nadaraya-Watson estimator and a Gaussian kernel to evaluate vertical strain response. A practical utilization of these techniques is illustrated by evaluating threshold shear strains for volume change with a procedure that takes into account uncertainties in the measured shear and vertical strains. My second topic concerns the seismic compression characteristics of non-plastic and low-plasticity silty sands with varying fines content (10 ≤ FC ≤ 60%). Simple shear testing was performed on various sand-fines mixtures at a range of modified Proctor relative compaction levels ( RC) and degrees-of-saturation (S

  15. Involvement of astrocytes in neurovascular communication.

    Science.gov (United States)

    Nuriya, M; Hirase, H

    2016-01-01

    The vascular interface of the brain is distinct from that of the peripheral tissue in that astrocytes, the most numerous glial cell type in the gray matter, cover the vasculature with their endfeet. This morphological feature of the gliovascular junction has prompted neuroscientists to suggest possible functional roles of astrocytes including astrocytic modulation of the vasculature. Additionally, astrocytes develop an intricate morphology that intimately apposes neuronal synapses, making them an ideal cellular mediator of neurovascular coupling. In this article, we first introduce the classical anatomical and physiological findings that led to the proposal of various gliovascular interaction models. Next, we touch on the technological advances in the past few decades that enabled investigations and evaluations of neuro-glio-vascular interactions in situ. We then review recent experimental findings on the roles of astrocytes in neurovascular coupling from the viewpoints of intra- and intercellular signalings in astrocytes. © 2016 Elsevier B.V. All rights reserved.

  16. Site specific comparison of H2, CH4 and compressed air energy storage in porous formations

    Science.gov (United States)

    Tilmann Pfeiffer, Wolf; Wang, Bo; Bauer, Sebastian

    2016-04-01

    The supply of energy from renewable sources like wind or solar power is subject to fluctuations determined by the climatic and weather conditions, and shortage periods can be expected on the order of days to weeks. Energy storage is thus required if renewable energy dominates the total energy production and has to compensate the shortages. Porous formations in the subsurface could provide large storage capacities for various energy carriers, such as hydrogen (H2), synthetic methane (CH4) or compressed air (CAES). All three energy storage options have similar requirements regarding the storage site characteristics and consequently compete for suitable subsurface structures. The aim of this work is to compare the individual storage methods for an individual storage site regarding the storage capacity as well as the achievable delivery rates. This objective is pursued using numerical simulation of the individual storage operations. In a first step, a synthetic anticline with a radius of 4 km, a drop of 900 m and a formation thickness of 20 m is used to compare the individual storage methods. The storage operations are carried out using -depending on the energy carrier- 5 to 13 wells placed in the top of the structure. A homogeneous parameter distribution is assumed with permeability, porosity and residual water saturation being 500 mD, 0.35 and 0.2, respectively. N2 is used as a cushion gas in the H2 storage simulations. In case of compressed air energy storage, a high discharge rate of 400 kg/s equating to 28.8 mio. m³/d at surface conditions is required to produce 320 MW of power. Using 13 wells the storage is capable of supplying the specified gas flow rate for a period of 31 hours. Two cases using 5 and 9 wells were simulated for both the H2 and the CH4 storage operation. The target withdrawal rates of 1 mio. sm³/d are maintained for the whole extraction period of one week in all simulations. However, the power output differs with the 5 well scenario producing

  17. Fractional dynamical model for neurovascular coupling

    KAUST Repository

    Belkhatir, Zehor

    2014-08-01

    The neurovascular coupling is a key mechanism linking the neural activity to the hemodynamic behavior. Modeling of this coupling is very important to understand the brain function but it is at the same time very complex due to the complexity of the involved phenomena. Many studies have reported a time delay between the neural activity and the cerebral blood flow, which has been described by adding a delay parameter in some of the existing models. An alternative approach is proposed in this paper, where a fractional system is used to model the neurovascular coupling. Thanks to its nonlocal property, a fractional derivative is suitable for modeling the phenomena with delay. The proposed model is coupled with the first version of the well-known balloon model, which relates the cerebral blood flow to the Blood Oxygen Level Dependent (BOLD) signal measured using functional Magnetic Resonance Imaging (fMRI). Through some numerical simulations, the properties of the fractional model are explained and some preliminary comparisons to a real BOLD data set are provided. © 2014 IEEE.

  18. Single-Site Active Iron-Based Bifunctional Oxygen Catalyst for a Compressible and Rechargeable Zinc-Air Battery.

    Science.gov (United States)

    Ma, Longtao; Chen, Shengmei; Pei, Zengxia; Huang, Yan; Liang, Guojin; Mo, Funian; Yang, Qi; Su, Jun; Gao, Yihua; Zapien, Juan Antonio; Zhi, Chunyi

    2018-02-27

    The exploitation of a high-efficient, low-cost, and stable non-noble-metal-based catalyst with oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) simultaneously, as air electrode material for a rechargeable zinc-air battery is significantly crucial. Meanwhile, the compressible flexibility of a battery is the prerequisite of wearable or/and portable electronics. Herein, we present a strategy via single-site dispersion of an Fe-N x species on a two-dimensional (2D) highly graphitic porous nitrogen-doped carbon layer to implement superior catalytic activity toward ORR/OER (with a half-wave potential of 0.86 V for ORR and an overpotential of 390 mV at 10 mA·cm -2 for OER) in an alkaline medium. Furthermore, an elastic polyacrylamide hydrogel based electrolyte with the capability to retain great elasticity even under a highly corrosive alkaline environment is utilized to develop a solid-state compressible and rechargeable zinc-air battery. The creatively developed battery has a low charge-discharge voltage gap (0.78 V at 5 mA·cm -2 ) and large power density (118 mW·cm -2 ). It could be compressed up to 54% strain and bent up to 90° without charge/discharge performance and output power degradation. Our results reveal that single-site dispersion of catalytic active sites on a porous support for a bifunctional oxygen catalyst as cathode integrating a specially designed elastic electrolyte is a feasible strategy for fabricating efficient compressible and rechargeable zinc-air batteries, which could enlighten the design and development of other functional electronic devices.

  19. [Diagnosis of peripheral neurovascular syndromes in miners exposed to vibration].

    Science.gov (United States)

    Naumenko, B S; Dvornichenko, H B; Iashchenko, A B

    2005-01-01

    1337 miners of iron-ore mines in Krivoi Rog were examined. 1163 of them underwent out-patient and the rest (174 patients) in-patient examination. 28% of miners were found to have peripheral neurovascular disorders. Main clinical signs of peripheral neurovascular syndromes of occupational origin and criteria of the diagnostics were defined. The application of the worked-out pathometric diagnostic tables will considerably increase the accuracy and the safety of the diagnosis (up to 94%), the efficacy of the treatment and quality of prognosis for many occupational diseases presented clinically with peripheral neurovascular syndromes.

  20. Significance of neurovascular contact in classical trigeminal neuralgia

    DEFF Research Database (Denmark)

    Maarbjerg, Stine; Wolfram, Frauke; Gozalov, Aydin

    2015-01-01

    and degree of neurovascular contact. Severe neurovascular contact was defined as displacement or atrophy of the trigeminal nerve. A total of 135 patients with classical trigeminal neuralgia were included. Average age of disease onset was 53.0 years (95% confidence interval mean 40.5-55.5) and current age...... was 60.1 years (95% % confidence interval mean 57.5-62.7). Eighty-two (61%, 95% confidence interval 52-69%) patients were female. Neurovascular contact was prevalent both on the symptomatic and asymptomatic side [89% versus 78%, P = 0.014, odds ratio = 2.4 (1.2-4.8), P = 0.017], while severe...

  1. Acetabular paralabral cyst causing compression of the sciatic nerve

    Directory of Open Access Journals (Sweden)

    Caoimhe Byrne, MB BCh BAO

    2017-12-01

    Full Text Available Acetabular paralabral cysts are common. They vary in their clinical presentation and may be asymptomatic or cause pain and restriction at the hip joint. In rare instances they may cause symptoms by compressing local neurovascular structures. We report a case of symptomatic compression of the sciatic nerve by a posteriorly displaced acetabular paralabral cyst.

  2. Prediction of surgical view of neurovascular decompression using interactive computer graphics.

    Science.gov (United States)

    Kin, Taichi; Oyama, Hiroshi; Kamada, Kyousuke; Aoki, Shigeki; Ohtomo, Kuni; Saito, Nobuhito

    2009-07-01

    To assess the value of an interactive visualization method for detecting the offending vessels in neurovascular compression syndrome in patients with facial spasm and trigeminal neuralgia. Computer graphics models are created by fusion of fast imaging employing steady-state acquisition and magnetic resonance angiography. High-resolution magnetic resonance angiography and fast imaging employing steady-state acquisition were performed preoperatively in 17 patients with neurovascular compression syndromes (facial spasm, n = 10; trigeminal neuralgia, n = 7) using a 3.0-T magnetic resonance imaging scanner. Computer graphics models were created with computer software and observed interactively for detection of offending vessels by rotation, enlargement, reduction, and retraction on a graphic workstation. Two-dimensional images were reviewed by 2 radiologists blinded to the clinical details, and 2 neurosurgeons predicted the offending vessel with the interactive visualization method before surgery. Predictions from the 2 imaging approaches were compared with surgical findings. The vessels identified during surgery were assumed to be the true offending vessels. Offending vessels were identified correctly in 16 of 17 patients (94%) using the interactive visualization method and in 10 of 17 patients using 2-dimensional images. These data demonstrated a significant difference (P = 0.015 by Fisher's exact method). The interactive visualization method data corresponded well with surgical findings (surgical field, offending vessels, and nerves). Virtual reality 3-dimensional computer graphics using fusion magnetic resonance angiography and fast imaging employing steady-state acquisition may be helpful for preoperative simulation.

  3. Compressed air energy storage: preliminary design and site development program in an aquifer. Final draft, Task 2: Volume 2 of 3. Characterize and explore potential sites and prepare research and development plan

    Energy Technology Data Exchange (ETDEWEB)

    None

    1980-12-01

    The characteristics of sites in Indiana and Illinois which are being investigated as potential sites for compressed air energy storage power plants are documented. These characteristics include geological considerations, economic factors, and environmental considerations. Extensive data are presented for 14 specific sites and a relative rating on the desirability of each site is derived. (LCL)

  4. Real-time direct measurement of spinal cord blood flow at the site of compression: relationship between blood flow recovery and motor deficiency in spinal cord injury.

    Science.gov (United States)

    Hamamoto, Yuichiro; Ogata, Tadanori; Morino, Tadao; Hino, Masayuki; Yamamoto, Haruyasu

    2007-08-15

    An in vivo study to measure rat spinal cord blood flow in real-time at the site of compression using a newly developed device. To evaluate the change in thoracic spinal cord blood flow by compression force and to clarify the association between blood flow recovery and motor deficiency after a spinal cord compression injury. Until now, no real-time measurement of spinal cord blood flow at the site of compression has been conducted. In addition, it has not been clearly determined whether blood flow recovery is related to motor function after a spinal cord injury. Our blood flow measurement system was a combination of a noncontact type laser Doppler system and a spinal cord compression device. The rat thoracic spinal cord was exposed at the 11th vertebra and spinal cord blood flow at the site of compression was continuously measured before, during, and after the compression. The functioning of the animal's hind-limbs was evaluated by the Basso, Beattie and Bresnahan scoring scale and the frequency of voluntary standing. Histologic changes such as permeability of blood-spinal cord barrier, microglia proliferation, and apoptotic cell death were examined in compressed spinal cord tissue. The spinal blood flow decreased on each increase in the compression force. After applying a 5-g weight, the blood flow decreased to compression), while no significant difference was observed between the 20-minute ischemia group and the sham group. In the 20-minute ischemia group, the rats whose spinal cord blood flow recovery was incomplete showed significant motor function loss compared with rats that completely recovered blood flow. Extensive breakdown of blood-spinal cord barrier integrity and the following microglia proliferation and apoptotic cell death were detected in the 40-minute complete ischemia group. Duration of ischemia/compression and blood flow recovery of the spinal cord are important factors in the recovery of motor function after a spinal cord injury.

  5. MR imaging of the cisternal segment of the posterior group of cranial nerves: Neurovascular relationships and abnormal changes

    Energy Technology Data Exchange (ETDEWEB)

    Liang Changhu, E-mail: tigerlch@163.co [Shandong University, Shandong Medical Imaging Research Institute, CT Room, 324, Jingwu Road, Jinan, Shandong (China); Du Yinglin, E-mail: duyinglinzhuo@sohu.co [Shandong Provincial Center for Disease Control and Prevention, Public Health Institute, 72, Jingshi Road, Jinan, Shandong (China); Xu Jinfa, E-mail: xuke5598@icom.c [Liao Cheng City People' s Hospital, Dongchang Road, Liaocheng, Shandong (China); Wu Lebin, E-mail: Lebinwu518@163.co [Shandong University, Shandong Medical Imaging Research Institute, CT Room, 324, Jingwu Road, Jinan, Shandong (China); Liu Cheng, E-mail: cacab2a@126.co [Shandong University, Shandong Medical Imaging Research Institute, CT Room, 324, Jingwu Road, Jinan, Shandong (China); Wang Ximing, E-mail: wxming369@163.co [Shandong University, Shandong Medical Imaging Research Institute, CT Room, 324, Jingwu Road, Jinan, Shandong (China); Wang Haiyan, E-mail: whyott@163.co [Shandong University, Shandong Medical Imaging Research Institute, CT Room, 324, Jingwu Road, Jinan, Shandong (China); Yu Fuhua, E-mail: changhu1970@163.co [Weifang Medical College, 7166, West Road Baotong Weifang, Shandong (China)

    2010-07-15

    Objective: To evaluate the detailed anatomic features, neurovascular relationships of the cisternal segment of the posterior group of cranial nerves (PGCN: IX, X, XI, XII); to evaluate the utility of magnetic resonance (MR) in demonstrating the PGCN with disorders caused by abnormal compression related to artery or tumor. Methods: A total of 59 volunteers, 12 patients with abnormal symptom in the PGCN underwent three-dimensional (3D) Fourier transformation constructive interference in steady-state (CISS) MR imaging, and 22 of these volunteers and 12 patients also underwent MR angiography in which a time-of-flight (TOF) sequence was used to further distinguish the PGCN from the adjacent blood vessels. Anatomical features, neurovascular relationships of the PGCN in 59 volunteers and abnormal changes in 12 patients caused by neurovascular compression or tumor were observed from multi-planar reconstruction (MPR) images, cryomicrotome section and 3D-CISS MR imaging of cranial cadaver were used to testify the PGCN displayed in 59 volunteers. Results: 3D-CISS MR imaging depicted the proximal cisternal segment of the cranial nerves complex (CN IX, X, XI) at the oblique axial, sagittal planes in 100% (118/118), 99% (117/118) of 118 sides; CNXII in the oblique axial, sagittal planes in 90% (106/118), 91% (107/118) of 118 sides. At the sagittal planes, the CN IX, X, XI were found parallel to each other in the cisternal segment in 45.2% (53/117) of 117 sides, gathering into a bundle of nerves complex before entering the jugular foramen (JF) in 54.7% (64/117) of 117sides. VAs were blood vessels more often identified, they were found to be in contact with the PGCN in 28.0% (33/118) of 118 sides, and not in contact in 72.0% (85/118) of 118 sides. 3D-CISS MR imaging of volunteers revealed the similar result corresponding to cryomicrotome section and 3D-CISS MR imaging of cranial cadaver. Twelve patients with abnormal changes in the PGCN were all displayed well, among them 8 were

  6. MR imaging of the cisternal segment of the posterior group of cranial nerves: Neurovascular relationships and abnormal changes

    International Nuclear Information System (INIS)

    Liang Changhu; Du Yinglin; Xu Jinfa; Wu Lebin; Liu Cheng; Wang Ximing; Wang Haiyan; Yu Fuhua

    2010-01-01

    Objective: To evaluate the detailed anatomic features, neurovascular relationships of the cisternal segment of the posterior group of cranial nerves (PGCN: IX, X, XI, XII); to evaluate the utility of magnetic resonance (MR) in demonstrating the PGCN with disorders caused by abnormal compression related to artery or tumor. Methods: A total of 59 volunteers, 12 patients with abnormal symptom in the PGCN underwent three-dimensional (3D) Fourier transformation constructive interference in steady-state (CISS) MR imaging, and 22 of these volunteers and 12 patients also underwent MR angiography in which a time-of-flight (TOF) sequence was used to further distinguish the PGCN from the adjacent blood vessels. Anatomical features, neurovascular relationships of the PGCN in 59 volunteers and abnormal changes in 12 patients caused by neurovascular compression or tumor were observed from multi-planar reconstruction (MPR) images, cryomicrotome section and 3D-CISS MR imaging of cranial cadaver were used to testify the PGCN displayed in 59 volunteers. Results: 3D-CISS MR imaging depicted the proximal cisternal segment of the cranial nerves complex (CN IX, X, XI) at the oblique axial, sagittal planes in 100% (118/118), 99% (117/118) of 118 sides; CNXII in the oblique axial, sagittal planes in 90% (106/118), 91% (107/118) of 118 sides. At the sagittal planes, the CN IX, X, XI were found parallel to each other in the cisternal segment in 45.2% (53/117) of 117 sides, gathering into a bundle of nerves complex before entering the jugular foramen (JF) in 54.7% (64/117) of 117sides. VAs were blood vessels more often identified, they were found to be in contact with the PGCN in 28.0% (33/118) of 118 sides, and not in contact in 72.0% (85/118) of 118 sides. 3D-CISS MR imaging of volunteers revealed the similar result corresponding to cryomicrotome section and 3D-CISS MR imaging of cranial cadaver. Twelve patients with abnormal changes in the PGCN were all displayed well, among them 8 were

  7. Visual cycle modulation in neurovascular retinopathy.

    Science.gov (United States)

    Akula, James D; Hansen, Ronald M; Tzekov, Radouil; Favazza, Tara L; Vyhovsky, Tanya C; Benador, Ilan Y; Mocko, Julie A; McGee, David; Kubota, Ryo; Fulton, Anne B

    2010-08-01

    Rats with oxygen-induced retinopathy (OIR) model the pediatric retinal disease retinopathy of prematurity (ROP). Recent findings in OIR rats imply a causal role for the rods in the ROP disease process, although only experimental manipulation of rod function can establish this role conclusively. Accordingly, a visual cycle modulator (VCM) - with no known direct effect on retinal vasculature - was administered to "50/10 model" OIR Sprague-Dawley rats to test the hypotheses that it would 1) alter rod function and 2) consequently alter vascular outcome. Four litters of pups (N=46) were studied. For two weeks, beginning on postnatal day (P) 7, the first and fourth litters were administered 6 mg kg(-1) N-retinylacetamide (the VCM) intraperitoneally; the second and third litters received vehicle (DMSO) alone. Following a longitudinal design, retinal function was assessed by electroretinography (ERG) and the status of the retinal vessels was monitored using computerized fundus photograph analysis. Rod photoreceptor and post-receptor response amplitudes were significantly higher in VCM-treated than in vehicle-treated rats; deactivation of phototransduction was also significantly more rapid. Notably, the arterioles of VCM-treated rats showed significantly greater recovery from OIR. Presuming that the VCM did not directly affect the retinal vessels, a causal role for the neural retina - particularly the rod photoreceptors - in OIR was confirmed. There was no evidence of negative alteration of photoreceptor function consequent to VCM treatment. This finding implicates the rods as a possible therapeutic target in neurovascular diseases such as ROP. Copyright 2010 Elsevier Ltd. All rights reserved.

  8. Neurovascular plexus theory for "escape pain phenomenon" in lower third molar surgery

    Directory of Open Access Journals (Sweden)

    Gururaj Arakeri

    2015-06-01

    Full Text Available Pain during extraction of impacted mandibular third molars which can occur despite adequate local anesthesia is termed as "escape pain phenomenon". Recently, it was described during elevation of a mesioangular impacted mandibular third molar and also while curetting an extracted third molar socket. This phenomenon has been overlooked, as it was previously considered secondary to pressure effect on the inferior alveolar neurovascular bundle (IANB. However, it is unlikely that the pain impulses originate from direct pressure on the IANB, as the nerve is blocked more proximally at its entry into the mandible. The authors speculated that the occasional presence of a neurovascular plexus (NVP independent of the IANB causes the escape of a pain impulse upon stimulation by root pressure or instrumentation. To validate the presence of such a plexus, a meticulous literature search and review were performed. The search revealed evidence of the occasional presence of a NVP consisting of auriculotemporal and/or retromolar neural filaments. The plexus may be present around the inferior alveolar artery or embedded within the IANB, and does not innervate the tooth. This plexus likely propagates pain impulses only upon stimulation by compression or instrumentation in the apical area of the tooth socket. This theory explains the absence of pain during tooth sectioning and bone guttering in the presence of a complete inferior alveolar nerve block.

  9. Micro Vascular Plug (MVP)-assisted vessel occlusion in neurovascular pathologies: technical results and initial clinical experience.

    Science.gov (United States)

    Beaty, Narlin B; Jindal, Gaurav; Gandhi, Dheeraj

    2015-10-01

    Deconstructive approaches may be necessary to treat a variety of neurovascular pathologies. Recently, a new device has become available for endovascular arterial occlusion that may have unique applications in neurovascular disease. The Micro Vascular Plug (MVP, Reverse Medical, Irvine, California, USA) has been designed for vessel occlusion through targeted embolization. To report the results from our initial experience with eight consecutive patients in whom the MVP was used to achieve endovascular occlusion of an artery in the head and neck. Eight consecutive patients treated over a nine-month period were included. The patients' radiographic and electronic medical records were retrospectively reviewed. Specifically demographic information, clinical indication, site of arterial occlusion, size of MVP, time to vessel occlusion, clinical complications, use of other secondary embolic agents, and clinical outcome were recorded. Follow-up information when available is presented. The MVP was used in eight patients for the treatment of neurovascular disease. Indications for treatment included post-traumatic head/neck bleeding (n=3), carotid-cavernous fistula (1), vertebral-vertebral fistula (1), giant fusiform vertebral aneurysm (1), stump-emboli after carotid dissection (1), and iatrogenic vertebral artery penetrating injury (1). One device was used in five patients, two in two patients, and one patient with extensive vertebral-vertebral venous fistula required three plugs to effectively trap the fistula from proximal and distal aspects. Vessel occlusion was obtained in MVP in neurovascular disease. Use of this device may be associated with shorter procedural times and cost savings in comparison with the use of microcoils for vessel occlusion. Our experience shows that MVP can have unique applications in neurovascular pathologies and it complements other occlusive devices. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted

  10. Restorative surgery of combined injuries of neurovascular structures of limbs

    Directory of Open Access Journals (Sweden)

    I. V. Pertsov

    2015-02-01

    Full Text Available Combined damage of neurovascular structures is complicate pathology and require repeated surgical interventions and often lead to permanent disability. Aim. To define the features of restorative surgical treatment of traumatic injuries of limbs neurovascular structures and to study the effect of regional hemodynamics on the nerve function restore. Methods and results. In 98 patients with combined trauma of the neurovascular structures microcirculation indicators were established with laser Doppler flowmetry and determine the degree of restoration of nerve function. Conclusion. Strong direct correlation between the degree of restoration of nerve function and microcirculation was detected, the correlation coefficient was +0.72 at t = 3,16 p<0,05. Careful surgical restoration of blood flow helps to improve microcirculation in the limbs, makes positive impact on the recovery of limb function.

  11. Brachytherapy radiation doses to the neurovascular bundles

    International Nuclear Information System (INIS)

    Di Biase, Steven J.; Wallner, Kent; Tralins, Kevin; Sutlief, Steven

    2000-01-01

    Purpose: To investigate the role of radiation dose to the neurovascular bundles (NVB) in brachytherapy-related impotence. Methods and Materials: Fourteen Pd-103 or I-125 implant patients were studied. For patients treated with implant alone, the prostate and margin (clinical target volume [CTV]) received a prescription dose of 144 Gy for I-125 or 115 Gy for Pd-103. Two patients received Pd-103 (90 Gy) with 46 Gy supplemental external beam radiation (EBRT). Axial CT images were acquired 2 to 4 hours postoperatively for postimplant dosimetry. Because the NVBs cannot be visualized on CT, NVB calculation points were determined according to previously published anatomic descriptions. Bilateral NVB points were considered to lie posterior-laterally, approximately 2 mm from the prostatic capsule. NVB doses were recorded bilaterally, at 0.5-cm intervals from the prostatic base. Results: For Pd-103, the average NVB doses ranged from 150 Gy to 260 Gy, or 130% to 226% of the prescription dose. For I-125, the average NVB dose ranged from 200 Gy to 325 Gy, or 140% to 225% of the prescription dose. These was no consistent relationship between the NVB dose and the distance from the prostatic base. To examine the possible effect of minor deviations of our calculation points from the true NVB location, we performed NVB calculations at points 2 mm medial or lateral from the NVB calculation point in 8 patients. Doses at these alternate calculation points were comparable, although there was greater variability with small changes in the calculation point if sources were located outside the capsule, near the NVB calculation point. Three patients who developed early postimplant impotence had maximal NVB doses that far exceeded the average values. Conclusions: In the next few years, we hope to clarify the role of high NVB radiation doses on potency, by correlating NVB dose calculations with a large number of patients enrolled in an ongoing I-125 versus Pd-103 trial for early-stage patients

  12. Hydrocolloid occlusion for the treatment of neurovascular corns

    DEFF Research Database (Denmark)

    Petersen, Lars Jelstrup; Beck, Jan Walther; Reumert, L N

    1991-01-01

    The goal of this study was to determine the effect of hydrocolloid occlusion on neurovascular corns. The design was an observer-blinded, randomized, controlled study. Thirty consecutive patients participated in the trial. The patients received curettage alone or curettage with hydrocolloid...... occlusion. Six treatments were given over 12 weeks. A follow-up examination was performed 3 months after termination of the trial. Outcome measures were the size of the corns, a discomfort score, and an overall judgment of the trial. The results demonstrated no benefit of occlusion for symptoms or signs...... of neurovascular corns. The patients treated with occlusion were, however, generally more satisfied than the conventional group....

  13. Mathematical Modeling of Neuro-Vascular Coupling in Rat Cerebellum

    DEFF Research Database (Denmark)

    Rasmussen, Tina

    Activity in the neurons called climbing fibers causes blood flow changes. But the physiological mechanisms which mediate the coupling are not well understood. This PhD thesis investigates the mechanisms of neuro-vascular coupling by means of mathematical methods. In experiments, the extracellularly...... measured field potential is used as an indicator of neuronal activity, and the cortical blood flow is measured by means of laser-Doppler flowmetry. Using system identification methods, these measurements have been used to construct and validate parametric mathematical models of the neuro-vascular system...

  14. CERCLA document flow: Compressing the schedule, saving costs, and expediting review at the Savannah River Site

    International Nuclear Information System (INIS)

    Hoffman, W.D.

    1991-01-01

    The purpose of this paper is to convey the logic of the CERCLA document flow including Work Plans, Characterization Studies, Risk Assessments, Remedial Investigations, Feasibility Studies, proposed plans, and Records of Decision. The intent is to show how schedules at the Savannah River Site are being formulated to accomplish work using an observational approach where carefully planned tasks can be initiated early and carried out in parallel. This paper will share specific proactive experience in working with the EPA to expedite projects, begin removal actions, take interim actions, speed document flow, and eliminate unnecessary documents from the review cycle

  15. Neurovascular Structures at Risk With Curved Retrograde TTC Fusion Nails.

    Science.gov (United States)

    de Cesar Netto, Cesar; Johannesmeyer, David; Cone, Brent; Araoye, Ibukunoluwa; Hudson, Parke William; Sahranavard, Bahman; Johnson, Michael; Shah, Ashish

    2017-10-01

    The purpose of this study was to assess the risk of iatrogenic injury to plantar neurovascular structures of the foot during insertion of a curved retrograde tibiotalocalcaneal (TTC) fusion nail. Ten below-knee thawed fresh-frozen cadaveric specimens underwent curved retrograde nailing of the ankle. The shortest distance between the nail and the main plantar neurovascular branches and injured structures were recorded during dissection. We also evaluated the relative position of these structures along 2 lines (AB, connecting the calcaneus to the first metatarsal, and BC, connecting the first and fifth metatarsal). The lateral plantar artery was found to be in direct contact with the nail 70% of the time, with a macroscopic laceration 30% of the time. The Baxter nerve was injured 20% of the time, as was the lateral plantar nerve. The medial plantar artery and nerve were never injured. The most proximal structure to cross line AB was the Baxter nerve followed by the lateral plantar artery, the nail, the lateral plantar nerve, and the medial plantar nerve. Our cadaveric anatomic study found that the most common structures at risk for iatrogenic injury by lateral curved retrograde TTC fusion nails were the lateral plantar artery and nerve, and the Baxter nerve. Determination of a true neurovascular safe zone is challenging and therefore warrants careful operative dissection to minimize neurovascular injuries.

  16. Recent progress in translational research on neurovascular and neurodegenerative disorders

    DEFF Research Database (Denmark)

    Demuth, Hans-Ulrich; Dijkhuizen, Rick M; Farr, Tracy D

    2017-01-01

    in neurovascular and dementia research. It highlights sessions from the 9th International Symposium on Neuroprotection and Neurorepair that have been discussed from April 19th to 22nd in Leipzig, Germany. To acknowledge the emerging culture of interdisciplinary collaboration and research, special emphasis is given...

  17. Neurovascular coupling and energy metabolism in the developing brain

    Science.gov (United States)

    Kozberg, M.; Hillman, E.

    2016-01-01

    In the adult brain, increases in local neural activity are almost always accompanied by increases in local blood flow. However, many functional imaging studies of the newborn and developing human brain have observed patterns of hemodynamic responses that differ from adult responses. Among the proposed mechanisms for the observed variations is that neurovascular coupling itself is still developing in the perinatal brain. Many of the components thought to be involved in actuating and propagating this hemodynamic response are known to still be developing postnatally, including perivascular cells such as astrocytes and pericytes. Both neural and vascular networks expand and are then selectively pruned over the first year of human life. Additionally, the metabolic demands of the newborn brain are still evolving. These changes are highly likely to affect early postnatal neurovascular coupling, and thus may affect functional imaging signals in this age group. This chapter will discuss the literature relating to neurovascular development. Potential effects of normal and aberrant development of neurovascular coupling on the newborn brain will also be explored, as well as ways to effectively utilize imaging techniques that rely on hemodynamic modulation such as fMRI and NIRS in younger populations. PMID:27130418

  18. A study on the secondary consolidation of Boom Clay at Essen site under loading and unloading compression

    International Nuclear Information System (INIS)

    Deng, Y.F.; Cui, Y.J.; Tang, A.M.; Li, X.L.; Sillen, X.

    2010-01-01

    Document available in extended abstract form only. Boom clay formation, a thick deposit of over-consolidated marine clay has been selected as a possible host material of nuclear waste disposal in Belgium. For this purpose, its deformation behaviour, especially its long-term deformation behaviour (secondary consolidation) is essential for the safety of the whole storage system and therefore needs to be investigated deeply. In the present work, odometer consolidation tests were performed on Boom clay taken from the Essen site. The loading and unloading were run in steps and the secondary consolidation coefficient C α (C α = de/dlogt) was determined for each step. This allows the secondary consolidation behaviour to be analysed. Four soil cores of Boom clay were taken from the site of Essen, Belgium, at the depths of 220-248 m. The geotechnical identification characteristics of these cores are similar: specific gravity, γ s = 2.64-2.68; liquid limit, w L = 68-78%; plastic limit, w P = 29-33%; and plastic index, I P 36-45. The soil water content (w) is between 26.5 and 29.7% and the void ratio (e) between 0.700 and 0.785. The blue methylene values (VBS) are equally similar, VBS = 6.20-6.67 (g/100 g). The clay fraction (< 2 μm) is relatively high (more than 50%). An example of the results obtained is presented (void ratio versus vertical stress and secondary consolidation coefficient versus vertical stress, determined in the e/log t plot) for the core taken at 227 m depth. After the installation of specimen in the odometer cell, an initial loading to the in-situ stress gave rise to a decrease of the void ratio from 0.730 to 0.651. The drainage system was then saturated for the subsequent loading/unloading paths in steps. The results show that the void ratio decreased to 0.270 when the vertical stress reached σ v = 32 MPa. A compression index Cc of about 0.31 can be estimated and the swelling index is estimated at 0.14. C α > 0 during loading and C α < 0 during

  19. NIRS - Near infrared spectroscopy - investigations in neurovascular diseases

    DEFF Research Database (Denmark)

    Schytz, Henrik Winther

    2015-01-01

    The purpose of this thesis was to explore and develop methods, where continuous wave near infrared spectroscopy (CW-NIRS) can be applied in different neurovascular diseases, in order to find biological markers that are useful in clinical neurology. To develop a new method to detect changes...... tomography (133Xe-SPECT) and the corrected BFI value. It was concluded, that it was not possible to obtain reliable BFI data with the ICG CW-NIRS method. NIRS measurements of low frequency oscillations (LFOs) may be a reliable method to investigate vascular alterations in neurovascular diseases......, but this requires an acceptable LFOs variation between hemispheres and over time in the healthy brain. The second study therefore investigated day-to-day and hemispheric variations in LFOs with NIRS. It was shown that NIRS might be useful in assessing LFOs between hemispheres, as well as interhemispheric phase...

  20. Discrete Event Simulation of Patient Admissions to a Neurovascular Unit

    Directory of Open Access Journals (Sweden)

    S. Hahn-Goldberg

    2014-01-01

    Full Text Available Evidence exists that clinical outcomes improve for stroke patients admitted to specialized Stroke Units. The Toronto Western Hospital created a Neurovascular Unit (NVU using beds from general internal medicine, Neurology and Neurosurgery to care for patients with stroke and acute neurovascular conditions. Using patient-level data for NVU-eligible patients, a discrete event simulation was created to study changes in patient flow and length of stay pre- and post-NVU implementation. Varying patient volumes and resources were tested to determine the ideal number of beds under various conditions. In the first year of operation, the NVU admitted 507 patients, over 66% of NVU-eligible patient volumes. With the introduction of the NVU, length of stay decreased by around 8%. Scenario testing showed that the current level of 20 beds is sufficient for accommodating the current demand and would continue to be sufficient with an increase in demand of up to 20%.

  1. Inherited neurovascular diseases affecting cerebral blood vessels and smooth muscle.

    Science.gov (United States)

    Sam, Christine; Li, Fei-Feng; Liu, Shu-Lin

    2015-10-01

    Neurovascular diseases are among the leading causes of mortality and permanent disability due to stroke, aneurysm, and other cardiovascular complications. Cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) and Marfan syndrome are two neurovascular disorders that affect smooth muscle cells through accumulation of granule and osmiophilic materials and defective elastic fiber formations respectively. Moyamoya disease, hereditary hemorrhagic telangiectasia (HHT), microcephalic osteodysplastic primordial dwarfism type II (MOPD II), and Fabry's disease are disorders that affect the endothelium cells of blood vessels through occlusion or abnormal development. While much research has been done on mapping out mutations in these diseases, the exact mechanisms are still largely unknown. This paper briefly introduces the pathogenesis, genetics, clinical symptoms, and current methods of treatment of the diseases in the hope that it can help us better understand the mechanism of these diseases and work on ways to develop better diagnosis and treatment.

  2. HYDRODISSECTION FOR PRESERVATION OF NEUROVASCULAR BUNDLE DURING RADICAL PROSTATECTOMY

    Directory of Open Access Journals (Sweden)

    H. S. Gevorgyan

    2016-01-01

    Full Text Available Nerve-sparing radical prostatectomy is one of the high-tech operations in urology, and the challenge of the surgeon is not only to remove the prostate tumor, but also to provide a high quality of life. The fact that most questions devoted from patients in a conversation with the surgeon before the operation are devoted to this issue, shows the importance and relevance. At present, the diagnostic methods allow significantly more likely to detect early  prostate cancer, making finding and treatment of these patients more affordable and allows to apply this operation.Lately, it seems urgent to explore the possibility of water jet dissection in the field of urology, in particular, for nerve-sparing prostatectomy. Preservation of erectile function depends largely on the quality of separating the neurovascular bundle. Standard use of electrocautery is associated with damage to the neurovascular bundle.  When performing operations using water-jet mobilization of prostate the selective dissection of tissue is performed. This avoids injury of neurovascular bundle and further postoperative complications. The use of this technique may allow the surgeon to provide a more accurate mobilization prostate and selectively controlled intersection vessels heading to the prostate from the neurovascular bundle, reduce intraoperative blood loss,  maintaining continence, erectile function.This literature review is considered by the experience of using nerve-sparing radical prostatectomy using a water-jet dissector, estimated intraoperative parameters using this method.However, we have the lack of extensive research capabilities of this technique when performing nerve-preserving radical prostatectomy, that does not allow to make a comprehensive presentation on the benefits of this technique and its effects on erectile function and quality of urination, further study of this issue in such a difficult category of patients.

  3. The effect of different anesthetics on neurovascular coupling

    Science.gov (United States)

    Franceschini, Maria Angela; Radhakrishnan, Harsha; Thakur, Kiran; Wu, Weicheng; Ruvinskaya, Svetlana; Carp, Stefan; Boas, David A.

    2010-01-01

    To date, the majority of neurovascular coupling studies focused on the thalamic afferents' activity in layer IV and the corresponding large spiking activity as responsible for functional hyperemia. This paper highlights the role of the secondary and late cortico-cortical transmission in neurovascular coupling. Simultaneous scalp electroencephalography (EEG) and diffuse optical imaging (DOI) measurements were obtained during multiple conditions of event-related electrical forepaw stimulation in 33 male Sprague-Dawley rats divided into 6 groups depending on the maintaining anesthetic - alpha-chloralose, pentobarbital, ketamine-xylazine, fentanyl-droperidol, isoflurane, or propofol. The somatosensory evoked potentials (SEP) were decomposed into four components and the question of which best predicts the hemodynamic responses was investigated. Results of the linear regression analysis show that the hemodynamic response is best correlated with the secondary and late cortico-cortical transmissions and not with the initial thalamic input activity in layer IV. Baseline cerebral blood flow (CBF) interacts with neural activity and influences the evoked hemodynamic responses. Finally, neurovascular coupling appears to be the same across all anesthetics used. PMID:20350606

  4. Venous compressions of the nerves in the lower limbs.

    Science.gov (United States)

    Artico, M; Stevanato, G; Ionta, B; Cesaroni, A; Bianchi, E; Morselli, C; Grippaudo, F R

    2012-06-01

    The lower limbs are frequently involved in neurovascular compression syndromes, owing to their anatomical, vascular and muscular characteristics and to the orthostatic position. These syndromes were identified by exclusion, using neuroimaging techniques and treated by microsurgical techniques. Eight patients with a neurovascular compression syndrome due to venous vascular lesions in the lower limbs (popliteal fossa, proximal and medial third of the inferior limb, tarsal tunnel) were selected. The symptomatology was characterized by pain, Tinel's sign, hyperalgesia, allodynia, numbness along the nerve course and foot weakness: all were exacerbated by the standing position, thus suggesting a neurovascular compression syndrome. Diagnostic tools comprised Doppler ultrasonography, Electromyography, CT 3D and MRI. Treatment consisted of microsurgery with neurovascular dissection. Following surgical treatment, rapid pain relief and a partial recovery of neurological deficits (including the ability to walk) was observed within 8-10 months. An early diagnosis of NCS using various neuroimaging techniques and prompt treatment may improve the response to surgical therapy. The aim of the case studies described is to improve understanding of these pathologies thus enabling correct clinical decisions.

  5. Foe or friend? Janus-faces of the neurovascular unit in the formation of brain metastases.

    Science.gov (United States)

    Wilhelm, Imola; Fazakas, Csilla; Molnár, Kinga; Végh, Attila G; Haskó, János; Krizbai, István A

    2018-04-01

    Despite the potential obstacle represented by the blood-brain barrier for extravasating malignant cells, metastases are more frequent than primary tumors in the central nervous system. Not only tightly interconnected endothelial cells can hinder metastasis formation, other cells of the brain microenvironment (like astrocytes and microglia) can also be very hostile, destroying the large majority of metastatic cells. However, malignant cells that are able to overcome these harmful mechanisms may benefit from the shielding and even support provided by cerebral endothelial cells, astrocytes and microglia, rendering the brain a sanctuary site against anti-tumor strategies. Thus, cells of the neurovascular unit have a Janus-faced attitude towards brain metastatic cells, being both destructive and protective. In this review, we present the main mechanisms of brain metastasis formation, including those involved in extravasation through the brain vasculature and survival in the cerebral environment.

  6. Neurovascular Saturation Thresholds Under High Intensity Auditory Stimulation During Wake

    Science.gov (United States)

    Schei, Jennifer L.; Van Nortwick, Amy S.; Meighan, Peter C.; Rector, David M.

    2012-01-01

    Coupling between neural activity and hemodynamic responses is important in understanding brain function, interpreting brain imaging signals, and assessing pathological conditions. Tissue state is a major factor in neurovascular coupling and may alter the relationship between neural and hemodynamic activity. However, most neurovascular coupling studies are performed under anesthetized or sedated states which may have severe consequences on coupling mechanisms. Our previous studies showed that following prolonged periods of sleep deprivation, evoked hemodynamic responses were muted despite consistent electrical responses, suggesting that sustained neural activity may decrease vascular compliance and limit blood perfusion. To investigate potential perfusion limitations during natural waking conditions, we simultaneously measured evoked response potentials (ERPs) and evoked hemodynamic responses using optical imaging techniques to increasing intensity auditory stimulation. The relationship between evoked hemodynamic responses and integrated ERPs followed a sigmoid relationship where the hemodynamic response approached saturation at lower stimulus intensities than the ERP. If limits in blood perfusion are caused by stretching of the vessel wall, then these results suggest there may be decreased vascular compliance due to sustained neural activity during wake, which could limit vascular responsiveness and local blood perfusion. Conditions that stress cerebral vasculature, such as sleep deprivation and some pathologies (e.g., epilepsy), may further decrease vascular compliance, limit metabolic delivery, and cause tissue trauma. While ERPs and evoked hemodynamic responses provide an indication of the correlated neural activity and metabolic demand, the relationship between these two responses is complex and the different measurement techniques are not directly correlated. Future studies are required to verify these findings and further explore neurovascular coupling during

  7. Preoperative evaluation of neurovascular relationship by using contrast-enhanced and unenhanced 3D time-of-flight MR angiography in patients with trigeminal neuralgia

    International Nuclear Information System (INIS)

    Qin, Zhou; Zhiling, Liu; Chuanfu, Li; Qingshi Zeng; Chuncheng, Qu; Shilei, Ni

    2011-01-01

    Background Microvascular decompression is an etiological strategy for the therapy of trigeminal neuralgia (TN). Preoperative identification of neurovascular compression, therefore, could have an impact on the determination of appropriate treatment for TN. Purpose To evaluate the value of contrast-enhanced and unenhanced three-dimensional (3D) time-of-flight (TOF) MR angiography in the visualization of neurovascular relationship in patients with TN. Material and Methods Thirty-seven patients with unilateral TN underwent unenhanced and contrast-enhanced 3D TOF MR angiography with a 3.0-T MR system. Images were reviewed by a radiologist blinded to clinical details. Vascular contact with the trigeminal nerve was identified, and the nature of the involved vessels (artery or vein) was determined. All patients underwent microvascular decompression. Results In 37 patients with TN, contrast-enhanced 3D TOF MR angiography identified surgically verified neurovascular contact in 35 of 36 symptomatic nerves, and there was no false-positive. Based on surgical findings, the sensitivity of MR imaging was 97.2% and specificity 100%. The nature of the offending vessel was correctly identified in 94.4% of the patients by using the combination of contrast-enhanced and unenhanced MR angiography. Conclusion Contrast-enhanced 3D TOF MR angiography is useful in the detection of vascular contact with the trigeminal nerve in patients with TN, and this MR imaging in combination with unenhanced MR angiography could help in the identification of the nature of the responsible vessels

  8. Intact neurovascular coupling during executive function in migraine without aura: interictal near-infrared spectroscopy study

    DEFF Research Database (Denmark)

    Schytz, H W; Ciftçi, K; Akin, A

    2010-01-01

    An altered neurovascular coupling has been proposed in migraine. We aimed to investigate neurovascular coupling during a mental task interictally in patients with migraine without aura (MO) by near-infrared spectroscopy (NIRS). Twelve migraineurs and 12 healthy controls were included. Using NIRS,...

  9. Necrostatin-1 Reduces Neurovascular Injury after Intracerebral Hemorrhage

    Directory of Open Access Journals (Sweden)

    Melanie D. King

    2014-01-01

    Full Text Available Intracerebral hemorrhage (ICH is the most common form of hemorrhagic stroke, accounting for 15% of all strokes. ICH has the highest acute mortality and the worst long-term prognosis of all stroke subtypes. Unfortunately, the dearth of clinically effective treatment options makes ICH the least treatable form of stroke, emphasizing the need for novel therapeutic targets. Recent work by our laboratory identified a novel role for the necroptosis inhibitor, necrostatin-1, in limiting neurovascular injury in tissue culture models of hemorrhagic injury. In the present study, we tested the hypothesis that necrostatin-1 reduces neurovascular injury after collagenase-induced ICH in mice. Necrostatin-1 significantly reduced hematoma volume by 54% at 72 h after-ICH, as compared to either sham-injured mice or mice administered an inactive, structural analogue of necrostatin-1. Necrostatin-1 also limited cell death by 48%, reduced blood-brain barrier opening by 51%, attenuated edema development to sham levels, and improved neurobehavioral outcomes after ICH. These data suggest a potential clinical utility for necrostatin-1 and/or novel necroptosis inhibitors as an adjunct therapy to reduce neurological injury and improve patient outcomes after ICH.

  10. New Wavelet Neurovascular Bundle for Bedside Evaluation of Cerebral Autoregulation and Neurovascular Coupling in Newborns with Hypoxic-Ischemic Encephalopathy.

    Science.gov (United States)

    Chalak, Lina F; Zhang, Rong

    2017-01-01

    Neonatal encephalopathy (NE) resulting from birth asphyxia constitutes a major global public health burden for millions of infants every year, and despite therapeutic hypothermia, half of these neonates have poor neurological outcomes. As new neuroprotective interventions are being studied in clinical trials, there is a critical need to establish physiological surrogate markers of therapeutic efficacy, to guide patient selection and/or to modify the therapeutic intervention. The challenge in the field of neonatal brain injury has been the difficulty of clinically discerning NE severity within the short therapeutic window after birth or of analyzing the dynamic aspects of the cerebral circulation in sick NE newborns. To address this roadblock, we have recently developed a new "wavelet neurovascular bundle" analytical system that can measure cerebral autoregulation (CA) and neurovascular coupling (NVC) at multiple time scales under dynamic, nonstationary clinical conditions. This wavelet analysis may allow noninvasive quantification at the bedside of (1) CA (combining metrics of blood pressure and cerebral near-infrared spectroscopy, NIRS) and (2) NVC (combining metrics obtained from NIRS and EEG) in newborns with encephalopathy without mathematical assumptions of linear and stationary systems. In this concept paper, we present case examples of NE using the proposed physiological wavelet metrics of CA and NVC. The new approach, once validated in large NE studies, has the potential to optimize the selection of candidates for therapeutic decision-making, and the prediction of neurocognitive outcomes. © 2017 S. Karger AG, Basel.

  11. Chitosan pads vs. manual compression to control bleeding sites after transbrachial arterial catheterization in a randomized trial

    International Nuclear Information System (INIS)

    Poretti, F.; Rosen, T.; Koerner, B.; Vorwerk, D.

    2005-01-01

    Purpose: until now, no mechanical closure devices were available to achieve fast and secure hemostasis for vessel closure after catheterization of small arterial vessels. Material and methods: eighty patients were randomized to evaluate the effect on hemostasis by use of a chitosan pad (Chito-Seal, Abbott Vascular Devices, Galway/Ireland) in comparison to manual compression after diagnostic transbrachial arterial catheterization. Hemostasis after three minutes and one hour as well as local development of a hematoma after one and twenty-four hours were assessed. Results: the use of chitosan pads significantly decreased the bleeding time in the first three minutes after manual compression time (p < 0.01). Significant decrease in bleeding risk at three minutes by use of the chitosan closure pads was also found in subgroups of patients with hypertension (p < 0.001) or diabetes (p < 0.01) and also in patients under anticoagulation therapy (p < 0.01). In addition, long-term protection from bleeding complications such as the risk of hematoma was decreased by the use of chitosan closure pads one hour (p < 0.01) or twenty-four hours (p < 0.001) after catheter removal. Conclusion: the use of an intravascular anchor or suture system is not safely applicable in these vessels due to the small diameter of the brachial artery. Our results document a significant improvement in hemostasis by using chitosan pads in these cases. (orig.)

  12. OCT/PS-OCT imaging of brachial plexus neurovascular structures

    Science.gov (United States)

    Raphael, David T.; Zhang, Jun; Zhang, Yaoping; Chen, Zhongping; Miller, Carol; Zhou, Li

    2004-07-01

    Introduction: Optical coherence tomography (OCT) allows high-resolution imaging (less than 10 microns) of tissue structures. A pilot study with OCT and polarization-sensitive OCT (PS-OCT) was undertaken to image ex-vivo neurovascular structures (vessels, nerves) of the canine brachial plexus. Methods: OCT is an interferometry-based optical analog of B-mode ultrasound, which can image through non-transparent biological tissues. With approval of the USC Animal Care and Use Committee, segments of the supra- and infraclavicular brachial plexus were excised from euthanized adult dogs, and the ex-vivo specimens were placed in cold pH-buffered physiologic solution. An OCT beam, in micrometer translational steps, scanned the fixed-position bisected specimens in transverse and longitudinal views. Two-dimensional images were obtained from identified arteries and nerves, with specific sections of interest stained with hematoxylin-eosin for later imaging through a surgical microscope. Results: with the beam scan direction transverse to arteries, the resulting OCT images showed an identifiable arterial lumen and arterial wall tissue layers. By comparison, transverse beam OCT images of nerves revealed a multitude of smaller nerve bundles contained within larger circular-shaped fascicles. PS-OCT imaging was helpful in showing the characteristic birefringence exhibited by arrayed neural structures. Discussion: High-resolution OCT imaging may be useful in the optical identification of neurovascular structures during attempted regional nerve blockade. If incorporated into a needle-shaped catheter endoscope, such a technology could prevent intraneural and intravascular injections immediately prior to local anesthetic injection. The major limitation of OCT is that it can form a coherent image of tissue structures only to a depth of 1.5 - 2 mm.

  13. Orthopaedic nurses' knowledge and interrater reliability of neurovascular assessments with 2-point discrimination test.

    Science.gov (United States)

    Turney, Jennifer; Raley Noble, Deana; Kim, Son Chae

    2013-01-01

    : This study was conducted to evaluate the effects of education on knowledge and interrater reliability of neurovascular assessments with 2-point discrimination (2-PD) test among pediatric orthopaedic nurses. : A pre- and posttest study was done among 60 nurses attending 2-hour educational sessions. Neurovascular assessments with 2-PD test were performed on 64 casted pediatric patients by the nurses and 5 nurse experts before and after the educational sessions. : The mean neurovascular assessment knowledge score was improved at posteducation compared with the preeducation (p < .001). The 2-PD test interrater reliability also improved from Cohen's kappa value of 0.24-0.48 at posteducation. : The 2-hour educational session may be effective in improving nurses' knowledge and the interrater reliability of neurovascular assessment with 2-PD test.

  14. Establishment of neurovascular congruency in the mouse whisker system by an independent patterning mechanism.

    Science.gov (United States)

    Oh, Won-Jong; Gu, Chenghua

    2013-10-16

    Nerves and vessels often run parallel to one another, a phenomenon that reflects their functional interdependency. Previous studies have suggested that neurovascular congruency in planar tissues such as skin is established through a "one-patterns-the-other" model, in which either the nervous system or the vascular system precedes developmentally and then instructs the other system to form using its established architecture as a template. Here, we find that, in tissues with complex three-dimensional structures such as the mouse whisker system, neurovascular congruency does not follow the previous model but rather is established via a mechanism in which nerves and vessels are patterned independently. Given the diversity of neurovascular structures in different tissues, guidance signals emanating from a central organizer in the specific target tissue may act as an important mechanism to establish neurovascular congruency patterns that facilitate unique target tissue function. Copyright © 2013 Elsevier Inc. All rights reserved.

  15. Non-Traumatic Anterior Dislocation of a Total Knee Replacement Associated with Neurovascular Injury

    Science.gov (United States)

    Aderinto, Joseph; Gross, Allan E; Rittenhouse, Bryan

    2009-01-01

    Prosthetic total knee replacements rarely dislocate. When dislocation does occur, it is usually in a posterior direction in association with a posterior stabilised, cruciate-sacrificing prosthesis. Neurovascular injury is unusual. In this report, we describe a case of anterior dislocation of a cruciate-retaining total knee replacement in a 67-year-old woman. The dislocation occurred in the absence of overt trauma and resulted in severe neurovascular injury. PMID:19686618

  16. Neurovascular abnormalities in brain disorders: highlights with angiogenesis and magnetic resonance imaging studies

    OpenAIRE

    Chen, Chiao-Chi V; Chen, Yu-Chen; Hsiao, Han-Yun; Chang, Chen; Chern, Yijuang

    2013-01-01

    The coupling between neuronal activity and vascular responses is controlled by the neurovascular unit (NVU), which comprises multiple cell types. Many different types of dysfunction in these cells may impair the proper control of vascular responses by the NVU. Magnetic resonance imaging, which is the most powerful tool available to investigate neurovascular structures or functions, will be discussed in the present article in relation to its applications and discoveries. Because aberrant angio...

  17. Early neurovascular dysfunction in a transgenic rat model of Alzheimer?s disease

    OpenAIRE

    Joo, Illsung L.; Lai, Aaron Y.; Bazzigaluppi, Paolo; Koletar, Margaret M.; Dorr, Adrienne; Brown, Mary E.; Thomason, Lynsie A. M.; Sled, John G.; McLaurin, JoAnne; Stefanovic, Bojana

    2017-01-01

    Alzheimer?s disease (AD), pathologically characterized by amyloid-? peptide (A?) accumulation, neurofibrillary tangle formation, and neurodegeneration, is thought to involve early-onset neurovascular abnormalities. Hitherto studies on AD-associated neurovascular injury have used animal models that exhibit only a subset of AD-like pathologies and demonstrated some A?-dependent vascular dysfunction and destabilization of neuronal network. The present work focuses on the early stage of disease p...

  18. Pore-water extraction from unsaturated tuff by triaxial and one-dimensional compression methods, Nevada Test Site, Nevada

    International Nuclear Information System (INIS)

    Mower, T.E.; Higgins, J.D.; Yang, In C.; Peters, C.A.

    1994-01-01

    The hydrologic system in the unsaturated tuff at Yucca Mountain, Nevada, is being evaluated for the US Department of Energy by the Yucca Mountain Project Branch of the US Geological Survey as a potential site for a high-level radioactive-waste repository. Part of this investigation includes a hydrochemical study that is being made to assess characteristics of the hydrologic system such as: traveltime, direction of flow, recharge and source relations, and types and magnitudes of chemical reactions in the unsaturated tuff. In addition, this hydrochemical information will be used in the study of the dispersive and corrosive effects of unsaturated-zone water on the radioactive-waste storage canisters. This report describes the design and validation of laboratory experimental procedures for extracting representative samples of uncontaminated pore water from welded and nonwelded, unsaturated tuffs from the Nevada Test Site

  19. Ultrastructure of neurovascular changes in human diabetic retinopathy.

    Science.gov (United States)

    Fehér, János; Taurone, Samanta; Spoletini, Marialuisa; Biró, Zsolt; Varsányi, Balázs; Scuderi, Gianluca; Orlando, Maria Patrizia; Turchetta, Rosaria; Micera, Alessandra; Artico, Marco

    2018-01-01

    The previous concept regarding diabetic retinopathy assigned a primary role to hyperglycemia-induced microvascular alterations, while neuronal and glial abnormalities were considered to be secondary to either ischemia or exudation. The aim of this study was to reveal the potential role of neuronal and glial cells in initial and advanced alterations of the retinopathy in human type 2 diabetes. Electron microscopy and histochemical studies were performed on 38 surgically removed human eyes (28 obtained from diabetic patients and 10 from non-diabetic patients). Morphometric analysis of basement membrane material and lipids was performed. An accumulation of metabolic by-products was found in the capillary wall with aging: this aspect was significantly more pronounced in diabetics. Müller glial cells were found to contribute to alterations of the capillary wall and to occlusion, as well as to the development of proliferative retinopathy and cystoid degeneration of the retina. Our results showed morphological evidence regarding the role of neuronal and glial cells in the pathology of diabetic retinopathy, prior and in addition to microangiopathy. These morphological findings support a neurovascular pathogenesis at the origin of diabetic retinopathy, thus the current treatment approach should be completed by neuroprotective measures.

  20. Cerebral Vascular Disease and Neurovascular Injury in Ischemic Stroke

    Science.gov (United States)

    Hu, Xiaoming; De Silva, T. Michael; Chen, Jun; Faraci, Frank M.

    2017-01-01

    The consequences of cerebrovascular disease are among the leading health issues worldwide. Large and small cerebral vessel disease can trigger stroke and contribute to the vascular component of other forms of neurological dysfunction and degeneration. Both forms of vascular disease are driven by diverse risk factors, with hypertension as the leading contributor. Despite the importance of neurovascular disease and subsequent injury following ischemic events, fundamental knowledge in these areas lag behind our current understanding of neuroprotection and vascular biology in general. The goal of this review is to address select key structural and functional changes in the vasculature that promote hypoperfusion and ischemia, while also affecting the extent of injury and effectiveness of therapy. In addition, as damage to the blood-brain barrier (BBB) is one of the major consequences of ischemia, we discuss cellular and molecular mechanisms underlying ischemia-induced changes in BBB integrity and function, including alterations in endothelial cells and the contribution of pericytes, immune cells, and matrix metalloproteinases. Identification of cell types, pathways, and molecules that control vascular changes before and after ischemia may result in novel approaches to slow the progression of cerebrovascular disease and lessen both the frequency and impact of ischemic events. PMID:28154097

  1. TWEAK and Fn14 in the neurovascular unit

    Directory of Open Access Journals (Sweden)

    Manuel eYepes

    2013-11-01

    Full Text Available The neurovascular unit (NVU is a dynamic structure assembled by endothelial cells, a basement membrane, perivascular astrocytes, pericytes, and surrounding neurons. The NVU regulates the passage of substances and cellular elements from the intravascular space into the brain parenchyma. This function, also known as blood-brain barrier (BBB, is regulated by the integrity of tight junctions proteins between endothelial cells, and the interaction between perivascular astrocytes and the basal lamina. The cytokine tumor necrosis factor-like weak inducer of apoptosis (TWEAK and its receptor fibroblast growth factor-inducible 14 (Fn14 are abundantly expressed in the NVU. Here we will review data indicating that the interaction between TWEAK and Fn14 in the endothelial cell - basement membrane - astrocyte interface regulates the function of the BBB following an ischemic/hypoxic injury, and that pharmacological inhibition of TWEAK-Fn14 is a promising target for the treatment of patients with neurological diseases that have a direct impact on the structure and function of the NVU.

  2. DNABIT Compress - Genome compression algorithm.

    Science.gov (United States)

    Rajarajeswari, Pothuraju; Apparao, Allam

    2011-01-22

    Data compression is concerned with how information is organized in data. Efficient storage means removal of redundancy from the data being stored in the DNA molecule. Data compression algorithms remove redundancy and are used to understand biologically important molecules. We present a compression algorithm, "DNABIT Compress" for DNA sequences based on a novel algorithm of assigning binary bits for smaller segments of DNA bases to compress both repetitive and non repetitive DNA sequence. Our proposed algorithm achieves the best compression ratio for DNA sequences for larger genome. Significantly better compression results show that "DNABIT Compress" algorithm is the best among the remaining compression algorithms. While achieving the best compression ratios for DNA sequences (Genomes),our new DNABIT Compress algorithm significantly improves the running time of all previous DNA compression programs. Assigning binary bits (Unique BIT CODE) for (Exact Repeats, Reverse Repeats) fragments of DNA sequence is also a unique concept introduced in this algorithm for the first time in DNA compression. This proposed new algorithm could achieve the best compression ratio as much as 1.58 bits/bases where the existing best methods could not achieve a ratio less than 1.72 bits/bases.

  3. Compression stockings

    Science.gov (United States)

    Call your health insurance or prescription plan: Find out if they pay for compression stockings. Ask if your durable medical equipment benefit pays for compression stockings. Get a prescription from your doctor. Find a medical equipment store where they can ...

  4. IGF-1 deficiency impairs neurovascular coupling in mice: implications for cerebromicrovascular aging.

    Science.gov (United States)

    Toth, Peter; Tarantini, Stefano; Ashpole, Nicole M; Tucsek, Zsuzsanna; Milne, Ginger L; Valcarcel-Ares, Noa M; Menyhart, Akos; Farkas, Eszter; Sonntag, William E; Csiszar, Anna; Ungvari, Zoltan

    2015-12-01

    Aging is associated with marked deficiency in circulating IGF-1, which has been shown to contribute to age-related cognitive decline. Impairment of moment-to-moment adjustment of cerebral blood flow (CBF) via neurovascular coupling is thought to play a critical role in the genesis of age-related cognitive impairment. To establish the link between IGF-1 deficiency and cerebromicrovascular impairment, neurovascular coupling mechanisms were studied in a novel mouse model of IGF-1 deficiency (Igf1(f/f) -TBG-Cre-AAV8) and accelerated vascular aging. We found that IGF-1-deficient mice exhibit neurovascular uncoupling and show a deficit in hippocampal-dependent spatial memory test, mimicking the aging phenotype. IGF-1 deficiency significantly impaired cerebromicrovascular endothelial function decreasing NO mediation of neurovascular coupling. IGF-1 deficiency also impaired glutamate-mediated CBF responses, likely due to dysregulation of astrocytic expression of metabotropic glutamate receptors and impairing mediation of CBF responses by eicosanoid gliotransmitters. Collectively, we demonstrate that IGF-1 deficiency promotes cerebromicrovascular dysfunction and neurovascular uncoupling mimicking the aging phenotype, which are likely to contribute to cognitive impairment. © 2015 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.

  5. Neurovascular and Neurometabolic Derailment in Aging and Alzheimer’s Disease

    Directory of Open Access Journals (Sweden)

    Cátia eLourenço

    2015-05-01

    Full Text Available The functional and structural integrity of the brain requires local adjustment of blood flow and regulated delivery of metabolic substrates to meet the metabolic demands imposed by neuronal activation. This process – neurovascular coupling – and ensued alterations of glucose and oxygen metabolism - neurometabolic coupling - are accomplished by concerted communication between neural and vascular cells. Evidence suggests that neuronal-derived nitric oxide (•NO is a key player in both phenomena. Alterations in the mechanisms underlying the intimate communication between neural cells and vessels ultimately lead to neuronal dysfunction. Both neurovascular and neurometabolic coupling are perturbed during brain aging and in age-related neuropathologies in close association with cognitive decline. However, despite decades of intense investigation, many aspects remain poorly understood, such as the impact of these alterations. In this review, we address neurovascular and neurometabolic derailment in aging and Alzheimer’s disease, discussing its significance in connection with •NO-related pathways.

  6. Inflammation and the neurovascular unit in the setting of focal cerebral ischemia.

    Science.gov (United States)

    del Zoppo, G J

    2009-02-06

    Responses to focal cerebral ischemia by neurons and adjacent microvessels are rapid, simultaneous, and topographically related. Recent observations indicate the simultaneous appearance of proteases by components of nearby microvessels that are also expressed by neurons in the ischemic territory, implying that the events could be coordinated. The structural relationship of neurons to their microvascular supply, the direct functional participation of glial cells, and the observation of a highly ordered microvessel-neuron response to ischemia suggest that these elements are arranged in and behave in a unitary fashion, the neurovascular unit. Their roles as a unit in the stimulation of cellular inflammation and the generation of inflammatory mediators during focal cerebral ischemia have not been explored yet. However, components of the neurovascular unit both generate and respond to these influences under the conditions of ischemia. Here we briefly explore the potential inter-relationships of the components of the neurovascular unit with respect to their potential roles in ischemia-induced inflammatory responses.

  7. The neurovascular relation in oxygen-induced retinopathy.

    Science.gov (United States)

    Akula, James D; Mocko, Julie A; Benador, Ilan Y; Hansen, Ronald M; Favazza, Tara L; Vyhovsky, Tanya C; Fulton, Anne B

    2008-01-01

    Longitudinal studies in rat models of retinopathy of prematurity (ROP) have demonstrated that abnormalities of retinal vasculature and function change hand-in-hand. In the developing retina, vascular and neural structures are under cooperative molecular control. In this study of rats with oxygen-induced retinopathy (OIR) models of ROP, mRNA expression of vascular endothelial growth factor (VEGF), semaphorin (Sema), and their neuropilin receptor (NRP) were examined during the course of retinopathy to evaluate their roles in the observed neurovascular congruency. Oxygen exposures designed to induce retinopathy were delivered to Sprague-Dawley rat pups (n=36) from postnatal day (P) 0 to P14 or from P7 to P14. Room-air-reared controls (n=18) were also studied. Sensitivities of the rod photoreceptors (S(rod)) and the postreceptor cells (Sm) were derived from electroretinographic (ERG) records. Arteriolar tortuosity, T(A), was derived from digital fundus images using Retinal Image multi-Scale Analysis (RISA) image analysis software. mRNA expression of VEGF(164), semaphorin IIIA (Sema3A), and neuropilin-1 (NRP-1) was evaluated by RT-PCR of retinal extracts. Tests were performed at P15-P16, P18-P19, and P25-P26. Relations among ERG, RISA, and PCR parameters were evaluated using linear regression on log transformed data. Sm was low and T(A) was high at young ages, then both resolved by P25-P26. VEGF(164) and Sema3A mRNA expression were also elevated early and decreased with age. Low Sm was significantly associated with high VEGF(164) and Sema3A expression. Low S(rod) was also significantly associated with high VEGF(164). S(rod) and Sm were both correlated with T(A). NRP-1 expression was little affected by OIR. The postreceptor retina appears to mediate the vascular abnormalities that characterize OIR. Because of the relationships revealed by these data, early treatment that targets the neural retina may mitigate the effects of ROP.

  8. Neurovascular abnormalities in brain disorders: highlights with angiogenesis and magnetic resonance imaging studies.

    Science.gov (United States)

    Chen, Chiao-Chi V; Chen, Yu-Chen; Hsiao, Han-Yun; Chang, Chen; Chern, Yijuang

    2013-07-05

    The coupling between neuronal activity and vascular responses is controlled by the neurovascular unit (NVU), which comprises multiple cell types. Many different types of dysfunction in these cells may impair the proper control of vascular responses by the NVU. Magnetic resonance imaging, which is the most powerful tool available to investigate neurovascular structures or functions, will be discussed in the present article in relation to its applications and discoveries. Because aberrant angiogenesis and vascular remodeling have been increasingly reported as being implicated in brain pathogenesis, this review article will refer to this hallmark event when suitable.

  9. Modeling neuro-vascular coupling in rat cerebellum: characterization of deviations from linearity

    DEFF Research Database (Denmark)

    Rasmussen, Tina; Holstein-Rathlou, Niels-Henrik; Lauritzen, Martin

    2009-01-01

    We investigated the quantitative relation between neuronal activity and blood flow by means of a general parametric mathematical model which described the neuro-vascular system as being dynamic, linear, time-invariant, and subjected to additive noise. The model was constructed from measurements...... and dips in blood flow responses to stimulation for 60 s, and overgrowth of blood flow responses to stimulation for 600 s. In another set of experiments, stimulation frequencies were in the range 0.5-10 Hz and the stimulation duration was 15 s. The neuro-vascular system could be approximated by the linear...

  10. EEG-NIRS based assessment of neurovascular coupling during anodal transcranial direct current stimulation--a stroke case series.

    Science.gov (United States)

    Dutta, Anirban; Jacob, Athira; Chowdhury, Shubhajit Roy; Das, Abhijit; Nitsche, Michael A

    2015-04-01

    A method for electroencephalography (EEG) - near-infrared spectroscopy (NIRS) based assessment of neurovascular coupling (NVC) during anodal transcranial direct current stimulation (tDCS). Anodal tDCS modulates cortical neural activity leading to a hemodynamic response, which was used to identify impaired NVC functionality. In this study, the hemodynamic response was estimated with NIRS. NIRS recorded changes in oxy-hemoglobin (HbO2) and deoxy-hemoglobin (Hb) concentrations during anodal tDCS-induced activation of the cortical region located under the electrode and in-between the light sources and detectors. Anodal tDCS-induced alterations in the underlying neuronal current generators were also captured with EEG. Then, a method for the assessment of NVC underlying the site of anodal tDCS was proposed that leverages the Hilbert-Huang Transform. The case series including four chronic (>6 months) ischemic stroke survivors (3 males, 1 female from age 31 to 76) showed non-stationary effects of anodal tDCS on EEG that correlated with the HbO2 response. Here, the initial dip in HbO2 at the beginning of anodal tDCS corresponded with an increase in the log-transformed mean-power of EEG within 0.5Hz-11.25Hz frequency band. The cross-correlation coefficient changed signs but was comparable across subjects during and after anodal tDCS. The log-transformed mean-power of EEG lagged HbO2 response during tDCS but then led post-tDCS. This case series demonstrated changes in the degree of neurovascular coupling to a 0.526 A/m(2) square-pulse (0-30 s) of anodal tDCS. The initial dip in HbO2 needs to be carefully investigated in a larger cohort, for example in patients with small vessel disease.

  11. Lateral femoral traction pin entry: risk to the femoral artery and other medial neurovascular structures

    Directory of Open Access Journals (Sweden)

    Appleton Paul

    2010-01-01

    Full Text Available Abstract Background Femoral skeletal traction assists in the reduction and transient stabilization of pelvic, acetabular, hip, and femoral fractures when splinting is ineffective. Traditional teaching has recommended a medial entry site for insertion of the traction pin in order to minimize injury to the femoral artery as it passes through Hunter's canal. The present anatomical study evaluates the risk to the femoral artery and other medial neurovascular structures using a lateral entry approach. Methods Six embalmed cadavers (twelve femurs were obtained for dissection. Steinman pins were drilled from lateral to medial at the level of the superior pole of the patella, at 2 cm, and at 4 cm proximal to this point. Medial superficial dissection was then performed to identify the saphenous nerve, the superior medial geniculate artery, the adductor hiatus, the tendinous insertion of the adductor magnus and the femoral artery. Measurements localizing these anatomic structures relative to the pins were obtained. Results The femoral artery was relatively safe and was no closer than 29.6 mm (mean from any of the three Steinman pins. The superior medial geniculate artery was the medial structure at most risk. Conclusions Lateral femoral traction pin entry is a safe procedure with minimal risk to the saphenous nerve and femoral artery. Of the structures examined, only the superior medial geniculate artery is at a risk of iatrogenic injury due to its position. The incidence of such injury in clinical practice and its clinical significance is not known. Lateral insertion facilitates traction pin placement since it minimizes the need to move the contralateral extremity out of the way of the drilling equipment or the need to elevate or externally rotate the injured extremity relative to the contralateral extremity.

  12. Persistent increase in oxygen consumption and impaired neurovascular coupling after spreading depression in rat neocortex.

    Science.gov (United States)

    Piilgaard, Henning; Lauritzen, Martin

    2009-09-01

    Cortical spreading depression (CSD) is associated with a dramatic failure of brain ion homeostasis and increased energy metabolism. There is strong clinical and experimental evidence to suggest that CSD is the mechanism of migraine, and involved in progressive neuronal injury in stroke and head trauma. Here we tested the hypothesis that single episodes of CSD induced acute hypoxia, and prolonged impairment of neurovascular and neurometabolic coupling. Cortical spreading depression was induced in rat frontal cortex, whereas cortical electrical activity and local field potentials (LFPs) were recorded by glass microelectrodes, cerebral blood flow (CBF) by laser-Doppler flowmetry, and tissue oxygen tension (tpO(2)) with polarographic microelectrodes. Cortical spreading depression increased cerebral metabolic rate of oxygen (CMRO(2)) by 71%+/-6.7% and CBF by 238%+/-48.1% for 1 to 2 mins. For the following 2 h, basal tpO(2) and CBF were reduced whereas basal CMRO(2) was persistently elevated by 8.1%+/-2.9%. In addition, within first hour after CSD we found impaired neurovascular coupling (LFP versus CBF), whereas neurometabolic coupling (LFP versus CMRO(2)) remained unaffected. Impaired neurovascular coupling was explained by both reduced vascular reactivity and suppressed function of cortical inhibitory interneurons. The protracted effects of CSD on basal CMRO(2) and neurovascular coupling may contribute to cellular dysfunction in patients with migraine and acutely injured cerebral cortex.

  13. Neurovascular cross talk in diabetic retinopathy: Pathophysiological roles and therapeutic implications

    Science.gov (United States)

    Moran, Elizabeth P.; Wang, Zhongxiao; Chen, Jing; Sapieha, Przemyslaw; Smith, Lois E. H.

    2016-01-01

    Diabetic retinopathy (DR) is the leading cause of blindness in the working-age population in developed countries, and its prevalence will increase as the global incidence of diabetes grows exponentially. DR begins with an early nonproliferative stage in which retinal blood vessels and neurons degenerate as a consequence of chronic hyperglycemia, resulting in vasoregression and persistent retinal ischemia, metabolic disequilibrium, and inflammation. This is conducive to overcompensatory pathological neovascularization associated with advanced proliferative DR. Although DR is considered a microvascular complication, the retinal microvasculature is intimately associated with and governed by neurons and glia; neurodegeneration, neuroinflammation, and dysregulation of neurovascular cross talk are responsible in part for vascular abnormalities in both early nonproliferative DR and advanced proliferative DR. Neuronal activity directly regulates microvascular dilation and blood flow in the process of neurovascular coupling. Retinal neurons also secrete guidance cues in response to injury, ischemia, or metabolic stress that may either promote or suppress vascular outgrowth, either alleviating or exacerbating DR, contingent on the stage of disease and retinal microenvironment. Neurodegeneration, impaired neurovascular coupling, and dysregulation of neuronal guidance cues are key events in the pathogenesis of DR, and correcting these events may prevent or delay development of advanced DR. The review discusses the mechanisms of neurovascular cross talk and its dysregulation in DR, and their potential therapeutic implications. PMID:27473938

  14. Dual energy CT at the synchrotron: A piglet model for neurovascular research

    International Nuclear Information System (INIS)

    Schueltke, Elisabeth; Kelly, Michael E.; Nemoz, Christian; Fiedler, Stefan; Ogieglo, Lissa; Crawford, Paul; Paterson, Jessica; Beavis, Cole; Esteve, Francois; Brochard, Thierry; Renier, Michel; Requardt, Herwig; Dallery, Dominique; Le Duc, Geraldine; Meguro, Kotoo

    2011-01-01

    Background: Although the quality of imaging techniques available for neurovascular angiography in the hospital environment has significantly improved over the last decades, the equipment used for clinical work is not always suited for neurovascular research in animal models. We have previously investigated the suitability of synchrotron-based K-edge digital subtraction angiography (KEDSA) after intravenous injection of iodinated contrast agent for neurovascular angiography in radiography mode in both rabbit and pig models. We now have used the KEDSA technique for the acquisition of three-dimensional images and dual energy CT. Materials and methods: All experiments were conducted at the biomedical beamline ID 17 of the European Synchrotron Radiation Facility (ESRF). A solid state germanium (Ge) detector was used for the acquisition of image pairs at 33.0 and 33.3 keV. Three-dimensional images were reconstructed from an image series containing 60 single images taken throughout a full rotation of 360 o . CT images were reconstructed from two half-acquisitions with 720 projections each. Results: The small detector field of view was a limiting factor in our experiments. Nevertheless, we were able to show that dual energy CT using the KEDSA technique available at ID 17 is suitable for neurovascular research in animal models.

  15. Dual energy CT at the synchrotron: a piglet model for neurovascular research.

    Science.gov (United States)

    Schültke, Elisabeth; Kelly, Michael E; Nemoz, Christian; Fiedler, Stefan; Ogieglo, Lissa; Crawford, Paul; Paterson, Jessica; Beavis, Cole; Esteve, Francois; Brochard, Thierry; Renier, Michel; Requardt, Herwig; Dallery, Dominique; Le Duc, Geraldine; Meguro, Kotoo

    2011-08-01

    Although the quality of imaging techniques available for neurovascular angiography in the hospital environment has significantly improved over the last decades, the equipment used for clinical work is not always suited for neurovascular research in animal models. We have previously investigated the suitability of synchrotron-based K-edge digital subtraction angiography (KEDSA) after intravenous injection of iodinated contrast agent for neurovascular angiography in radiography mode in both rabbit and pig models. We now have used the KEDSA technique for the acquisition of three-dimensional images and dual energy CT. All experiments were conducted at the biomedical beamline ID 17 of the European Synchrotron Radiation Facility (ESRF). A solid state germanium (Ge) detector was used for the acquisition of image pairs at 33.0 and 33.3 keV. Three-dimensional images were reconstructed from an image series containing 60 single images taken throughout a full rotation of 360°. CT images were reconstructed from two half-acquisitions with 720 projections each. The small detector field of view was a limiting factor in our experiments. Nevertheless, we were able to show that dual energy CT using the KEDSA technique available at ID 17 is suitable for neurovascular research in animal models. Copyright © 2010. Published by Elsevier Ireland Ltd.

  16. Control of the neurovascular coupling by nitric oxide-dependent regulation of astrocytic Ca2+ signaling

    Directory of Open Access Journals (Sweden)

    Manuel Francisco Muñoz

    2015-03-01

    Full Text Available Neuronal activity must be tightly coordinated with blood flow to keep proper brain function, which is achieved by a mechanism known as neurovascular coupling. Then, an increase in synaptic activity leads to a dilation of local parenchymal arterioles that matches the enhanced metabolic demand. Neurovascular coupling is orchestrated by astrocytes. These glial cells are located between neurons and the microvasculature, with the astrocytic endfeet ensheathing the vessels, which allows fine intercellular communication. The neurotransmitters released during neuronal activity reach astrocytic receptors and trigger a Ca2+ signaling that propagates to the endfeet, activating the release of vasoactive factors and arteriolar dilation. The astrocyte Ca2+ signaling is coordinated by gap junction channels and hemichannels formed by connexins (Cx43 and Cx30 and channels formed by pannexins (Panx-1. The neuronal activity-initiated Ca2+ waves are propagated among neighboring astrocytes directly via gap junctions or through ATP release via connexin hemichannels or pannexin channels. In addition, Ca2+ entry via connexin hemichannels or pannexin channels may participate in the regulation of the astrocyte signaling-mediated neurovascular coupling. Interestingly, nitric oxide (NO can activate connexin hemichannel by S-nitrosylation and the Ca2+-dependent NO-synthesizing enzymes endothelial NO synthase (eNOS and neuronal NOS (nNOS are expressed in astrocytes. Therefore, the astrocytic Ca2+ signaling triggered in neurovascular coupling may activate NO production, which, in turn, may lead to Ca2+ influx through hemichannel activation. Furthermore, NO release from the hemichannels located at astrocytic endfeet may contribute to the vasodilation of parenchymal arterioles. In this review, we discuss the mechanisms involved in the regulation of the astrocytic Ca2+ signaling that mediates neurovascular coupling, with a special emphasis in the possible participation of NO in

  17. Low-energy Shock Wave Therapy Ameliorates Erectile Dysfunction in a Pelvic Neurovascular Injuries Rat Model.

    Science.gov (United States)

    Li, Huixi; Matheu, Melanie P; Sun, Fionna; Wang, Lin; Sanford, Melissa T; Ning, Hongxiu; Banie, Lia; Lee, Yung-Chin; Xin, Zhongcheng; Guo, Yinglu; Lin, Guiting; Lue, Tom F

    2016-01-01

    Erectile dysfunction (ED) caused by pelvic injuries is a common complication of civil and battlefield trauma with multiple neurovascular factors involved, and no effective therapeutic approach is available. To test the effect and mechanisms of low-energy shock wave (LESW) therapy in a rat ED model induced by pelvic neurovascular injuries. Thirty-two male Sprague-Dawley rats injected with 5-ethynyl-2'-deoxyuridine (EdU) at newborn were divided into 4 groups: sham surgery (Sham), pelvic neurovascular injury by bilateral cavernous nerve injury and internal pudendal bundle injury (PVNI), PVNI treated with LESW at low energy (Low), and PVNI treated with LESW at high energy (High). After LESW treatment, rats underwent erectile function measurement and the tissues were harvested for histologic and molecular study. To examine the effect of LESW on Schwann cells, in vitro studies were conducted. The intracavernous pressure (ICP) measurement, histological examination, and Western blot (WB) were conducted. Cell cycle, Schwann cell activation-related markers were examined in in vitro experiments. LESW treatment improves erectile function in a rat model of pelvic neurovascular injury by leading to angiogenesis, tissue restoration, and nerve generation with more endogenous EdU(+) progenitor cells recruited to the damaged area and activation of Schwann cells. LESW facilitates more complete re-innervation of penile tissue with regeneration of neuronal nitric oxide synthase (nNOS)-positive nerves from the MPG to the penis. In vitro experiments demonstrated that LESW has a direct effect on Schwann cell proliferation. Schwann cell activation-related markers including p-Erk1/2 and p75 were upregulated after LESW treatment. LESW-induced endogenous progenitor cell recruitment and Schwann cell activation coincides with angiogenesis, tissue, and nerve generation in a rat model of pelvic neurovascular injuries. Copyright © 2016 International Society for Sexual Medicine. Published by

  18. Multi-modal assessment of neurovascular coupling during cerebral ischaemia and reperfusion using remote middle cerebral artery occlusion

    DEFF Research Database (Denmark)

    Sutherland, Brad A; Fordsmann, Jonas C; Martin, Chris

    2017-01-01

    . Male Wistar rats were subjected to remote middle cerebral artery occlusion, where a long filament was advanced intraluminally through a guide cannula in the common carotid artery. Transcallosal stimulation evoked increases in blood flow, tissue oxygenation and neuronal activity, which were diminished...... that neurovascular dysfunction was not sustained. These data show for the first time that the rat remote middle cerebral artery occlusion model coupled with transcallosal stimulation provides a novel method for continuous assessment of hyperacute neurovascular coupling changes during ischaemia and reperfusion......Hyperacute changes in cerebral blood flow during cerebral ischaemia and reperfusion are important determinants of injury. Cerebral blood flow is regulated by neurovascular coupling, and disruption of neurovascular coupling contributes to brain plasticity and repair problems. However, it is unknown...

  19. 3-D Imaging Reveals Participation of Donor Islet Schwann Cells and Pericytes in Islet Transplantation and Graft Neurovascular Regeneration

    OpenAIRE

    Juang, Jyuhn-Huarng; Kuo, Chien-Hung; Peng, Shih-Jung; Tang, Shiue-Cheng

    2015-01-01

    The primary cells that participate in islet transplantation are the endocrine cells. However, in the islet microenvironment, the endocrine cells are closely associated with the neurovascular tissues consisting of the Schwann cells and pericytes, which form sheaths/barriers at the islet exterior and interior borders. The two cell types have shown their plasticity in islet injury, but their roles in transplantation remain unclear. In this research, we applied 3-dimensional neurovascular histolo...

  20. Cerebellopontine angle and internal auditory canal: neurovascular anatomy on gas CT cisternograms

    International Nuclear Information System (INIS)

    Bird, C.R.; Hasso, A.N.; Drayer, B.P.; Hinshaw, D.B. Jr.; Thompson, J.R.

    1985-01-01

    The authors reviewed 103 normal gas CT cisternograms to delineate the appearance of normal neurovascular structures in the cerebellopontine angle (CPA) and internal auditory canal (IAC). Cranial nerves VII and VIII were identified in the CPA in 97% of cases, either separately (53%) or as a bundle (44%). Intracanalicular branches of the VIIIth cranial nerve were identified in 20% of cases, and cranial nerve V was visualized in the CPA in 14%. The characteristic vascular loop, usually the anterior inferior cerebellar artery, was visible in 35% of cases, and, in 22% of visualized cases, was in an intracanalicular location. In 10% of cases, greater than 66% of the IAC was occupied by the neurovascular bundle. Familiarity with the normal anatomy and variations seen on gas CT cisternograms is necessary to prevent false-positive interpretations

  1. Sensory-Evoked Intrinsic Imaging Signals in the Olfactory Bulb Are Independent of Neurovascular Coupling

    Directory of Open Access Journals (Sweden)

    Roberto Vincis

    2015-07-01

    Full Text Available Functional brain-imaging techniques used in humans and animals, such as functional MRI and intrinsic optical signal (IOS imaging, are thought to largely rely on neurovascular coupling and hemodynamic responses. Here, taking advantage of the well-described micro-architecture of the mouse olfactory bulb, we dissected the nature of odor-evoked IOSs. Using in vivo pharmacology in transgenic mouse lines reporting activity in different cell types, we show that parenchymal IOSs are largely independent of neurotransmitter release and neurovascular coupling. Furthermore, our results suggest that odor-evoked parenchymal IOSs originate from changes in light scattering of olfactory sensory neuron axons, mostly due to water movement following action potential propagation. Our study sheds light on a direct correlate of neuronal activity, which may be used for large-scale functional brain imaging.

  2. Wellhead compression

    Energy Technology Data Exchange (ETDEWEB)

    Harrington, Joe [Sertco Industries, Inc., Okemah, OK (United States); Vazquez, Daniel [Hoerbiger Service Latin America Inc., Deerfield Beach, FL (United States); Jacobs, Denis Richard [Hoerbiger do Brasil Industria de Equipamentos, Cajamar, SP (Brazil)

    2012-07-01

    Over time, all wells experience a natural decline in oil and gas production. In gas wells, the major problems are liquid loading and low downhole differential pressures which negatively impact total gas production. As a form of artificial lift, wellhead compressors help reduce the tubing pressure resulting in gas velocities above the critical velocity needed to surface water, oil and condensate regaining lost production and increasing recoverable reserves. Best results come from reservoirs with high porosity, high permeability, high initial flow rates, low decline rates and high total cumulative production. In oil wells, excessive annulus gas pressure tends to inhibit both oil and gas production. Wellhead compression packages can provide a cost effective solution to these problems by reducing the system pressure in the tubing or annulus, allowing for an immediate increase in production rates. Wells furthest from the gathering compressor typically benefit the most from wellhead compression due to system pressure drops. Downstream compressors also benefit from higher suction pressures reducing overall compression horsepower requirements. Special care must be taken in selecting the best equipment for these applications. The successful implementation of wellhead compression from an economical standpoint hinges on the testing, installation and operation of the equipment. Key challenges and suggested equipment features designed to combat those challenges and successful case histories throughout Latin America are discussed below.(author)

  3. Purinergic signaling triggers endfoot high-amplitude Ca2+ signals and causes inversion of neurovascular coupling after subarachnoid hemorrhage.

    Science.gov (United States)

    Pappas, Anthony C; Koide, Masayo; Wellman, George C

    2016-11-01

    Neurovascular coupling supports brain metabolism by matching focal increases in neuronal activity with local arteriolar dilation. Previously, we demonstrated that an emergence of spontaneous endfoot high-amplitude Ca 2+ signals (eHACSs) caused a pathologic shift in neurovascular coupling from vasodilation to vasoconstriction in brain slices obtained from subarachnoid hemorrhage model animals. Extracellular purine nucleotides (e.g., ATP) can trigger astrocyte Ca 2+ oscillations and may be elevated following subarachnoid hemorrhage. Here, the role of purinergic signaling in subarachnoid hemorrhage-induced eHACSs and inversion of neurovascular coupling was examined by imaging parenchymal arteriolar diameter and astrocyte Ca 2+ signals in rat brain slices using two-photon fluorescent and infrared-differential interference contrast microscopy. We report that broad-spectrum inhibition of purinergic (P2) receptors using suramin blocked eHACSs and restored vasodilatory neurovascular coupling after subarachnoid hemorrhage. Importantly, eHACSs were also abolished using a cocktail of inhibitors targeting G q -coupled P2Y receptors. Further, activation of P2Y receptors in brain slices from un-operated animals triggered high-amplitude Ca 2+ events resembling eHACSs and disrupted neurovascular coupling. Neither tetrodotoxin nor bafilomycin A1 affected eHACSs suggesting that purine nucleotides are not released by ongoing neurotransmission and/or vesicular release after subarachnoid hemorrhage. These results indicate that purinergic signaling via P2Y receptors contributes to subarachnoid hemorrhage-induced eHACSs and inversion of neurovascular coupling. © The Author(s) 2016.

  4. A dynamic model of neurovascular coupling: implications for blood vessel dilation and constriction

    OpenAIRE

    Zheng, Y.; Pan, Y.; Harris, S.; Billings, S.A.; Coca, D.; Berwick, J.; Jones, M.; Kennerley, A.; Johnston, D.; Martin, C.; Devonshire, I.M.; Mayhew, J.

    2010-01-01

    Neurovascular coupling in response to stimulation of the rat barrel cortex was investigated using concurrent multichannel electrophysiology and laser Doppler flowmetry. The data were used to build a linear dynamic model relating neural activity to blood flow. Local field potential time series were subject to current source density analysis, and the time series of a layer IV sink of the barrel cortex was used as the input to the model. The model output was the time series of the changes in reg...

  5. Human Albumin Improves Long-Term Behavioral Sequelae After Subarachnoid Hemorrhage Through Neurovascular Remodeling.

    Science.gov (United States)

    Xie, Yi; Liu, Wenhua; Zhang, Xiaohao; Wang, Liumin; Xu, Lili; Xiong, Yunyun; Yang, Lian; Sang, Hongfei; Ye, Ruidong; Liu, Xinfeng

    2015-10-01

    Subarachnoid hemorrhage results in significant long-lasting neurologic sequelae. Here, we investigated whether human albumin improves long-term outcomes in experimental subarachnoid hemorrhage and whether neurovascular remodeling is involved in the protection of albumin. Laboratory investigation. Hospital research laboratory. Male Sprague-Dawley rats. Rats underwent subarachnoid hemorrhage by endovascular perforation. Albumin of either 0.63 or 1.25 g/kg was injected IV immediately after the surgery. Modified Garcia test, beam-walking test, novel object recognition, and Morris water maze were employed to determine the behavioral deficits. The effects of albumin on early neurovascular dysfunction and chronic synaptic plasticity were also studied. Both doses of albumin significantly improved the sensorimotor scores (F = 31.277; p = 0.001) and cognitive performance (F = 7.982; p = 0.001 in novel object recognition test; and F = 3.431; p = 0.026 in the latency analysis of Morris water maze test) for at least 40 days after subarachnoid hemorrhage. There were remarkable microvasculature hypoperfusion, intracranial pressure rise, early vasoconstriction, neural apoptosis, and degeneration in subarachnoid hemorrhage rats, with albumin significantly attenuating such neurovascular dysfunction. Furthermore, albumin markedly prevented blood-brain barrier disruption, as indicated by less blood-brain barrier leakage, preserved blood-brain barrier-related proteins, and dampened gelatinase activities. The expressions of key synaptic elements were up-regulated with albumin supplementation in both acute and chronic phases. Accordingly, a higher dendritic spine density was observed in the prefrontal and hippocampal areas of albumin-treated subarachnoid hemorrhage animals. Albumin at low-to-moderate doses markedly improves long-term neurobehavioral sequelae after subarachnoid hemorrhage, which may involve an integrated process of neurovascular remodeling.

  6. Lactate Receptor Sites Link Neurotransmission, Neurovascular Coupling, and Brain Energy Metabolism

    DEFF Research Database (Denmark)

    Lauritzen, Knut H; Morland, Cecilie; Puchades, Maja

    2013-01-01

    The G-protein-coupled lactate receptor, GPR81 (HCA1), is known to promote lipid storage in adipocytes by downregulating cAMP levels. Here, we show that GPR81 is also present in the mammalian brain, including regions of the cerebral neocortex and hippocampus, where it can be activated by physiolog......The G-protein-coupled lactate receptor, GPR81 (HCA1), is known to promote lipid storage in adipocytes by downregulating cAMP levels. Here, we show that GPR81 is also present in the mammalian brain, including regions of the cerebral neocortex and hippocampus, where it can be activated...

  7. Early neurovascular dysfunction in a transgenic rat model of Alzheimer's disease.

    Science.gov (United States)

    Joo, Illsung L; Lai, Aaron Y; Bazzigaluppi, Paolo; Koletar, Margaret M; Dorr, Adrienne; Brown, Mary E; Thomason, Lynsie A M; Sled, John G; McLaurin, JoAnne; Stefanovic, Bojana

    2017-04-12

    Alzheimer's disease (AD), pathologically characterized by amyloid-β peptide (Aβ) accumulation, neurofibrillary tangle formation, and neurodegeneration, is thought to involve early-onset neurovascular abnormalities. Hitherto studies on AD-associated neurovascular injury have used animal models that exhibit only a subset of AD-like pathologies and demonstrated some Aβ-dependent vascular dysfunction and destabilization of neuronal network. The present work focuses on the early stage of disease progression and uses TgF344-AD rats that recapitulate a broader repertoire of AD-like pathologies to investigate the cerebrovascular and neuronal network functioning using in situ two-photon fluorescence microscopy and laminar array recordings of local field potentials, followed by pathological analyses of vascular wall morphology, tau hyperphosphorylation, and amyloid plaques. Concomitant to widespread amyloid deposition and tau hyperphosphorylation, cerebrovascular reactivity was strongly attenuated in cortical penetrating arterioles and venules of TgF344-AD rats in comparison to those in non-transgenic littermates. Blood flow elevation to hypercapnia was abolished in TgF344-AD rats. Concomitantly, the phase-amplitude coupling of the neuronal network was impaired, evidenced by decreased modulation of theta band phase on gamma band amplitude. These results demonstrate significant neurovascular network dysfunction at an early stage of AD-like pathology. Our study identifies early markers of pathology progression and call for development of combinatorial treatment plans.

  8. Early neurovascular dysfunction in a transgenic rat model of Alzheimer’s disease

    Science.gov (United States)

    Joo, Illsung L.; Lai, Aaron Y.; Bazzigaluppi, Paolo; Koletar, Margaret M.; Dorr, Adrienne; Brown, Mary E.; Thomason, Lynsie A. M.; Sled, John G.; McLaurin, JoAnne; Stefanovic, Bojana

    2017-01-01

    Alzheimer’s disease (AD), pathologically characterized by amyloid-β peptide (Aβ) accumulation, neurofibrillary tangle formation, and neurodegeneration, is thought to involve early-onset neurovascular abnormalities. Hitherto studies on AD-associated neurovascular injury have used animal models that exhibit only a subset of AD-like pathologies and demonstrated some Aβ-dependent vascular dysfunction and destabilization of neuronal network. The present work focuses on the early stage of disease progression and uses TgF344-AD rats that recapitulate a broader repertoire of AD-like pathologies to investigate the cerebrovascular and neuronal network functioning using in situ two-photon fluorescence microscopy and laminar array recordings of local field potentials, followed by pathological analyses of vascular wall morphology, tau hyperphosphorylation, and amyloid plaques. Concomitant to widespread amyloid deposition and tau hyperphosphorylation, cerebrovascular reactivity was strongly attenuated in cortical penetrating arterioles and venules of TgF344-AD rats in comparison to those in non-transgenic littermates. Blood flow elevation to hypercapnia was abolished in TgF344-AD rats. Concomitantly, the phase-amplitude coupling of the neuronal network was impaired, evidenced by decreased modulation of theta band phase on gamma band amplitude. These results demonstrate significant neurovascular network dysfunction at an early stage of AD-like pathology. Our study identifies early markers of pathology progression and call for development of combinatorial treatment plans. PMID:28401931

  9. MRI Markers of Neurodegenerative and Neurovascular Changes in Relation to Postoperative Delirium and Postoperative Cognitive Decline.

    Science.gov (United States)

    Kant, Ilse M J; de Bresser, Jeroen; van Montfort, Simone J T; Slooter, Arjen J C; Hendrikse, Jeroen

    2017-10-01

    Postoperative delirium (POD) and postoperative cognitive decline (POCD) are common in elderly patients. The aim of the present review was to explore the association of neurodegenerative and neurovascular changes with the occurrence of POD and POCD. Fifteen MRI studies were identified by combining multiple search terms for POD, POCD, and brain imaging. These studies described a total of 1,422 patients and were all observational in design. Neurodegenerative changes (global and regional brain volumes) did not show a consistent association with the occurrence of POD (four studies) or POCD (two studies). In contrast, neurovascular changes (white matter hyperintensities and cerebral infarcts) were more consistently associated with the occurrence of POD (seven studies) and POCD (five studies). In conclusion, neurovascular changes appear to be consistently associated with the occurrence of POD and POCD, and may identify patients at increased risk of these conditions. Larger prospective studies are needed to study the consistency of these findings and to unravel the underlying pathophysiological mechanisms. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  10. Benchmarking Telestroke Proficiency: Page-to-Needle Time Among Neurovascular Fellows and Attendings.

    Science.gov (United States)

    Jagolino-Cole, Amanda L; Bozorgui, Shima; Ankrom, Christy M; Bambhroliya, Arvind B; Cossey, Tiffany D; Trevino, Alyssa D; Savitz, Sean I; Wu, Tzu-Ching; Vahidy, Farhaan S

    2017-09-01

    Formal telestroke training for neurovascular fellows (NVFs) is necessary because of growing use of telestroke technologies in the management of acute ischemic stroke; yet, educational approaches and training benchmarks are not formalized. Time between telestroke consultant page and tissue-type plasminogen activator administration (page-to-needle time, PTNT) can provide an objective measure of proficiency. We compared PTNT between NVFs and neurovascular attendings (NVAs) and evaluated changes in PTNT with experience. We identified suspected acute ischemic stroke patients in our telestroke registry from July 2013 to December 2015 who received tissue-type plasminogen activator. Using multivariable quantile regression, we estimated the difference and 95% confidence interval in median PTNT between NVFs and NVAs. We also report the coefficient of change in PTNT over increasing number of telestroke consults. NVFs evaluated 53.7% of 618 tissue-type plasminogen activator cases over telestroke. NVAs had significantly shorter PTNT compared with NVFs, with a difference in median PTNT of -9 minutes (95% confidence interval, -12.3 to -5.7). This difference persisted when adjusted for relative tissue-type plasminogen activator contraindications. For each additional telestroke consult, PTNT decreased by 0.07 minutes for NVFs or NVAs ( P =0.02 and importance of integrating telestroke training into supervised neurovascular fellowships to increase proficiency prior to independent practice and suggest that PTNT can be a benchmark for tracking proficiency. © 2017 American Heart Association, Inc.

  11. Speech Compression

    Directory of Open Access Journals (Sweden)

    Jerry D. Gibson

    2016-06-01

    Full Text Available Speech compression is a key technology underlying digital cellular communications, VoIP, voicemail, and voice response systems. We trace the evolution of speech coding based on the linear prediction model, highlight the key milestones in speech coding, and outline the structures of the most important speech coding standards. Current challenges, future research directions, fundamental limits on performance, and the critical open problem of speech coding for emergency first responders are all discussed.

  12. Early disrupted neurovascular coupling and changed event level hemodynamic response function in type 2 diabetes: an fMRI study.

    Science.gov (United States)

    Duarte, João V; Pereira, João M S; Quendera, Bruno; Raimundo, Miguel; Moreno, Carolina; Gomes, Leonor; Carrilho, Francisco; Castelo-Branco, Miguel

    2015-10-01

    Type 2 diabetes (T2DM) patients develop vascular complications and have increased risk for neurophysiological impairment. Vascular pathophysiology may alter the blood flow regulation in cerebral microvasculature, affecting neurovascular coupling. Reduced fMRI signal can result from decreased neuronal activation or disrupted neurovascular coupling. The uncertainty about pathophysiological mechanisms (neurodegenerative, vascular, or both) underlying brain function impairments remains. In this cross-sectional study, we investigated if the hemodynamic response function (HRF) in lesion-free brains of patients is altered by measuring BOLD (Blood Oxygenation Level-Dependent) response to visual motion stimuli. We used a standard block design to examine the BOLD response and an event-related deconvolution approach. Importantly, the latter allowed for the first time to directly extract the true shape of HRF without any assumption and probe neurovascular coupling, using performance-matched stimuli. We discovered a change in HRF in early stages of diabetes. T2DM patients show significantly different fMRI response profiles. Our visual paradigm therefore demonstrated impaired neurovascular coupling in intact brain tissue. This implies that functional studies in T2DM require the definition of HRF, only achievable with deconvolution in event-related experiments. Further investigation of the mechanisms underlying impaired neurovascular coupling is needed to understand and potentially prevent the progression of brain function decrements in diabetes.

  13. Volumetric BOLD fMRI simulation: from neurovascular coupling to multivoxel imaging

    International Nuclear Information System (INIS)

    Chen, Zikuan; Calhoun, Vince

    2012-01-01

    The blood oxygenation-level dependent (BOLD) functional magnetic resonance imaging (fMRI) modality has been numerically simulated by calculating single voxel signals. However, the observation on single voxel signals cannot provide information regarding the spatial distribution of the signals. Specifically, a single BOLD voxel signal simulation cannot answer the fundamental question: is the magnetic resonance (MR) image a replica of its underling magnetic susceptibility source? In this paper, we address this problem by proposing a multivoxel volumetric BOLD fMRI simulation model and a susceptibility expression formula for linear neurovascular coupling process, that allow us to examine the BOLD fMRI procedure from neurovascular coupling to MR image formation. Since MRI technology only senses the magnetism property, we represent a linear neurovascular-coupled BOLD state by a magnetic susceptibility expression formula, which accounts for the parameters of cortical vasculature, intravascular blood oxygenation level, and local neuroactivity. Upon the susceptibility expression of a BOLD state, we carry out volumetric BOLD fMRI simulation by calculating the fieldmap (established by susceptibility magnetization) and the complex multivoxel MR image (by intravoxel dephasing). Given the predefined susceptibility source and the calculated complex MR image, we compare the MR magnitude (phase, respectively) image with the predefined susceptibility source (the calculated fieldmap) by spatial correlation. The spatial correlation between the MR magnitude image and the magnetic susceptibility source is about 0.90 for the settings of T E = 30 ms, B 0 = 3 T, voxel size = 100 micron, vessel radius = 3 micron, and blood volume fraction = 2%. Using these parameters value, the spatial correlation between the MR phase image and the susceptibility-induced fieldmap is close to 1.00. Our simulation results show that the MR magnitude image is not an exact replica of the magnetic susceptibility

  14. Acute Resveratrol Consumption Improves Neurovascular Coupling Capacity in Adults with Type 2 Diabetes Mellitus

    Directory of Open Access Journals (Sweden)

    Rachel H.X. Wong

    2016-07-01

    Full Text Available Background: Poor cerebral perfusion may contribute to cognitive impairment in type 2 diabetes mellitus (T2DM. We conducted a randomized controlled trial to test the hypothesis that resveratrol can enhance cerebral vasodilator function and thereby alleviate the cognitive deficits in T2DM. We have already reported that acute resveratrol consumption improved cerebrovascular responsiveness (CVR to hypercapnia. We now report the effects of resveratrol on neurovascular coupling capacity (CVR to cognitive stimuli, cognitive performance and correlations with plasma resveratrol concentrations. Methods: Thirty-six T2DM adults aged 40–80 years were randomized to consume single doses of resveratrol (0, 75, 150 and 300 mg at weekly intervals. Transcranial Doppler ultrasound was used to monitor changes in blood flow velocity (BFV during a cognitive test battery. The battery consisted of dual-tasking (finger tapping with both Trail Making task and Serial Subtraction 3 task and a computerized multi-tasking test that required attending to four tasks simultaneously. CVR to cognitive tasks was calculated as the per cent increase in BFV from pre-test basal to peak mean blood flow velocity and also as the area under the curve for BFV. Results: Compared to placebo, 75 mg resveratrol significantly improved neurovascular coupling capacity, which correlated with plasma total resveratrol levels. Enhanced performance on the multi-tasking test battery was also evident following 75 mg and 300 mg of resveratrol. Conclusion: a single 75 mg dose of resveratrol was able to improve neurovascular coupling and cognitive performance in T2DM. Evaluation of benefits of chronic resveratrol supplementation is now warranted.

  15. Accessory neurovascular foramina on the lingual surface of mandible: Incidence, topography, and clinical implications

    Directory of Open Access Journals (Sweden)

    B V Murlimanju

    2012-01-01

    Full Text Available Context: It was suggested that the accessory neurovascular foramina of the mandible might be of significance in relation to the effectiveness of local anesthesia following the routine inferior alveolar nerve block. Aims: To investigate the incidence of neurovascular foramina over the lingual surface of the mandible in South Indian population. Settings and Design: The study was conducted at the department of anatomy. Materials and Methods: The study included 67 human adult dry mandibles, the exact ages and sexes of which were not known. The location and number of neurovascular foramina were topographically analyzed. Statistical Analysis Used: Descriptive statistics. Results: The foramina were observed in 64 mandibles (95.5% and were often multiple in most of the cases. They were located between the two medial incisors in 8 mandibles (1.9%, between the medial and lateral incisor in 34 mandibles (50.7%; 25-bilateral; 7-right; 2-left, between the lateral incisor and canine in 7 mandibles (10.4%; 2-bilateral; 3-right; 2-left, between the canine and first premolar in 6 cases (8.9%; 3 on each side. Foramina were also present around the genial tubercle in 56 mandibles (83.6%. Among them, 52 mandibles showed a single foramen just above the genial tubercle, 34 mandibles had foramina below the tubercles, 13 mandibles had foramina on the right side of genial tubercle and 17 were having on the left side. Conclusion: Since the anatomical details of these foramina are important to various fields of dentistry and oncology, the present investigation was undertaken. The clinical significance and implications are emphasized.

  16. Microvascular Decompression for Classical Trigeminal Neuralgia Caused by Venous Compression: Novel Anatomic Classifications and Surgical Strategy.

    Science.gov (United States)

    Wu, Min; Fu, Xianming; Ji, Ying; Ding, Wanhai; Deng, Dali; Wang, Yehan; Jiang, Xiaofeng; Niu, Chaoshi

    2018-05-01

    Microvascular decompression of the trigeminal nerve is the most effective treatment for trigeminal neuralgia. However, when encountering classical trigeminal neuralgia caused by venous compression, the procedure becomes much more difficult, and failure or recurrence because of incomplete decompression may become frequent. This study aimed to investigate the anatomic variation of the culprit veins and discuss the surgical strategy for different types. We performed a retrospective analysis of 64 consecutive cases in whom veins were considered as responsible vessels alone or combined with other adjacent arteries. The study classified culprit veins according to operative anatomy and designed personalized approaches and decompression management according to different forms of compressive veins. Curative effects were assessed by the Barrow Neurological Institute (BNI) pain intensity score and BNI facial numbness score. The most commonly encountered veins were the superior petrosal venous complex (SPVC), which was artificially divided into 4 types according to both venous tributary distribution and empty point site. We synthetically considered these factors and selected an approach to expose the trigeminal root entry zone, including the suprafloccular transhorizontal fissure approach and infratentorial supracerebellar approach. The methods of decompression consist of interposing and transposing by using Teflon, and sometimes with the aid of medical adhesive. Nerve combing (NC) of the trigeminal root was conducted in situations of extremely difficult neurovascular compression, instead of sacrificing veins. Pain completely disappeared in 51 patients, and the excellent outcome rate was 79.7%. There were 13 patients with pain relief treated with reoperation. Postoperative complications included 10 cases of facial numbness, 1 case of intracranial infection, and 1 case of high-frequency hearing loss. The accuracy recognition of anatomic variation of the SPVC is crucial for the

  17. Augmented reality in neurovascular surgery: feasibility and first uses in the operating room.

    Science.gov (United States)

    Kersten-Oertel, Marta; Gerard, Ian; Drouin, Simon; Mok, Kelvin; Sirhan, Denis; Sinclair, David S; Collins, D Louis

    2015-11-01

    The aim of this report is to present a prototype augmented reality (AR) intra-operative brain imaging system. We present our experience of using this new neuronavigation system in neurovascular surgery and discuss the feasibility of this technology for aneurysms, arteriovenous malformations (AVMs), and arteriovenous fistulae (AVFs). We developed an augmented reality system that uses an external camera to capture the live view of the patient on the operating room table and to merge this view with pre-operative volume-rendered vessels. We have extensively tested the system in the laboratory and have used the system in four surgical cases: one aneurysm, two AVMs and one AVF case. The developed AR neuronavigation system allows for precise patient-to-image registration and calibration of the camera, resulting in a well-aligned augmented reality view. Initial results suggest that augmented reality is useful for tailoring craniotomies, localizing vessels of interest, and planning resection corridors. Augmented reality is a promising technology for neurovascular surgery. However, for more complex anomalies such as AVMs and AVFs, better visualization techniques that allow one to distinguish between arteries and veins and determine the absolute depth of a vessel of interest are needed.

  18. The significance of the neurovascular structures passing through the spinoglenoid notch

    International Nuclear Information System (INIS)

    Atekin, Mustafa; Demiryiirek, Deniz; Bayramoglu, Alp; Tuccar, Eray

    2003-01-01

    To define the detailed anatomy of the neurovascular bundle at the spinoglenoid notch and to report the dimensions of these structures in cadavers. In the present study, the external diameters of suprascapular artery, vein and nerve were measured at the spinoglenoid region in 18 formalin fixed cadavers (36 soulders) by using a caliper. The study was carried out in the dissection laboratory of Anatomy Department of Hacettepe University ,Ankara University, Ankara and Mersin University ,Mersin,Turkey, between2002 and 2003.The average external diameter for suprascapular vein was 2.6 mmand nerve was 2.2 mm. The spinoglenoid notch was roofed by the spinoglenoid ligament and appeared as a fibroosseous foramen in all cadavers. We found that vascular structures (suprascapular artery and vein )occupied 68.5% and the suprascapular nerve occupied 31.5% of this foramen. Although the diameters of the vascular structures at the spinoglenoid notch measured by magnetic resonance imaging have been reported,to our knowledge, external diameters of these structures at the spinoglenoid notch have not been described in cadavers. We believe that detailed anatomy of suprascapular neurovascular bundle at the spinoglenoid notch should be appreciated for better understanding of risk factors possibly causing the sprascapular nerve entrapment syndrome specially for those who are involved in voilent ovehead sports activities such as volleyball and baseball. (author)

  19. Neurovascular structures of the mandibular angle and condyle: a comprehensive anatomical review.

    Science.gov (United States)

    Yang, Hun-Mu; Won, Sung-Yoon; Kim, Hee-Jin; Hu, Kyung-Seok

    2015-11-01

    Various surgical interventions including esthetic surgery, salivary gland excision, and open reduction of fracture have been performed in the area around the mandibular angle and condyle. This study aimed to comprehensively review the anatomy of the neurovascular structures on the angle and condyle with recent anatomic and clinical research. We provide detailed information about the branching and distributing patterns of the neurovascular structures at the mandibular angle and condyle, with reported data of measurements and proportions from previous anatomical and clinical research. Our report should serve to help practitioners gain a better understanding of the area in order or reduce potential complications during local procedures. Reckless manipulation during mandibular angle reduction could mutilate arterial branches, not only from the facial artery, but also from the external carotid artery. The transverse facial artery and superficial temporal artery could be damaged during approach and incision in the condylar area. The marginal mandibular branch of the facial nerve can be easily damaged during submandibular gland excision or facial rejuvenation treatment. The main trunk of the facial nerve and its upper and lower distinct divisions have been damaged during parotidectomy, rhytidectomy, and open reductions of condylar fractures. By revisiting the information in the present study, surgeons will be able to more accurately prevent procedure-related complications, such as iatrogenic vascular accidents on the mandibular angle and condyle, complete and partial facial palsy, gustatory sweating (Frey syndrome), and traumatic neuroma after parotidectomy.

  20. Role of pattern recognition receptors of the neurovascular unit in inflamm-aging.

    Science.gov (United States)

    Wilhelm, Imola; Nyúl-Tóth, Ádám; Kozma, Mihály; Farkas, Attila E; Krizbai, István A

    2017-11-01

    Aging is associated with chronic inflammation partly mediated by increased levels of damage-associated molecular patterns, which activate pattern recognition receptors (PRRs) of the innate immune system. Furthermore, many aging-related disorders are associated with inflammation. PRRs, such as Toll-like receptors (TLRs) and nucleotide-binding oligomerization domain-like receptors (NLRs), are expressed not only in cells of the innate immune system but also in other cells, including cells of the neurovascular unit and cerebral vasculature forming the blood-brain barrier. In this review, we summarize our present knowledge about the relationship between activation of PRRs expressed by cells of the neurovascular unit-blood-brain barrier, chronic inflammation, and aging-related pathologies of the brain. The most important damage-associated molecular pattern-sensing PRRs in the brain are TLR2, TLR4, and NLR family pyrin domain-containing protein-1 and pyrin domain-containing protein-3, which are activated during physiological and pathological aging in microglia, neurons, astrocytes, and possibly endothelial cells and pericytes. Copyright © 2017 the American Physiological Society.

  1. Curcumin-loaded embryonic stem cell exosomes restored neurovascular unit following ischemia-reperfusion injury.

    Science.gov (United States)

    Kalani, Anuradha; Chaturvedi, Pankaj; Kamat, Pradip K; Maldonado, Claudio; Bauer, Philip; Joshua, Irving G; Tyagi, Suresh C; Tyagi, Neetu

    2016-10-01

    We tested whether the combined nano-formulation, prepared with curcumin (anti-inflammatory and neuroprotective molecule) and embryonic stem cell exosomes (MESC-exo cur ), restored neurovascular loss following an ischemia reperfusion (IR) injury in mice. IR-injury was created in 8-10 weeks old mice and divided into two groups. Out of two IR-injured groups, one group received intranasal administration of MESC-exo cur for 7days. Similarly, two sham groups were made and one group received MESC-exo cur treatment. The study determined that MESC-exo cur treatment reduced neurological score, infarct volume and edema following IR-injury. As compared to untreated IR group, MESC-exo cur treated-IR group showed reduced inflammation and N-methyl-d-aspartate receptor expression. Treatment of MESC-exo cur also reduced astrocytic GFAP expression and alleviated the expression of NeuN positive neurons in IR-injured mice. In addition, MESC-exo cur treatment restored vascular endothelial tight (claudin-5 and occludin) and adherent (VE-cadherin) junction proteins in IR-injured mice as compared to untreated IR-injured mice. These results suggest that combining the potentials of embryonic stem cell exosomes and curcumin can help neurovascular restoration following ischemia-reperfusion injury in mice. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Hereditary hemorrhagic telangiectasia in children: endovascular treatment of neurovascular malformations. Results in 31 patients

    International Nuclear Information System (INIS)

    Krings, T.; Chng, S.M.; Ozanne, A.; Alvarez, H.; Lasjaunias, P.L.; Rodesch, G.

    2005-01-01

    Hereditary hemorrhagic telangiectasia (HHT) is a heterogeneous disease that can present with a variety of clinical manifestations. The neurovascular complications of this disease, especially in children, may be potentially devastating. The purpose of this article was to review the therapeutic results of endovascular treatment of neurovascular malformations in children. A total of 31 patients under the age of 16 were included in this retrospective analysis. All children were treated in a single center. Twenty children presented with 28 arteriovenous (AV) fistulae, including seven children with spinal AV fistulae and 14 children with cerebral AV fistulae (one child had both a spinal and cerebral fistulae). Eleven children had small nidus-type AV malformations. All embolizations were performed employing superselective glue injection. Follow-up ranged between 3 and 168 months (mean 66 months). A total of 115 feeding vessels were embolized in 81 single sessions, resulting in a mean overall occlusion rate of the malformation of 77.4% (ranging from 30 to 100%). Two of 31 patients (6.5%) died as a direct complication of the embolization procedure; two patients (6.5%) had a persistent new neurological deficit; eight patients (26.7%) were clinically unchanged following the procedure; in 13 patients (41.9%) an amelioration of symptoms but no cure could be achieved; and six patients (19.4%) were completely asymptomatic following the endovascular procedure. (orig.)

  3. Relationship between the internal laryngeal nerve and the triticeal cartilage: a potentially unrecognized compression site during anterior cervical spine and carotid endarterectomy operations.

    Science.gov (United States)

    Tubbs, R Shane; Dixon, Joshua F; Loukas, Marios; Shoja, Mohammadali M; Cohen-Gadol, Aaron A

    2010-06-01

    The triticeal cartilage has received scant attention in the literature. To date, its relationship to the nearby internal laryngeal nerve has not been studied. Therefore, to elucidate further this anatomic relationship and its potential surgical implications, this study was performed. Eighty-six adult cadaveric sides underwent dissection of the internal laryngeal nerve near its penetration of the thyrohyoid membrane. The relationship of this nerve to the triticeal cartilage was documented. Measurements and histological analysis were performed on all cartilage specimens. We identified triticeal cartilage in 51% of the specimens and found it to be hyaline in nature. The triticeal cartilage was located in the upper, middle, and lower thirds of the thyrohyoid membrane in 14%, 66%, and 20% of sides, respectively. Regardless of the position of the triticeal cartilage within the thyrohyoid membrane, the internal laryngeal nerve crossed directly over the triticeal cartilage on 59% of sides. When present, the internal laryngeal nerve will cross over the triticeal cartilage in the majority of individuals. This relationship should be borne in mind during surgical manipulation in this area and when placing retractors during anterior neck operations including cervical discectomy/fusion and carotid endarterectomy. Compression of the internal laryngeal nerve against the solid triticeal cartilage can cause laryngeal nerve palsy and increase the risk of resultant postoperative aspiration.

  4. DNABIT Compress – Genome compression algorithm

    OpenAIRE

    Rajarajeswari, Pothuraju; Apparao, Allam

    2011-01-01

    Data compression is concerned with how information is organized in data. Efficient storage means removal of redundancy from the data being stored in the DNA molecule. Data compression algorithms remove redundancy and are used to understand biologically important molecules. We present a compression algorithm, “DNABIT Compress” for DNA sequences based on a novel algorithm of assigning binary bits for smaller segments of DNA bases to compress both repetitive and non repetitive DNA sequence. Our ...

  5. DNABIT Compress – Genome compression algorithm

    Science.gov (United States)

    Rajarajeswari, Pothuraju; Apparao, Allam

    2011-01-01

    Data compression is concerned with how information is organized in data. Efficient storage means removal of redundancy from the data being stored in the DNA molecule. Data compression algorithms remove redundancy and are used to understand biologically important molecules. We present a compression algorithm, “DNABIT Compress” for DNA sequences based on a novel algorithm of assigning binary bits for smaller segments of DNA bases to compress both repetitive and non repetitive DNA sequence. Our proposed algorithm achieves the best compression ratio for DNA sequences for larger genome. Significantly better compression results show that “DNABIT Compress” algorithm is the best among the remaining compression algorithms. While achieving the best compression ratios for DNA sequences (Genomes),our new DNABIT Compress algorithm significantly improves the running time of all previous DNA compression programs. Assigning binary bits (Unique BIT CODE) for (Exact Repeats, Reverse Repeats) fragments of DNA sequence is also a unique concept introduced in this algorithm for the first time in DNA compression. This proposed new algorithm could achieve the best compression ratio as much as 1.58 bits/bases where the existing best methods could not achieve a ratio less than 1.72 bits/bases. PMID:21383923

  6. A THEMIS Survey of Flux Ropes and Traveling Compression Regions: Location of the Near-Earth Reconnection Site During Solar Minimum

    Science.gov (United States)

    Imber, S. M.; Slavin, J. A.; Auster, H. U.; Angelopoulos, V.

    2011-01-01

    A statistical study of flux ropes and traveling compression regions (TCRs) during the Time History of Events and Macroscale Interactions during Substorms (THEMIS) second tail season has been performed. A combined total of 135 flux ropes and TCRs in the range GSM X approx -14 to -31 R(sub E) were identified, many of these occurring in series of two or more events separated by a few tens of seconds. Those occurring within 10 min of each other were combined into aggregated reconnection events. For the purposes of this survey, these are most likely the products of reconnect ion occurring simultaneously at multiple, closely spaced x-lines as opposed to statistically independent episodes of reconnection. The 135 flux ropes and TCRs were grouped into 87 reconnection events; of these, 28 were moving tailward and 59 were moving Earthward. The average location of the near-Earth x-line determined from statistical analysis of these reconnection events is (X(sub GSM), Y*(sub GSM)) = (-30R(sub E), 5R(sub E)), where Y* includes a correction for the solar aberration angle. A strong east-west asymmetry is present in the tailward events, with >80% being observed at GSM Y* > O. Our results indicate that the Earthward flows are similarly asymmetric in the midtail region, becoming more symmetric inside - 18 R(sub E). Superposed epoch analyses indicate that the occurrence of reconnection closer to the Earth, i.e., X > -20 R(sub E), is associated with elevated solar wind velocity and enhanced negative interplanetary magnetic field B(sub z). Reconnection events taking place closer to the Earth are also far more effective in producing geomagnetic activity, judged by the AL index, than reconnection initiated beyond X approx -25 R(sub E).

  7. Simultaneous functional photoacoustic microscopy and electrocorticography reveal the impact of rtPA on dynamic neurovascular functions after cerebral ischemia.

    Science.gov (United States)

    Bandla, Aishwarya; Liao, Lun-De; Chan, Su Jing; Ling, Ji Min; Liu, Yu-Hang; Shih, Yen-Yu Ian; Pan, Han-Chi; Wong, Peter Tsun-Hon; Lai, Hsin-Yi; King, Nicolas Kon Kam; Chen, You-Yin; Ng, Wai Hoe; Thakor, Nitish V

    2018-06-01

    The advance of thrombolytic therapy has been hampered by the lack of optimization of the therapy during the hyperacute phase of focal ischemia. Here, we investigate neurovascular dynamics using a custom-designed hybrid electrocorticography (ECoG)-functional photoacoustic microscopy (fPAM) imaging system during the hyperacute phase (first 6 h) of photothrombotic ischemia (PTI) in male Wistar rats following recombinant tissue plasminogen activator (rtPA)-mediated thrombolysis. We reported, for the first time, the changes in neural activity and cerebral hemodynamic responses following rtPA infusion at different time points post PTI. Interestingly, very early administration of rtPA ( 4 h post PTI) resulted in the deterioration of neurovascular function. A therapeutic window between 1 and 3 h post PTI was found to improve recovery of neurovascular function (i.e. significant restoration of neural activity to 93 ± 4.2% of baseline and hemodynamics to 81 ± 2.1% of baseline, respectively). The novel combination of fPAM and ECoG enables direct mapping of neurovascular dynamics and serves as a platform to evaluate potential interventions for stroke.

  8. Brachytherapy in the conservative treatment of soft tissue sarcomas extending to neurovascular structures: an analysis of 38 cases

    International Nuclear Information System (INIS)

    Thomas, L.; Delannes, M.; Stoeckle, E.; Martel, P.; Pigneux, J.; Daly-Schveitzer, N.; Bui, B.N.; Chevreau, C.; Kantor, G.

    1996-01-01

    To evaluate the tolerance of neurovascular structures to brachytherapy, a retrospective review of our series was undertaken. Between May 1986 and January 1994, 85 patients with soft tissue sarcomas underwent conservative surgery and low-dose rate interstitial irradiation. Thirty-eight patients had tumors extending to neurovascular structures. Brachytherapy was part of initial treatment in 30 patients and was done in 7 cases for recurrent sarcomas. Afterloading catethers for brachytherapy were inserted intraoperatively and placed direct upon or under the neurovascular structures in the tumor bed. A mean dose of 20 Gy was delivered to the target volume. Thirty patients received 45 to 50 Gy of postoperative external irradiation. With a median follow-up of 39 months, the 3-year actuarial survival was 82.9%, the 3-year disease-free survival was 71.9% and the 3-year actuarial local control was 91%. The 3-year actuarial incidence of distant metastase was 28%. Acute side effects occurred in 12 patients requiring conservative surgical procedures in 6 cases. Significant late toxicity occurred in 8 patients : 2 lymphoedemas interfering with normal activity, 1 partial artery stenosis, 5 peripheral neuropathy (2 grade 2, 3 grade 3). Late toxicity has led to significant impairment of mobility in 4 patients. Limb preservation was achieved in every patient, no amputation was required. We conclude that integration of brachytherapy in the conservative treatment of soft tissue sarcomas extending to neurovascular structures can provide excellent local control with an acceptable level of toxicity

  9. Sural artery perforator flap with posterior tibial neurovascular decompression for recurrent foot ulcer in leprosy patients

    Directory of Open Access Journals (Sweden)

    Ismail, Hossam El-din Ali

    2017-01-01

    Full Text Available Introduction: The sensory loss and alteration of the shape of the foot make the foot liable to trauma and pressure, and subsequently cause more callus formation, blisters, and ulcers. Foot ulcers usually are liable to secondary infection as cellulitis or osteomyelitis, and may result in amputations. Foot ulcers are a major problem and a major cause of handicaps in leprosy patients. The current study is to present our clinical experience and evaluate the use of sural flap with posterior tibial neurovascular decompression (PTND in recurrent foot ulcers in leprosy patients.Patient and methods: A total number of 9 patients were suffering from chronic sequelae of leprosy as recurrent foot ulcers. All the patients were reconstructed with the reverse sural artery fasciocutaneous flap with posterior tibial neurovascular decompression from September 2012 to August 2015. Six patients were male and three were female with a mean age of 39.8 years (range, 30–50 years. All the soft tissue defects were in the weight-bearing area of the inside of the foot. The flap sizes ranged from 15/4 to 18/6 cm. Mean follow-up period was 21.2 months (range, 35–2 months.Results: All the flaps healed uneventfully. There was no major complication as total flap necrosis. Only minor complications occurred which were treated without surgical intervention except in two patients who developed superficial necrosis of the skin paddle. Surgical debridement was done one week later. The flap was completely viable after surgery, and the contour of the foot was restored. We found that an improvement of sensation occurred in those patients in whom the anesthesia started one year ago or less and no sensory recovery in patient in whom the anesthesia had lasted for more than two years.Conclusion: The reverse sural artery flap with posterior tibial neurovascular decompression provides a reliable method for recurrent foot soft tissue reconstruction in leprosy patients with encouraging

  10. Optimum SNR data compression in hardware using an Eigencoil array.

    Science.gov (United States)

    King, Scott B; Varosi, Steve M; Duensing, G Randy

    2010-05-01

    With the number of receivers available on clinical MRI systems now ranging from 8 to 32 channels, data compression methods are being explored to lessen the demands on the computer for data handling and processing. Although software-based methods of compression after reception lessen computational requirements, a hardware-based method before the receiver also reduces the number of receive channels required. An eight-channel Eigencoil array is constructed by placing a hardware radiofrequency signal combiner inline after preamplification, before the receiver system. The Eigencoil array produces signal-to-noise ratio (SNR) of an optimal reconstruction using a standard sum-of-squares reconstruction, with peripheral SNR gains of 30% over the standard array. The concept of "receiver channel reduction" or MRI data compression is demonstrated, with optimal SNR using only four channels, and with a three-channel Eigencoil, superior sum-of-squares SNR was achieved over the standard eight-channel array. A three-channel Eigencoil portion of a product neurovascular array confirms in vivo SNR performance and demonstrates parallel MRI up to R = 3. This SNR-preserving data compression method advantageously allows users of MRI systems with fewer receiver channels to achieve the SNR of higher-channel MRI systems. (c) 2010 Wiley-Liss, Inc.

  11. Patient Satisfaction After Femoral Arterial Access Site Closure Using the ExoSeal® Vascular Closure Device Compared to Manual Compression: A Prospective Intra-individual Comparative Study

    International Nuclear Information System (INIS)

    Pieper, Claus Christian; Thomas, Daniel; Nadal, Jennifer; Willinek, Winfried A.; Schild, Hans Heinz; Meyer, Carsten

    2016-01-01

    PurposeTo intra-individually compare discomfort levels and patient satisfaction after arterial access closure using the ExoSeal ® vascular closure device (VCD) and manual compression (MC) in a prospective study design.MethodsPatients undergoing two planned interventions from 07/2013 to 09/2014 could participate in the study. Access closure was performed with an ExoSeal ® -VCD in one and MC in the other intervention. Patients were clinically and sonographically examined and were given questionnaires 1 day after intervention [groin- and back-pain during bedrest (100-point visual analog scale; 0: no pain); comfortability of bedrest (10-point Likert scale, 1: comfortable), satisfaction with closure (10-point Likert scale, 1: very satisfied)]. Results were analyzed in a cross-over design.Results48 patients (29 male, median age 62.5 (32–88) years) were included. An ExoSeal ® -VCD was used first in 25 cases. As four of these subsequently refused MC as second intervention, data from 44 patients could be analyzed. All closures were technically successful (successful device deployment) without major complications. Groin- and back-pain after VCD-use/MC was 0 (0–15) vs. 10 (0–80) and 0 (0–75) vs. 25 (0–90), respectively (p < 0.0001). Bedrest after VCD-use was more comfortable than after MC [1 (range 1–7) vs. 6 (2–10); p < 0.0001]. Satisfaction with the closure procedure and with the intervention in general was higher after VCD-use compared to MC [1 (1–3) vs. 5 (2–10) and 1 (1–2) vs. 2 (1–4), respectively; p < 0.0001].ConclusionIntra-individual comparison showed pain levels and discomfort to be significantly lower after ExoSeal ® use compared to MC. VCD closure was associated with higher satisfaction both with the closure itself and with the intervention in general

  12. Wavelets: Applications to Image Compression-II

    Indian Academy of Sciences (India)

    Wavelets: Applications to Image Compression-II. Sachin P ... successful application of wavelets in image com- ... b) Soft threshold: In this case, all the coefficients x ..... [8] http://www.jpeg.org} Official site of the Joint Photographic Experts Group.

  13. Seneca Compressed Air Energy Storage (CAES) Project

    Energy Technology Data Exchange (ETDEWEB)

    None

    2012-11-30

    This document provides specifications for the process air compressor for a compressed air storage project, requests a budgetary quote, and provides supporting information, including compressor data, site specific data, water analysis, and Seneca CAES value drivers.

  14. Anatomical Evaluation of the Proximity of Neurovascular Structures During Arthroscopically Assisted Acromioclavicular Joint Reconstruction: A Cadaveric Pilot Study.

    Science.gov (United States)

    Banaszek, Daniel; Pickell, Michael; Wilson, Evan; Ducsharm, Melissa; Hesse, Daniel; Easteal, Ron; Bardana, Davide D

    2017-01-01

    The purpose of this study was to examine the safety of an arthroscopic technique for acromioclavicular joint (ACJ) reconstruction by investigating its proximity to important neurovascular structures. Six shoulders from 4 cadaveric specimens were used for ACJ reconstruction in this study. The procedure consists of performing an arthroscopic acromioclavicular (AC) reduction with a double button construct, followed by coracoclavicular ligament reconstruction without drilling clavicular tunnels. Shoulders were subsequently dissected in order to identify and measure distances to adjacent neurovascular structures. The suprascapular artery and nerve were the closest neurovascular structures to implanted materials. The mean distances were 8.2 (standard deviation [SD] = 3.6) mm to the suprascapular nerve and 5.6 (SD = 4.2) mm to the suprascapular artery. The mean distance of the suprascapular nerve from implants was found to be greater than 5 mm (P = .040), while the distance to the suprascapular artery was not (P > .5). Neither difference was statistically significant (P = .80 for artery; P = .08 for nerve). Mini-open, arthroscopically assisted ACJ reconstruction safely avoids the surrounding nerves, with no observed damage to any neurovascular structures including the suprascapular nerve and artery, and may be a viable alternative to open techniques. However, surgeons must remain cognizant of possible close proximity to the suprascapular artery. This study represents an evaluation of the safety and feasibility of a minimally invasive ACJ reconstruction as it relates to the proximity of neurovascular structures. Copyright © 2016 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

  15. The temporal evolution of a facial pain syndrome associated with neurovascular contact

    DEFF Research Database (Denmark)

    Khan, Sabrina; Wibrandt, Ida; Rochat, Per Bjørnstad

    2015-01-01

    BACKGROUND: Trigeminal autonomic cephalalgias are primary headaches characterized by unilateral pain and cranial autonomic symptoms. However, associated autonomic symptoms have also been reported in other headaches and facial pains, e.g. trigeminal neuralgia, with the clinical differentiation...... proving a complex task. CASE: A 54-year-old man presented with right-sided, sharp, intense facial pain in the distribution area of the trigeminal nerve. Pain duration was from seconds to a few minutes, and trigger factors included ipsilateral touching of the skin and hair. Over the next ten years...... revealed a right-sided deviation of the basilar artery at the level of pons, creating neurovascular contact with the trigeminal nerve. Microvascular decompression was performed, and symptoms resolved within days. CONCLUSION: Differentiating between trigeminal autonomic cephalalgias and trigeminal neuralgia...

  16. Persistent increase in oxygen consumption and impaired neurovascular coupling after spreading depression in rat neocortex

    DEFF Research Database (Denmark)

    Hansen, Henning Piilgaard; Lauritzen, Martin

    2009-01-01

    trauma. Here we tested the hypothesis that single episodes of CSD induced acute hypoxia, and prolonged impairment of neurovascular and neurometabolic coupling. Cortical spreading depression was induced in rat frontal cortex, whereas cortical electrical activity and local field potentials (LFPs) were......Cortical spreading depression (CSD) is associated with a dramatic failure of brain ion homeostasis and increased energy metabolism. There is strong clinical and experimental evidence to suggest that CSD is the mechanism of migraine, and involved in progressive neuronal injury in stroke and head...... recorded by glass microelectrodes, cerebral blood flow (CBF) by laser-Doppler flowmetry, and tissue oxygen tension (tpO(2)) with polarographic microelectrodes. Cortical spreading depression increased cerebral metabolic rate of oxygen (CMRO(2)) by 71%+/-6.7% and CBF by 238%+/-48.1% for 1 to 2 mins...

  17. The use of neurovascular ultrasound versus digital subtraction angiography in acute ischemic stroke

    Directory of Open Access Journals (Sweden)

    Marcos C. Lange

    2015-03-01

    Full Text Available Cervical and intracranial arterial evaluation is an important issue for acute ischemic stroke (IS. Objective Compare the use of the neurovascular ultrasound examination (NVUE to digital subtraction angiography (DSA in acute IS patients for diagnosing significant extracranial and intracranial arteriopathy. Method Nonconsecutive patients with IS or transient ischemic attack admitted within 12 hours of the onset of symptoms were evaluated retrospectively. Standardized NVUE and DSA were done in all patients within the first 120 hours of hospital admission. Results Twenty-four patients were included in the study. Compared to DSA, the NVUE demonstrated 94.7% sensitivity and 100% specificity for identifying symptomatic extracranial and/or intracranial arteriopathy. Conclusion The standardized NVUE technique demonstrated high sensitivity and specificity compared to DSA for diagnosing arterial abnormalities in acute IS patients.

  18. Neurovascular coupling to D2/D3 dopamine receptor occupancy using simultaneous PET/functional MRI

    DEFF Research Database (Denmark)

    Sander, Christin Y; Hooker, Jacob M; Catana, Ciprian

    2013-01-01

    This study employed simultaneous neuroimaging with positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) to demonstrate the relationship between changes in receptor occupancy measured by PET and changes in brain activity inferred by fMRI. By administering the D2/D3...... dopamine receptor antagonist [(11)C]raclopride at varying specific activities to anesthetized nonhuman primates, we mapped associations between changes in receptor occupancy and hemodynamics [cerebral blood volume (CBV)] in the domains of space, time, and dose. Mass doses of raclopride above tracer levels...... caused increases in CBV and reductions in binding potential that were localized to the dopamine-rich striatum. Moreover, similar temporal profiles were observed for specific binding estimates and changes in CBV. Injection of graded raclopride mass doses revealed a monotonic coupling between neurovascular...

  19. "In situ preparation": new surgical procedure indicated for soft-tissue sarcoma of a lower limb in close proximity to major neurovascular structures.

    Science.gov (United States)

    Matsumoto, Seiichi; Kawaguchi, Noriyoshi; Manabe, Jun; Matsushita, Yasushi

    2002-02-01

    When soft-tissue sarcomas occur near neurovascular structures, preoperative images cannot always reveal the accurate relationship between the tumor and these structures. Therefore, in some patients, neurovascular structures are sacrificed unnecessarily. In other patients, neurovascular structures are preserved with an inappropriate margin, followed by local recurrence. The objective of this study was to evaluate a new surgical method, "in situ preparation" (ISP), which enables the preparation of neurovascular bundles and the intraoperative evaluation of the surgical margin without contamination by tumor cells. With this method, additional procedures, including pasteurization, alcohol soaking, and distilled water soaking of the preserved neurovascular bundle can also be performed to preserve the continuity of vessels. Between April 1992 and December 1998, 18 patients with soft-tissue sarcoma were operated on using ISP. The tumor and neurovascular structure were lifted en bloc from the surgical bed and separated from the field by the use of a vinyl sheet. The consistency of the neurovascular structures was preserved. The tissue block could be freely turned around and the neurovascular structure was separated from the block through the nearest approach. The margin between the tumor and neurovascular structure was evaluated, and an additional procedure, such as pasteurization, alcohol soaking or distilled water soaking, was performed, according to the safety of the surgical margin. Only one patient showed recurrence after ISP. Complications after ISP were arterial occlusion in two patients and nerve palsy in three patients. The main cause of these complications was the long period of pasteurization; modified additional procedures could prevent such complications. ISP is a useful method with which to ensure a safe surgical margin and good functional results.

  20. Measurement of neurovascular coupling in human motor cortex using simultaneous transcranial doppler (TCD) and electroencephalography (EEG).

    Science.gov (United States)

    Alam, Monzurul; Ahmed, Ghazanfar; Ling, Yan To; Zheng, Yong-Ping

    2018-05-25

    Event-related desynchronization (ERD) is a relative power decrease of electroencephalogram (EEG) signals in a specific frequency band during physical motor execution, while transcranial Doppler (TCD) measures cerebral blood flow velocity. The objective of this study was to investigate the neurovascular coupling in the motor cortex by using an integrated EEG and TCD system, and to find any difference in hemodynamic responses in healthy young male and female adults. Approach: 30 healthy volunteers, aged 20-30 years were recruited for this study. The subjects were asked to perform a motor task for the duration of a provided visual cue. Simultaneous EEG and TCD recording was carried out using a new integrated system to detect the ERD arising from the EEG signals, and to measure the mean blood flow velocity of the left and right middle cerebral arteries from bilateral TCD signals. Main Results: The results showed a significant decrease in EEG power in mu band (7.5-12.5 Hz) during the motor task compared to the resting phase. It showed significant increase in desynchronization on the contralateral side of the motor task compared to the ipsilateral side. Mean blood flow velocity during the task phase was significantly higher in comparison with the resting phase at the contralateral side. The results also showed a significantly higher increase in the percentage of mean blood flow velocity in the contralateral side of motor task compared to the ipsilateral side. However, no significant difference in desynchronization, or change of mean blood flow velocity was found between males and females. Significance: A combined TCD-EEG system successfully detects ERD and blood flow velocity in cerebral arteries, and can be used as a useful tool to study neurovascular coupling in the brain. There is no significant difference in the hemodynamic responses in healthy young males and females. © 2018 Institute of Physics and Engineering in Medicine.

  1. Micro-angiography for neuro-vascular imaging. I. Experimental evaluation and feasibility

    International Nuclear Information System (INIS)

    Ganguly, Arundhuti; Rudin, Stephen; Bednarek, Daniel R.; Hoffmann, Kenneth R.; Kyprianou, Iacovos S.

    2003-01-01

    Minimally invasive image-guided neuro-vascular interventions require very high image-resolution and quality, specifically over regions-of-interest (ROI) crucial to the procedure. ROI imaging or micro-angiography, allows limited patient integral radiation dose while permitting rapid frame transfer of high-resolution images. The design and performance of a charge coupled device (CCD) based x-ray detector or micro-angiographic camera was assessed for neuro-vascular procedures. The detector consists of a 250-μm-thick CsI(Tl) phosphor fiber-optically coupled through a 1.8:1 taper to a CCD chip, with an effective image pixel size of 50 μm and a frame rate of 5 fps in the 2:1 pixel-binned mode. The characteristics of the camera including the modulation transfer function (MTF), the noise equivalent quanta, the detective quantum efficiency, observer studies, and the effect of geometric magnification were evaluated. The MTF was found to have nonzero (1.7%) value at the Nyquist frequency of 10 cycles/mm, while the DQE(0) had a value of ∼55%. All values were measured using head equivalent attenuating material in the beam at 80 kVp. Human observer studies performed using the 2 Alternative Forced Choice method revealed that iodinated vessels with inner diameter of 100 μm and 2 cm in length can be seen with a confidence level greater than 75%. The observer studies included a comparison with ideal observer performance calculations based on the integral signal to noise ratio in the image. Probabilities of visualization of various objects of interest in a neuro-intervention, such as stents, were assessed. A geometric magnification of 1 was found to be best for imaging under neuro-angiographic conditions. The detector appeared to satisfy all the demands of neuro-angiography and showed promise as an improvement over existing angiographic detectors

  2. Mechanistic Mathematical Modeling Tests Hypotheses of the Neurovascular Coupling in fMRI.

    Directory of Open Access Journals (Sweden)

    Karin Lundengård

    2016-06-01

    Full Text Available Functional magnetic resonance imaging (fMRI measures brain activity by detecting the blood-oxygen-level dependent (BOLD response to neural activity. The BOLD response depends on the neurovascular coupling, which connects cerebral blood flow, cerebral blood volume, and deoxyhemoglobin level to neuronal activity. The exact mechanisms behind this neurovascular coupling are not yet fully investigated. There are at least three different ways in which these mechanisms are being discussed. Firstly, mathematical models involving the so-called Balloon model describes the relation between oxygen metabolism, cerebral blood volume, and cerebral blood flow. However, the Balloon model does not describe cellular and biochemical mechanisms. Secondly, the metabolic feedback hypothesis, which is based on experimental findings on metabolism associated with brain activation, and thirdly, the neurotransmitter feed-forward hypothesis which describes intracellular pathways leading to vasoactive substance release. Both the metabolic feedback and the neurotransmitter feed-forward hypotheses have been extensively studied, but only experimentally. These two hypotheses have never been implemented as mathematical models. Here we investigate these two hypotheses by mechanistic mathematical modeling using a systems biology approach; these methods have been used in biological research for many years but never been applied to the BOLD response in fMRI. In the current work, model structures describing the metabolic feedback and the neurotransmitter feed-forward hypotheses were applied to measured BOLD responses in the visual cortex of 12 healthy volunteers. Evaluating each hypothesis separately shows that neither hypothesis alone can describe the data in a biologically plausible way. However, by adding metabolism to the neurotransmitter feed-forward model structure, we obtained a new model structure which is able to fit the estimation data and successfully predict new

  3. Developmental switch in neurovascular coupling in the immature rodent barrel cortex.

    Directory of Open Access Journals (Sweden)

    Christoph M Zehendner

    Full Text Available Neurovascular coupling (NVC in the adult central nervous system (CNS is a mechanism that provides regions of the brain with more oxygen and glucose upon increased levels of neural activation. Hemodynamic changes that go along with neural activation evoke a blood oxygen level-dependent (BOLD signal in functional magnetic resonance imaging (fMRI that can be used to study brain activity non-invasively. A correct correlation of the BOLD signal to neural activity is pivotal to understand this signal in neuronal development, health and disease. However, the function of NVC during development is largely unknown. The rodent whisker-to-barrel cortex is an experimentally well established model to study neurovascular interdependences. Using extracellular multi-electrode recordings and laser-Doppler-flowmetry (LDF we show in the murine barrel cortex of postnatal day 7 (P7 and P30 mice in vivo that NVC undergoes a physiological shift during the first month of life. In the mature CNS it is well accepted that cortical sensory processing results in a rise in regional cerebral blood flow (rCBF. We show in P7 animals that rCBF decreases during prolonged multi-whisker stimulation and goes along with multi unit activity (MUA fatigue. In contrast at P30, MUA remains stable during repetitive stimulation and is associated with an increase in rCBF. Further we characterize in both age groups the responses in NVC to single sensory stimuli. We suggest that the observed shift in NVC is an important process in cortical development that may be of high relevance for the correct interpretation of brain activity e.g. in fMRI studies of the immature central nervous system (CNS.

  4. Effects of diet and exercise training on neurovascular control during mental stress in obese women

    Directory of Open Access Journals (Sweden)

    A.C. Tonacio

    2006-01-01

    Full Text Available Since neurovascular control is altered in obese subjects, we hypothesized that weight loss by diet (D or diet plus exercise training (D + ET would improve neurovascular control during mental stress in obese women. In a study with a dietary reduction of 600 kcal/day with or without exercise training for 4 months, 53 obese women were subdivided in D (N = 22, 33 ± 1 years, BMI 34 ± 1 kg/m², D + ET (N = 22, 33 ± 1 years, BMI 33 ± 1 kg/m², and nonadherent (NA, N = 9, 35 ± 2 years, BMI 33 ± 1 kg/m² groups. Muscle sympathetic nerve activity (MSNA was measured by microneurography and forearm blood flow by venous occlusion plethysmography. Mental stress was elicited by a 3-min Stroop color word test. Weight loss was similar between D and D + ET groups (87 ± 2 vs 79 ± 2 and 85 ± 2 vs 76 ± 2 kg, respectively, P < 0.05 with a significant reduction in MSNA during mental stress (58 ± 2 vs 50 ± 2, P = 0.0001, and 59 ± 3 vs 50 ± 2 bursts/100 beats, P = 0.0001, respectively, although the magnitude of the response was unchanged. Forearm vascular conductance during mental stress was significantly increased only in D + ET (2.74 ± 0.22 vs 3.52 ± 0.19 units, P = 0.02. Weight loss reduces MSNA during mental stress in obese women. The increase in forearm vascular conductance after weight loss provides convincing evidence for D + ET interventions as a nonpharmacologic therapy of human obesity.

  5. Metal Hydride Compression

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Terry A. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Bowman, Robert [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Smith, Barton [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Anovitz, Lawrence [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jensen, Craig [Hawaii Hydrogen Carriers LLC, Honolulu, HI (United States)

    2017-07-01

    Conventional hydrogen compressors often contribute over half of the cost of hydrogen stations, have poor reliability, and have insufficient flow rates for a mature FCEV market. Fatigue associated with their moving parts including cracking of diaphragms and failure of seal leads to failure in conventional compressors, which is exacerbated by the repeated starts and stops expected at fueling stations. Furthermore, the conventional lubrication of these compressors with oil is generally unacceptable at fueling stations due to potential fuel contamination. Metal hydride (MH) technology offers a very good alternative to both conventional (mechanical) and newly developed (electrochemical, ionic liquid pistons) methods of hydrogen compression. Advantages of MH compression include simplicity in design and operation, absence of moving parts, compactness, safety and reliability, and the possibility to utilize waste industrial heat to power the compressor. Beyond conventional H2 supplies of pipelines or tanker trucks, another attractive scenario is the on-site generating, pressuring and delivering pure H2 at pressure (≥ 875 bar) for refueling vehicles at electrolysis, wind, or solar generating production facilities in distributed locations that are too remote or widely distributed for cost effective bulk transport. MH hydrogen compression utilizes a reversible heat-driven interaction of a hydride-forming metal alloy with hydrogen gas to form the MH phase and is a promising process for hydrogen energy applications [1,2]. To deliver hydrogen continuously, each stage of the compressor must consist of multiple MH beds with synchronized hydrogenation & dehydrogenation cycles. Multistage pressurization allows achievement of greater compression ratios using reduced temperature swings compared to single stage compressors. The objectives of this project are to investigate and demonstrate on a laboratory scale a two-stage MH hydrogen (H2) gas compressor with a

  6. Compression of surface myoelectric signals using MP3 encoding.

    Science.gov (United States)

    Chan, Adrian D C

    2011-01-01

    The potential of MP3 compression of surface myoelectric signals is explored in this paper. MP3 compression is a perceptual-based encoder scheme, used traditionally to compress audio signals. The ubiquity of MP3 compression (e.g., portable consumer electronics and internet applications) makes it an attractive option for remote monitoring and telemedicine applications. The effects of muscle site and contraction type are examined at different MP3 encoding bitrates. Results demonstrate that MP3 compression is sensitive to the myoelectric signal bandwidth, with larger signal distortion associated with myoelectric signals that have higher bandwidths. Compared to other myoelectric signal compression techniques reported previously (embedded zero-tree wavelet compression and adaptive differential pulse code modulation), MP3 compression demonstrates superior performance (i.e., lower percent residual differences for the same compression ratios).

  7. Cyclosporine A, FK506, and NIM811 ameliorate prolonged CBF reduction and impaired neurovascular coupling after cortical spreading depression

    DEFF Research Database (Denmark)

    Hansen, Henning Piilgaard; Witgen, Brent Marvin; Rasmussen, Peter

    2011-01-01

    Cortical spreading depression (CSD) is associated with mitochondrial depolarization, increasing intracellular Ca(2+), and the release of free fatty acids, which favor opening of the mitochondrial permeability transition pore (mPTP) and activation of calcineurin (CaN). Here, we test the hypothesis...... and the specific CaN blocker FK506. Cortical spreading depression was induced in rat frontal cortex. Electrocortical activity was recorded by glass microelectrodes, CBF by laser Doppler flowmetry, and tissue oxygen tension with polarographic microelectrodes. Electrocortical activity, basal CBF, CMRO(2......), and neurovascular and neurometabolic coupling were unaffected by all three drugs under control conditions. NIM811 augmented the rise in CBF observed during CSD. Cyclosporine A and FK506 ameliorated the persistent decrease in CBF after CSD. All three drugs prevented disruption of neurovascular coupling after CSD...

  8. The false equivalent of terrible triad of elbow combined with neurovascular damage in a rugby player - A new case report.

    Directory of Open Access Journals (Sweden)

    Hassan BOUSSAKRI

    2014-12-01

    Full Text Available  Terrible triad is a severe traumatic injury of the elbow. We report a new variety of this clinical entity originating from a rare combination of injuries, namely the fracture-dislocation of the right elbow. The symptoms are acute ischemia of the hand with neurological damage following a sport accident suffered by a professional rugby player. We treated him surgically after immediate reduction of the dislocation. The short-term monitoring was clinical, while in the medium-term it was radiological and electrophysiological. On the whole, our (clinical, electrophysiological and radiological results obtained initially, and medium-term during the last consultation, were satisfactory. The objective of this study is to draw attention to this clinical and radiological variety, as well as to its neurovascular complications and to discuss its therapeutic treatment. During the vascular and neurologic exam we should pay attention to and systematically look for neurovascular complications when treating a similar clinical case.

  9. 3-D Imaging Reveals Participation of Donor Islet Schwann Cells and Pericytes in Islet Transplantation and Graft Neurovascular Regeneration.

    Science.gov (United States)

    Juang, Jyuhn-Huarng; Kuo, Chien-Hung; Peng, Shih-Jung; Tang, Shiue-Cheng

    2015-02-01

    The primary cells that participate in islet transplantation are the endocrine cells. However, in the islet microenvironment, the endocrine cells are closely associated with the neurovascular tissues consisting of the Schwann cells and pericytes, which form sheaths/barriers at the islet exterior and interior borders. The two cell types have shown their plasticity in islet injury, but their roles in transplantation remain unclear. In this research, we applied 3-dimensional neurovascular histology with cell tracing to reveal the participation of Schwann cells and pericytes in mouse islet transplantation. Longitudinal studies of the grafts under the kidney capsule identify that the donor Schwann cells and pericytes re-associate with the engrafted islets at the peri-graft and perivascular domains, respectively, indicating their adaptability in transplantation. Based on the morphological proximity and cellular reactivity, we propose that the new islet microenvironment should include the peri-graft Schwann cell sheath and perivascular pericytes as an integral part of the new tissue.

  10. A Compressive Superresolution Display

    KAUST Repository

    Heide, Felix; Gregson, James; Wetzstein, Gordon; Raskar, Ramesh; Heidrich, Wolfgang

    2014-01-01

    In this paper, we introduce a new compressive display architecture for superresolution image presentation that exploits co-design of the optical device configuration and compressive computation. Our display allows for superresolution, HDR, or glasses-free 3D presentation.

  11. A Compressive Superresolution Display

    KAUST Repository

    Heide, Felix

    2014-06-22

    In this paper, we introduce a new compressive display architecture for superresolution image presentation that exploits co-design of the optical device configuration and compressive computation. Our display allows for superresolution, HDR, or glasses-free 3D presentation.

  12. Microbunching and RF Compression

    International Nuclear Information System (INIS)

    Venturini, M.; Migliorati, M.; Ronsivalle, C.; Ferrario, M.; Vaccarezza, C.

    2010-01-01

    Velocity bunching (or RF compression) represents a promising technique complementary to magnetic compression to achieve the high peak current required in the linac drivers for FELs. Here we report on recent progress aimed at characterizing the RF compression from the point of view of the microbunching instability. We emphasize the development of a linear theory for the gain function of the instability and its validation against macroparticle simulations that represents a useful tool in the evaluation of the compression schemes for FEL sources.

  13. Preoperative evaluation of neurovascular relationships for microvascular decompression in the cerebellopontine angle in a virtual reality environment.

    Science.gov (United States)

    Du, Zhuo-Ying; Gao, Xiang; Zhang, Xiao-Luo; Wang, Zhi-Qiu; Tang, Wei-Jun

    2010-09-01

    In this paper the authors' goal was to evaluate the feasibility and efficacy of a virtual reality (VR) system in preoperative planning for microvascular decompression (MVD) procedures treating idiopathic trigeminal neuralgia and hemifacial spasm. The system's role in surgical simulation and training was also assessed. Between May 2008 and April 2009, the authors used the Dextroscope system to visualize the neurovascular complex and simulate MVD in the cerebellopontine angle in a VR environment in 16 patients (6 patients had trigeminal neuralgia and 10 had hemifacial spasm). Reconstructions were carried out 2-3 days before MVD. Images were printed in a red-blue stereoscopic format for teaching and discussion and were brought into the operating room to be compared with real-time intraoperative findings. The VR environment was a powerful aid for spatial understanding of the neurovascular relationship in MVD for operating surgeons and trainees. Through an initial series of comparison/confirmation experiences, the senior neurosurgeon became accustomed to the system. He could predict intraoperative problems and simulate surgical maneuvering, which increased his confidence in performing the procedure. The Dextroscope system is an easy and rapid method to create a stereoscopic neurovascular model for MVD that is highly concordant with intraoperative findings. It effectively shortens the learning curve and adds to the surgeon's confidence.

  14. Mining compressing sequential problems

    NARCIS (Netherlands)

    Hoang, T.L.; Mörchen, F.; Fradkin, D.; Calders, T.G.K.

    2012-01-01

    Compression based pattern mining has been successfully applied to many data mining tasks. We propose an approach based on the minimum description length principle to extract sequential patterns that compress a database of sequences well. We show that mining compressing patterns is NP-Hard and

  15. Association between neurovascular contact on MRI and response to gamma knife radiosurgery in trigeminal neuralgia

    International Nuclear Information System (INIS)

    Erbay, Sami H.; Bhadelia, Rafeeque A.; Gupta, Punita; O'Callaghan, Mark; Yun, Eric; Oljeski, Steven; Riesenburger, Ron

    2006-01-01

    Treatment with gamma knife radiosurgery (GKRS) provides adequate short-term pain control in about 70% of the patients with intractable trigeminal neuralgia (TN). The purpose of our study was to evaluate whether the presence of neurovascular contact (NVC) at the root entry zone of the trigeminal nerve on pre-gamma knife MR imaging predicts an increased likelihood of an adequate response to GKRS.We studied 40 consecutive patients who underwent GKRS for treatment of intractable TN. Two neuroradiologists blinded to the side of symptoms analyzed pre-treatment constructive interference in steady state (CISS) images to determine the presence of NVC by consensus. An adequate response was defined as freedom from pain with or without reduced need for medical therapy. Adequate short-term response to GKRS was seen in 29 (72.5%) of 40 patients. NVC was seen in 30 of the 40 patients. Twenty-five (83.3%) of 30 patients with NVC had adequate short-term response to GKRS. Only four (40%) of the 10 patients without NVC had adequate response to GKRS (X 2 =7.06; P<0.01). Patients with NVC were seven times more likely to have an adequate response to GKRS than those without NVC (odds ratio =7.5).The presence of NVC on pre-treatment MR imaging predicts an increased likelihood of an adequate response to GKRS. (orig.)

  16. Imaging the cranial nerves: part II: primary and secondary neoplastic conditions and neurovascular conflicts

    Energy Technology Data Exchange (ETDEWEB)

    Borges, Alexandra [Instituto Portugues de Oncologia Francisco Gentil- Centro de Lisboa, Radiology Department, Lisboa Codex (Portugal); Casselman, Jan [A. Z. St Jan Brugge and A. Z. St Augustinus Antwerpen Hospitals, Department of Radiology, Antwerp (Belgium)

    2007-09-15

    There have been unprecedented improvements in cross-sectional imaging in the last decades. The emergence of volumetric CT, higher field MR scanners and higher resolution MR sequences is largely responsible for the increasing diagnostic yield of imaging in patients presenting with cranial nerve deficits. The introduction of parallel MR imaging in combination with small surface coils allows the depiction of submillimetric nerves and nerve branches, and volumetric CT and MR imaging is able to provide high quality multiplanar and curved reconstructions that can follow the often complex course of cranial nerves. Seeking the cause of a cranial nerve deficit is a common indication for imaging, and it is not uncommon that radiologists are the first specialists to see a patient with a cranial neuropathy. To increase the diagnostic yield of imaging, high-resolution studies with smaller fields of view are required. To keep imaging studies within a reasonable time frame, it is mandatory to tailor the study according to neuro-topographic testing. This review article focuses on the contribution of current imaging techniques in the depiction of primary and secondary neoplastic conditions affecting the cranial nerves as well as on neurovascular conflicts, an increasingly recognized cause of cranial neuralgias. (orig.)

  17. Imaging the cranial nerves: part II: primary and secondary neoplastic conditions and neurovascular conflicts

    International Nuclear Information System (INIS)

    Borges, Alexandra; Casselman, Jan

    2007-01-01

    There have been unprecedented improvements in cross-sectional imaging in the last decades. The emergence of volumetric CT, higher field MR scanners and higher resolution MR sequences is largely responsible for the increasing diagnostic yield of imaging in patients presenting with cranial nerve deficits. The introduction of parallel MR imaging in combination with small surface coils allows the depiction of submillimetric nerves and nerve branches, and volumetric CT and MR imaging is able to provide high quality multiplanar and curved reconstructions that can follow the often complex course of cranial nerves. Seeking the cause of a cranial nerve deficit is a common indication for imaging, and it is not uncommon that radiologists are the first specialists to see a patient with a cranial neuropathy. To increase the diagnostic yield of imaging, high-resolution studies with smaller fields of view are required. To keep imaging studies within a reasonable time frame, it is mandatory to tailor the study according to neuro-topographic testing. This review article focuses on the contribution of current imaging techniques in the depiction of primary and secondary neoplastic conditions affecting the cranial nerves as well as on neurovascular conflicts, an increasingly recognized cause of cranial neuralgias. (orig.)

  18. Neurovascular complications due to the Hippocrates method for reducing anterior shoulder dislocations.

    Science.gov (United States)

    Regauer, Markus; Polzer, Hans; Mutschler, Wolf

    2014-01-18

    In spite of the fact that the Hippocrates method hardly has been evaluated in a scientific manner and numerous associated iatrogenic complications have been reported, this method remains to be one of the most common techniques for reducing anterior shoulder dislocations. We report the case of a 69-year-old farmer under coumarin anticoagulant therapy who sustained acute first time anterior dislocation of his dominant right shoulder. By using the Hippocrates method with the patient under general anaesthesia, the brachial vein was injured and an increasing hematoma subsequently caused brachial plexus paresis by pressure. After surgery for decompression and vascular suturing, symptoms declined rapidly, but brachial plexus paresis still was not fully reversible after 3 mo of follow-up. The hazardousness of using the Hippocrates method can be explained by traction on the outstretched arm with force of the operator's body weight, direct trauma to the axillary region by the physician's heel, and the topographic relations of neurovascular structures and the dislocated humeral head. As there is a variety of alternative reduction techniques which have been evaluated scientifically and proofed to be safe, we strongly caution against the use of the Hippocrates method as a first line technique for reducing anterior shoulder dislocations, especially in elder patients with fragile vessels or under anticoagulant therapy, and recommend the scapular manipulation technique or the Milch technique, for example, as a first choice.

  19. Neurovascular Response during Exercise and Mental Stress in Anabolic Steroid Users.

    Science.gov (United States)

    Porello, Rafael Armani; Dos Santos, Marcelo Rodrigues; DE Souza, Francis Ribeiro; DA Fonseca, Guilherme Wesley Peixoto; Sayegh, Ana Luiza Carrari; DE Oliveira, Tiago Franco; Akiho, César Abreu; Yonamine, Maurício; Pereira, Rosa Maria Rodrigues; Negrão, Carlos Eduardo; Alves, Maria-Janieire DE Nazaré Nunes

    2018-03-01

    Increased resting muscle sympathetic nerve activity (MSNA) and lower forearm blood flow (FBF) were observed in young men who use anabolic androgenic steroids (AAS). However, the response of MSNA and FBF in AAS users triggered by muscle mechanoreflex and central command has never been tested. In addition, we evaluated the blood pressure (BP) and heart rate (HR) responses during these maneuvers. Nineteen AAS users (AASU) 31 ± 6 yr of age and 18 AAS nonusers (AASNU) 29 ± 4 yr of age were recruited. All participants were involved in strength training. AAS use was determined using a urine test (liquid chromatography with tandem mass spectrometry). MSNA was measured using the microneurography technique. FBF was measured by using venous occlusion plethysmography. BP was measured using an automatic oscillometric device. HR was recorded continuously through ECG. Isometric handgrip exercise was performed at 30% of the maximal voluntary contraction for 3 min, and mental stress was elicited by the Stroop color-word test for 4 min. The MSNA and FBF responses during exercise were similar between AASU and AASNU, with a trend toward higher MSNA (bursts per minute; P = 0.084) and lower forearm vascular conductance (FVC; units; P = 0.084) in AASU than in AASNU. During mental stress, AASU showed a significantly higher MSNA (P stress) stimulation, AASU have exacerbated MSNA and blunted vasodilation. Therefore, mental stress seems to exacerbate neurovascular control throughout stress reaction situations in AASU.

  20. Tandem-robot assisted laparoscopic radical prostatectomy to improve the neurovascular bundle visualization: a feasibility study.

    Science.gov (United States)

    Han, Misop; Kim, Chunwoo; Mozer, Pierre; Schäfer, Felix; Badaan, Shadie; Vigaru, Bogdan; Tseng, Kenneth; Petrisor, Doru; Trock, Bruce; Stoianovici, Dan

    2011-02-01

    To examine the feasibility of image-guided navigation using transrectal ultrasound (TRUS) to visualize the neurovascular bundle (NVB) during robot-assisted laparoscopic radical prostatectomy (RALP). The preservation of the NVB during radical prostatectomy improves the postoperative recovery of sexual potency. The accompanying blood vessels in the NVB can serve as a macroscopic landmark to localize the microscopic cavernous nerves in the NVB. A novel, robotic transrectal ultrasound probe manipulator (TRUS Robot) and three-dimensional (3-D) reconstruction software were developed and used concurrently with the daVinci surgical robot (Intuitive Surgical, Inc., Sunnyvale, CA) in a tandem-robot assisted laparoscopic radical prostatectomy (T-RALP). After appropriate approval and informed consent were obtained, 3 subjects underwent T-RALP without associated complications. The TRUS Robot allowed a steady handling and remote manipulation of the TRUS probe during T-RALP. It also tracked the TRUS probe position accurately and allowed 3-D image reconstruction of the prostate and surrounding structures. Image navigation was performed by observing the tips of the daVinci surgical instruments in the live TRUS image. Blood vessels in the NVB were visualized using Doppler ultrasound. Intraoperative 3-D image-guided navigation in T-RALP is feasible. The use of TRUS during radical prostatectomy can potentially improve the visualization and preservation of the NVB. Further studies are needed to assess the clinical benefit of T-RALP. Copyright © 2011 Elsevier Inc. All rights reserved.

  1. Three-Dimensional Blood-Brain Barrier Model for in vitro Studies of Neurovascular Pathology

    Science.gov (United States)

    Cho, Hansang; Seo, Ji Hae; Wong, Keith H. K.; Terasaki, Yasukazu; Park, Joseph; Bong, Kiwan; Arai, Ken; Lo, Eng H.; Irimia, Daniel

    2015-10-01

    Blood-brain barrier (BBB) pathology leads to neurovascular disorders and is an important target for therapies. However, the study of BBB pathology is difficult in the absence of models that are simple and relevant. In vivo animal models are highly relevant, however they are hampered by complex, multi-cellular interactions that are difficult to decouple. In vitro models of BBB are simpler, however they have limited functionality and relevance to disease processes. To address these limitations, we developed a 3-dimensional (3D) model of BBB on a microfluidic platform. We verified the tightness of the BBB by showing its ability to reduce the leakage of dyes and to block the transmigration of immune cells towards chemoattractants. Moreover, we verified the localization at endothelial cell boundaries of ZO-1 and VE-Cadherin, two components of tight and adherens junctions. To validate the functionality of the BBB model, we probed its disruption by neuro-inflammation mediators and ischemic conditions and measured the protective function of antioxidant and ROCK-inhibitor treatments. Overall, our 3D BBB model provides a robust platform, adequate for detailed functional studies of BBB and for the screening of BBB-targeting drugs in neurological diseases.

  2. Regulation of cerebrospinal fluid (CSF) flow in neurodegenerative, neurovascular and neuroinflammatory disease.

    Science.gov (United States)

    Simon, Matthew J; Iliff, Jeffrey J

    2016-03-01

    Cerebrospinal fluid (CSF) circulation and turnover provides a sink for the elimination of solutes from the brain interstitium, serving an important homeostatic role for the function of the central nervous system. Disruption of normal CSF circulation and turnover is believed to contribute to the development of many diseases, including neurodegenerative conditions such as Alzheimer's disease, ischemic and traumatic brain injury, and neuroinflammatory conditions such as multiple sclerosis. Recent insights into CSF biology suggesting that CSF and interstitial fluid exchange along a brain-wide network of perivascular spaces termed the 'glymphatic' system suggest that CSF circulation may interact intimately with glial and vascular function to regulate basic aspects of brain function. Dysfunction within this glial vascular network, which is a feature of the aging and injured brain, is a potentially critical link between brain injury, neuroinflammation and the development of chronic neurodegeneration. Ongoing research within this field may provide a powerful new framework for understanding the common links between neurodegenerative, neurovascular and neuroinflammatory disease, in addition to providing potentially novel therapeutic targets for these conditions. This article is part of a Special Issue entitled: Neuro Inflammation edited by Helga E. de Vries and Markus Schwaninger. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Memantine mediates neuroprotection via regulating neurovascular unit in a mouse model of focal cerebral ischemia.

    Science.gov (United States)

    Chen, Zheng-Zhen; Yang, Dan-Dan; Zhao, Zhan; Yan, Hui; Ji, Juan; Sun, Xiu-Lan

    2016-04-01

    Memantine is a low-moderate affinity and uncompetitive N-methyl-d-aspartate receptor (NMDAR) antagonist, which is also a potential neuroprotectant in acute ischemic stroke for its particular action profiles. The present study was to reveal the mechanisms involved in the neuroprotection of memantine. We used a mouse model of permanent focal cerebral ischemia via middle cerebral artery occlusion to verify our hypothesis. 2,3,5-Triphenyltetrazolium chloride staining was used to compare infarct size. The amount of astrocytes and the somal volume of the microglia cell body were analyzed by immunohistochemistry and stereological estimates. Western blotting was used to determine the protein expressions. Memantine prevented cerebral ischemia-induced brain infarct and neuronal injury, and reduced oxygen-glucose deprivation-induced cortical neuronal apoptosis. Moreover, memantine reduced the amount of the damaged astrocytes and over activated microglia after 24h of ischemia. In the early phase of ischemia, higher production of MMP-9 was observed, and thereby collagen IV was dramatically disrupted. Meanwhile, the post-synaptic density protein 95(PSD-95) was also severely cleavaged. Memantine decreased MMP-9 secretion, prevented the degradation of collagen IV in mouse brain. PSD-95 cleavage was also inhibited by memantine. These results suggested that memantine exerted neuroprotection effects in acute ischemic brain damage, partially via improving the functions of neurovascular unit. Taking all these findings together, we consider that memantine might be a promising protective agent against ischemic stroke. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Coil embolization of anterior circulation aneurysms supported by the solitaire trademark AB neurovascular remodeling device

    International Nuclear Information System (INIS)

    Klisch, Joachim; Clajus, Christin; Sychra, Vojtech; Eger, Cornelia; Strasilla, Christoph; Rosahl, Steffen; Gerlach, Ruediger; Baer, Ingrid; Hoch, Heinrich; Herbon, Uta; Borota, Ljubisa; Jonasson, Per; Liebig, Thomas

    2010-01-01

    The purpose of the study is to evaluate patients with wide-necked or complex aneurysms of the anterior circulation who underwent Solitaire trademark AB Neurovascular Remodeling Device-assisted coil embolization. From February 2008 to March 2009, consecutive data were collected from 45 patients with anterior circulation aneurysms. Eighteen of the patients presented with acute subarachnoid hemorrhage. Forty-six aneurysms were treated with the aid of different applications (n=49) of the Solitaire trademark AB Remodeling Device followed by standard coiling procedure (n = 43) using bioactive coils or/and bare coils. Successful positioning of the remodeling device was obtained in 95.9% of the cases. There were two thromboembolic complications (4.1%) and one severe vasospasm requiring retrieval of the device. Permanent procedural morbidity was observed in one patient (2%). The proportion of patients in whom Raymond class 1 occlusion was obtained was 53.5% (n=23). Raymond class 2 occlusion was achieved in 42% (n=18) and Raymond class 3 occlusion in 4.7% (n=2). Thirty-nine patients left the hospital with a good clinical status. The initial technical and clinical results of Solitaire trademark AB device-assisted coiling of aneurysms in the anterior circulation are highly encouraging. This technique may enhance the possibilities of the endovascular treatment of these aneurysms in clinical routine. (orig.)

  5. Advancing Cardiovascular, Neurovascular and Renal Magnetic Resonance Imaging in Small Rodents Using Cryogenic Radiofrequency Coil Technology

    Directory of Open Access Journals (Sweden)

    Thoralf eNiendorf

    2015-11-01

    Full Text Available Research in pathologies of the brain, heart and kidney have gained immensely from the plethora of studies that have helped shape new methods in magnetic resonance (MR for characterizing preclinical disease models. Methodical probing into preclinical animal models by MR is invaluable since it allows a careful interpretation and extrapolation of data derived from these models to human disease. In this review we will focus on the applications of cryogenic radiofrequency (RF coils in small animal MR as a means of boosting image quality (e.g. by supporting MR microscopy and making data acquisition more efficient (e.g. by reducing measuring time; both being important constituents for thorough investigational studies on animal models of disease. This review attempts to make the (biomedical imaging, molecular medicine and pharmaceutical communities aware of this productive ferment and its outstanding significance for anatomical and functional MR in small rodents. The goal is to inspire a more intense interdisciplinary collaboration across the fields to further advance and progress non-invasive MR methods that ultimately support thorough (pathophysiological characterization of animal disease models. In this review, current and potential future applications for the RF coil technology in cardiovascular, neurovascular and renal disease will be discussed.

  6. Evaluation of compression tests of site concrete

    Directory of Open Access Journals (Sweden)

    Sharma, R. C.

    1973-03-01

    Full Text Available Not availableEn estos últimos años, en la India, se está dedicando gran atención al control estadístico de la calidad durante su elaboración y valoración del producto acabado. En este artículo se trata de una forma breve de los métodos empleados para esta finalidad en la producción del hormigón.

  7. Neurovascular-neuroenergetic coupling axis in the brain: master regulation by nitric oxide and consequences in aging and neurodegeneration.

    Science.gov (United States)

    Lourenço, Cátia F; Ledo, Ana; Barbosa, Rui M; Laranjinha, João

    2017-07-01

    The strict energetic demands of the brain require that nutrient supply and usage be fine-tuned in accordance with the specific temporal and spatial patterns of ever-changing levels of neuronal activity. This is achieved by adjusting local cerebral blood flow (CBF) as a function of activity level - neurovascular coupling - and by changing how energy substrates are metabolized and shuttled amongst astrocytes and neurons - neuroenergetic coupling. Both activity-dependent increase of CBF and O 2 and glucose utilization by active neural cells are inextricably linked, establishing a functional metabolic axis in the brain, the neurovascular-neuroenergetic coupling axis. This axis incorporates and links previously independent processes that need to be coordinated in the normal brain. We here review evidence supporting the role of neuronal-derived nitric oxide ( • NO) as the master regulator of this axis. Nitric oxide is produced in tight association with glutamatergic activation and, diffusing several cell diameters, may interact with different molecular targets within each cell type. Hemeproteins such as soluble guanylate cyclase, cytochrome c oxidase and hemoglobin, with which • NO reacts at relatively fast rates, are but a few of the key in determinants of the regulatory role of • NO in the neurovascular-neuroenergetic coupling axis. Accordingly, critical literature supporting this concept is discussed. Moreover, in view of the controversy regarding the regulation of catabolism of different neural cells, we further discuss key aspects of the pathways through which • NO specifically up-regulates glycolysis in astrocytes, supporting lactate shuttling to neurons for oxidative breakdown. From a biomedical viewpoint, derailment of neurovascular-neuroenergetic axis is precociously linked to aberrant brain aging, cognitive impairment and neurodegeneration. Thus, we summarize current knowledge of how both neurovascular and neuroenergetic coupling are compromised in

  8. Compression for radiological images

    Science.gov (United States)

    Wilson, Dennis L.

    1992-07-01

    The viewing of radiological images has peculiarities that must be taken into account in the design of a compression technique. The images may be manipulated on a workstation to change the contrast, to change the center of the brightness levels that are viewed, and even to invert the images. Because of the possible consequences of losing information in a medical application, bit preserving compression is used for the images used for diagnosis. However, for archiving the images may be compressed to 10 of their original size. A compression technique based on the Discrete Cosine Transform (DCT) takes the viewing factors into account by compressing the changes in the local brightness levels. The compression technique is a variation of the CCITT JPEG compression that suppresses the blocking of the DCT except in areas of very high contrast.

  9. MP3 compression of Doppler ultrasound signals.

    Science.gov (United States)

    Poepping, Tamie L; Gill, Jeremy; Fenster, Aaron; Holdsworth, David W

    2003-01-01

    The effect of lossy, MP3 compression on spectral parameters derived from Doppler ultrasound (US) signals was investigated. Compression was tested on signals acquired from two sources: 1. phase quadrature and 2. stereo audio directional output. A total of 11, 10-s acquisitions of Doppler US signal were collected from each source at three sites in a flow phantom. Doppler signals were digitized at 44.1 kHz and compressed using four grades of MP3 compression (in kilobits per second, kbps; compression ratios in brackets): 1400 kbps (uncompressed), 128 kbps (11:1), 64 kbps (22:1) and 32 kbps (44:1). Doppler spectra were characterized by peak velocity, mean velocity, spectral width, integrated power and ratio of spectral power between negative and positive velocities. The results suggest that MP3 compression on digital Doppler US signals is feasible at 128 kbps, with a resulting 11:1 compression ratio, without compromising clinically relevant information. Higher compression ratios led to significant differences for both signal sources when compared with the uncompressed signals. Copyright 2003 World Federation for Ultrasound in Medicine & Biology

  10. Radiological Image Compression

    Science.gov (United States)

    Lo, Shih-Chung Benedict

    The movement toward digital images in radiology presents the problem of how to conveniently and economically store, retrieve, and transmit the volume of digital images. Basic research into image data compression is necessary in order to move from a film-based department to an efficient digital -based department. Digital data compression technology consists of two types of compression technique: error-free and irreversible. Error -free image compression is desired; however, present techniques can only achieve compression ratio of from 1.5:1 to 3:1, depending upon the image characteristics. Irreversible image compression can achieve a much higher compression ratio; however, the image reconstructed from the compressed data shows some difference from the original image. This dissertation studies both error-free and irreversible image compression techniques. In particular, some modified error-free techniques have been tested and the recommended strategies for various radiological images are discussed. A full-frame bit-allocation irreversible compression technique has been derived. A total of 76 images which include CT head and body, and radiographs digitized to 2048 x 2048, 1024 x 1024, and 512 x 512 have been used to test this algorithm. The normalized mean -square-error (NMSE) on the difference image, defined as the difference between the original and the reconstructed image from a given compression ratio, is used as a global measurement on the quality of the reconstructed image. The NMSE's of total of 380 reconstructed and 380 difference images are measured and the results tabulated. Three complex compression methods are also suggested to compress images with special characteristics. Finally, various parameters which would effect the quality of the reconstructed images are discussed. A proposed hardware compression module is given in the last chapter.

  11. The assessment of neurovascular coupling with the Addenbrooke's Cognitive Examination: a functional transcranial Doppler ultrasonographic study.

    Science.gov (United States)

    Beishon, Lucy C; Williams, Claire A L; Panerai, Ronney B; Robinson, Thompson G; Haunton, Victoria J

    2018-03-01

    Cerebrovascular dysfunction occurs early in dementia and can be identified by transcranial Doppler ultrasonography (TCD). Few studies have examined cerebral blood flow velocity (CBFv) responses to a detailed cognitive battery. This study aimed to characterize all CBFv responses, and the effect of hemispheric dominance, to the Addenbrooke's Cognitive Examination (ACE-III) in healthy volunteers. Forty volunteers underwent continuous bilateral TCD, beat-to-beat blood pressure (MAP; Finapres), heart rate (HR; electrocardiogram), and end-tidal CO 2 (ETCO 2 ; capnography) monitoring. After a 5-min baseline period, all tasks from the ACE-III were performed in 3 sections (A: attention, fluency, memory; B: language; C: visuospatial, memory). Data are population mean normalized percentage (PM%) change from a 20-s baseline period before task initiation. Forty bilateral data sets were obtained (27 women, 37 right-hand dominant). All paradigms produced a sharp increase in CBFv in both dominant (PM% range: 3.29 to 9.70%) and nondominant (PM% range: 4.34 to 11.63%) hemispheres at task initiation, with associated increases in MAP (PM% range: 3.06 to 16.04%). ETCO 2 did not differ significantly at task initiation (PM% range: -1.1 to 2.4%, P > 0.05). HR differed significantly across A and C tasks at initiation (PM% range: -1.1 to 2.4%, P cognitively impaired population. NEW & NOTEWORTHY This study is the first to provide a normative data set of cerebral blood flow velocity (CBFv) responses to a complete cognitive assessment (Addenbrooke's Cognitive Examination, ACE-III) in a large sample ( n = 40) of healthy volunteers. All tasks produced peak and sustained increases in CBFv to different extents. The ACE-III is a feasible tool to assess neurovascular coupling with transcranial Doppler ultrasonography. These data can be used to inform the most appropriate cognitive task to elicit CBFv responses for future studies.

  12. Rescue of cortical neurovascular functions during the hyperacute phase of ischemia by peripheral sensory stimulation.

    Science.gov (United States)

    Liao, Lun-De; Liu, Yu-Hang; Lai, Hsin-Yi; Bandla, Aishwarya; Shih, Yen-Yu Ian; Chen, You-Yin; Thakor, Nitish V

    2015-03-01

    To investigate the potential therapeutic effects of peripheral sensory stimulation during the hyperacute phase of stroke, the present study utilized electrophysiology and photoacoustic imaging techniques to evaluate neural and vascular responses of the rat cortex following ischemic insult. We employed a rat model of photothrombotic ischemia (PTI), which targeted the forelimb region of the primary somatosensory cortex (S1FL), due to its high reproducibility in creating localized ischemic injury. We also established a hybrid, dual-modality system, including six-channel electrocorticography (ECoG) and functional photoacoustic microscopy (fPAM), termed ECoG-fPAM, to image brain functional responses to peripheral sensory stimulation during the hyperacute phase of PTI. Our results showed that the evoked cerebral blood volume (CBV) and hemoglobin oxygen saturation (SO2) recovered to 84±7.4% and 79±6.2% of the baseline, respectively, when stimulation was delivered within 2.5 h following PTI induction. Moreover, neural activity significantly recovered, with 77±8.6%, 76±5.3% and 89±8.2% recovery for the resting-state inter-hemispheric coherence, alpha-to-delta ratio (ADR) and somatosensory evoked potential (SSEP), respectively. Additionally, we integrated the CBV or SO2 with ADR values as a recovery indicator (RI) to assess functional recovery after PTI. The RI indicated that 80±4.2% of neurovascular function was preserved when stimulation was delivered within 2.5h. Additionally, stimulation treatment within this optimal time window resulted in a minimal infarct volume in the ischemic hemisphere (4.6±2.1%). In contrast, the infarct volume comprised 13.7±1.7% of the ischemic hemisphere when no stimulation treatment was applied. Copyright © 2014. Published by Elsevier Inc.

  13. Baroreflex and neurovascular responses to skeletal muscle mechanoreflex activation in humans: an exercise in integrative physiology.

    Science.gov (United States)

    Drew, Rachel C

    2017-12-01

    Cardiovascular adjustments to exercise resulting in increased blood pressure (BP) and heart rate (HR) occur in response to activation of several neural mechanisms: the exercise pressor reflex, central command, and the arterial baroreflex. Neural inputs from these feedback and feedforward mechanisms integrate in the cardiovascular control centers in the brain stem and modulate sympathetic and parasympathetic neural outflow, resulting in the increased BP and HR observed during exercise. Another specific consequence of the central neural integration of these inputs during exercise is increased sympathetic neural outflow directed to the kidneys, causing renal vasoconstriction, a key reflex mechanism involved in blood flow redistribution during increased skeletal muscle work. Studies in humans have shown that muscle mechanoreflex activation inhibits cardiac vagal outflow, decreasing the sensitivity of baroreflex control of HR. Metabolite sensitization of muscle mechanoreceptors can lead to reduced sensitivity of baroreflex control of HR, with thromboxane being one of the metabolites involved, via greater inhibition of cardiac vagal outflow without affecting baroreflex control of BP or baroreflex resetting. Muscle mechanoreflex activation appears to play a predominant role in causing renal vasoconstriction, both in isolation and in the presence of local metabolites. Limited investigations in older adults and patients with cardiovascular-related disease have provided some insight into how the influence of muscle mechanoreflex activation on baroreflex function and renal vasoconstriction is altered in these populations. However, future research is warranted to better elucidate the specific effect of muscle mechanoreflex activation on baroreflex and neurovascular responses with aging and cardiovascular-related disease. Copyright © 2017 the American Physiological Society.

  14. Compressed sensing & sparse filtering

    CERN Document Server

    Carmi, Avishy Y; Godsill, Simon J

    2013-01-01

    This book is aimed at presenting concepts, methods and algorithms ableto cope with undersampled and limited data. One such trend that recently gained popularity and to some extent revolutionised signal processing is compressed sensing. Compressed sensing builds upon the observation that many signals in nature are nearly sparse (or compressible, as they are normally referred to) in some domain, and consequently they can be reconstructed to within high accuracy from far fewer observations than traditionally held to be necessary. Apart from compressed sensing this book contains other related app

  15. Robot-assisted laparoscopic radical prostatectomy with early retrograde release of the neurovascular bundle and endopelvic fascia sparing

    Directory of Open Access Journals (Sweden)

    George Augusto Monteiro Lins de Albuquerque

    Full Text Available ABSTRACT Introduction Robotic-assisted radical prostatectomy (RAP is the dominant minimally invasive surgical treatment for patients with localized prostate cancer. The introduction of robotic assistance has the potential to improve surgical outcomes and reduce the steep learning curve associated with conventional laparoscopic radical prostatectomy. The purpose of this video is to demonstrate the early retrograde release of the neurovascular bundle without open the endopelvic fascia during RAP. Materials and Methods A 51-year old male, presenting histological diagnosis of prostate adenocarcinoma, Gleason 6 (3+3, in 4 cores of 12, with an initial PSA=3.41ng/dl and the digital rectal examination demonstrating a prostate with hardened nodule in the right lobe of the prostate base (clinical stage T2a. Surgical treatment with the robot-assisted technique was offered as initial therapeutic option and the critical technical point was the early retrograde release of the neurovascular bundle with endopelvic fascia preservation, during radical prostatectomy. Results The operative time was of 89 minutes, blood loss was 100ml. No drain was left in the peritoneal cavity. The patient was discharged within 24 hours. There were no intraoperative or immediate postoperative complications. The pathological evaluation revealed prostate adenocarcinoma, Gleason 6, with free surgical margins and seminal vesicles free of neoplastic involvement (pathologic stage T2a. At 3-month-follow-up, the patient lies with undetectable PSA, continent and potent. Conclusion This is a feasible technique combining the benefits of retrograde release of the neurovascular bundle, the preservation of the pubo-prostatic collar and the preservation of the antero-lateral cavernous nerves.

  16. Anisotropic Concrete Compressive Strength

    DEFF Research Database (Denmark)

    Gustenhoff Hansen, Søren; Jørgensen, Henrik Brøner; Hoang, Linh Cao

    2017-01-01

    When the load carrying capacity of existing concrete structures is (re-)assessed it is often based on compressive strength of cores drilled out from the structure. Existing studies show that the core compressive strength is anisotropic; i.e. it depends on whether the cores are drilled parallel...

  17. Experiments with automata compression

    NARCIS (Netherlands)

    Daciuk, J.; Yu, S; Daley, M; Eramian, M G

    2001-01-01

    Several compression methods of finite-state automata are presented and evaluated. Most compression methods used here are already described in the literature. However, their impact on the size of automata has not been described yet. We fill that gap, presenting results of experiments carried out on

  18. Increased 20-HETE synthesis explains reduced cerebral blood flow but not impaired neurovascular coupling after cortical spreading depression in rat cerebral cortex

    DEFF Research Database (Denmark)

    Fordsmann, Jonas Christoffer; ko, Rebecca; Choi, Hyun B

    2013-01-01

    Cortical spreading depression (CSD) is associated with release of arachidonic acid (AA), impaired neurovascular coupling, and reduced cerebral blood flow (CBF), caused by cortical vasoconstriction. We tested the hypothesis that the released AA is metabolized by the cytochrome P450 enzyme to produce...... neurovascular coupling after CSD. These findings suggest that CSD-induced increments in 20-HETE cause the reduction in CBF after CSD, and that the attenuation of stimulation-induced CBF responses after CSD has a different mechanism. We suggest that blockade of 20-HETE synthesis may be clinically relevant...

  19. Increase of arginase activity in old apolipoprotein-E deficient mice under Western diet associated with changes in neurovascular unit

    Directory of Open Access Journals (Sweden)

    Badaut Jérôme

    2012-06-01

    Full Text Available Abstract Aging and atherosclerosis are well-recognized risk factors for cardiac and neurovascular diseases. The Apolipoprotein E deficient (ApoE−/− mouse on a high-fat diet is a classical model of atherosclerosis, characterized by the presence of atherosclerotic plaques in extracranial vessels but not in cerebral arteries. Increase in arginase activity was shown to participate in vascular dysfunction in the peripheral arteries of atherosclerotic mice by changing the level of nitric oxide (NO. NO plays a key role in the physiological functions of the neurovascular unit (NVU. However, the regulation of arginase expression and activity in the brain was never investigated in association with changes in the NVU, ApoE deficiency and high fat diet. Fourteen-month-old ApoE−/− mice on high-fat diet exhibited deposition of lipids in the NVU, impairment of blood–brain barrier properties, astrogliosis and an increase of aquaporin 4 staining. In association with these changes, brain arginase activity was significantly increased in the old ApoE−/− mice as compared to old wild type mice, with an increase in the level of arginase type I in the blood vessels. In conclusion, aging in this classical mouse model of atherosclerosis induces an increase in the level and activity of arginase I that may impair NO synthesis and contribute to changes in the NVU leading to blood–brain barrier leakage and inflammation.

  20. Skeletal Muscle Neurovascular Coupling, Oxidative Capacity, and Microvascular Function with 'One Stop Shop' Near-infrared Spectroscopy.

    Science.gov (United States)

    Rosenberry, Ryan; Chung, Susie; Nelson, Michael D

    2018-02-20

    Exercise represents a major hemodynamic stress that demands a highly coordinated neurovascular response in order to match oxygen delivery to metabolic demand. Reactive hyperemia (in response to a brief period of tissue ischemia) is an independent predictor of cardiovascular events and provides important insight into vascular health and vasodilatory capacity. Skeletal muscle oxidative capacity is equally important in health and disease, as it determines the energy supply for myocellular processes. Here, we describe a simple, non-invasive approach using near-infrared spectroscopy to assess each of these major clinical endpoints (reactive hyperemia, neurovascular coupling, and muscle oxidative capacity) during a single clinic or laboratory visit. Unlike Doppler ultrasound, magnetic resonance images/spectroscopy, or invasive catheter-based flow measurements or muscle biopsies, our approach is less operator-dependent, low-cost, and completely non-invasive. Representative data from our lab taken together with summary data from previously published literature illustrate the utility of each of these end-points. Once this technique is mastered, application to clinical populations will provide important mechanistic insight into exercise intolerance and cardiovascular dysfunction.

  1. 3-D Imaging Reveals Participation of Donor Islet Schwann Cells and Pericytes in Islet Transplantation and Graft Neurovascular Regeneration

    Directory of Open Access Journals (Sweden)

    Jyuhn-Huarng Juang

    2015-02-01

    Full Text Available The primary cells that participate in islet transplantation are the endocrine cells. However, in the islet microenvironment, the endocrine cells are closely associated with the neurovascular tissues consisting of the Schwann cells and pericytes, which form sheaths/barriers at the islet exterior and interior borders. The two cell types have shown their plasticity in islet injury, but their roles in transplantation remain unclear. In this research, we applied 3-dimensional neurovascular histology with cell tracing to reveal the participation of Schwann cells and pericytes in mouse islet transplantation. Longitudinal studies of the grafts under the kidney capsule identify that the donor Schwann cells and pericytes re-associate with the engrafted islets at the peri-graft and perivascular domains, respectively, indicating their adaptability in transplantation. Based on the morphological proximity and cellular reactivity, we propose that the new islet microenvironment should include the peri-graft Schwann cell sheath and perivascular pericytes as an integral part of the new tissue.

  2. Anthropometric assessment of cervical neurovascular structures using CTA to determine zone-specific vulnerability to penetrating fragmentation injuries

    International Nuclear Information System (INIS)

    Breeze, J.; West, A.; Clasper, J.

    2013-01-01

    Aim: To determine military-specific cervical neurovascular and external anthropometric data to scale future numerical injury models of the neck and improve body armour design with a view to prevention or mitigation of combat neck injury. Materials and methods: Contrast-enhanced computed tomography (CT) angiograms of 50 UK servicemen were analysed. Mean diameters and distances from the skin surface were determined for the carotid artery (CA), internal jugular vein (IJV), vertebral artery (VA) and spinal cord (SC) at the three surgical neck zones. Horizontal neck circumference at C6 and three potential vertical cervical anthropometric measurements were analysed to determine which had the least variability between subjects. Results: The diameters of cervical vascular structures are greater and the vessels more superficial as the anatomical plane moves caudally. The SC and VA are better protected than the IJV and CA due to their greater depth and bony coverage, except for the VA in zone 1. Conclusion: Future cervical anthropometric assessments should use the vertical angle of mandible to mid-claviclular distance in combination with the horizontal neck circumference as these demonstrated the least variability. Cervical neurovascular structures are least vulnerable posterosuperiorly and therefore extending the posterior aspect of a ballistic helmet inferiorly or adding a nape protector would appear to be less justified. Cervical vessels are most vulnerable in zone 1 and a circumferential collar of ballistic material at least 75 mm high would cover this area in 95% of this population.

  3. Compressive laser ranging.

    Science.gov (United States)

    Babbitt, Wm Randall; Barber, Zeb W; Renner, Christoffer

    2011-12-15

    Compressive sampling has been previously proposed as a technique for sampling radar returns and determining sparse range profiles with a reduced number of measurements compared to conventional techniques. By employing modulation on both transmission and reception, compressive sensing in ranging is extended to the direct measurement of range profiles without intermediate measurement of the return waveform. This compressive ranging approach enables the use of pseudorandom binary transmit waveforms and return modulation, along with low-bandwidth optical detectors to yield high-resolution ranging information. A proof-of-concept experiment is presented. With currently available compact, off-the-shelf electronics and photonics, such as high data rate binary pattern generators and high-bandwidth digital optical modulators, compressive laser ranging can readily achieve subcentimeter resolution in a compact, lightweight package.

  4. PI3K/Akt Pathway Contributes to Neurovascular Unit Protection of Xiao-Xu-Ming Decoction against Focal Cerebral Ischemia and Reperfusion Injury in Rats

    Directory of Open Access Journals (Sweden)

    Rui Lan

    2013-01-01

    Full Text Available In the present study, we used a focal cerebral ischemia and reperfusion rat model to investigate the protective effects of Xiao-Xu-Ming decoction (XXMD on neurovascular unit and to examine the role of PI3K (phosphatidylinositol 3-kinase/Akt pathway in this protection. The cerebral ischemia was induced by 90 min of middle cerebral artery occlusion. Cerebral infarct area was measured by tetrazolium staining, and neurological function was observed at 24 h after reperfusion. DNA fragmentation assay, combined with immunofluorescence, was performed to evaluate apoptosis of neuron, astrocyte, and vascular endothelial cell which constitute neurovascular unit. The expression levels of proteins involved in PI3K/Akt pathway were detected by Western blot. The results showed that XXMD improved neurological function, decreased cerebral infarct area and neuronal damage, and attenuated cellular apoptosis in neurovascular unit, while these effects were abolished by inhibition of PI3K/Akt with LY294002. We also found that XXMD upregulated p-PDKl, p-Akt, and p-GSK3β expression levels, which were partly reversed by LY294002. In addition, the increases of p-PTEN and p-c-Raf expression levels on which LY294002 had no effect were also observed in response to XXMD treatment. The data indicated the protective effects of XXMD on neurovascular unit partly through the activation of PI3K/Akt pathway.

  5. Systolic Compression of Epicardial Coronary and Intramural Arteries

    Science.gov (United States)

    Mohiddin, Saidi A.; Fananapazir, Lameh

    2002-01-01

    It has been suggested that systolic compression of epicardial coronary arteries is an important cause of myocardial ischemia and sudden death in children with hypertrophic cardiomyopathy. We examined the associations between sudden death, systolic coronary compression of intra- and epicardial arteries, myocardial perfusion abnormalities, and severity of hypertrophy in children with hypertrophic cardiomyopathy. We reviewed the angiograms from 57 children with hypertrophic cardiomyopathy for the presence of coronary and septal artery compression; coronary compression was present in 23 (40%). The left anterior descending artery was most often affected, and multiple sites were found in 4 children. Myocardial perfusion abnormalities were more frequently present in children with coronary compression than in those without (94% vs 47%, P = 0.002). Coronary compression was also associated with more severe septal hypertrophy and greater left ventricular outflow gradient. Septal branch compression was present in 65% of the children and was significantly associated with coronary compression, severity of septal hypertrophy, and outflow obstruction. Multivariate analysis showed that septal thickness and septal branch compression, but not coronary compression, were independent predictors of perfusion abnormalities. Coronary compression was not associated with symptom severity, ventricular tachycardia, or a worse prognosis. We conclude that compression of coronary arteries and their septal branches is common in children with hypertrophic cardiomyopathy and is related to the magnitude of left ventricular hypertrophy. Our findings suggest that coronary compression does not make an important contribution to myocardial ischemia in hypertrophic cardiomyopathy; however, left ventricular hypertrophy and compression of intramural arteries may contribute significantly. (Tex Heart Inst J 2002;29:290–8) PMID:12484613

  6. Uniaxial compression test series on Bullfrog Tuff

    International Nuclear Information System (INIS)

    Price, R.H.; Jones, A.K.; Nimick, K.G.

    1982-04-01

    Nineteen uniaxial compressive experiments were performed on samples of the Bullfrog Member of the Crater Flat Tuff, obtained from drillhole USW-G1 at Yucca Mountain on the Nevada Test Site. The water saturated samples were deformed at a nominal strain rate of 10 -5 sec -1 , atmospheric pressure and room temperature. Resultant unconfined compressive strengths, axial strains to failure, Young's moduli and Poisson's ratios ranged from 4.63 to 153. MPa, .0028 to .0058, 2.03 to 28.9 GPa and .08 to .16, respectively

  7. Aquaporin-4 Functionality and Virchow-Robin Space Water Dynamics: Physiological Model for Neurovascular Coupling and Glymphatic Flow.

    Science.gov (United States)

    Nakada, Tsutomu; Kwee, Ingrid L; Igarashi, Hironaka; Suzuki, Yuji

    2017-08-18

    The unique properties of brain capillary endothelium, critical in maintaining the blood-brain barrier (BBB) and restricting water permeability across the BBB, have important consequences on fluid hydrodynamics inside the BBB hereto inadequately recognized. Recent studies indicate that the mechanisms underlying brain water dynamics are distinct from systemic tissue water dynamics. Hydrostatic pressure created by the systolic force of the heart, essential for interstitial circulation and lymphatic flow in systemic circulation, is effectively impeded from propagating into the interstitial fluid inside the BBB by the tightly sealed endothelium of brain capillaries. Instead, fluid dynamics inside the BBB is realized by aquaporin-4 (AQP-4), the water channel that connects astrocyte cytoplasm and extracellular (interstitial) fluid. Brain interstitial fluid dynamics, and therefore AQP-4, are now recognized as essential for two unique functions, namely, neurovascular coupling and glymphatic flow, the brain equivalent of systemic lymphatics.

  8. Optical pulse compression

    International Nuclear Information System (INIS)

    Glass, A.J.

    1975-01-01

    The interest in using large lasers to achieve a very short and intense pulse for generating fusion plasma has provided a strong impetus to reexamine the possibilities of optical pulse compression at high energy. Pulse compression allows one to generate pulses of long duration (minimizing damage problems) and subsequently compress optical pulses to achieve the short pulse duration required for specific applications. The ideal device for carrying out this program has not been developed. Of the two approaches considered, the Gires--Tournois approach is limited by the fact that the bandwidth and compression are intimately related, so that the group delay dispersion times the square of the bandwidth is about unity for all simple Gires--Tournois interferometers. The Treacy grating pair does not suffer from this limitation, but is inefficient because diffraction generally occurs in several orders and is limited by the problem of optical damage to the grating surfaces themselves. Nonlinear and parametric processes were explored. Some pulse compression was achieved by these techniques; however, they are generally difficult to control and are not very efficient. (U.S.)

  9. Exploiting neurovascular coupling: a Bayesian sequential Monte Carlo approach applied to simulated EEG fNIRS data

    Science.gov (United States)

    Croce, Pierpaolo; Zappasodi, Filippo; Merla, Arcangelo; Chiarelli, Antonio Maria

    2017-08-01

    Objective. Electrical and hemodynamic brain activity are linked through the neurovascular coupling process and they can be simultaneously measured through integration of electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS). Thanks to the lack of electro-optical interference, the two procedures can be easily combined and, whereas EEG provides electrophysiological information, fNIRS can provide measurements of two hemodynamic variables, such as oxygenated and deoxygenated hemoglobin. A Bayesian sequential Monte Carlo approach (particle filter, PF) was applied to simulated recordings of electrical and neurovascular mediated hemodynamic activity, and the advantages of a unified framework were shown. Approach. Multiple neural activities and hemodynamic responses were simulated in the primary motor cortex of a subject brain. EEG and fNIRS recordings were obtained by means of forward models of volume conduction and light propagation through the head. A state space model of combined EEG and fNIRS data was built and its dynamic evolution was estimated through a Bayesian sequential Monte Carlo approach (PF). Main results. We showed the feasibility of the procedure and the improvements in both electrical and hemodynamic brain activity reconstruction when using the PF on combined EEG and fNIRS measurements. Significance. The investigated procedure allows one to combine the information provided by the two methodologies, and, by taking advantage of a physical model of the coupling between electrical and hemodynamic response, to obtain a better estimate of brain activity evolution. Despite the high computational demand, application of such an approach to in vivo recordings could fully exploit the advantages of this combined brain imaging technology.

  10. A three-dimensional study of the musculotendinous and neurovascular architecture of the gracilis muscle: application to functional muscle transfer.

    Science.gov (United States)

    Fattah, A Y; Ravichandiran, K; Zuker, R M; Agur, A M R

    2013-09-01

    Muscle transfer is used to restore function typically using a single vector of contraction. Although its use with two independently functional muscular units has been employed, in order to refine this concept we endeavoured to detail the intramuscular anatomy of gracilis, a muscle commonly used for transfer. A novel method to capture intramuscular fibre bundle and neurovascular arrangement was used to create a three-dimensional (3D) digital model that allowed for accurate representation of the relationships between all the intramuscular structures to facilitate flap planning. Twenty gracilis muscles were harvested from 15 cadavers. All components of the muscle were digitised using a Microscribe G2 Digitiser. The data were exported to the 3D animation software Autodesk(®) Maya(®) 2012 whereupon it was rendered into a 3D model that can be exported as static images or videos. Neurovascular anatomy and muscle architecture were analysed from these models, and fibre bundle length, pennation angle and physiological cross-sectional area were calculated from digitised data. The muscle is composed of a variable number of distinct longitudinal segments with muscle fibres spiralling onto the tendon. The main artery to the muscle has three main intramuscular patterns of distribution. The venae comitantes drain discrete zones without intramuscular macroscopic anastomoses. The minor pedicles form an anastomotic chain along the anterior border of the muscle and all vessels were biased to the deep surface. The nerve is related to the vessels in a variable manner and both run between longitudinal muscular compartments. The digitisation technique may be used to advance knowledge of intramuscular architecture and it demonstrated that the gracilis muscle is comprised of four to seven muscular compartments, each representing a functional unit that may theoretically be differentially activated and could be harnessed for more sophisticated muscle transfers. Copyright © 2013 British

  11. Isentropic Compression of Argon

    International Nuclear Information System (INIS)

    Oona, H.; Solem, J.C.; Veeser, L.R.; Ekdahl, C.A.; Rodriquez, P.J.; Younger, S.M.; Lewis, W.; Turley, W.D.

    1997-01-01

    We are studying the transition of argon from an insulator to a conductor by compressing the frozen gas isentropically to pressures at which neighboring atomic orbitals overlap sufficiently to allow some electron motion between atoms. Argon and the other rare gases have closed electron shells and therefore remain montomic, even when they solidify. Their simple structure makes it likely that any measured change in conductivity is due to changes in the atomic structure, not in molecular configuration. As the crystal is compressed the band gap closes, allowing increased conductivity. We have begun research to determine the conductivity at high pressures, and it is our intention to determine the compression at which the crystal becomes a metal

  12. Pulsed Compression Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Roestenberg, T. [University of Twente, Enschede (Netherlands)

    2012-06-07

    The advantages of the Pulsed Compression Reactor (PCR) over the internal combustion engine-type chemical reactors are briefly discussed. Over the last four years a project concerning the fundamentals of the PCR technology has been performed by the University of Twente, Enschede, Netherlands. In order to assess the feasibility of the application of the PCR principle for the conversion methane to syngas, several fundamental questions needed to be answered. Two important questions that relate to the applicability of the PCR for any process are: how large is the heat transfer rate from a rapidly compressed and expanded volume of gas, and how does this heat transfer rate compare to energy contained in the compressed gas? And: can stable operation with a completely free piston as it is intended with the PCR be achieved?.

  13. Medullary compression syndrome

    International Nuclear Information System (INIS)

    Barriga T, L.; Echegaray, A.; Zaharia, M.; Pinillos A, L.; Moscol, A.; Barriga T, O.; Heredia Z, A.

    1994-01-01

    The authors made a retrospective study in 105 patients treated in the Radiotherapy Department of the National Institute of Neoplasmic Diseases from 1973 to 1992. The objective of this evaluation was to determine the influence of radiotherapy in patients with medullary compression syndrome in aspects concerning pain palliation and improvement of functional impairment. Treatment sheets of patients with medullary compression were revised: 32 out of 39 of patients (82%) came to hospital by their own means and continued walking after treatment, 8 out of 66 patients (12%) who came in a wheelchair or were bedridden, could mobilize by their own after treatment, 41 patients (64%) had partial alleviation of pain after treatment. In those who came by their own means and did not change their characteristics, functional improvement was observed. It is concluded that radiotherapy offers palliative benefit in patients with medullary compression syndrome. (authors). 20 refs., 5 figs., 6 tabs

  14. Graph Compression by BFS

    Directory of Open Access Journals (Sweden)

    Alberto Apostolico

    2009-08-01

    Full Text Available The Web Graph is a large-scale graph that does not fit in main memory, so that lossless compression methods have been proposed for it. This paper introduces a compression scheme that combines efficient storage with fast retrieval for the information in a node. The scheme exploits the properties of the Web Graph without assuming an ordering of the URLs, so that it may be applied to more general graphs. Tests on some datasets of use achieve space savings of about 10% over existing methods.

  15. [A case of medulla oblongata compression by tortuous vertebral arteries presenting with spastic quadriplegia].

    Science.gov (United States)

    Kamada, Takashi; Tateishi, Takahisa; Yamashita, Tamayo; Nagata, Shinji; Ohyagi, Yasumasa; Kira, Jun-Ichi

    2013-01-01

    We report a 58-year-old man showing spastic paraparesis due to medulla oblongata compression by tortuous vertebral arteries. He noticed weakness of both legs and gait disturbance at the age of 58 years and his symptoms progressively worsened during the following several months. General physical findings were normal. Blood pressure was normal and there were no signs of arteriosclerosis. Neurological examination on admission revealed lower-limb-dominant spasticity in all four extremities, lower-limb weakness, hyperreflexia in all extremities with positive Wartenberg's, Babinski's and Chaddock's signs, mild hypesthesia and hypopallesthesia in both lower limbs, and spastic gait. Cranial nerves were all normal. Serum was negative for antibodies against human T-cell lymphotropic virus-1 antibody. Nerve conduction and needle electromyographic studies of all four limbs revealed normal findings. Cervical, thoracic and lumbo-sacral magnetic resonance imaging (MRI) findings were all normal. Brain MRI and magnetic resonance angiography demonstrated bilateral tortuous vertebral arteries compressing the medulla oblongata. Neurovascular decompression of the right vertebral artery was performed because compression of the right side was more severe than that of the left side. Post-operative MRI revealed outward translocation of the right vertebral artery and relieved compression of the medulla oblongata on the right side. The patient's symptoms and neurological findings improved gradually after the operation. Bilateral pyramidal tract signs without cranial nerve dysfunction due to compression of the medulla oblongata by tortuous vertebral arteries are extremely rare and clinically indistinguishable from hereditary spastic paraplegia (HSP). Although we did not perform a genetic test for HSP, we consider that the spastic paraparesis and mild lower-limb hypesthesia were caused by compression of the medulla oblongata by bilateral tortuous vertebral arteries based on the post

  16. Compressible generalized Newtonian fluids

    Czech Academy of Sciences Publication Activity Database

    Málek, Josef; Rajagopal, K.R.

    2010-01-01

    Roč. 61, č. 6 (2010), s. 1097-1110 ISSN 0044-2275 Institutional research plan: CEZ:AV0Z20760514 Keywords : power law fluid * uniform temperature * compressible fluid Subject RIV: BJ - Thermodynamics Impact factor: 1.290, year: 2010

  17. Temporal compressive sensing systems

    Science.gov (United States)

    Reed, Bryan W.

    2017-12-12

    Methods and systems for temporal compressive sensing are disclosed, where within each of one or more sensor array data acquisition periods, one or more sensor array measurement datasets comprising distinct linear combinations of time slice data are acquired, and where mathematical reconstruction allows for calculation of accurate representations of the individual time slice datasets.

  18. Compression of Infrared images

    DEFF Research Database (Denmark)

    Mantel, Claire; Forchhammer, Søren

    2017-01-01

    best for bits-per-pixel rates below 1.4 bpp, while HEVC obtains best performance in the range 1.4 to 6.5 bpp. The compression performance is also evaluated based on maximum errors. These results also show that HEVC can achieve a precision of 1°C with an average of 1.3 bpp....

  19. Gas compression infrared generator

    International Nuclear Information System (INIS)

    Hug, W.F.

    1980-01-01

    A molecular gas is compressed in a quasi-adiabatic manner to produce pulsed radiation during each compressor cycle when the pressure and temperature are sufficiently high, and part of the energy is recovered during the expansion phase, as defined in U.S. Pat. No. 3,751,666; characterized by use of a cylinder with a reciprocating piston as a compressor

  20. Chitosan pads vs. manual compression to control bleeding sites after transbrachial arterial catheterization in a randomized trial; Randomisierte Untersuchung zur Anwendung eines Chitosan-Gerinnungspads zur Blutstillung bei transbrachialen Angiographien

    Energy Technology Data Exchange (ETDEWEB)

    Poretti, F.; Rosen, T.; Koerner, B.; Vorwerk, D. [Inst. fuer diagnostische und interventionelle Radiologie, Klinikum Ingolstadt (Germany)

    2005-09-01

    Purpose: until now, no mechanical closure devices were available to achieve fast and secure hemostasis for vessel closure after catheterization of small arterial vessels. Material and methods: eighty patients were randomized to evaluate the effect on hemostasis by use of a chitosan pad (Chito-Seal, Abbott Vascular Devices, Galway/Ireland) in comparison to manual compression after diagnostic transbrachial arterial catheterization. Hemostasis after three minutes and one hour as well as local development of a hematoma after one and twenty-four hours were assessed. Results: the use of chitosan pads significantly decreased the bleeding time in the first three minutes after manual compression time (p < 0.01). Significant decrease in bleeding risk at three minutes by use of the chitosan closure pads was also found in subgroups of patients with hypertension (p < 0.001) or diabetes (p < 0.01) and also in patients under anticoagulation therapy (p < 0.01). In addition, long-term protection from bleeding complications such as the risk of hematoma was decreased by the use of chitosan closure pads one hour (p < 0.01) or twenty-four hours (p < 0.001) after catheter removal. Conclusion: the use of an intravascular anchor or suture system is not safely applicable in these vessels due to the small diameter of the brachial artery. Our results document a significant improvement in hemostasis by using chitosan pads in these cases. (orig.)

  1. Compressible Fluid Suspension Performance Testing

    National Research Council Canada - National Science Library

    Hoogterp, Francis

    2003-01-01

    ... compressible fluid suspension system that was designed and installed on the vehicle by DTI. The purpose of the tests was to evaluate the possible performance benefits of the compressible fluid suspension system...

  2. Compression of ground-motion data

    International Nuclear Information System (INIS)

    Long, J.W.

    1981-04-01

    Ground motion data has been recorded for many years at Nevada Test Site and is now stored on thousands of digital tapes. The recording format is very inefficient in terms of space on tape. This report outlines a method to compress the data onto a few hundred tapes while maintaining the accuracy of the recording and allowing restoration of any file to the original format for future use. For future digitizing a more efficient format is described and suggested

  3. LZ-Compressed String Dictionaries

    OpenAIRE

    Arz, Julian; Fischer, Johannes

    2013-01-01

    We show how to compress string dictionaries using the Lempel-Ziv (LZ78) data compression algorithm. Our approach is validated experimentally on dictionaries of up to 1.5 GB of uncompressed text. We achieve compression ratios often outperforming the existing alternatives, especially on dictionaries containing many repeated substrings. Our query times remain competitive.

  4. Tree compression with top trees

    DEFF Research Database (Denmark)

    Bille, Philip; Gørtz, Inge Li; Landau, Gad M.

    2013-01-01

    We introduce a new compression scheme for labeled trees based on top trees [3]. Our compression scheme is the first to simultaneously take advantage of internal repeats in the tree (as opposed to the classical DAG compression that only exploits rooted subtree repeats) while also supporting fast...

  5. Tree compression with top trees

    DEFF Research Database (Denmark)

    Bille, Philip; Gørtz, Inge Li; Landau, Gad M.

    2015-01-01

    We introduce a new compression scheme for labeled trees based on top trees. Our compression scheme is the first to simultaneously take advantage of internal repeats in the tree (as opposed to the classical DAG compression that only exploits rooted subtree repeats) while also supporting fast...

  6. Confocal Microscopy Study of Neurovascular Distribution in Facial Port Wine Stains (Capillary Malformation

    Directory of Open Access Journals (Sweden)

    Cheng-Jen Chang

    2008-07-01

    Conclusion: Nerve density was decreased in all evaluated PWS sites, and this may be a factor in lesion pathogenesis. PWS blood vessel size correlated with the PDL blanching response and may prove to be a useful prognostic indicator of therapeutic outcome.

  7. Distribution of temperature changes and neurovascular coupling in rat brain following 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy") exposure.

    Science.gov (United States)

    Coman, Daniel; Sanganahalli, Basavaraju G; Jiang, Lihong; Hyder, Fahmeed; Behar, Kevin L

    2015-10-01

    (+/-)3,4-methylenedioxymethamphetamine (MDMA, "ecstasy") is an abused psychostimulant that produces strong monoaminergic stimulation and whole-body hyperthermia. MDMA-induced thermogenesis involves activation of uncoupling proteins (UCPs), primarily a type specific to skeletal muscle (UCP-3) and absent from the brain, although other UCP types are expressed in the brain (e.g. thalamus) and might contribute to thermogenesis. Since neuroimaging of brain temperature could provide insights into MDMA action, we measured spatial distributions of systemically administered MDMA-induced temperature changes and dynamics in rat cortex and subcortex using a novel magnetic resonance method, Biosensor Imaging of Redundant Deviation in Shifts (BIRDS), with an exogenous temperature-sensitive probe (thulium ion and macrocyclic chelate 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethyl-1,4,7,10-tetraacetate (DOTMA(4-))). The MDMA-induced temperature rise was greater in the cortex than in the subcortex (1.6 ± 0.4 °C versus 1.3 ± 0.4 °C) and occurred more rapidly (2.0 ± 0.2 °C/h versus 1.5 ± 0.2 °C/h). MDMA-induced temperature changes and dynamics in the cortex and body were correlated, although the body temperature exceeded the cortex temperature before and after MDMA. Temperature, neuronal activity, and blood flow (CBF) were measured simultaneously in the cortex and subcortex (i.e. thalamus) to investigate possible differences of MDMA-induced warming across brain regions. MDMA-induced warming correlated with increases in neuronal activity and blood flow in the cortex, suggesting that the normal neurovascular response to increased neural activity was maintained. In contrast to the cortex, a biphasic relationship was seen in the subcortex (i.e. thalamus), with a decline in CBF as temperature and neural activity rose, transitioning to a rise in CBF for temperature above 37 °C, suggesting that MDMA affected CBF and neurovascular coupling differently in subcortical regions

  8. Distribution of temperature changes and neurovascular coupling in rat brain following 3,4-methylenedioxymethamphetamine (MDMA,‘ecstasy’) exposure

    Science.gov (United States)

    Coman, Daniel; Sanganahalli, Basavaraju G.; Jiang, Lihong; Hyder, Fahmeed; Behar, Kevin L.

    2015-01-01

    (+/−)3,4-methylenedioxymethamphetamine (MDMA, ‘ecstasy’) is an abused psychostimulant producing strong monoaminergic stimulation and whole-body hyperthermia. MDMA-induced thermogenesis involves activation of uncoupling proteins (UCP), primarily a type specific to skeletal muscle (UCP-3) and which is absent in brain, although other UCP types are expressed in brain (e.g., thalamus) and might contribute to thermogenesis. Since neuroimaging of brain temperature could provide insights of MDMA action, we measured spatial distributions of systemically-administered MDMA-induced temperature changes and dynamics in rat cortex and subcortex using a novel magnetic resonance method, Biosensor Imaging of Redundant Deviation of Shifts (BIRDS), with an exogenous temperature-sensitive probe (thulium ion and macrocyclic chelate 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethyl-1,4,7,10-tetraacetate (DOTMA4−)). The MDMA-induced temperature rise in cortex was greater than in subcortex (1.6±0.4°C vs. 1.3±0.4°C) and occurred more rapidly (2.0±0.2°C/h vs. 1.5±0.2°C/h). MDMA-induced temperature changes and dynamics in cortex and body were correlated, although body temperature exceeded cortex before and after MDMA. Temperature, neuronal activity, and blood flow (CBF) were measured simultaneously in cortex and subcortex (i.e., thalamus) to investigate possible differences of MDMA-induced warming across brain regions. MDMA-induced warming correlated with increases in neuronal activity and blood flow in cortex, suggesting that the normal neurovascular response to increased neural activity was maintained. In contrast to cortex, a biphasic relationship was seen in subcortex (i.e., thalamus), with a decline in CBF as temperature and neural activity rose, transitioning to a rise in CBF for temperature >37°C, suggesting that MDMA affected CBF and neurovascular coupling differently in subcortical regions. Considering that MDMA effects on CBF and heat dissipation (as well as

  9. Digital cinema video compression

    Science.gov (United States)

    Husak, Walter

    2003-05-01

    The Motion Picture Industry began a transition from film based distribution and projection to digital distribution and projection several years ago. Digital delivery and presentation offers the prospect to increase the quality of the theatrical experience for the audience, reduce distribution costs to the distributors, and create new business opportunities for the theater owners and the studios. Digital Cinema also presents an opportunity to provide increased flexibility and security of the movies for the content owners and the theater operators. Distribution of content via electronic means to theaters is unlike any of the traditional applications for video compression. The transition from film-based media to electronic media represents a paradigm shift in video compression techniques and applications that will be discussed in this paper.

  10. Fingerprints in compressed strings

    DEFF Research Database (Denmark)

    Bille, Philip; Gørtz, Inge Li; Cording, Patrick Hagge

    2017-01-01

    In this paper we show how to construct a data structure for a string S of size N compressed into a context-free grammar of size n that supports efficient Karp–Rabin fingerprint queries to any substring of S. That is, given indices i and j, the answer to a query is the fingerprint of the substring S......[i,j]. We present the first O(n) space data structures that answer fingerprint queries without decompressing any characters. For Straight Line Programs (SLP) we get O(log⁡N) query time, and for Linear SLPs (an SLP derivative that captures LZ78 compression and its variations) we get O(log⁡log⁡N) query time...

  11. WSNs Microseismic Signal Subsection Compression Algorithm Based on Compressed Sensing

    Directory of Open Access Journals (Sweden)

    Zhouzhou Liu

    2015-01-01

    Full Text Available For wireless network microseismic monitoring and the problems of low compression ratio and high energy consumption of communication, this paper proposes a segmentation compression algorithm according to the characteristics of the microseismic signals and the compression perception theory (CS used in the transmission process. The algorithm will be collected as a number of nonzero elements of data segmented basis, by reducing the number of combinations of nonzero elements within the segment to improve the accuracy of signal reconstruction, while taking advantage of the characteristics of compressive sensing theory to achieve a high compression ratio of the signal. Experimental results show that, in the quantum chaos immune clone refactoring (Q-CSDR algorithm for reconstruction algorithm, under the condition of signal sparse degree higher than 40, to be more than 0.4 of the compression ratio to compress the signal, the mean square error is less than 0.01, prolonging the network life by 2 times.

  12. Compressed sensing electron tomography

    International Nuclear Information System (INIS)

    Leary, Rowan; Saghi, Zineb; Midgley, Paul A.; Holland, Daniel J.

    2013-01-01

    The recent mathematical concept of compressed sensing (CS) asserts that a small number of well-chosen measurements can suffice to reconstruct signals that are amenable to sparse or compressible representation. In addition to powerful theoretical results, the principles of CS are being exploited increasingly across a range of experiments to yield substantial performance gains relative to conventional approaches. In this work we describe the application of CS to electron tomography (ET) reconstruction and demonstrate the efficacy of CS–ET with several example studies. Artefacts present in conventional ET reconstructions such as streaking, blurring of object boundaries and elongation are markedly reduced, and robust reconstruction is shown to be possible from far fewer projections than are normally used. The CS–ET approach enables more reliable quantitative analysis of the reconstructions as well as novel 3D studies from extremely limited data. - Highlights: • Compressed sensing (CS) theory and its application to electron tomography (ET) is described. • The practical implementation of CS–ET is outlined and its efficacy demonstrated with examples. • High fidelity tomographic reconstruction is possible from a small number of images. • The CS–ET reconstructions can be more reliably segmented and analysed quantitatively. • CS–ET is applicable to different image content by choice of an appropriate sparsifying transform

  13. Efficiency at Sorting Cards in Compressed Air

    Science.gov (United States)

    Poulton, E. C.; Catton, M. J.; Carpenter, A.

    1964-01-01

    At a site where compressed air was being used in the construction of a tunnel, 34 men sorted cards twice, once at normal atmospheric pressure and once at 3½, 2½, or 2 atmospheres absolute pressure. An additional six men sorted cards twice at normal atmospheric pressure. When the task was carried out for the first time, all the groups of men performing at raised pressure were found to yield a reliably greater proportion of very slow responses than the group of men performing at normal pressure. There was reliably more variability in timing at 3½ and 2½ atmospheres absolute than at normal pressure. At 3½ atmospheres absolute the average performance was also reliably slower. When the task was carried out for the second time, exposure to 3½ atmospheres absolute pressure had no reliable effect. Thus compressed air affected performance only while the task was being learnt; it had little effect after practice. No reliable differences were found related to age, to length of experience in compressed air, or to the duration of the exposure to compressed air, which was never less than 10 minutes at 3½ atmospheres absolute pressure. PMID:14180485

  14. Cholesterol as a modifying agent of the neurovascular unit structure and function under physiological and pathological conditions.

    Science.gov (United States)

    Czuba, Ewelina; Steliga, Aleksandra; Lietzau, Grażyna; Kowiański, Przemysław

    2017-08-01

    The brain, demanding constant level of cholesterol, precisely controls its synthesis and homeostasis. The brain cholesterol pool is almost completely separated from the rest of the body by the functional blood-brain barrier (BBB). Only a part of cholesterol pool can be exchanged with the blood circulation in the form of the oxysterol metabolites such, as 27-hydroxycholesterol (27-OHC) and 24S-hydroxycholesterol (24S-OHC). Not only neurons but also blood vessels and neuroglia, constituting neurovascular unit (NVU), are crucial for the brain cholesterol metabolism and undergo precise regulation by numerous modulators, metabolites and signal molecules. In physiological conditions maintaining the optimal cholesterol concentration is important for the energetic metabolism, composition of cell membranes and myelination. However, a growing body of evidence indicates the consequences of the cholesterol homeostasis dysregulation in several pathophysiological processes. There is a causal relationship between hypercholesterolemia and 1) development of type 2 diabetes due to long-term high-fat diet consumption, 2) significance of the oxidative stress consequences for cerebral amyloid angiopathy and neurodegenerative diseases, 3) insulin resistance on progression of the neurodegenerative brain diseases. In this review, we summarize the current state of knowledge concerning the cholesterol influence upon functioning of the NVU under physiological and pathological conditions.

  15. Neurovascular Content of the Mandibular Canal and Its Clinical Relevance: A Literature Review of the Related Anatomical and Radiological Studies

    Directory of Open Access Journals (Sweden)

    Eliades Apostolos N.

    2014-11-01

    Full Text Available In literature, anatomical variations of the inferior alveolar nerve branches (infratemporal, extraosseous and intraosseous are reported and their importance in clinical practice is discussed too. The spatial vessels’ position in relationship with the nerve in the mandibular canal was explored, which is of clinical significance in impacted third molar and implant surgery. It is believed that the neurovascular content of the main mandibular canal follows any variations of the mandibular canal i.e. bifid mandibular, retromolar and accessory mental canals. Retrospective studies and case reports reported the presence of multiple foramina on the medial surface of the ramus, near the main mandibular foramen. In some cases, one supplementary mandibular foramen was found to be connected with the lower third molar, which is called “temporal crest canal”. Others found an accessory mandibular foramen that led into a second mandibular canal which joined the main mandibular canal (double anteriorly. The bony canals contained a terminal branch of the anterior trunk of the mandibular nerve or a branch of inferior alveolar nerve before it entered the mandibular foramen.

  16. Mechanism of Mitochondrial Connexin43′s Protection of the Neurovascular Unit under Acute Cerebral Ischemia-Reperfusion Injury

    Directory of Open Access Journals (Sweden)

    Shuai Hou

    2016-05-01

    Full Text Available We observed mitochondrial connexin43 (mtCx43 expression under cerebral ischemia-reperfusion (I/R injury, analyzed its regulation, and explored its protective mechanisms. Wistar rats were divided into groups based on injections received before middle cerebral artery occlusion (MCAO. Cerebral infarction volume was detected by 2,3,5-triphenyltetrazolim chloride staining, and cell apoptosis was observed by transferase dUTP nick end labeling. We used transmission electron microscopy to observe mitochondrial morphology and determined superoxide dismutase (SOD activity and malondialdehyde (MDA content. MtCx43, p-mtCx43, protein kinase C (PKC, and p-PKC expression were detected by Western blot. Compared with those in the IR group, cerebral infarction volumes in the carbenoxolone (CBX and diazoxide (DZX groups were obviously smaller, and the apoptosis indices were down-regulated. Mitochondrial morphology was damaged after I/R, especially in the IR and 5-hydroxydecanoic acid (5-HD groups. Similarly, decreased SOD activity and increased MDA were observed after MCAO; CBX, DZX, and phorbol-12-myristate-13-acetate (PMA reduced mitochondrial functional injury. Expression of mtCx43 and p-mtCx43 and the p-Cx43/Cx43 ratio were significantly lower in the IR group than in the sham group. These abnormalities were ameliorated by CBX, DZX, and PMA. MtCx43 may protect the neurovascular unit from acute cerebral IR injury via PKC activation induced by mitoKATP channel agonists.

  17. The potential complications of open carpal tunnel release surgery to the ulnar neurovascular bundle and its branches: A cadaveric study.

    Science.gov (United States)

    Boughton, O; Adds, P J; Jayasinghe, J A P

    2010-07-01

    This study investigated the ulnar artery and the ulnar nerve and its branches in the palm to assess how frequently they may be at risk of damage during open carpal tunnel release surgery. Twenty-one formalin-embalmed cadaveric hands were dissected, and the proximity of the ulnar neurovascular bundle to two different lines of incision, the 3rd and 4th interdigital web space axis and the ring finger axis, was assessed and compared. It was found that an incision in the latter (ring finger) axis put the ulnar artery at risk in 12 of 21 specimens, whereas an incision in the former axis (3rd/4th interdigital web space) put the ulnar artery at risk in only two specimens. In 15 hands at least one structure (the ulnar artery or a branch of the ulnar nerve) was at risk in the ring finger axis compared to only seven hands in the axis of the 3rd/4th interdigital web space. We conclude that the ulnar artery and branches of the ulnar nerve are at increased risk of damage with an incision in the axis of the ring finger. The importance of using a blunt dissection technique under direct vision during surgery to identify and preserve these structures and median nerve branches is emphasized. (c) 2010 Wiley-Liss, Inc.

  18. Analysis of compressive fracture in rock using statistical techniques

    Energy Technology Data Exchange (ETDEWEB)

    Blair, S.C.

    1994-12-01

    Fracture of rock in compression is analyzed using a field-theory model, and the processes of crack coalescence and fracture formation and the effect of grain-scale heterogeneities on macroscopic behavior of rock are studied. The model is based on observations of fracture in laboratory compression tests, and incorporates assumptions developed using fracture mechanics analysis of rock fracture. The model represents grains as discrete sites, and uses superposition of continuum and crack-interaction stresses to create cracks at these sites. The sites are also used to introduce local heterogeneity. Clusters of cracked sites can be analyzed using percolation theory. Stress-strain curves for simulated uniaxial tests were analyzed by studying the location of cracked sites, and partitioning of strain energy for selected intervals. Results show that the model implicitly predicts both development of shear-type fracture surfaces and a strength-vs-size relation that are similar to those observed for real rocks. Results of a parameter-sensitivity analysis indicate that heterogeneity in the local stresses, attributed to the shape and loading of individual grains, has a first-order effect on strength, and that increasing local stress heterogeneity lowers compressive strength following an inverse power law. Peak strength decreased with increasing lattice size and decreasing mean site strength, and was independent of site-strength distribution. A model for rock fracture based on a nearest-neighbor algorithm for stress redistribution is also presented and used to simulate laboratory compression tests, with promising results.

  19. Compressive Transient Imaging

    KAUST Repository

    Sun, Qilin

    2017-04-01

    High resolution transient/3D imaging technology is of high interest in both scientific research and commercial application. Nowadays, all of the transient imaging methods suffer from low resolution or time consuming mechanical scanning. We proposed a new method based on TCSPC and Compressive Sensing to achieve a high resolution transient imaging with a several seconds capturing process. Picosecond laser sends a serious of equal interval pulse while synchronized SPAD camera\\'s detecting gate window has a precise phase delay at each cycle. After capturing enough points, we are able to make up a whole signal. By inserting a DMD device into the system, we are able to modulate all the frames of data using binary random patterns to reconstruct a super resolution transient/3D image later. Because the low fill factor of SPAD sensor will make a compressive sensing scenario ill-conditioned, We designed and fabricated a diffractive microlens array. We proposed a new CS reconstruction algorithm which is able to denoise at the same time for the measurements suffering from Poisson noise. Instead of a single SPAD senor, we chose a SPAD array because it can drastically reduce the requirement for the number of measurements and its reconstruction time. Further more, it not easy to reconstruct a high resolution image with only one single sensor while for an array, it just needs to reconstruct small patches and a few measurements. In this thesis, we evaluated the reconstruction methods using both clean measurements and the version corrupted by Poisson noise. The results show how the integration over the layers influence the image quality and our algorithm works well while the measurements suffer from non-trival Poisson noise. It\\'s a breakthrough in the areas of both transient imaging and compressive sensing.

  20. Fast Compressive Tracking.

    Science.gov (United States)

    Zhang, Kaihua; Zhang, Lei; Yang, Ming-Hsuan

    2014-10-01

    It is a challenging task to develop effective and efficient appearance models for robust object tracking due to factors such as pose variation, illumination change, occlusion, and motion blur. Existing online tracking algorithms often update models with samples from observations in recent frames. Despite much success has been demonstrated, numerous issues remain to be addressed. First, while these adaptive appearance models are data-dependent, there does not exist sufficient amount of data for online algorithms to learn at the outset. Second, online tracking algorithms often encounter the drift problems. As a result of self-taught learning, misaligned samples are likely to be added and degrade the appearance models. In this paper, we propose a simple yet effective and efficient tracking algorithm with an appearance model based on features extracted from a multiscale image feature space with data-independent basis. The proposed appearance model employs non-adaptive random projections that preserve the structure of the image feature space of objects. A very sparse measurement matrix is constructed to efficiently extract the features for the appearance model. We compress sample images of the foreground target and the background using the same sparse measurement matrix. The tracking task is formulated as a binary classification via a naive Bayes classifier with online update in the compressed domain. A coarse-to-fine search strategy is adopted to further reduce the computational complexity in the detection procedure. The proposed compressive tracking algorithm runs in real-time and performs favorably against state-of-the-art methods on challenging sequences in terms of efficiency, accuracy and robustness.

  1. SeqCompress: an algorithm for biological sequence compression.

    Science.gov (United States)

    Sardaraz, Muhammad; Tahir, Muhammad; Ikram, Ataul Aziz; Bajwa, Hassan

    2014-10-01

    The growth of Next Generation Sequencing technologies presents significant research challenges, specifically to design bioinformatics tools that handle massive amount of data efficiently. Biological sequence data storage cost has become a noticeable proportion of total cost in the generation and analysis. Particularly increase in DNA sequencing rate is significantly outstripping the rate of increase in disk storage capacity, which may go beyond the limit of storage capacity. It is essential to develop algorithms that handle large data sets via better memory management. This article presents a DNA sequence compression algorithm SeqCompress that copes with the space complexity of biological sequences. The algorithm is based on lossless data compression and uses statistical model as well as arithmetic coding to compress DNA sequences. The proposed algorithm is compared with recent specialized compression tools for biological sequences. Experimental results show that proposed algorithm has better compression gain as compared to other existing algorithms. Copyright © 2014 Elsevier Inc. All rights reserved.

  2. Comparative data compression techniques and multi-compression results

    International Nuclear Information System (INIS)

    Hasan, M R; Ibrahimy, M I; Motakabber, S M A; Ferdaus, M M; Khan, M N H

    2013-01-01

    Data compression is very necessary in business data processing, because of the cost savings that it offers and the large volume of data manipulated in many business applications. It is a method or system for transmitting a digital image (i.e., an array of pixels) from a digital data source to a digital data receiver. More the size of the data be smaller, it provides better transmission speed and saves time. In this communication, we always want to transmit data efficiently and noise freely. This paper will provide some compression techniques for lossless text type data compression and comparative result of multiple and single compression, that will help to find out better compression output and to develop compression algorithms

  3. Analysis by compression

    DEFF Research Database (Denmark)

    Meredith, David

    MEL is a geometric music encoding language designed to allow for musical objects to be encoded parsimoniously as sets of points in pitch-time space, generated by performing geometric transformations on component patterns. MEL has been implemented in Java and coupled with the SIATEC pattern...... discovery algorithm to allow for compact encodings to be generated automatically from in extenso note lists. The MEL-SIATEC system is founded on the belief that music analysis and music perception can be modelled as the compression of in extenso descriptions of musical objects....

  4. Compressive Fatigue in Wood

    DEFF Research Database (Denmark)

    Clorius, Christian Odin; Pedersen, Martin Bo Uhre; Hoffmeyer, Preben

    1999-01-01

    An investigation of fatigue failure in wood subjected to load cycles in compression parallel to grain is presented. Small clear specimens of spruce are taken to failure in square wave formed fatigue loading at a stress excitation level corresponding to 80% of the short term strength. Four...... frequencies ranging from 0.01 Hz to 10 Hz are used. The number of cycles to failure is found to be a poor measure of the fatigue performance of wood. Creep, maximum strain, stiffness and work are monitored throughout the fatigue tests. Accumulated creep is suggested identified with damage and a correlation...

  5. Compressive full waveform lidar

    Science.gov (United States)

    Yang, Weiyi; Ke, Jun

    2017-05-01

    To avoid high bandwidth detector, fast speed A/D converter, and large size memory disk, a compressive full waveform LIDAR system, which uses a temporally modulated laser instead of a pulsed laser, is studied in this paper. Full waveform data from NEON (National Ecological Observatory Network) are used. Random binary patterns are used to modulate the source. To achieve 0.15 m ranging resolution, a 100 MSPS A/D converter is assumed to make measurements. SPIRAL algorithm with canonical basis is employed when Poisson noise is considered in the low illuminated condition.

  6. Free compression tube. Applications

    Science.gov (United States)

    Rusu, Ioan

    2012-11-01

    During the flight of vehicles, their propulsion energy must overcome gravity, to ensure the displacement of air masses on vehicle trajectory, to cover both energy losses from the friction between a solid surface and the air and also the kinetic energy of reflected air masses due to the impact with the flying vehicle. The flight optimization by increasing speed and reducing fuel consumption has directed research in the aerodynamics field. The flying vehicles shapes obtained through studies in the wind tunnel provide the optimization of the impact with the air masses and the airflow along the vehicle. By energy balance studies for vehicles in flight, the author Ioan Rusu directed his research in reducing the energy lost at vehicle impact with air masses. In this respect as compared to classical solutions for building flight vehicles aerodynamic surfaces which reduce the impact and friction with air masses, Ioan Rusu has invented a device which he named free compression tube for rockets, registered with the State Office for Inventions and Trademarks of Romania, OSIM, deposit f 2011 0352. Mounted in front of flight vehicles it eliminates significantly the impact and friction of air masses with the vehicle solid. The air masses come into contact with the air inside the free compression tube and the air-solid friction is eliminated and replaced by air to air friction.

  7. Photon compression in cylinders

    International Nuclear Information System (INIS)

    Ensley, D.L.

    1977-01-01

    It has been shown theoretically that intense microwave radiation is absorbed non-classically by a newly enunciated mechanism when interacting with hydrogen plasma. Fields > 1 Mg, lambda > 1 mm are within this regime. The predicted absorption, approximately P/sub rf/v/sub theta/sup e/, has not yet been experimentally confirmed. The applications of such a coupling are many. If microwave bursts approximately > 5 x 10 14 watts, 5 ns can be generated, the net generation of power from pellet fusion as well as various military applications becomes feasible. The purpose, then, for considering gas-gun photon compression is to obtain the above experimental capability by converting the gas kinetic energy directly into microwave form. Energies of >10 5 joules cm -2 and powers of >10 13 watts cm -2 are potentially available for photon interaction experiments using presently available technology. The following topics are discussed: microwave modes in a finite cylinder, injection, compression, switchout operation, and system performance parameter scaling

  8. Fingerprints in Compressed Strings

    DEFF Research Database (Denmark)

    Bille, Philip; Cording, Patrick Hagge; Gørtz, Inge Li

    2013-01-01

    The Karp-Rabin fingerprint of a string is a type of hash value that due to its strong properties has been used in many string algorithms. In this paper we show how to construct a data structure for a string S of size N compressed by a context-free grammar of size n that answers fingerprint queries...... derivative that captures LZ78 compression and its variations) we get O(loglogN) query time. Hence, our data structures has the same time and space complexity as for random access in SLPs. We utilize the fingerprint data structures to solve the longest common extension problem in query time O(logNlogℓ) and O....... That is, given indices i and j, the answer to a query is the fingerprint of the substring S[i,j]. We present the first O(n) space data structures that answer fingerprint queries without decompressing any characters. For Straight Line Programs (SLP) we get O(logN) query time, and for Linear SLPs (an SLP...

  9. Compressive sensing in medical imaging.

    Science.gov (United States)

    Graff, Christian G; Sidky, Emil Y

    2015-03-10

    The promise of compressive sensing, exploitation of compressibility to achieve high quality image reconstructions with less data, has attracted a great deal of attention in the medical imaging community. At the Compressed Sensing Incubator meeting held in April 2014 at OSA Headquarters in Washington, DC, presentations were given summarizing some of the research efforts ongoing in compressive sensing for x-ray computed tomography and magnetic resonance imaging systems. This article provides an expanded version of these presentations. Sparsity-exploiting reconstruction algorithms that have gained popularity in the medical imaging community are studied, and examples of clinical applications that could benefit from compressive sensing ideas are provided. The current and potential future impact of compressive sensing on the medical imaging field is discussed.

  10. Generalized massive optimal data compression

    Science.gov (United States)

    Alsing, Justin; Wandelt, Benjamin

    2018-05-01

    In this paper, we provide a general procedure for optimally compressing N data down to n summary statistics, where n is equal to the number of parameters of interest. We show that compression to the score function - the gradient of the log-likelihood with respect to the parameters - yields n compressed statistics that are optimal in the sense that they preserve the Fisher information content of the data. Our method generalizes earlier work on linear Karhunen-Loéve compression for Gaussian data whilst recovering both lossless linear compression and quadratic estimation as special cases when they are optimal. We give a unified treatment that also includes the general non-Gaussian case as long as mild regularity conditions are satisfied, producing optimal non-linear summary statistics when appropriate. As a worked example, we derive explicitly the n optimal compressed statistics for Gaussian data in the general case where both the mean and covariance depend on the parameters.

  11. Chest compression rates and survival following out-of-hospital cardiac arrest.

    Science.gov (United States)

    Idris, Ahamed H; Guffey, Danielle; Pepe, Paul E; Brown, Siobhan P; Brooks, Steven C; Callaway, Clifton W; Christenson, Jim; Davis, Daniel P; Daya, Mohamud R; Gray, Randal; Kudenchuk, Peter J; Larsen, Jonathan; Lin, Steve; Menegazzi, James J; Sheehan, Kellie; Sopko, George; Stiell, Ian; Nichol, Graham; Aufderheide, Tom P

    2015-04-01

    Guidelines for cardiopulmonary resuscitation recommend a chest compression rate of at least 100 compressions/min. A recent clinical study reported optimal return of spontaneous circulation with rates between 100 and 120/min during cardiopulmonary resuscitation for out-of-hospital cardiac arrest. However, the relationship between compression rate and survival is still undetermined. Prospective, observational study. Data is from the Resuscitation Outcomes Consortium Prehospital Resuscitation IMpedance threshold device and Early versus Delayed analysis clinical trial. Adults with out-of-hospital cardiac arrest treated by emergency medical service providers. None. Data were abstracted from monitor-defibrillator recordings for the first five minutes of emergency medical service cardiopulmonary resuscitation. Multiple logistic regression assessed odds ratio for survival by compression rate categories (compression fraction and depth, first rhythm, and study site. Compression rate data were available for 10,371 patients; 6,399 also had chest compression fraction and depth data. Age (mean±SD) was 67±16 years. Chest compression rate was 111±19 per minute, compression fraction was 0.70±0.17, and compression depth was 42±12 mm. Circulation was restored in 34%; 9% survived to hospital discharge. After adjustment for covariates without chest compression depth and fraction (n=10,371), a global test found no significant relationship between compression rate and survival (p=0.19). However, after adjustment for covariates including chest compression depth and fraction (n=6,399), the global test found a significant relationship between compression rate and survival (p=0.02), with the reference group (100-119 compressions/min) having the greatest likelihood for survival. After adjustment for chest compression fraction and depth, compression rates between 100 and 120 per minute were associated with greatest survival to hospital discharge.

  12. Introduction to compressible fluid flow

    CERN Document Server

    Oosthuizen, Patrick H

    2013-01-01

    IntroductionThe Equations of Steady One-Dimensional Compressible FlowSome Fundamental Aspects of Compressible FlowOne-Dimensional Isentropic FlowNormal Shock WavesOblique Shock WavesExpansion Waves - Prandtl-Meyer FlowVariable Area FlowsAdiabatic Flow with FrictionFlow with Heat TransferLinearized Analysis of Two-Dimensional Compressible FlowsHypersonic and High-Temperature FlowsHigh-Temperature Gas EffectsLow-Density FlowsBibliographyAppendices

  13. Mammographic compression in Asian women.

    Science.gov (United States)

    Lau, Susie; Abdul Aziz, Yang Faridah; Ng, Kwan Hoong

    2017-01-01

    To investigate: (1) the variability of mammographic compression parameters amongst Asian women; and (2) the effects of reducing compression force on image quality and mean glandular dose (MGD) in Asian women based on phantom study. We retrospectively collected 15818 raw digital mammograms from 3772 Asian women aged 35-80 years who underwent screening or diagnostic mammography between Jan 2012 and Dec 2014 at our center. The mammograms were processed using a volumetric breast density (VBD) measurement software (Volpara) to assess compression force, compression pressure, compressed breast thickness (CBT), breast volume, VBD and MGD against breast contact area. The effects of reducing compression force on image quality and MGD were also evaluated based on measurement obtained from 105 Asian women, as well as using the RMI156 Mammographic Accreditation Phantom and polymethyl methacrylate (PMMA) slabs. Compression force, compression pressure, CBT, breast volume, VBD and MGD correlated significantly with breast contact area (pAsian women. The median compression force should be about 8.1 daN compared to the current 12.0 daN. Decreasing compression force from 12.0 daN to 9.0 daN increased CBT by 3.3±1.4 mm, MGD by 6.2-11.0%, and caused no significant effects on image quality (p>0.05). Force-standardized protocol led to widely variable compression parameters in Asian women. Based on phantom study, it is feasible to reduce compression force up to 32.5% with minimal effects on image quality and MGD.

  14. Patient Satisfaction After Femoral Arterial Access Site Closure Using the ExoSeal{sup ®} Vascular Closure Device Compared to Manual Compression: A Prospective Intra-individual Comparative Study

    Energy Technology Data Exchange (ETDEWEB)

    Pieper, Claus Christian, E-mail: claus.christian.pieper@ukb.uni-bonn.de; Thomas, Daniel, E-mail: daniel.thomas@ukb.uni-bonn.de [University of Bonn, Department of Radiology (Germany); Nadal, Jennifer, E-mail: jennifer.nadal@ukb.uni-bonn.de [University of Bonn, Institute for Medical Biometry, Informatics and Epidemiology (Germany); Willinek, Winfried A., E-mail: w.willinek@bk-trier.de; Schild, Hans Heinz, E-mail: hans.schild@ukb.uni-bonn.de; Meyer, Carsten, E-mail: carsten.meyer@ukb.uni-bonn.de [University of Bonn, Department of Radiology (Germany)

    2016-01-15

    PurposeTo intra-individually compare discomfort levels and patient satisfaction after arterial access closure using the ExoSeal{sup ®} vascular closure device (VCD) and manual compression (MC) in a prospective study design.MethodsPatients undergoing two planned interventions from 07/2013 to 09/2014 could participate in the study. Access closure was performed with an ExoSeal{sup ®}-VCD in one and MC in the other intervention. Patients were clinically and sonographically examined and were given questionnaires 1 day after intervention [groin- and back-pain during bedrest (100-point visual analog scale; 0: no pain); comfortability of bedrest (10-point Likert scale, 1: comfortable), satisfaction with closure (10-point Likert scale, 1: very satisfied)]. Results were analyzed in a cross-over design.Results48 patients (29 male, median age 62.5 (32–88) years) were included. An ExoSeal{sup ®}-VCD was used first in 25 cases. As four of these subsequently refused MC as second intervention, data from 44 patients could be analyzed. All closures were technically successful (successful device deployment) without major complications. Groin- and back-pain after VCD-use/MC was 0 (0–15) vs. 10 (0–80) and 0 (0–75) vs. 25 (0–90), respectively (p < 0.0001). Bedrest after VCD-use was more comfortable than after MC [1 (range 1–7) vs. 6 (2–10); p < 0.0001]. Satisfaction with the closure procedure and with the intervention in general was higher after VCD-use compared to MC [1 (1–3) vs. 5 (2–10) and 1 (1–2) vs. 2 (1–4), respectively; p < 0.0001].ConclusionIntra-individual comparison showed pain levels and discomfort to be significantly lower after ExoSeal{sup ®} use compared to MC. VCD closure was associated with higher satisfaction both with the closure itself and with the intervention in general.

  15. A comparison of radiation dose to the neurovascular bundles in men with and without prostate brachytherapy-induced erectile dysfunction

    International Nuclear Information System (INIS)

    Merrick, Gregory S.; Butler, Wayne M.; Dorsey, Anthony T.; Lief, Jonathan H.; Donzella, Joseph G.

    2000-01-01

    Purpose: The etiology of erectile dysfunction after definitive local therapy for carcinoma of the prostate gland represents a multifactorial phenomenon including neurogenic compromise, venous insufficiency, local trauma, and psychogenic causes. It has been suggested that impotence after prostate brachytherapy is a consequence of excessive radiation dose to the neurovascular bundles (NVB). Herein we evaluate the potential relationship between radiation dose to the NVB and the development of erectile dysfunction following prostate brachytherapy. Methods and Materials: The radiation dose to the NVB was evaluated for 33 patients who developed erectile dysfunction (ED) following brachytherapy plus 21 additional patients who were potent before and subsequent to brachytherapy. Of the 54 patient study group, the median follow up was 37 months, and 25 patients were managed with 125 I as a monotherapeutic approach and 29 received 103 Pd as a boost following 45 Gy of external beam radiation therapy. Radiographic localization of the NVB was performed via a two-dimensional geometric model that placed 3-NVB calculation points on the left and right posterolateral side of each 5-mm CT slice. Parameters evaluated included dose-surface histograms, dose parameters via point doses on each slice, the magnitude of the dose in relationship to the distance from the base, and the relationship between NVB radiation dose in patients with and without ED, patient response to sildenafil and case sequence number. Results: In terms of percent prescribed minimum peripheral dose (% mPD), there was no significant difference in mean neurovascular bundle dose between potent and impotent patients, between the isotopes ( 125 I or 103 Pd), mono- or boost therapy, or side of the prostate for which the overall average was 217% ± 55% of mPD. There was also no significant dosimetric difference in terms of response to sildenafil based on a multivariate analysis which included % mPD and various dose

  16. Expansions of the neurovascular scleral canal and contained optic nerve occur early in the hypertonic saline rat experimental glaucoma model.

    Science.gov (United States)

    Pazos, Marta; Yang, Hongli; Gardiner, Stuart K; Cepurna, William O; Johnson, Elaine C; Morrison, John C; Burgoyne, Claude F

    2016-04-01

    To characterize early optic nerve head (ONH) structural change in rat experimental glaucoma (EG). Unilateral intraocular pressure (IOP) elevation was induced in Brown Norway rats by hypertonic saline injection into the episcleral veins and animals were sacrificed 4 weeks later by perfusion fixation. Optic nerve cross-sections were graded from 1 (normal) to 5 (extensive injury) by 5 masked observers. ONHs with peripapillary retina and sclera were embedded, serial sectioned, 3-D reconstructed, delineated, and quantified. Overall and animal-specific EG versus Control eye ONH parameter differences were assessed globally and regionally by linear mixed effect models with significance criteria adjusted for multiple comparisons. Expansions of the optic nerve and surrounding anterior scleral canal opening achieved statistical significance overall (p < 0.0022), and in 7 of 8 EG eyes (p < 0.005). In at least 5 EG eyes, significant expansions (p < 0.005) in Bruch's membrane opening (BMO) (range 3-10%), the anterior and posterior scleral canal openings (8-21% and 5-21%, respectively), and the optic nerve at the anterior and posterior scleral canal openings (11-30% and 8-41%, respectively) were detected. Optic nerve expansion was greatest within the superior and inferior quadrants. Optic nerve expansion at the posterior scleral canal opening was significantly correlated to optic nerve damage (R = 0.768, p = 0.042). In the rat ONH, the optic nerve and surrounding BMO and neurovascular scleral canal expand early in their response to chronic experimental IOP elevation. These findings provide phenotypic landmarks and imaging targets for detecting the development of experimental glaucomatous optic neuropathy in the rat eye. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Topiramate improves neurovascular function, epidermal nerve fiber morphology, and metabolism in patients with type 2 diabetes mellitus

    Directory of Open Access Journals (Sweden)

    Boyd A

    2010-12-01

    Full Text Available Amanda L Boyd, Patricia M Barlow, Gary L Pittenger, Kathryn F Simmons, Aaron I VinikDepartment of Internal Medicine, Eastern Virginia Medical School, Norfolk, VA, USAPurpose: To assess the effects of topiramate on C-fiber function, nerve fiber morphology, and metabolism (including insulin sensitivity, obesity, and dyslipidemia in type 2 diabetes.Patients and methods: We conducted an 18-week, open-label trial treating patients with topiramate. Twenty subjects with type 2 diabetes and neuropathy (61.5 ± 1.29 years; 15 male, 5 female were enrolled and completed the trial. Neuropathy was evaluated by total neuropathy scores, nerve conduction studies, quantitative sensory tests, laser Doppler skin blood flow, and intraepidermal nerve fibers in skin biopsies.Results: Topiramate treatment improved symptoms compatible with C-fiber dysfunction. Weight, blood pressure, and hemoglobin A1c also improved. Laser Doppler skin blood flow improved significantly after 12 weeks of treatment, but returned to baseline at 18 weeks. After 18 weeks of treatment there was a significant increase in intraepidermal nerve fiber length at the forearm, thigh, and proximal leg. Intraepidermal nerve fiber density was significantly increased by topiramate in the proximal leg.Conclusion: This study is the first to demonstrate that it is possible to induce skin intraepidermal nerve fiber regeneration accompanied by enhancement of neurovascular function, translating into improved symptoms as well as sensory nerve function. The simultaneous improvement of selective metabolic indices may play a role in this effect, but this remains to be determined.Keywords: diabetic neuropathy, skin blood flow, skin biopsy, diabetes

  18. Presurgical visualization of the neurovascular relationship in trigeminal neuralgia with 3D modeling using free Slicer software.

    Science.gov (United States)

    Han, Kai-Wei; Zhang, Dan-Feng; Chen, Ji-Gang; Hou, Li-Jun

    2016-11-01

    To explore whether segmentation and 3D modeling are more accurate in the preoperative detection of the neurovascular relationship (NVR) in patients with trigeminal neuralgia (TN) compared to MRI fast imaging employing steady-state acquisition (FIESTA). Segmentation and 3D modeling using 3D Slicer were conducted for 40 patients undergoing MRI FIESTA and microsurgical vascular decompression (MVD). The NVR, as well as the offending vessel determined by MRI FIESTA and 3D Slicer, was reviewed and compared with intraoperative manifestations using SPSS. The k agreement between the MRI FIESTA and operation in determining the NVR was 0.232 and that between the 3D modeling and operation was 0.6333. There was no significant difference between these two procedures (χ 2  = 8.09, P = 0.088). The k agreement between the MRI FIESTA and operation in determining the offending vessel was 0.373, and that between the 3D modeling and operation was 0.922. There were significant differences between two of them (χ 2  = 82.01, P = 0.000). The sensitivity and specificity for MRI FIESTA in determining the NVR were 87.2 % and 100 %, respectively, and for 3D modeling were both 100 %. The segmentation and 3D modeling were more accurate than MRI FIESTA in preoperative verification of the NVR and offending vessel. This was consistent with surgical manifestations and was more helpful for the preoperative decision and surgical plan.

  19. Neurovascular bundle–sparing radiotherapy for prostate cancer using MRI-CT registration: A dosimetric feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Cassidy, R.J., E-mail: richardjcassidy@emory.edu [Department of Radiation Oncology, Winship Cancer Institute of Emory University, Atlanta, GA (United States); Yang, X.; Liu, T.; Thomas, M. [Department of Radiation Oncology, Winship Cancer Institute of Emory University, Atlanta, GA (United States); Nour, S.G. [Department of Radiology, Emory University, Atlanta, GA (United States); Jani, A.B. [Department of Radiation Oncology, Winship Cancer Institute of Emory University, Atlanta, GA (United States)

    2016-01-01

    Purpose: Sexual dysfunction after radiotherapy for prostate cancer remains an important late adverse toxicity. The neurovascular bundles (NVB) that lie posterolaterally to the prostate are typically spared during prostatectomy, but in traditional radiotherapy planning they are not contoured as an organ-at-risk with dose constraints. Our goal was to determine the dosimetric feasibility of “NVB-sparing” prostate radiotherapy while still delivering adequate dose to the prostate. Methods: Twenty-five consecutive patients with prostate cancer (with no extraprostatic disease on pelvic magnetic resonance imaging [MRI]) who that were treated with external beam radiotherapy, with the same primary planning target volume margins, to a dose of 79.2 Gy were evaluated. Pelvic MRI and simulation computed tomography scans were registered using dedicated software to allow for bilateral NVB target delineation on T2-weighted MRI. A volumetric modulated arc therapy plan was generated using the NVB bilaterally with 2 mm margin as an organ to spare and compared to the patient’s previously delivered plan. Dose-volume histogram endpoints for NVB, rectum, bladder, and planning target volume 79.2 were compared between the 2 plans using a 2-tailed paired t-test. Results: The V70 for the NVB was significantly lower on the NVB-sparing plan (p <0.01), while rectum and bladder endpoints were similar. Target V100% was similar but V{sub 105%} was higher for the NVB-sparing plans (p <0.01). Conclusions: “NVB-sparing” radiotherapy is dosimetrically feasible using CT-MRI registration, and for volumetric modulated arc therapy technology — target coverage is acceptable without increased dose to other normal structures, but with higher target dose inhomogeneity. The clinical impact of “NVB-sparing” radiotherapy is currently under study at our institution.

  20. Troxerutin and Cerebroprotein Hydrolysate Injection Protects Neurovascular Units from Oxygen-Glucose Deprivation and Reoxygenation-Induced Injury In Vitro

    Directory of Open Access Journals (Sweden)

    Hóngyi Zhào

    2018-01-01

    Full Text Available Cerebral ischemia/reperfusion (I/R injury involves complex events of cellular and molecular processes. Previous studies suggest that a neurovascular unit (NVU acts as an intricate network to maintain the neuronal homeostatic microenvironment. The present study established an NVU model for oxygen-glucose deprivation and reoxygenation (OGD/R damage, trying to target the major components of the NVU using a coculture of rat neurons, astrocytes, and rat brain microvascular endothelial cells (rBMECs to investigate the therapeutic effects of troxerutin and cerebroprotein hydrolysate injections (TCHis. The study observed that OGD/R downregulated the expressions of GAP-43, Claudin-5, and AQP-4 obviously detected by Western blotting and immunocytochemical analysis, respectively, while TCHi ameliorated the effect of OGD/R significantly. Meanwhile, TCHi alleviated the abnormalities of ultrastructure of neurons and rBMECs induced by OGD/R. Furthermore, both levels of inflammatory cytokines (IL-1β, IL-6, and TNF-α and cell adhesion molecules (VCAM-1 and ICAM-1 detected by ELISA in NVU supernatant were found elevated significantly through OGD/R, but TCHi ameliorated the trend. In addition, TCHi also mitigated the increase of proapoptotic factors (Bax, p53, and caspase-3 induced by OGD/R in NVU model statistically. All these findings demonstrated that TCHis played a protective role, which was reflected in anti-inflammation, antiapoptosis, and blood–brain barrier maintenance. The results of the study concluded that the NVU is an ideal target and TCHi acts as a neuroprotective agent against cerebral I/R injuries.

  1. Adiabatic compression and radiative compression of magnetic fields

    International Nuclear Information System (INIS)

    Woods, C.H.

    1980-01-01

    Flux is conserved during mechanical compression of magnetic fields for both nonrelativistic and relativistic compressors. However, the relativistic compressor generates radiation, which can carry up to twice the energy content of the magnetic field compressed adiabatically. The radiation may be either confined or allowed to escape

  2. Vacancy behavior in a compressed fcc Lennard-Jones crystal

    International Nuclear Information System (INIS)

    Beeler, J.R. Jr.

    1981-12-01

    This computer experiment study concerns the determination of the stable vacancy configuration in a compressed fcc Lennard-Jones crystal and the migration of this defect in a compressed crystal. Isotropic and uniaxial compression stress conditions were studied. The isotropic and uniaxial compression magnitudes employed were 0.94 less than or equal to eta less than or equal to 1.5, and 1.0 less than or equal to eta less than or equal to 1.5, respectively. The site-centered vacancy (SCV) was the stable vacancy configuration whenever cubic symmetry was present. This includes all of the isotropic compression cases and the particular uniaxial compression case (eta = √2) that give a bcc structure. In addition, the SCV was the stable configuration for uniaxial compression eta 1.20, the SV-OP is an extended defect and, therefore, a saddle point for SV-OP migration could not be determined. The mechanism for the transformation from the SCV to the SV-OP as the stable form at eta = 1.29 appears to be an alternating sign [101] and/or [011] shear process

  3. Waves and compressible flow

    CERN Document Server

    Ockendon, Hilary

    2016-01-01

    Now in its second edition, this book continues to give readers a broad mathematical basis for modelling and understanding the wide range of wave phenomena encountered in modern applications.  New and expanded material includes topics such as elastoplastic waves and waves in plasmas, as well as new exercises.  Comprehensive collections of models are used to illustrate the underpinning mathematical methodologies, which include the basic ideas of the relevant partial differential equations, characteristics, ray theory, asymptotic analysis, dispersion, shock waves, and weak solutions. Although the main focus is on compressible fluid flow, the authors show how intimately gasdynamic waves are related to wave phenomena in many other areas of physical science.   Special emphasis is placed on the development of physical intuition to supplement and reinforce analytical thinking. Each chapter includes a complete set of carefully prepared exercises, making this a suitable textbook for students in applied mathematics, ...

  4. Application specific compression : final report.

    Energy Technology Data Exchange (ETDEWEB)

    Melgaard, David Kennett; Byrne, Raymond Harry; Myers, Daniel S.; Harrison, Carol D.; Lee, David S.; Lewis, Phillip J.; Carlson, Jeffrey J.

    2008-12-01

    With the continuing development of more capable data gathering sensors, comes an increased demand on the bandwidth for transmitting larger quantities of data. To help counteract that trend, a study was undertaken to determine appropriate lossy data compression strategies for minimizing their impact on target detection and characterization. The survey of current compression techniques led us to the conclusion that wavelet compression was well suited for this purpose. Wavelet analysis essentially applies a low-pass and high-pass filter to the data, converting the data into the related coefficients that maintain spatial information as well as frequency information. Wavelet compression is achieved by zeroing the coefficients that pertain to the noise in the signal, i.e. the high frequency, low amplitude portion. This approach is well suited for our goal because it reduces the noise in the signal with only minimal impact on the larger, lower frequency target signatures. The resulting coefficients can then be encoded using lossless techniques with higher compression levels because of the lower entropy and significant number of zeros. No significant signal degradation or difficulties in target characterization or detection were observed or measured when wavelet compression was applied to simulated and real data, even when over 80% of the coefficients were zeroed. While the exact level of compression will be data set dependent, for the data sets we studied, compression factors over 10 were found to be satisfactory where conventional lossless techniques achieved levels of less than 3.

  5. Compressed Baryonic Matter of Astrophysics

    OpenAIRE

    Guo, Yanjun; Xu, Renxin

    2013-01-01

    Baryonic matter in the core of a massive and evolved star is compressed significantly to form a supra-nuclear object, and compressed baryonic matter (CBM) is then produced after supernova. The state of cold matter at a few nuclear density is pedagogically reviewed, with significant attention paid to a possible quark-cluster state conjectured from an astrophysical point of view.

  6. Streaming Compression of Hexahedral Meshes

    Energy Technology Data Exchange (ETDEWEB)

    Isenburg, M; Courbet, C

    2010-02-03

    We describe a method for streaming compression of hexahedral meshes. Given an interleaved stream of vertices and hexahedral our coder incrementally compresses the mesh in the presented order. Our coder is extremely memory efficient when the input stream documents when vertices are referenced for the last time (i.e. when it contains topological finalization tags). Our coder then continuously releases and reuses data structures that no longer contribute to compressing the remainder of the stream. This means in practice that our coder has only a small fraction of the whole mesh in memory at any time. We can therefore compress very large meshes - even meshes that do not file in memory. Compared to traditional, non-streaming approaches that load the entire mesh and globally reorder it during compression, our algorithm trades a less compact compressed representation for significant gains in speed, memory, and I/O efficiency. For example, on the 456k hexahedra 'blade' mesh, our coder is twice as fast and uses 88 times less memory (only 3.1 MB) with the compressed file increasing about 3% in size. We also present the first scheme for predictive compression of properties associated with hexahedral cells.

  7. Data Compression with Linear Algebra

    OpenAIRE

    Etler, David

    2015-01-01

    A presentation on the applications of linear algebra to image compression. Covers entropy, the discrete cosine transform, thresholding, quantization, and examples of images compressed with DCT. Given in Spring 2015 at Ocean County College as part of the honors program.

  8. Images compression in nuclear medicine

    International Nuclear Information System (INIS)

    Rebelo, M.S.; Furuie, S.S.; Moura, L.

    1992-01-01

    The performance of two methods for images compression in nuclear medicine was evaluated. The LZW precise, and Cosine Transformed, approximate, methods were analyzed. The results were obtained, showing that the utilization of approximated method produced images with an agreeable quality for visual analysis and compression rates, considerably high than precise method. (C.G.C.)

  9. Compressive Sensing in Communication Systems

    DEFF Research Database (Denmark)

    Fyhn, Karsten

    2013-01-01

    . The need for cheaper, smarter and more energy efficient wireless devices is greater now than ever. This thesis addresses this problem and concerns the application of the recently developed sampling theory of compressive sensing in communication systems. Compressive sensing is the merging of signal...... acquisition and compression. It allows for sampling a signal with a rate below the bound dictated by the celebrated Shannon-Nyquist sampling theorem. In some communication systems this necessary minimum sample rate, dictated by the Shannon-Nyquist sampling theorem, is so high it is at the limit of what...... with using compressive sensing in communication systems. The main contribution of this thesis is two-fold: 1) a new compressive sensing hardware structure for spread spectrum signals, which is simpler than the current state-of-the-art, and 2) a range of algorithms for parameter estimation for the class...

  10. Evaluation of mammogram compression efficiency

    International Nuclear Information System (INIS)

    Przelaskowski, A.; Surowski, P.; Kukula, A.

    2005-01-01

    Lossy image coding significantly improves performance over lossless methods, but a reliable control of diagnostic accuracy regarding compressed images is necessary. The acceptable range of compression ratios must be safe with respect to as many objective criteria as possible. This study evaluates the compression efficiency of digital mammograms in both numerically lossless (reversible) and lossy (irreversible) manner. Effective compression methods and concepts were examined to increase archiving and telediagnosis performance. Lossless compression as a primary applicable tool for medical applications was verified on a set 131 mammograms. Moreover, nine radiologists participated in the evaluation of lossy compression of mammograms. Subjective rating of diagnostically important features brought a set of mean rates given for each test image. The lesion detection test resulted in binary decision data analyzed statistically. The radiologists rated and interpreted malignant and benign lesions, representative pathology symptoms, and other structures susceptible to compression distortions contained in 22 original and 62 reconstructed mammograms. Test mammograms were collected in two radiology centers for three years and then selected according to diagnostic content suitable for an evaluation of compression effects. Lossless compression efficiency of the tested coders varied, but CALIC, JPEG-LS, and SPIHT performed the best. The evaluation of lossy compression effects affecting detection ability was based on ROC-like analysis. Assuming a two-sided significance level of p=0.05, the null hypothesis that lower bit rate reconstructions are as useful for diagnosis as the originals was false in sensitivity tests with 0.04 bpp mammograms. However, verification of the same hypothesis with 0.1 bpp reconstructions suggested their acceptance. Moreover, the 1 bpp reconstructions were rated very similarly to the original mammograms in the diagnostic quality evaluation test, but the

  11. Compression etiology in tendinopathy.

    Science.gov (United States)

    Almekinders, Louis C; Weinhold, Paul S; Maffulli, Nicola

    2003-10-01

    Recent studies have emphasized that the etiology of tendinopathy is not as simple as was once thought. The etiology is likely to be multifactorial. Etiologic factors may include some of the traditional factors such as overuse, inflexibility, and equipment problems; however, other factors need to be considered as well, such as age-related tendon degeneration and biomechanical considerations as outlined in this article. More research is needed to determine the significance of stress-shielding and compression in tendinopathy. If they are confirmed to play a role, this finding may significantly alter our approach in both prevention and in treatment through exercise therapy. The current biomechanical studies indicate that certain joint positions are more likely to place tensile stress on the area of the tendon commonly affected by tendinopathy. These joint positions seem to be different than the traditional positions for stretching exercises used for prevention and rehabilitation of tendinopathic conditions. Incorporation of different joint positions during stretching exercises may exert more uniform, controlled tensile stress on these affected areas of the tendon and avoid stresshielding. These exercises may be able to better maintain the mechanical strength of that region of the tendon and thereby avoid injury. Alternatively, they could more uniformly stress a healing area of the tendon in a controlled manner, and thereby stimulate healing once an injury has occurred. Additional work will have to prove if a change in rehabilitation exercises is more efficacious that current techniques.

  12. Compressible Vortex Ring

    Science.gov (United States)

    Elavarasan, Ramasamy; Arakeri, Jayawant; Krothapalli, Anjaneyulu

    1999-11-01

    The interaction of a high-speed vortex ring with a shock wave is one of the fundamental issues as it is a source of sound in supersonic jets. The complex flow field induced by the vortex alters the propagation of the shock wave greatly. In order to understand the process, a compressible vortex ring is studied in detail using Particle Image Velocimetry (PIV) and shadowgraphic techniques. The high-speed vortex ring is generated from a shock tube and the shock wave, which precedes the vortex, is reflected back by a plate and made to interact with the vortex. The shadowgraph images indicate that the reflected shock front is influenced by the non-uniform flow induced by the vortex and is decelerated while passing through the vortex. It appears that after the interaction the shock is "split" into two. The PIV measurements provided clear picture about the evolution of the vortex at different time interval. The centerline velocity traces show the maximum velocity to be around 350 m/s. The velocity field, unlike in incompressible rings, contains contributions from both the shock and the vortex ring. The velocity distribution across the vortex core, core diameter and circulation are also calculated from the PIV data.

  13. Advances in compressible turbulent mixing

    International Nuclear Information System (INIS)

    Dannevik, W.P.; Buckingham, A.C.; Leith, C.E.

    1992-01-01

    This volume includes some recent additions to original material prepared for the Princeton International Workshop on the Physics of Compressible Turbulent Mixing, held in 1988. Workshop participants were asked to emphasize the physics of the compressible mixing process rather than measurement techniques or computational methods. Actual experimental results and their meaning were given precedence over discussions of new diagnostic developments. Theoretical interpretations and understanding were stressed rather than the exposition of new analytical model developments or advances in numerical procedures. By design, compressibility influences on turbulent mixing were discussed--almost exclusively--from the perspective of supersonic flow field studies. The papers are arranged in three topical categories: Foundations, Vortical Domination, and Strongly Coupled Compressibility. The Foundations category is a collection of seminal studies that connect current study in compressible turbulent mixing with compressible, high-speed turbulent flow research that almost vanished about two decades ago. A number of contributions are included on flow instability initiation, evolution, and transition between the states of unstable flow onset through those descriptive of fully developed turbulence. The Vortical Domination category includes theoretical and experimental studies of coherent structures, vortex pairing, vortex-dynamics-influenced pressure focusing. In the Strongly Coupled Compressibility category the organizers included the high-speed turbulent flow investigations in which the interaction of shock waves could be considered an important source for production of new turbulence or for the enhancement of pre-existing turbulence. Individual papers are processed separately

  14. Mammography image compression using Wavelet

    International Nuclear Information System (INIS)

    Azuhar Ripin; Md Saion Salikin; Wan Hazlinda Ismail; Asmaliza Hashim; Norriza Md Isa

    2004-01-01

    Image compression plays an important role in many applications like medical imaging, televideo conferencing, remote sensing, document and facsimile transmission, which depend on the efficient manipulation, storage, and transmission of binary, gray scale, or color images. In Medical imaging application such Picture Archiving and Communication System (PACs), the image size or image stream size is too large and requires a large amount of storage space or high bandwidth for communication. Image compression techniques are divided into two categories namely lossy and lossless data compression. Wavelet method used in this project is a lossless compression method. In this method, the exact original mammography image data can be recovered. In this project, mammography images are digitized by using Vider Sierra Plus digitizer. The digitized images are compressed by using this wavelet image compression technique. Interactive Data Language (IDLs) numerical and visualization software is used to perform all of the calculations, to generate and display all of the compressed images. Results of this project are presented in this paper. (Author)

  15. Advances in compressible turbulent mixing

    Energy Technology Data Exchange (ETDEWEB)

    Dannevik, W.P.; Buckingham, A.C.; Leith, C.E. [eds.

    1992-01-01

    This volume includes some recent additions to original material prepared for the Princeton International Workshop on the Physics of Compressible Turbulent Mixing, held in 1988. Workshop participants were asked to emphasize the physics of the compressible mixing process rather than measurement techniques or computational methods. Actual experimental results and their meaning were given precedence over discussions of new diagnostic developments. Theoretical interpretations and understanding were stressed rather than the exposition of new analytical model developments or advances in numerical procedures. By design, compressibility influences on turbulent mixing were discussed--almost exclusively--from the perspective of supersonic flow field studies. The papers are arranged in three topical categories: Foundations, Vortical Domination, and Strongly Coupled Compressibility. The Foundations category is a collection of seminal studies that connect current study in compressible turbulent mixing with compressible, high-speed turbulent flow research that almost vanished about two decades ago. A number of contributions are included on flow instability initiation, evolution, and transition between the states of unstable flow onset through those descriptive of fully developed turbulence. The Vortical Domination category includes theoretical and experimental studies of coherent structures, vortex pairing, vortex-dynamics-influenced pressure focusing. In the Strongly Coupled Compressibility category the organizers included the high-speed turbulent flow investigations in which the interaction of shock waves could be considered an important source for production of new turbulence or for the enhancement of pre-existing turbulence. Individual papers are processed separately.

  16. Association between silent embolic cerebral infarction and continuous increase of P2Y12 reaction units after neurovascular stenting.

    Science.gov (United States)

    Kim, Bum Joon; Kwon, Joo Y; Jung, Jin-Man; Lee, Deok Hee; Kang, Dong-Wha; Kim, Jong S; Kwon, Sun U

    2014-10-01

    Endovascular procedures are one of the important treatment options for steno-occlusive arteries in ischemic stroke patients. However, embolic complications after such procedures are always a concern. The authors investigated the association between serial change of residual platelet reactivity and silent embolic cerebral infarction (SECI) after endovascular treatment. Ischemic stroke patients undergoing stenting of intra- or extracranial arteries were recruited prospectively. Residual platelet reactivity, represented by aspirin reaction units (ARUs) and P2Y12 reaction units (PRUs), was measured serially (6 hours before, immediately after, and 24 hours after the procedure). A loading dosage of aspirin (500 mg) and/or clopidogrel (300 mg) was given 24 hours before the procedure to patients naïve to antiplatelet agents, whereas the usual dosage (aspirin 100 mg and clopidogrel 75 mg) was continued for patients who had previously been taking these agents for more than a week. Diffusion-weighted MRI was performed before and 24 hours after the procedure to detect new SECIs. Clinical characteristics, baseline ARU and PRU values, and the change in ARU and PRU values after stenting were compared between patients with and without SECIs. Among 69 consecutive patients who underwent neurovascular stent insertion, 41 patients (59.4%) had poststenting SECIs. The lesion was located only at the vascular territory of the stented vessel in 21 patients (51.2%), outside the stented vessel territory in 8 patients (19.5%), and both inside and outside in 12 patients (29.3%). The occurrence of SECIs was not associated with the baseline ARU or PRU value, but was associated with PRU increase after stenting (36 ± 73 vs -12 ± 59, p = 0.007), deployment of a longer stent (31.1 ± 16.5 mm vs 21.8 ± 9.9 mm, p = 0.01), and stent insertion in extracranial arteries (78.1% vs 45.2%, p = 0.008). Stent length (OR 1.066, p = 0.01) and PRU change (OR 1.009, p = 0.04) were independently associated with

  17. Context-Aware Image Compression.

    Directory of Open Access Journals (Sweden)

    Jacky C K Chan

    Full Text Available We describe a physics-based data compression method inspired by the photonic time stretch wherein information-rich portions of the data are dilated in a process that emulates the effect of group velocity dispersion on temporal signals. With this coding operation, the data can be downsampled at a lower rate than without it. In contrast to previous implementation of the warped stretch compression, here the decoding can be performed without the need of phase recovery. We present rate-distortion analysis and show improvement in PSNR compared to compression via uniform downsampling.

  18. Compressive sensing for urban radar

    CERN Document Server

    Amin, Moeness

    2014-01-01

    With the emergence of compressive sensing and sparse signal reconstruction, approaches to urban radar have shifted toward relaxed constraints on signal sampling schemes in time and space, and to effectively address logistic difficulties in data acquisition. Traditionally, these challenges have hindered high resolution imaging by restricting both bandwidth and aperture, and by imposing uniformity and bounds on sampling rates.Compressive Sensing for Urban Radar is the first book to focus on a hybrid of two key areas: compressive sensing and urban sensing. It explains how reliable imaging, tracki

  19. Efficient Lossy Compression for Compressive Sensing Acquisition of Images in Compressive Sensing Imaging Systems

    Directory of Open Access Journals (Sweden)

    Xiangwei Li

    2014-12-01

    Full Text Available Compressive Sensing Imaging (CSI is a new framework for image acquisition, which enables the simultaneous acquisition and compression of a scene. Since the characteristics of Compressive Sensing (CS acquisition are very different from traditional image acquisition, the general image compression solution may not work well. In this paper, we propose an efficient lossy compression solution for CS acquisition of images by considering the distinctive features of the CSI. First, we design an adaptive compressive sensing acquisition method for images according to the sampling rate, which could achieve better CS reconstruction quality for the acquired image. Second, we develop a universal quantization for the obtained CS measurements from CS acquisition without knowing any a priori information about the captured image. Finally, we apply these two methods in the CSI system for efficient lossy compression of CS acquisition. Simulation results demonstrate that the proposed solution improves the rate-distortion performance by 0.4~2 dB comparing with current state-of-the-art, while maintaining a low computational complexity.

  20. Compressed gas fuel storage system

    Science.gov (United States)

    Wozniak, John J.; Tiller, Dale B.; Wienhold, Paul D.; Hildebrand, Richard J.

    2001-01-01

    A compressed gas vehicle fuel storage system comprised of a plurality of compressed gas pressure cells supported by shock-absorbing foam positioned within a shape-conforming container. The container is dimensioned relative to the compressed gas pressure cells whereby a radial air gap surrounds each compressed gas pressure cell. The radial air gap allows pressure-induced expansion of the pressure cells without resulting in the application of pressure to adjacent pressure cells or physical pressure to the container. The pressure cells are interconnected by a gas control assembly including a thermally activated pressure relief device, a manual safety shut-off valve, and means for connecting the fuel storage system to a vehicle power source and a refueling adapter. The gas control assembly is enclosed by a protective cover attached to the container. The system is attached to the vehicle with straps to enable the chassis to deform as intended in a high-speed collision.

  1. Compressed sensing for distributed systems

    CERN Document Server

    Coluccia, Giulio; Magli, Enrico

    2015-01-01

    This book presents a survey of the state-of-the art in the exciting and timely topic of compressed sensing for distributed systems. It has to be noted that, while compressed sensing has been studied for some time now, its distributed applications are relatively new. Remarkably, such applications are ideally suited to exploit all the benefits that compressed sensing can provide. The objective of this book is to provide the reader with a comprehensive survey of this topic, from the basic concepts to different classes of centralized and distributed reconstruction algorithms, as well as a comparison of these techniques. This book collects different contributions on these aspects. It presents the underlying theory in a complete and unified way for the first time, presenting various signal models and their use cases. It contains a theoretical part collecting latest results in rate-distortion analysis of distributed compressed sensing, as well as practical implementations of algorithms obtaining performance close to...

  2. Nonlinear compression of optical solitons

    Indian Academy of Sciences (India)

    linear pulse propagation is the nonlinear Schrödinger (NLS) equation [1]. There are ... Optical pulse compression finds important applications in optical fibres. The pulse com ..... to thank CSIR, New Delhi for financial support in the form of SRF.

  3. Stiffness, resilience, compressibility

    Energy Technology Data Exchange (ETDEWEB)

    Leu, Bogdan M. [Argonne National Laboratory, Advanced Photon Source (United States); Sage, J. Timothy, E-mail: jtsage@neu.edu [Northeastern University, Department of Physics and Center for Interdisciplinary Research on Complex Systems (United States)

    2016-12-15

    The flexibility of a protein is an important component of its functionality. We use nuclear resonance vibrational spectroscopy (NRVS) to quantify the flexibility of the heme iron environment in the electron-carrying protein cytochrome c by measuring the stiffness and the resilience. These quantities are sensitive to structural differences between the active sites of different proteins, as illustrated by a comparative analysis with myoglobin. The elasticity of the entire protein, on the other hand, can be probed quantitatively from NRVS and high energy-resolution inelastic X-ray scattering (IXS) measurements, an approach that we used to extract the bulk modulus of cytochrome c.

  4. Experiences with delta compression of data produced by DIII

    International Nuclear Information System (INIS)

    Henline, P.A.

    1986-01-01

    The amount of data collected for each tokamak experimental shot is rapidly increasing. This is caused by many factors, including more diagnostic experiments, reduced cost of electronics hardware (especially memory), and longer plasma duration. The design goal for the DIII-D tokamak is 25 Mbytes of data per shot. In order to store the shot data as one logical unit, the delta compression algorithm, as it was implemented at ORNL by E. Blair, is being used. Statistics on compression factors, times, and general usage will be presented for actual DIII data. Data for 8-, 10-, and 12-bit digitizers will be highlighted since this hardware is common to most sites

  5. 29 CFR 1917.154 - Compressed air.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Compressed air. 1917.154 Section 1917.154 Labor Regulations...) MARINE TERMINALS Related Terminal Operations and Equipment § 1917.154 Compressed air. Employees shall be... this part during cleaning with compressed air. Compressed air used for cleaning shall not exceed a...

  6. Double-compression method for biomedical images

    Science.gov (United States)

    Antonenko, Yevhenii A.; Mustetsov, Timofey N.; Hamdi, Rami R.; Małecka-Massalska, Teresa; Orshubekov, Nurbek; DzierŻak, RóŻa; Uvaysova, Svetlana

    2017-08-01

    This paper describes a double compression method (DCM) of biomedical images. A comparison of image compression factors in size JPEG, PNG and developed DCM was carried out. The main purpose of the DCM - compression of medical images while maintaining the key points that carry diagnostic information. To estimate the minimum compression factor an analysis of the coding of random noise image is presented.

  7. Impact of lossy compression on diagnostic accuracy of radiographs for periapical lesions

    Science.gov (United States)

    Eraso, Francisco E.; Analoui, Mostafa; Watson, Andrew B.; Rebeschini, Regina

    2002-01-01

    OBJECTIVES: The purpose of this study was to evaluate the lossy Joint Photographic Experts Group compression for endodontic pretreatment digital radiographs. STUDY DESIGN: Fifty clinical charge-coupled device-based, digital radiographs depicting periapical areas were selected. Each image was compressed at 2, 4, 8, 16, 32, 48, and 64 compression ratios. One root per image was marked for examination. Images were randomized and viewed by four clinical observers under standardized viewing conditions. Each observer read the image set three times, with at least two weeks between each reading. Three pre-selected sites per image (mesial, distal, apical) were scored on a five-scale score confidence scale. A panel of three examiners scored the uncompressed images, with a consensus score for each site. The consensus score was used as the baseline for assessing the impact of lossy compression on the diagnostic values of images. The mean absolute error between consensus and observer scores was computed for each observer, site, and reading session. RESULTS: Balanced one-way analysis of variance for all observers indicated that for compression ratios 48 and 64, there was significant difference between mean absolute error of uncompressed and compressed images (P <.05). After converting the five-scale score to two-level diagnostic values, the diagnostic accuracy was strongly correlated (R (2) = 0.91) with the compression ratio. CONCLUSION: The results of this study suggest that high compression ratios can have a severe impact on the diagnostic quality of the digital radiographs for detection of periapical lesions.

  8. Perceptual Image Compression in Telemedicine

    Science.gov (United States)

    Watson, Andrew B.; Ahumada, Albert J., Jr.; Eckstein, Miguel; Null, Cynthia H. (Technical Monitor)

    1996-01-01

    The next era of space exploration, especially the "Mission to Planet Earth" will generate immense quantities of image data. For example, the Earth Observing System (EOS) is expected to generate in excess of one terabyte/day. NASA confronts a major technical challenge in managing this great flow of imagery: in collection, pre-processing, transmission to earth, archiving, and distribution to scientists at remote locations. Expected requirements in most of these areas clearly exceed current technology. Part of the solution to this problem lies in efficient image compression techniques. For much of this imagery, the ultimate consumer is the human eye. In this case image compression should be designed to match the visual capacities of the human observer. We have developed three techniques for optimizing image compression for the human viewer. The first consists of a formula, developed jointly with IBM and based on psychophysical measurements, that computes a DCT quantization matrix for any specified combination of viewing distance, display resolution, and display brightness. This DCT quantization matrix is used in most recent standards for digital image compression (JPEG, MPEG, CCITT H.261). The second technique optimizes the DCT quantization matrix for each individual image, based on the contents of the image. This is accomplished by means of a model of visual sensitivity to compression artifacts. The third technique extends the first two techniques to the realm of wavelet compression. Together these two techniques will allow systematic perceptual optimization of image compression in NASA imaging systems. Many of the image management challenges faced by NASA are mirrored in the field of telemedicine. Here too there are severe demands for transmission and archiving of large image databases, and the imagery is ultimately used primarily by human observers, such as radiologists. In this presentation I will describe some of our preliminary explorations of the applications

  9. [The importance of the thermometric method for assessing the function of mucoperiosteal flaps in uranostaphyloplasty with/without transection of the neurovascular bundles in the rehabilitation of patients with congenital cleft palate].

    Science.gov (United States)

    Bernadskiĭ, Iu I; Khar'kov, L V; Prudnikov, V M

    1990-01-01

    The nature and degree of reflow to the mucoperiosteal flaps was evaluated using a distant thermometry of the cleft palate in 67 children under uranostaphyloplasty and in early postsurgical period. In extracting the neurovascular bundles from their channels heat reflow to the palate was more fast and pronounced than with the bundles sectioned.

  10. Evaluation of a new image compression technique

    International Nuclear Information System (INIS)

    Algra, P.R.; Kroon, H.M.; Noordveld, R.B.; DeValk, J.P.J.; Seeley, G.W.; Westerink, P.H.

    1988-01-01

    The authors present the evaluation of a new image compression technique, subband coding using vector quantization, on 44 CT examinations of the upper abdomen. Three independent radiologists reviewed the original images and compressed versions. The compression ratios used were 16:1 and 20:1. Receiver operating characteristic analysis showed no difference in the diagnostic contents between originals and their compressed versions. Subjective visibility of anatomic structures was equal. Except for a few 20:1 compressed images, the observers could not distinguish compressed versions from original images. They conclude that subband coding using vector quantization is a valuable method for data compression in CT scans of the abdomen

  11. Building indifferentiable compression functions from the PGV compression functions

    DEFF Research Database (Denmark)

    Gauravaram, P.; Bagheri, Nasour; Knudsen, Lars Ramkilde

    2016-01-01

    Preneel, Govaerts and Vandewalle (PGV) analysed the security of single-block-length block cipher based compression functions assuming that the underlying block cipher has no weaknesses. They showed that 12 out of 64 possible compression functions are collision and (second) preimage resistant. Black......, Rogaway and Shrimpton formally proved this result in the ideal cipher model. However, in the indifferentiability security framework introduced by Maurer, Renner and Holenstein, all these 12 schemes are easily differentiable from a fixed input-length random oracle (FIL-RO) even when their underlying block...

  12. Compression of Probabilistic XML Documents

    Science.gov (United States)

    Veldman, Irma; de Keijzer, Ander; van Keulen, Maurice

    Database techniques to store, query and manipulate data that contains uncertainty receives increasing research interest. Such UDBMSs can be classified according to their underlying data model: relational, XML, or RDF. We focus on uncertain XML DBMS with as representative example the Probabilistic XML model (PXML) of [10,9]. The size of a PXML document is obviously a factor in performance. There are PXML-specific techniques to reduce the size, such as a push down mechanism, that produces equivalent but more compact PXML documents. It can only be applied, however, where possibilities are dependent. For normal XML documents there also exist several techniques for compressing a document. Since Probabilistic XML is (a special form of) normal XML, it might benefit from these methods even more. In this paper, we show that existing compression mechanisms can be combined with PXML-specific compression techniques. We also show that best compression rates are obtained with a combination of PXML-specific technique with a rather simple generic DAG-compression technique.

  13. Plasma heating by adiabatic compression

    International Nuclear Information System (INIS)

    Ellis, R.A. Jr.

    1972-01-01

    These two lectures will cover the following three topics: (i) The application of adiabatic compression to toroidal devices is reviewed. The special case of adiabatic compression in tokamaks is considered in more detail, including a discussion of the equilibrium, scaling laws, and heating effects. (ii) The ATC (Adiabatic Toroidal Compressor) device which was completed in May 1972, is described in detail. Compression of a tokamak plasma across a static toroidal field is studied in this device. The device is designed to produce a pre-compression plasma with a major radius of 17 cm, toroidal field of 20 kG, and current of 90 kA. The compression leads to a plasma with major radius of 38 cm and minor radius of 10 cm. Scaling laws imply a density increase of a factor 6, temperature increase of a factor 3, and current increase of a factor 2.4. An additional feature of ATC is that it is a large tokamak which operates without a copper shell. (iii) Data which show that the expected MHD behavior is largely observed is presented and discussed. (U.S.)

  14. Concurrent data compression and protection

    International Nuclear Information System (INIS)

    Saeed, M.

    2009-01-01

    Data compression techniques involve transforming data of a given format, called source message, to data of a smaller sized format, called codeword. The primary objective of data encryption is to ensure security of data if it is intercepted by an eavesdropper. It transforms data of a given format, called plaintext, to another format, called ciphertext, using an encryption key or keys. Thus, combining the processes of compression and encryption together must be done in this order, that is, compression followed by encryption because all compression techniques heavily rely on the redundancies which are inherently a part of a regular text or speech. The aim of this research is to combine two processes of compression (using an existing scheme) with a new encryption scheme which should be compatible with encoding scheme embedded in encoder. The novel technique proposed by the authors is new, unique and is highly secured. The deployment of sentinel marker' enhances the security of the proposed TR-One algorithm from 2/sup 44/ ciphertexts to 2/sup 44/ +2/sub 20/ ciphertexts thus imposing extra challenges to the intruders. (author)

  15. Radiologic image compression -- A review

    International Nuclear Information System (INIS)

    Wong, S.; Huang, H.K.; Zaremba, L.; Gooden, D.

    1995-01-01

    The objective of radiologic image compression is to reduce the data volume of and to achieve a lot bit rate in the digital representation of radiologic images without perceived loss of image quality. However, the demand for transmission bandwidth and storage space in the digital radiology environment, especially picture archiving and communication systems (PACS) and teleradiology, and the proliferating use of various imaging modalities, such as magnetic resonance imaging, computed tomography, ultrasonography, nuclear medicine, computed radiography, and digital subtraction angiography, continue to outstrip the capabilities of existing technologies. The availability of lossy coding techniques for clinical diagnoses further implicates many complex legal and regulatory issues. This paper reviews the recent progress of lossless and lossy radiologic image compression and presents the legal challenges of using lossy compression of medical records. To do so, the authors first describe the fundamental concepts of radiologic imaging and digitization. Then, the authors examine current compression technology in the field of medical imaging and discuss important regulatory policies and legal questions facing the use of compression in this field. The authors conclude with a summary of future challenges and research directions. 170 refs

  16. 30 CFR 75.1730 - Compressed air; general; compressed air systems.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Compressed air; general; compressed air systems... Compressed air; general; compressed air systems. (a) All pressure vessels shall be constructed, installed... Safety and Health district office. (b) Compressors and compressed-air receivers shall be equipped with...

  17. Mammographic compression – A need for mechanical standardization

    Energy Technology Data Exchange (ETDEWEB)

    Branderhorst, Woutjan, E-mail: w.branderhorst@amc.nl [Academic Medical Center, Department of Biomedical Engineering & Physics, P.O. Box 22660, 1100 DD Amsterdam (Netherlands); Sigmascreening B.V., Meibergdreef 45, 1105 BA Amsterdam (Netherlands); Groot, Jerry E. de, E-mail: jerry.degroot@sigmascreening.com [Academic Medical Center, Department of Biomedical Engineering & Physics, P.O. Box 22660, 1100 DD Amsterdam (Netherlands); Highnam, Ralph, E-mail: ralph.highnam@volparasolutions.com [Volpara Solutions Limited, P.O. Box 24404, Manners St Central, Wellington 6142 (New Zealand); Chan, Ariane, E-mail: ariane.chan@volparasolutions.com [Volpara Solutions Limited, P.O. Box 24404, Manners St Central, Wellington 6142 (New Zealand); Böhm-Vélez, Marcela, E-mail: marcelabvelez@gmail.com [Weinstein Imaging Associates, 5850 Centre Avenue, Pittsburgh, PA 15206 (United States); Broeders, Mireille J.M., E-mail: mireille.broeders@radboudumc.nl [Radboud University Medical Center, Department for Health Evidence, P.O. Box 9101, 6500 HB Nijmegen (Netherlands); LRCB Dutch Reference Center for Screening, P.O. Box 6873, 6503 GJ Nijmegen (Netherlands); Heeten, Gerard J. den, E-mail: g.denheeten@lrcb.nl [Academic Medical Center, Department of Radiology, P.O. Box 22660, 1100 DD Amsterdam (Netherlands); LRCB Dutch Reference Center for Screening, P.O. Box 6873, 6503 GJ Nijmegen (Netherlands); Grimbergen, Cornelis A., E-mail: c.a.grimbergen@amc.uva.nl [Academic Medical Center, Department of Biomedical Engineering & Physics, P.O. Box 22660, 1100 DD Amsterdam (Netherlands); Sigmascreening B.V., Meibergdreef 45, 1105 BA Amsterdam (Netherlands)

    2015-04-15

    Highlights: •We studied mechanical breast compression practice in two different clinical sites. •We visualized the distributions of not only the applied force but also the pressure. •The applied pressure was highly variable, both within and between the data sets. •The average applied pressure and the variation were higher for smaller breasts. •A proposal for improved individualization, by standardizing pressure, is discussed. -- Abstract: Background: A lack of consistent guidelines regarding mammographic compression has led to wide variation in its technical execution. Breast compression is accomplished by means of a compression paddle, resulting in a certain contact area between the paddle and the breast. This procedure is associated with varying levels of discomfort or pain. On current mammography systems, the only mechanical parameter available in estimating the degree of compression is the physical entity of force (daN). Recently, researchers have suggested that pressure (kPa), resulting from a specific force divided by contact area on a breast, might be a more appropriate parameter for standardization. Software has now become available which enables device-independent cross-comparisons of key mammographic metrics, such as applied compression pressure (force divided by contact area), breast density and radiation dose, between patient populations. Purpose: To compare the current compression practice in mammography between different imaging sites in the Netherlands and the United States from a mechanical point of view, and to investigate whether the compression protocols in these countries can be improved by standardization of pressure (kPa) as an objective mechanical parameter. Materials and methods: We retrospectively studied the available parameters of a set of 37,518 mammographic compressions (9188 women) from the Dutch national breast cancer screening programme (NL data set) and of another set of 7171 compressions (1851 women) from a breast imaging

  18. Origin of the low compressibility in hard nitride spinels

    DEFF Research Database (Denmark)

    Mori-Sánchez, P.; Marqués, M.; Beltrán, A.

    2003-01-01

    A microscopic investigation of first-principles electron densities of gamma-A(3)N(4) (A:C,Si,Ge) spinels reveals a clear relationship between the compressibility and the chemical bonding of these materials. Three striking findings emanate from this analysis: (i) the chemical graph is governed...... by a network of highly directional strong bonds with covalent character in gamma-C3N4 and different degrees of ionic polarization in gamma-Si3N4 and gamma-Ge3N4, (ii) nitrogen is the lowest compressible atom controlling the trend in the bulk modulus of the solids, and (iii) the group-IV counterions show strong...... site dependent compressibilities enhancing the difficulty in the synthesis of the spinel phases of these nitrides....

  19. Rectal perforation by compressed air.

    Science.gov (United States)

    Park, Young Jin

    2017-07-01

    As the use of compressed air in industrial work has increased, so has the risk of associated pneumatic injury from its improper use. However, damage of large intestine caused by compressed air is uncommon. Herein a case of pneumatic rupture of the rectum is described. The patient was admitted to the Emergency Room complaining of abdominal pain and distension. His colleague triggered a compressed air nozzle over his buttock. On arrival, vital signs were stable but physical examination revealed peritoneal irritation and marked distension of the abdomen. Computed tomography showed a large volume of air in the peritoneal cavity and subcutaneous emphysema at the perineum. A rectal perforation was found at laparotomy and the Hartmann procedure was performed.

  20. Compact torus compression of microwaves

    International Nuclear Information System (INIS)

    Hewett, D.W.; Langdon, A.B.

    1985-01-01

    The possibility that a compact torus (CT) might be accelerated to large velocities has been suggested by Hartman and Hammer. If this is feasible one application of these moving CTs might be to compress microwaves. The proposed mechanism is that a coaxial vacuum region in front of a CT is prefilled with a number of normal electromagnetic modes on which the CT impinges. A crucial assumption of this proposal is that the CT excludes the microwaves and therefore compresses them. Should the microwaves penetrate the CT, compression efficiency is diminished and significant CT heating results. MFE applications in the same parameters regime have found electromagnetic radiation capable of penetrating, heating, and driving currents. We report here a cursory investigation of rf penetration using a 1-D version of a direct implicit PIC code

  1. Premixed autoignition in compressible turbulence

    Science.gov (United States)

    Konduri, Aditya; Kolla, Hemanth; Krisman, Alexander; Chen, Jacqueline

    2016-11-01

    Prediction of chemical ignition delay in an autoignition process is critical in combustion systems like compression ignition engines and gas turbines. Often, ignition delay times measured in simple homogeneous experiments or homogeneous calculations are not representative of actual autoignition processes in complex turbulent flows. This is due the presence of turbulent mixing which results in fluctuations in thermodynamic properties as well as chemical composition. In the present study the effect of fluctuations of thermodynamic variables on the ignition delay is quantified with direct numerical simulations of compressible isotropic turbulence. A premixed syngas-air mixture is used to remove the effects of inhomogeneity in the chemical composition. Preliminary results show a significant spatial variation in the ignition delay time. We analyze the topology of autoignition kernels and identify the influence of extreme events resulting from compressibility and intermittency. The dependence of ignition delay time on Reynolds and turbulent Mach numbers is also quantified. Supported by Basic Energy Sciences, Dept of Energy, United States.

  2. Lossless Compression of Broadcast Video

    DEFF Research Database (Denmark)

    Martins, Bo; Eriksen, N.; Faber, E.

    1998-01-01

    We investigate several techniques for lossless and near-lossless compression of broadcast video.The emphasis is placed on the emerging international standard for compression of continous-tone still images, JPEG-LS, due to its excellent compression performance and moderatecomplexity. Except for one...... cannot be expected to code losslessly at a rate of 125 Mbit/s. We investigate the rate and quality effects of quantization using standard JPEG-LS quantization and two new techniques: visual quantization and trellis quantization. Visual quantization is not part of baseline JPEG-LS, but is applicable...... in the framework of JPEG-LS. Visual tests show that this quantization technique gives much better quality than standard JPEG-LS quantization. Trellis quantization is a process by which the original image is altered in such a way as to make lossless JPEG-LS encoding more effective. For JPEG-LS and visual...

  3. Efficient access of compressed data

    International Nuclear Information System (INIS)

    Eggers, S.J.; Shoshani, A.

    1980-06-01

    A compression technique is presented that allows a high degree of compression but requires only logarithmic access time. The technique is a constant suppression scheme, and is most applicable to stable databases whose distribution of constants is fairly clustered. Furthermore, the repeated use of the technique permits the suppression of a multiple number of different constants. Of particular interest is the application of the constant suppression technique to databases the composite key of which is made up of an incomplete cross product of several attribute domains. The scheme for compressing the full cross product composite key is well known. This paper, however, also handles the general, incomplete case by applying the constant suppression technique in conjunction with a composite key suppression scheme

  4. Compressibility of rotating black holes

    International Nuclear Information System (INIS)

    Dolan, Brian P.

    2011-01-01

    Interpreting the cosmological constant as a pressure, whose thermodynamically conjugate variable is a volume, modifies the first law of black hole thermodynamics. Properties of the resulting thermodynamic volume are investigated: the compressibility and the speed of sound of the black hole are derived in the case of nonpositive cosmological constant. The adiabatic compressibility vanishes for a nonrotating black hole and is maximal in the extremal case--comparable with, but still less than, that of a cold neutron star. A speed of sound v s is associated with the adiabatic compressibility, which is equal to c for a nonrotating black hole and decreases as the angular momentum is increased. An extremal black hole has v s 2 =0.9 c 2 when the cosmological constant vanishes, and more generally v s is bounded below by c/√(2).

  5. Compressive behavior of fine sand.

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Bradley E. (Air Force Research Laboratory, Eglin, FL); Kabir, Md. E. (Purdue University, West Lafayette, IN); Song, Bo; Chen, Wayne (Purdue University, West Lafayette, IN)

    2010-04-01

    The compressive mechanical response of fine sand is experimentally investigated. The strain rate, initial density, stress state, and moisture level are systematically varied. A Kolsky bar was modified to obtain uniaxial and triaxial compressive response at high strain rates. A controlled loading pulse allows the specimen to acquire stress equilibrium and constant strain-rates. The results show that the compressive response of the fine sand is not sensitive to strain rate under the loading conditions in this study, but significantly dependent on the moisture content, initial density and lateral confinement. Partially saturated sand is more compliant than dry sand. Similar trends were reported in the quasi-static regime for experiments conducted at comparable specimen conditions. The sand becomes stiffer as initial density and/or confinement pressure increases. The sand particle size become smaller after hydrostatic pressure and further smaller after dynamic axial loading.

  6. Correlations between quality indexes of chest compression.

    Science.gov (United States)

    Zhang, Feng-Ling; Yan, Li; Huang, Su-Fang; Bai, Xiang-Jun

    2013-01-01

    Cardiopulmonary resuscitation (CPR) is a kind of emergency treatment for cardiopulmonary arrest, and chest compression is the most important and necessary part of CPR. The American Heart Association published the new Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care in 2010 and demanded for better performance of chest compression practice, especially in compression depth and rate. The current study was to explore the relationship of quality indexes of chest compression and to identify the key points in chest compression training and practice. Totally 219 healthcare workers accepted chest compression training by using Laerdal ACLS advanced life support resuscitation model. The quality indexes of chest compression, including compression hands placement, compression rate, compression depth, and chest wall recoil as well as self-reported fatigue time were monitored by the Laerdal Computer Skills and Reporting System. The quality of chest compression was related to the gender of the compressor. The indexes in males, including self-reported fatigue time, the accuracy of compression depth and the compression rate, the accuracy of compression rate, were higher than those in females. However, the accuracy of chest recoil was higher in females than in males. The quality indexes of chest compression were correlated with each other. The self-reported fatigue time was related to all the indexes except the compression rate. It is necessary to offer CPR training courses regularly. In clinical practice, it might be better to change the practitioner before fatigue, especially for females or weak practitioners. In training projects, more attention should be paid to the control of compression rate, in order to delay the fatigue, guarantee enough compression depth and improve the quality of chest compression.

  7. Subsurface Profile Mapping using 3-D Compressive Wave Imaging

    Directory of Open Access Journals (Sweden)

    Hazreek Z A M

    2017-01-01

    Full Text Available Geotechnical site investigation related to subsurface profile mapping was commonly performed to provide valuable data for design and construction stage based on conventional drilling techniques. From past experience, drilling techniques particularly using borehole method suffer from limitations related to expensive, time consuming and limited data coverage. Hence, this study performs subsurface profile mapping using 3-D compressive wave imaging in order to minimize those conventional method constraints. Field measurement and data analysis of compressive wave (p-wave, vp was performed using seismic refraction survey (ABEM Terraloc MK 8, 7 kg of sledgehammer and 24 units of vertical geophone and OPTIM (SeisOpt@Picker & SeisOpt@2D software respectively. Then, 3-D compressive wave distribution of subsurface studied was obtained using analysis of SURFER software. Based on 3-D compressive wave image analyzed, it was found that subsurface profile studied consist of three main layers representing top soil (vp = 376 – 600 m/s, weathered material (vp = 900 – 2600 m/s and bedrock (vp > 3000 m/s. Thickness of each layer was varied from 0 – 2 m (first layer, 2 – 20 m (second layer and 20 m and over (third layer. Moreover, groundwater (vp = 1400 – 1600 m/s starts to be detected at 2.0 m depth from ground surface. This study has demonstrated that geotechnical site investigation data related to subsurface profiling was applicable to be obtained using 3-D compressive wave imaging. Furthermore, 3-D compressive wave imaging was performed based on non destructive principle in ground exploration thus consider economic, less time, large data coverage and sustainable to our environment.

  8. The Blood-Brain Barrier and the EphR/Ephrin System: Perspectives on a Link Between Neurovascular and Neuropsychiatric Disorders

    Directory of Open Access Journals (Sweden)

    Victoria A. Malik

    2018-04-01

    Full Text Available Interactions among endothelial cells (EC forming blood vessels and their surrounding cell types are essential to establish the blood-brain barrier (BBB, an integral part of the neurovascular unit (NVU. Research on the NVU has recently seen a renaissance to especially understand the neurobiology of vascular and brain pathologies and their frequently occurring comorbidities. Diverse signaling molecules activated in the near proximity of blood vessels trigger paracellular pathways which regulate the formation and stabilization of tight junctions (TJ between EC and thereby influence BBB permeability. Among regulatory molecules, the erythropoietin-producing-hepatocellular carcinoma receptors (EphR and their Eph receptor-interacting signals (ephrins play a pivotal role in EC differentiation, angiogenesis and BBB integrity. Multiple EphR-ligand interactions between EC and other cell types influence different aspects of angiogenesis and BBB formation. Such interactions additionally control BBB sealing properties and thus the penetration of substances into the brain parenchyma. Thus, they play critical roles in the healthy brain and during the pathogenesis of brain disorders. In this mini-review article, we aim at integrating the constantly growing literature about the functional roles of the EphR/ephrin system for the development of the vascular system and the BBB and in the pathogenesis of neurovascular and neuropsychiatric disorders. We suggest the hypothesis that a disrupted EphR/ephrin signaling at the BBB might represent an underappreciated molecular hub of disease comorbidity. Finally, we propose the possibility that the EphR/ephrin system bears the potential of becoming a novel target for the development of alternative therapeutic treatments, focusing on such comorbidities.

  9. Excessive chest compression rate is associated with insufficient compression depth in prehospital cardiac arrest

    NARCIS (Netherlands)

    Monsieurs, Koenraad G.; De Regge, Melissa; Vansteelandt, Kristof; De Smet, Jeroen; Annaert, Emmanuel; Lemoyne, Sabine; Kalmar, Alain F.; Calle, Paul A.

    2012-01-01

    Background and goal of study: The relationship between chest compression rate and compression depth is unknown. In order to characterise this relationship, we performed an observational study in prehospital cardiac arrest patients. We hypothesised that faster compressions are associated with

  10. The impact of chest compression rates on quality of chest compressions : a manikin study

    OpenAIRE

    Field, Richard A.; Soar, Jasmeet; Davies, Robin P.; Akhtar, Naheed; Perkins, Gavin D.

    2012-01-01

    Purpose\\ud Chest compressions are often performed at a variable rate during cardiopulmonary resuscitation (CPR). The effect of compression rate on other chest compression quality variables (compression depth, duty-cycle, leaning, performance decay over time) is unknown. This randomised controlled cross-over manikin study examined the effect of different compression rates on the other chest compression quality variables.\\ud Methods\\ud Twenty healthcare professionals performed two minutes of co...

  11. Economic and technical feasibility study of compressed air storage

    Energy Technology Data Exchange (ETDEWEB)

    1976-03-01

    The results of a study of the economic and technical feasibility of compressed air energy storage (CAES) are presented. The study, which concentrated primarily on the application of underground air storage with combustion turbines, consisted of two phases. In the first phase a general assessment of the technical alternatives, economic characteristics and the institutional constraints associated with underground storage of compressed air for utility peaking application was carried out. The goal of this assessment was to identify potential barrier problems and to define the incentive for the implementation of compressed air storage. In the second phase, the general conclusions of the assessment were tested by carrying out the conceptual design of a CAES plant at two specific sites, and a program of further work indicated by the assessment study was formulated. The conceptual design of a CAES plant employing storage in an aquifer and that of a plant employing storage in a conventionally excavated cavern employing a water leg to maintain constant pressure are shown. Recommendations for further work, as well as directions of future turbo-machinery development, are made. It is concluded that compressed air storage is technically feasible for off-peak energy storage, and, depending on site conditions, CAES plants may be favored over simple cycle turbine plants to meet peak demands. (LCL)

  12. Compressed air system audit in a chemical company

    Energy Technology Data Exchange (ETDEWEB)

    Radgen, P. [Fraunhofer ISI, Karlsruhe (Germany)

    2005-07-01

    This paper describes the results achieved during a compressed air system audit at a chemical company in Switzerland. The aim of the audit conducted in Muttenz at the site of Clariant Schweiz AG was to analyse the installed compressed air system and its operation in order to identify energy and cost saving potentials. Because there was measurement equipment already installed, it was not necessary to install a new meter. Instead the existing data had to be extracted from the controlled system and regrouped for the analysis. Aggregated data for 2003 and 2004 and a set of detailed data acquired in the course of one week were used for the analysis. The audit identified a number of measures to improve the compressed air system, but had to conclude that the saving potentials at this site are below average. The audit included the compressors, the air treatment and air distribution up to production or storage buildings. The saving potential identified was quantified as about 300 000 kWh/a, or 13.3% of the compressed air energy demand. The cost savings were calculated to be around 41 852 Swiss Franks. (orig.)

  13. Compressing Data Cube in Parallel OLAP Systems

    Directory of Open Access Journals (Sweden)

    Frank Dehne

    2007-03-01

    Full Text Available This paper proposes an efficient algorithm to compress the cubes in the progress of the parallel data cube generation. This low overhead compression mechanism provides block-by-block and record-by-record compression by using tuple difference coding techniques, thereby maximizing the compression ratio and minimizing the decompression penalty at run-time. The experimental results demonstrate that the typical compression ratio is about 30:1 without sacrificing running time. This paper also demonstrates that the compression method is suitable for Hilbert Space Filling Curve, a mechanism widely used in multi-dimensional indexing.

  14. CEPRAM: Compression for Endurance in PCM RAM

    OpenAIRE

    González Alberquilla, Rodrigo; Castro Rodríguez, Fernando; Piñuel Moreno, Luis; Tirado Fernández, Francisco

    2017-01-01

    We deal with the endurance problem of Phase Change Memories (PCM) by proposing Compression for Endurance in PCM RAM (CEPRAM), a technique to elongate the lifespan of PCM-based main memory through compression. We introduce a total of three compression schemes based on already existent schemes, but targeting compression for PCM-based systems. We do a two-level evaluation. First, we quantify the performance of the compression, in terms of compressed size, bit-flips and how they are affected by e...

  15. Entropy, Coding and Data Compression

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 9. Entropy, Coding and Data Compression. S Natarajan. General Article Volume 6 Issue 9 September 2001 pp 35-45. Fulltext. Click here to view fulltext PDF. Permanent link: https://www.ias.ac.in/article/fulltext/reso/006/09/0035-0045 ...

  16. Shock compression of synthetic opal

    International Nuclear Information System (INIS)

    Inoue, A; Okuno, M; Okudera, H; Mashimo, T; Omurzak, E; Katayama, S; Koyano, M

    2010-01-01

    Structural change of synthetic opal by shock-wave compression up to 38.1 GPa has been investigated by using SEM, X-ray diffraction method (XRD), Infrared (IR) and Raman spectroscopies. Obtained information may indicate that the dehydration and polymerization of surface silanole due to high shock and residual temperature are very important factors in the structural evolution of synthetic opal by shock compression. Synthetic opal loses opalescence by 10.9 and 18.4 GPa of shock pressures. At 18.4 GPa, dehydration and polymerization of surface silanole and transformation of network structure may occur simultaneously. The 4-membered ring of TO 4 tetrahedrons in as synthetic opal may be relaxed to larger ring such as 6-membered ring by high residual temperature. Therefore, the residual temperature may be significantly high at even 18.4 GPa of shock compression. At 23.9 GPa, opal sample recovered the opalescence. Origin of this opalescence may be its layer structure by shock compression. Finally, sample fuse by very high residual temperature at 38.1 GPa and the structure closes to that of fused SiO 2 glass. However, internal silanole groups still remain even at 38.1 GPa.

  17. Range Compressed Holographic Aperture Ladar

    Science.gov (United States)

    2017-06-01

    entropy saturation behavior of the estimator is analytically described. Simultaneous range-compression and aperture synthesis is experimentally...4 2.1 Circular and Inverse -Circular HAL...2.3 Single Aperture, Multi-λ Imaging ...................................................................................... 14 2.4 Simultaneous Range

  18. Compression of Probabilistic XML documents

    NARCIS (Netherlands)

    Veldman, Irma

    2009-01-01

    Probabilistic XML (PXML) files resulting from data integration can become extremely large, which is undesired. For XML there are several techniques available to compress the document and since probabilistic XML is in fact (a special form of) XML, it might benefit from these methods even more. In

  19. Shock compression of synthetic opal

    Science.gov (United States)

    Inoue, A.; Okuno, M.; Okudera, H.; Mashimo, T.; Omurzak, E.; Katayama, S.; Koyano, M.

    2010-03-01

    Structural change of synthetic opal by shock-wave compression up to 38.1 GPa has been investigated by using SEM, X-ray diffraction method (XRD), Infrared (IR) and Raman spectroscopies. Obtained information may indicate that the dehydration and polymerization of surface silanole due to high shock and residual temperature are very important factors in the structural evolution of synthetic opal by shock compression. Synthetic opal loses opalescence by 10.9 and 18.4 GPa of shock pressures. At 18.4 GPa, dehydration and polymerization of surface silanole and transformation of network structure may occur simultaneously. The 4-membered ring of TO4 tetrahedrons in as synthetic opal may be relaxed to larger ring such as 6-membered ring by high residual temperature. Therefore, the residual temperature may be significantly high at even 18.4 GPa of shock compression. At 23.9 GPa, opal sample recovered the opalescence. Origin of this opalescence may be its layer structure by shock compression. Finally, sample fuse by very high residual temperature at 38.1 GPa and the structure closes to that of fused SiO2 glass. However, internal silanole groups still remain even at 38.1 GPa.

  20. Shock compression of synthetic opal

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, A; Okuno, M; Okudera, H [Department of Earth Sciences, Kanazawa University Kanazawa, Ishikawa, 920-1192 (Japan); Mashimo, T; Omurzak, E [Shock Wave and Condensed Matter Research Center, Kumamoto University, Kumamoto, 860-8555 (Japan); Katayama, S; Koyano, M, E-mail: okuno@kenroku.kanazawa-u.ac.j [JAIST, Nomi, Ishikawa, 923-1297 (Japan)

    2010-03-01

    Structural change of synthetic opal by shock-wave compression up to 38.1 GPa has been investigated by using SEM, X-ray diffraction method (XRD), Infrared (IR) and Raman spectroscopies. Obtained information may indicate that the dehydration and polymerization of surface silanole due to high shock and residual temperature are very important factors in the structural evolution of synthetic opal by shock compression. Synthetic opal loses opalescence by 10.9 and 18.4 GPa of shock pressures. At 18.4 GPa, dehydration and polymerization of surface silanole and transformation of network structure may occur simultaneously. The 4-membered ring of TO{sub 4} tetrahedrons in as synthetic opal may be relaxed to larger ring such as 6-membered ring by high residual temperature. Therefore, the residual temperature may be significantly high at even 18.4 GPa of shock compression. At 23.9 GPa, opal sample recovered the opalescence. Origin of this opalescence may be its layer structure by shock compression. Finally, sample fuse by very high residual temperature at 38.1 GPa and the structure closes to that of fused SiO{sub 2} glass. However, internal silanole groups still remain even at 38.1 GPa.

  1. Force balancing in mammographic compression

    International Nuclear Information System (INIS)

    Branderhorst, W.; Groot, J. E. de; Lier, M. G. J. T. B. van; Grimbergen, C. A.; Neeter, L. M. F. H.; Heeten, G. J. den; Neeleman, C.

    2016-01-01

    Purpose: In mammography, the height of the image receptor is adjusted to the patient before compressing the breast. An inadequate height setting can result in an imbalance between the forces applied by the image receptor and the paddle, causing the clamped breast to be pushed up or down relative to the body during compression. This leads to unnecessary stretching of the skin and other tissues around the breast, which can make the imaging procedure more painful for the patient. The goal of this study was to implement a method to measure and minimize the force imbalance, and to assess its feasibility as an objective and reproducible method of setting the image receptor height. Methods: A trial was conducted consisting of 13 craniocaudal mammographic compressions on a silicone breast phantom, each with the image receptor positioned at a different height. The image receptor height was varied over a range of 12 cm. In each compression, the force exerted by the compression paddle was increased up to 140 N in steps of 10 N. In addition to the paddle force, the authors measured the force exerted by the image receptor and the reaction force exerted on the patient body by the ground. The trial was repeated 8 times, with the phantom remounted at a slightly different orientation and position between the trials. Results: For a given paddle force, the obtained results showed that there is always exactly one image receptor height that leads to a balance of the forces on the breast. For the breast phantom, deviating from this specific height increased the force imbalance by 9.4 ± 1.9 N/cm (6.7%) for 140 N paddle force, and by 7.1 ± 1.6 N/cm (17.8%) for 40 N paddle force. The results also show that in situations where the force exerted by the image receptor is not measured, the craniocaudal force imbalance can still be determined by positioning the patient on a weighing scale and observing the changes in displayed weight during the procedure. Conclusions: In mammographic breast

  2. Adiabatic compression of ion rings

    International Nuclear Information System (INIS)

    Larrabee, D.A.; Lovelace, R.V.

    1982-01-01

    A study has been made of the compression of collisionless ion rings in an increasing external magnetic field, B/sub e/ = zB/sub e/(t), by numerically implementing a previously developed kinetic theory of ring compression. The theory is general in that there is no limitation on the ring geometry or the compression ratio, lambdaequivalentB/sub e/ (final)/B/sub e/ (initial)> or =1. However, the motion of a single particle in an equilibrium is assumed to be completely characterized by its energy H and canonical angular momentum P/sub theta/ with the absence of a third constant of the motion. The present computational work assumes that plasma currents are negligible, as is appropriate for a low-temperature collisional plasma. For a variety of initial ring geometries and initial distribution functions (having a single value of P/sub theta/), it is found that the parameters for ''fat'', small aspect ratio rings follow general scaling laws over a large range of compression ratios, 1 3 : The ring radius varies as lambda/sup -1/2/; the average single particle energy as lambda/sup 0.72/; the root mean square energy spread as lambda/sup 1.1/; and the total current as lambda/sup 0.79/. The field reversal parameter is found to saturate at values typically between 2 and 3. For large compression ratios the current density is found to ''hollow out''. This hollowing tends to improve the interchange stability of an embedded low β plasma. The implications of these scaling laws for fusion reactor systems are discussed

  3. Effect of compressibility on the hypervelocity penetration

    Science.gov (United States)

    Song, W. J.; Chen, X. W.; Chen, P.

    2018-02-01

    We further consider the effect of rod strength by employing the compressible penetration model to study the effect of compressibility on hypervelocity penetration. Meanwhile, we define different instances of penetration efficiency in various modified models and compare these penetration efficiencies to identify the effects of different factors in the compressible model. To systematically discuss the effect of compressibility in different metallic rod-target combinations, we construct three cases, i.e., the penetrations by the more compressible rod into the less compressible target, rod into the analogously compressible target, and the less compressible rod into the more compressible target. The effects of volumetric strain, internal energy, and strength on the penetration efficiency are analyzed simultaneously. It indicates that the compressibility of the rod and target increases the pressure at the rod/target interface. The more compressible rod/target has larger volumetric strain and higher internal energy. Both the larger volumetric strain and higher strength enhance the penetration or anti-penetration ability. On the other hand, the higher internal energy weakens the penetration or anti-penetration ability. The two trends conflict, but the volumetric strain dominates in the variation of the penetration efficiency, which would not approach the hydrodynamic limit if the rod and target are not analogously compressible. However, if the compressibility of the rod and target is analogous, it has little effect on the penetration efficiency.

  4. The Effect of Al on the Compressibility of Silicate Perovskite

    Science.gov (United States)

    Walter, M. J.; Kubo, A.; Yoshino, T.; Koga, K. T.; Ohishi, Y.

    2003-12-01

    Experimental data on compressibility of aluminous silicate perovskite show widely disparate results. Several studies show that Al causes a dramatic increase in compressibility1-3, while another study indicates a mild decrease in compressibility4. Here we report new results for the effect of Al on the room-temperature compressibility of perovskite using in situ X-ray diffraction in the diamond anvil cell from 30 to 100 GPa. We studied compressibility of perovskite in the system MgSiO3-Al2O3 in compositions with 0 to 25 mol% Al. Perovskite was synthesized from starting glasses using laser-heating in the DAC, with KBr as a pressure medium. Diffraction patterns were obtained using monochromatic radiation and an imaging plate detector at beamline BL10XU, SPring8, Japan. Addition of Al into the perovskite structure causes systematic increases in orthorhombic distortion and unit cell volume at ambient conditions (V0). Compression of the perovskite unit cell is anisotropic, with the a axis about 25% and 3% more compressive than the b and c axes, respectively. The magnitude of orthorhombic distortion increases with pressure, but aluminous perovskite remains stable to at least 100 GPa. Our results show that Al causes only a mild increase in compressibility, with the bulk modulus (K0) decreasing at a rate of 0.7 GPa/0.01 XAl. This increase in compressibility is consistent with recent ab initio calculations if Al mixes into both the 6- and 8-coordinated sites by coupled substitution5, where 2 Al3+ = Mg2+ + Si4+. Our results together with those of [4] indicate that this substitution mechanism predominates throughout the lower mantle. Previous mineralogic models indicating the upper and lower mantle are compositionally similar in terms of major elements remain effectively unchanged because solution of 5 mol% Al into perovskite has a minor effect on density. 1. Zhang & Weidner (1999). Science 284, 782-784. 2. Kubo et al. (2000) Proc. Jap. Acad. 76B, 103-107. 3. Daniel et al

  5. Flux compression generators as plasma compression power sources

    International Nuclear Information System (INIS)

    Fowler, C.M.; Caird, R.S.; Erickson, D.J.; Freeman, B.L.; Thomson, D.B.; Garn, W.B.

    1979-01-01

    A survey is made of applications where explosive-driven magnetic flux compression generators have been or can be used to directly power devices that produce dense plasmas. Representative examples are discussed that are specific to the theta pinch, the plasma gun, the dense plasma focus and the Z pinch. These examples are used to illustrate the high energy and power capabilities of explosive generators. An application employing a rocket-borne, generator-powered plasma gun emphasizes the size and weight potential of flux compression power supplies. Recent results from a local effort to drive a dense plasma focus are provided. Imploding liners ae discussed in the context of both the theta and Z pinches

  6. ADVANCED RECIPROCATING COMPRESSION TECHNOLOGY (ARCT)

    Energy Technology Data Exchange (ETDEWEB)

    Danny M. Deffenbaugh; Klaus Brun; Ralph E. Harris; J. Pete Harrell; Robert J. Mckee; J. Jeffrey Moore; Steven J. Svedeman; Anthony J. Smalley; Eugene L. Broerman; Robert A Hart; Marybeth G. Nored; Ryan S. Gernentz; Shane P. Siebenaler

    2005-12-01

    The U.S. natural gas pipeline industry is facing the twin challenges of increased flexibility and capacity expansion. To meet these challenges, the industry requires improved choices in gas compression to address new construction and enhancement of the currently installed infrastructure. The current fleet of installed reciprocating compression is primarily slow-speed integral machines. Most new reciprocating compression is and will be large, high-speed separable units. The major challenges with the fleet of slow-speed integral machines are: limited flexibility and a large range in performance. In an attempt to increase flexibility, many operators are choosing to single-act cylinders, which are causing reduced reliability and integrity. While the best performing units in the fleet exhibit thermal efficiencies between 90% and 92%, the low performers are running down to 50% with the mean at about 80%. The major cause for this large disparity is due to installation losses in the pulsation control system. In the better performers, the losses are about evenly split between installation losses and valve losses. The major challenges for high-speed machines are: cylinder nozzle pulsations, mechanical vibrations due to cylinder stretch, short valve life, and low thermal performance. To shift nozzle pulsation to higher orders, nozzles are shortened, and to dampen the amplitudes, orifices are added. The shortened nozzles result in mechanical coupling with the cylinder, thereby, causing increased vibration due to the cylinder stretch mode. Valve life is even shorter than for slow speeds and can be on the order of a few months. The thermal efficiency is 10% to 15% lower than slow-speed equipment with the best performance in the 75% to 80% range. The goal of this advanced reciprocating compression program is to develop the technology for both high speed and low speed compression that will expand unit flexibility, increase thermal efficiency, and increase reliability and integrity

  7. The task of control digital image compression

    OpenAIRE

    TASHMANOV E.B.; МАМАTOV М.S.

    2014-01-01

    In this paper we consider the relationship of control tasks and image compression losses. The main idea of this approach is to allocate structural lines simplified image and further compress the selected data

  8. Discrete Wigner Function Reconstruction and Compressed Sensing

    OpenAIRE

    Zhang, Jia-Ning; Fang, Lei; Ge, Mo-Lin

    2011-01-01

    A new reconstruction method for Wigner function is reported for quantum tomography based on compressed sensing. By analogy with computed tomography, Wigner functions for some quantum states can be reconstructed with less measurements utilizing this compressed sensing based method.

  9. Compressibility Analysis of the Tongue During Speech

    National Research Council Canada - National Science Library

    Unay, Devrim

    2001-01-01

    .... In this paper, 3D compression and expansion analysis of the tongue will be presented. Patterns of expansion and compression have been compared for different syllables and various repetitions of each syllable...

  10. Compressed normalized block difference for object tracking

    Science.gov (United States)

    Gao, Yun; Zhang, Dengzhuo; Cai, Donglan; Zhou, Hao; Lan, Ge

    2018-04-01

    Feature extraction is very important for robust and real-time tracking. Compressive sensing provided a technical support for real-time feature extraction. However, all existing compressive tracking were based on compressed Haar-like feature, and how to compress many more excellent high-dimensional features is worth researching. In this paper, a novel compressed normalized block difference feature (CNBD) was proposed. For resisting noise effectively in a highdimensional normalized pixel difference feature (NPD), a normalized block difference feature extends two pixels in the original formula of NPD to two blocks. A CNBD feature can be obtained by compressing a normalized block difference feature based on compressive sensing theory, with the sparse random Gaussian matrix as the measurement matrix. The comparative experiments of 7 trackers on 20 challenging sequences showed that the tracker based on CNBD feature can perform better than other trackers, especially than FCT tracker based on compressed Haar-like feature, in terms of AUC, SR and Precision.

  11. On Normalized Compression Distance and Large Malware

    OpenAIRE

    Borbely, Rebecca Schuller

    2015-01-01

    Normalized Compression Distance (NCD) is a popular tool that uses compression algorithms to cluster and classify data in a wide range of applications. Existing discussions of NCD's theoretical merit rely on certain theoretical properties of compression algorithms. However, we demonstrate that many popular compression algorithms don't seem to satisfy these theoretical properties. We explore the relationship between some of these properties and file size, demonstrating that this theoretical pro...

  12. Image quality (IQ) guided multispectral image compression

    Science.gov (United States)

    Zheng, Yufeng; Chen, Genshe; Wang, Zhonghai; Blasch, Erik

    2016-05-01

    Image compression is necessary for data transportation, which saves both transferring time and storage space. In this paper, we focus on our discussion on lossy compression. There are many standard image formats and corresponding compression algorithms, for examples, JPEG (DCT -- discrete cosine transform), JPEG 2000 (DWT -- discrete wavelet transform), BPG (better portable graphics) and TIFF (LZW -- Lempel-Ziv-Welch). The image quality (IQ) of decompressed image will be measured by numerical metrics such as root mean square error (RMSE), peak signal-to-noise ratio (PSNR), and structural Similarity (SSIM) Index. Given an image and a specified IQ, we will investigate how to select a compression method and its parameters to achieve an expected compression. Our scenario consists of 3 steps. The first step is to compress a set of interested images by varying parameters and compute their IQs for each compression method. The second step is to create several regression models per compression method after analyzing the IQ-measurement versus compression-parameter from a number of compressed images. The third step is to compress the given image with the specified IQ using the selected compression method (JPEG, JPEG2000, BPG, or TIFF) according to the regressed models. The IQ may be specified by a compression ratio (e.g., 100), then we will select the compression method of the highest IQ (SSIM, or PSNR). Or the IQ may be specified by a IQ metric (e.g., SSIM = 0.8, or PSNR = 50), then we will select the compression method of the highest compression ratio. Our experiments tested on thermal (long-wave infrared) images (in gray scales) showed very promising results.

  13. Speech Data Compression using Vector Quantization

    OpenAIRE

    H. B. Kekre; Tanuja K. Sarode

    2008-01-01

    Mostly transforms are used for speech data compressions which are lossy algorithms. Such algorithms are tolerable for speech data compression since the loss in quality is not perceived by the human ear. However the vector quantization (VQ) has a potential to give more data compression maintaining the same quality. In this paper we propose speech data compression algorithm using vector quantization technique. We have used VQ algorithms LBG, KPE and FCG. The results table s...

  14. Considerations and Algorithms for Compression of Sets

    DEFF Research Database (Denmark)

    Larsson, Jesper

    We consider compression of unordered sets of distinct elements. After a discus- sion of the general problem, we focus on compressing sets of fixed-length bitstrings in the presence of statistical information. We survey techniques from previous work, suggesting some adjustments, and propose a novel...... compression algorithm that allows transparent incorporation of various estimates for probability distribution. Our experimental results allow the conclusion that set compression can benefit from incorporat- ing statistics, using our method or variants of previously known techniques....

  15. A biological compression model and its applications.

    Science.gov (United States)

    Cao, Minh Duc; Dix, Trevor I; Allison, Lloyd

    2011-01-01

    A biological compression model, expert model, is presented which is superior to existing compression algorithms in both compression performance and speed. The model is able to compress whole eukaryotic genomes. Most importantly, the model provides a framework for knowledge discovery from biological data. It can be used for repeat element discovery, sequence alignment and phylogenetic analysis. We demonstrate that the model can handle statistically biased sequences and distantly related sequences where conventional knowledge discovery tools often fail.

  16. FRESCO: Referential compression of highly similar sequences.

    Science.gov (United States)

    Wandelt, Sebastian; Leser, Ulf

    2013-01-01

    In many applications, sets of similar texts or sequences are of high importance. Prominent examples are revision histories of documents or genomic sequences. Modern high-throughput sequencing technologies are able to generate DNA sequences at an ever-increasing rate. In parallel to the decreasing experimental time and cost necessary to produce DNA sequences, computational requirements for analysis and storage of the sequences are steeply increasing. Compression is a key technology to deal with this challenge. Recently, referential compression schemes, storing only the differences between a to-be-compressed input and a known reference sequence, gained a lot of interest in this field. In this paper, we propose a general open-source framework to compress large amounts of biological sequence data called Framework for REferential Sequence COmpression (FRESCO). Our basic compression algorithm is shown to be one to two orders of magnitudes faster than comparable related work, while achieving similar compression ratios. We also propose several techniques to further increase compression ratios, while still retaining the advantage in speed: 1) selecting a good reference sequence; and 2) rewriting a reference sequence to allow for better compression. In addition,we propose a new way of further boosting the compression ratios by applying referential compression to already referentially compressed files (second-order compression). This technique allows for compression ratios way beyond state of the art, for instance,4,000:1 and higher for human genomes. We evaluate our algorithms on a large data set from three different species (more than 1,000 genomes, more than 3 TB) and on a collection of versions of Wikipedia pages. Our results show that real-time compression of highly similar sequences at high compression ratios is possible on modern hardware.

  17. Subjective evaluation of compressed image quality

    Science.gov (United States)

    Lee, Heesub; Rowberg, Alan H.; Frank, Mark S.; Choi, Hyung-Sik; Kim, Yongmin

    1992-05-01

    Lossy data compression generates distortion or error on the reconstructed image and the distortion becomes visible as the compression ratio increases. Even at the same compression ratio, the distortion appears differently depending on the compression method used. Because of the nonlinearity of the human visual system and lossy data compression methods, we have evaluated subjectively the quality of medical images compressed with two different methods, an intraframe and interframe coding algorithms. The evaluated raw data were analyzed statistically to measure interrater reliability and reliability of an individual reader. Also, the analysis of variance was used to identify which compression method is better statistically, and from what compression ratio the quality of a compressed image is evaluated as poorer than that of the original. Nine x-ray CT head images from three patients were used as test cases. Six radiologists participated in reading the 99 images (some were duplicates) compressed at four different compression ratios, original, 5:1, 10:1, and 15:1. The six readers agree more than by chance alone and their agreement was statistically significant, but there were large variations among readers as well as within a reader. The displacement estimated interframe coding algorithm is significantly better in quality than that of the 2-D block DCT at significance level 0.05. Also, 10:1 compressed images with the interframe coding algorithm do not show any significant differences from the original at level 0.05.

  18. H.264/AVC Video Compression on Smartphones

    Science.gov (United States)

    Sharabayko, M. P.; Markov, N. G.

    2017-01-01

    In this paper, we studied the usage of H.264/AVC video compression tools by the flagship smartphones. The results show that only a subset of tools is used, meaning that there is still a potential to achieve higher compression efficiency within the H.264/AVC standard, but the most advanced smartphones are already reaching the compression efficiency limit of H.264/AVC.

  19. Relationship between the edgewise compression strength of ...

    African Journals Online (AJOL)

    The results of this study were used to determine the linear regression constants in the Maltenfort model by correlating the measured board edgewise compression strength (ECT) with the predicted strength, using the paper components' compression strengths, measured with the short-span compression test (SCT) and the ...

  20. The function profile of compressed-air and ultrasonic nebulizers.

    Science.gov (United States)

    Wu, Hsin-Lin; Lin, Yung-Zen; Wu, Wei-Fong; Huang, Fu-Yuan

    2003-01-01

    In order to study the detailed function of two kinds of nebulizers commonly used in clinical asthma treatment, compressed-air and ultrasonic, this study was conducted. At the beginning, various flow rates were adjusted, paired with different volumes of solutions in the container. The changes of temperature, pH, and osmolality during the course of nebulization were examined. Normal saline, terbutaline, and fenoterol solutions were used as the nebulized solutions. The study was performed in an environment in ambient temperature around 20 degrees C and relative humidity around 70%. The results showed a minimal 6 L/min flow rate was required to nebulize the solution when using the compressed-air nebulizer. The dead volume was about 0.8 ml for compressed-air and 8.5 ml for the ultrasonic nebulizer. When using the compressed-air nebulizer, the temperature, both in the solution and at the mouthpiece site, dropped gradually. On the contrary, the temperatures at both sites increased a little bit when using the ultrasonic nebulizer. The pH values of pure terbutaline and fenoterol nebulized solutions were acidic (3.58 and 3.00 respectively). The osmolality of terbutaline and fenoterol nebulized solutions were isotonic. The osmolality increased gradually during the course of nebulization, to a greater extent in the compressed-air nebulizer. In conclusion, both types of nebulizers have their special features. The ultrasonic nebulizer displays less extent in change of temperature and osmolality during nebulization and is expected to be a better device in treating asthmatic patients in terms of lesser effect on cooling and changing the osmolality of airway mucosa.

  1. Using autoencoders for mammogram compression.

    Science.gov (United States)

    Tan, Chun Chet; Eswaran, Chikkannan

    2011-02-01

    This paper presents the results obtained for medical image compression using autoencoder neural networks. Since mammograms (medical images) are usually of big sizes, training of autoencoders becomes extremely tedious and difficult if the whole image is used for training. We show in this paper that the autoencoders can be trained successfully by using image patches instead of the whole image. The compression performances of different types of autoencoders are compared based on two parameters, namely mean square error and structural similarity index. It is found from the experimental results that the autoencoder which does not use Restricted Boltzmann Machine pre-training yields better results than those which use this pre-training method.

  2. Culture: copying, compression, and conventionality.

    Science.gov (United States)

    Tamariz, Mónica; Kirby, Simon

    2015-01-01

    Through cultural transmission, repeated learning by new individuals transforms cultural information, which tends to become increasingly compressible (Kirby, Cornish, & Smith, ; Smith, Tamariz, & Kirby, ). Existing diffusion chain studies include in their design two processes that could be responsible for this tendency: learning (storing patterns in memory) and reproducing (producing the patterns again). This paper manipulates the presence of learning in a simple iterated drawing design experiment. We find that learning seems to be the causal factor behind the increase in compressibility observed in the transmitted information, while reproducing is a source of random heritable innovations. Only a theory invoking these two aspects of cultural learning will be able to explain human culture's fundamental balance between stability and innovation. Copyright © 2014 Cognitive Science Society, Inc.

  3. Instability of ties in compression

    DEFF Research Database (Denmark)

    Buch-Hansen, Thomas Cornelius

    2013-01-01

    Masonry cavity walls are loaded by wind pressure and vertical load from upper floors. These loads results in bending moments and compression forces in the ties connecting the outer and the inner wall in a cavity wall. Large cavity walls are furthermore loaded by differential movements from...... the temperature gradient between the outer and the inner wall, which results in critical increase of the bending moments in the ties. Since the ties are loaded by combined compression and moment forces, the loadbearing capacity is derived from instability equilibrium equations. Most of them are iterative, since...... exact instability solutions are complex to derive, not to mention the extra complexity introducing dimensional instability from the temperature gradients. Using an inverse variable substitution and comparing an exact theory with an analytical instability solution a method to design tie...

  4. Diagnostic imaging of compression neuropathy

    International Nuclear Information System (INIS)

    Weishaupt, D.; Andreisek, G.

    2007-01-01

    Compression-induced neuropathy of peripheral nerves can cause severe pain of the foot and ankle. Early diagnosis is important to institute prompt treatment and to minimize potential injury. Although clinical examination combined with electrophysiological studies remain the cornerstone of the diagnostic work-up, in certain cases, imaging may provide key information with regard to the exact anatomic location of the lesion or aid in narrowing the differential diagnosis. In other patients with peripheral neuropathies of the foot and ankle, imaging may establish the etiology of the condition and provide information crucial for management and/or surgical planning. MR imaging and ultrasound provide direct visualization of the nerve and surrounding abnormalities. Bony abnormalities contributing to nerve compression are best assessed by radiographs and CT. Knowledge of the anatomy, the etiology, typical clinical findings, and imaging features of peripheral neuropathies affecting the peripheral nerves of the foot and ankle will allow for a more confident diagnosis. (orig.) [de

  5. [Medical image compression: a review].

    Science.gov (United States)

    Noreña, Tatiana; Romero, Eduardo

    2013-01-01

    Modern medicine is an increasingly complex activity , based on the evidence ; it consists of information from multiple sources : medical record text , sound recordings , images and videos generated by a large number of devices . Medical imaging is one of the most important sources of information since they offer comprehensive support of medical procedures for diagnosis and follow-up . However , the amount of information generated by image capturing gadgets quickly exceeds storage availability in radiology services , generating additional costs in devices with greater storage capacity . Besides , the current trend of developing applications in cloud computing has limitations, even though virtual storage is available from anywhere, connections are made through internet . In these scenarios the optimal use of information necessarily requires powerful compression algorithms adapted to medical activity needs . In this paper we present a review of compression techniques used for image storage , and a critical analysis of them from the point of view of their use in clinical settings.

  6. Compressed optimization of device architectures

    Energy Technology Data Exchange (ETDEWEB)

    Frees, Adam [Univ. of Wisconsin, Madison, WI (United States). Dept. of Physics; Gamble, John King [Microsoft Research, Redmond, WA (United States). Quantum Architectures and Computation Group; Ward, Daniel Robert [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Center for Computing Research; Blume-Kohout, Robin J [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Center for Computing Research; Eriksson, M. A. [Univ. of Wisconsin, Madison, WI (United States). Dept. of Physics; Friesen, Mark [Univ. of Wisconsin, Madison, WI (United States). Dept. of Physics; Coppersmith, Susan N. [Univ. of Wisconsin, Madison, WI (United States). Dept. of Physics

    2014-09-01

    Recent advances in nanotechnology have enabled researchers to control individual quantum mechanical objects with unprecedented accuracy, opening the door for both quantum and extreme- scale conventional computation applications. As these devices become more complex, designing for facility of control becomes a daunting and computationally infeasible task. Here, motivated by ideas from compressed sensing, we introduce a protocol for the Compressed Optimization of Device Architectures (CODA). It leads naturally to a metric for benchmarking and optimizing device designs, as well as an automatic device control protocol that reduces the operational complexity required to achieve a particular output. Because this protocol is both experimentally and computationally efficient, it is readily extensible to large systems. For this paper, we demonstrate both the bench- marking and device control protocol components of CODA through examples of realistic simulations of electrostatic quantum dot devices, which are currently being developed experimentally for quantum computation.

  7. Compressed air energy storage system

    Science.gov (United States)

    Ahrens, Frederick W.; Kartsounes, George T.

    1981-01-01

    An internal combustion reciprocating engine is operable as a compressor during slack demand periods utilizing excess power from a power grid to charge air into an air storage reservoir and as an expander during peak demand periods to feed power into the power grid utilizing air obtained from the air storage reservoir together with combustible fuel. Preferably the internal combustion reciprocating engine is operated at high pressure and a low pressure turbine and compressor are also employed for air compression and power generation.

  8. Compressing spatio-temporal trajectories

    DEFF Research Database (Denmark)

    Gudmundsson, Joachim; Katajainen, Jyrki; Merrick, Damian

    2009-01-01

    such that the most common spatio-temporal queries can still be answered approximately after the compression has taken place. In the process, we develop an implementation of the Douglas–Peucker path-simplification algorithm which works efficiently even in the case where the polygonal path given as input is allowed...... to self-intersect. For a polygonal path of size n, the processing time is O(nlogkn) for k=2 or k=3 depending on the type of simplification....

  9. [Compression treatment for burned skin].

    Science.gov (United States)

    Jaafar, Fadhel; Lassoued, Mohamed A; Sahnoun, Mahdi; Sfar, Souad; Cheikhrouhou, Morched

    2012-02-01

    The regularity of a compressive knit is defined as its ability to perform its function in a burnt skin. This property is essential to avoid the phenomenon of rejection of the material or toxicity problems But: Make knits biocompatible with high burnet of human skin. We fabric knits of elastic material. To ensure good adhesion to the skin, we made elastic material, typically a tight loop knitted. The Length of yarn absorbed by stitch and the raw matter are changed with each sample. The physical properties of each sample are measured and compared. Surface modifications are made to these samples by impregnation of microcapsules based on jojoba oil. Knits are compressif, elastic in all directions, light, thin, comfortable, and washable for hygiene issues. In addition, the washing can find their compressive properties. The Jojoba Oil microcapsules hydrated the human burnet skin. This moisturizer is used to the firmness of the wound and it gives flexibility to the skin. Compressive Knits are biocompatible with burnet skin. The mixture of natural and synthetic fibers is irreplaceable in terms comfort and regularity.

  10. Compressibility effects on turbulent mixing

    Science.gov (United States)

    Panickacheril John, John; Donzis, Diego

    2016-11-01

    We investigate the effect of compressibility on passive scalar mixing in isotropic turbulence with a focus on the fundamental mechanisms that are responsible for such effects using a large Direct Numerical Simulation (DNS) database. The database includes simulations with Taylor Reynolds number (Rλ) up to 100, turbulent Mach number (Mt) between 0.1 and 0.6 and Schmidt number (Sc) from 0.5 to 1.0. We present several measures of mixing efficiency on different canonical flows to robustly identify compressibility effects. We found that, like shear layers, mixing is reduced as Mach number increases. However, data also reveal a non-monotonic trend with Mt. To assess directly the effect of dilatational motions we also present results with both dilatational and soleniodal forcing. Analysis suggests that a small fraction of dilatational forcing decreases mixing time at higher Mt. Scalar spectra collapse when normalized by Batchelor variables which suggests that a compressive mechanism similar to Batchelor mixing in incompressible flows might be responsible for better mixing at high Mt and with dilatational forcing compared to pure solenoidal mixing. We also present results on scalar budgets, in particular on production and dissipation. Support from NSF is gratefully acknowledged.

  11. Image compression of bone images

    International Nuclear Information System (INIS)

    Hayrapetian, A.; Kangarloo, H.; Chan, K.K.; Ho, B.; Huang, H.K.

    1989-01-01

    This paper reports a receiver operating characteristic (ROC) experiment conducted to compare the diagnostic performance of a compressed bone image with the original. The compression was done on custom hardware that implements an algorithm based on full-frame cosine transform. The compression ratio in this study is approximately 10:1, which was decided after a pilot experiment. The image set consisted of 45 hand images, including normal images and images containing osteomalacia and osteitis fibrosa. Each image was digitized with a laser film scanner to 2,048 x 2,048 x 8 bits. Six observers, all board-certified radiologists, participated in the experiment. For each ROC session, an independent ROC curve was constructed and the area under that curve calculated. The image set was randomized for each session, as was the order for viewing the original and reconstructed images. Analysis of variance was used to analyze the data and derive statistically significant results. The preliminary results indicate that the diagnostic quality of the reconstructed image is comparable to that of the original image

  12. Compressing DNA sequence databases with coil

    Directory of Open Access Journals (Sweden)

    Hendy Michael D

    2008-05-01

    Full Text Available Abstract Background Publicly available DNA sequence databases such as GenBank are large, and are growing at an exponential rate. The sheer volume of data being dealt with presents serious storage and data communications problems. Currently, sequence data is usually kept in large "flat files," which are then compressed using standard Lempel-Ziv (gzip compression – an approach which rarely achieves good compression ratios. While much research has been done on compressing individual DNA sequences, surprisingly little has focused on the compression of entire databases of such sequences. In this study we introduce the sequence database compression software coil. Results We have designed and implemented a portable software package, coil, for compressing and decompressing DNA sequence databases based on the idea of edit-tree coding. coil is geared towards achieving high compression ratios at the expense of execution time and memory usage during compression – the compression time represents a "one-off investment" whose cost is quickly amortised if the resulting compressed file is transmitted many times. Decompression requires little memory and is extremely fast. We demonstrate a 5% improvement in compression ratio over state-of-the-art general-purpose compression tools for a large GenBank database file containing Expressed Sequence Tag (EST data. Finally, coil can efficiently encode incremental additions to a sequence database. Conclusion coil presents a compelling alternative to conventional compression of flat files for the storage and distribution of DNA sequence databases having a narrow distribution of sequence lengths, such as EST data. Increasing compression levels for databases having a wide distribution of sequence lengths is a direction for future work.

  13. Prefrontal white matter pathology in air pollution exposed Mexico City young urbanites and their potential impact on neurovascular unit dysfunction and the development of Alzheimer's disease

    International Nuclear Information System (INIS)

    Calderón-Garcidueñas, Lilian; Reynoso-Robles, Rafael; Vargas- Martínez, Javier; Gómez-Maqueo-Chew, Aline; Pérez-Guillé, Beatriz; Mukherjee, Partha S.; Torres-Jardón, Ricardo; Perry, George; Gónzalez-Maciel, Angélica

    2016-01-01

    Millions of urban children are chronically exposed to high concentrations of air pollutants, i.e., fine particulate matter (PM 2.5 ) and ozone, associated with increased risk for Alzheimer's disease. Compared with children living with clear air those in Mexico City (MC) exhibit systemic, brain and intrathecal inflammation, low CSF Aβ 42, breakdown of the BBB, attention and short-term memory deficits, prefrontal white matter hyperintensities, damage to epithelial and endothelial barriers, tight junction and neural autoantibodies, and Alzheimer and Parkinson's hallmarks. The prefrontal white matter is a target of air pollution. We examined by light and electron microscopy the prefrontal white matter of MC dogs (n: 15, age 3.17±0.74 years), children and teens (n: 34, age: 12.64±4.2 years) versus controls. Major findings in MC residents included leaking capillaries and small arterioles with extravascular lipids and erythrocytes, lipofuscin in pericytes, smooth muscle and endothelial cells (EC), thickening of cerebrovascular basement membranes with small deposits of amyloid, patchy absence of the perivascular glial sheet, enlarged Virchow–Robin spaces and nanosize particles (20–48 nm) in EC, basement membranes, axons and dendrites. Tight junctions, a key component of the neurovascular unit (NVU) were abnormal in MC versus control dogs (χ 2 <0.0001), and white matter perivascular damage was significantly worse in MC dogs (p=0.002). The integrity of the NVU, an interactive network of vascular, glial and neuronal cells is compromised in MC young residents. Characterizing the early NVU damage and identifying biomarkers of neurovascular dysfunction may provide a fresh insight into Alzheimer pathogenesis and open opportunities for pediatric neuroprotection. - Highlights: • The prefrontal white matter is a target of air pollution. • Tight junctions, key neurovascular unit elements, are abnormal in young urbanites. • Identifying neurovascular dysfunction

  14. Envera Variable Compression Ratio Engine

    Energy Technology Data Exchange (ETDEWEB)

    Charles Mendler

    2011-03-15

    Aggressive engine downsizing, variable compression ratio and use of the Atkinson cycle are being combined to improve fuel economy by up to 40 percent relative to port fuel injected gasoline engines, while maintaining full engine power. Approach Engine downsizing is viewed by US and foreign automobile manufacturers as one of the best options for improving fuel economy. While this strategy has already demonstrated a degree of success, downsizing and fuel economy gains are currently limited. With new variable compression ratio technology however, the degree of engine downsizing and fuel economy improvement can be greatly increased. A small variable compression ratio (VCR) engine has the potential to return significantly higher vehicle fuel economy while also providing high power. Affordability and potential for near term commercialization are key attributes of the Envera VCR engine. VCR Technology To meet torque and power requirements, a smaller engine needs to do more work per stroke. This is typically accomplished by boosting the incoming charge with either a turbo or supercharger so that more energy is present in the cylinder per stroke to do the work. With current production engines the degree of engine boosting (which correlates to downsizing) is limited by detonation (combustion knock) at high boost levels. Additionally, the turbo or supercharger needs to be responsive and efficient while providing the needed boost. VCR technology eliminates the limitation of engine knock at high load levels by reducing compression ratio to {approx}9:1 (or whatever level is appropriate) when high boost pressures are needed. By reducing the compression ratio during high load demand periods there is increased volume in the cylinder at top dead center (TDC) which allows more charge (or energy) to be present in the cylinder without increasing the peak pressure. Cylinder pressure is thus kept below the level at which the engine would begin to knock. When loads on the engine are low

  15. Compression of Fe-Si-H alloys

    Science.gov (United States)

    Tagawa, S.; Ohta, K.; Hirose, K.

    2014-12-01

    The light elements in the Earth's core have not been fully identified yet, but hydrogen is now collecting more attention in part because recent planet formation theory suggests that large amount of water should have been brought to the Earth during its formation (giant-impact stage). Nevertheless, the effect of hydrogen on the property of iron alloys is little known so far. The earlier experimental study by Hirao et al. [2004 GRL] examined the compression behavior of dhcp FeHx (x ≈ 1) and found that it becomes much stiffer than pure iron above 50 GPa, where magnetization disappears. Here we examined the solubility of hydrogen into iron-rich Fe-Si alloys and the compression behavior of dhcp Fe-Si-H alloy at room temperature. Fe+6.5wt.%Si or Fe+9wt.%Si foil was loaded into a diamond-anvil cell (DAC), and then liquid hydrogen was introduced at temperatures below 20 K. X-ray diffraction measurements at SPring-8 revealed the formation of a dhcp phase with or without thermal annealing by laser above 8.4 GPa. The concentration of hydrogen in such dhcp lattice was calculated following the formula reported by Fukai [1992]; y = 0.5 and 0.2 for Fe-6.5wt.%Si-H or Fe-9wt.%Si-H alloys, respectively when y is defined as Fe(1-x)SixHy. Unlike Fe-H alloy, hydrogen didn't fully occupy the octahedral sites even under hydrogen-saturated conditions in the case of Fe-Si-H system. Anomaly was observed in obtained pressure-volume curve around 44 Å3 of unit-cell volume for both Fe-6.5wt.%Si-H and Fe-9wt.%Si-H alloys, which may be related to the spin transition in the dhcp phase. They became slightly stiffer at higher pressures, but their compressibility was still similar to that of pure iron.

  16. JPEG and wavelet compression of ophthalmic images

    Science.gov (United States)

    Eikelboom, Robert H.; Yogesan, Kanagasingam; Constable, Ian J.; Barry, Christopher J.

    1999-05-01

    This study was designed to determine the degree and methods of digital image compression to produce ophthalmic imags of sufficient quality for transmission and diagnosis. The photographs of 15 subjects, which inclined eyes with normal, subtle and distinct pathologies, were digitized to produce 1.54MB images and compressed to five different methods: (i) objectively by calculating the RMS error between the uncompressed and compressed images, (ii) semi-subjectively by assessing the visibility of blood vessels, and (iii) subjectively by asking a number of experienced observers to assess the images for quality and clinical interpretation. Results showed that as a function of compressed image size, wavelet compressed images produced less RMS error than JPEG compressed images. Blood vessel branching could be observed to a greater extent after Wavelet compression compared to JPEG compression produced better images then a JPEG compression for a given image size. Overall, it was shown that images had to be compressed to below 2.5 percent for JPEG and 1.7 percent for Wavelet compression before fine detail was lost, or when image quality was too poor to make a reliable diagnosis.

  17. ROLE OF MRI IN EVALUATION OF COMPRESSIVE MYELOPATHY

    Directory of Open Access Journals (Sweden)

    Raseshkumar Rasiklal Vyas

    2017-03-01

    Full Text Available BACKGROUND Aim of the study was to find out various causes of compressive myelopathy and to characterise them. MATERIALS AND METHODS Total of 48 cases were analysed over a period of January 2016 to January 2017 and were evaluated using MRI spine studies. RESULTS MRI, because of its exemplary tissue characterisation and high contrast resolution, excellently demonstrates the anatomical details and pathological process. Thus, is a superior modality in diagnosing Spinal cord lesions as well as associated soft tissue injuries, inter-vertebral discs and ligaments. In our study, traumatic injuries (43% were found to be the most common cause of Compressive myelopathy, other were Infections (23%, primary malignancies (17%, and Metastasis (17%. Thoracic spine was found to be the most frequent site in cases of Traumatic injuries. 40 out of total 48 cases had extradural, and the rest 8 had intra-dural compressive lesions. CONCLUSION The study concludes that patients with suspected Compressive myelopathies benefit from evaluation with MRI, which is highly accurate for characterising and identifying the underlying aetiology, as well as associated features. Thus, explicitly helps in stating the long-term prognosis of the patient.

  18. An alternative noninvasive technique for the treatment of iatrogenic femoral pseudoaneurysms: stethoscope-guided compression.

    Science.gov (United States)

    Korkmaz, Ahmet; Duyuler, Serkan; Kalayci, Süleyman; Türker, Pinar; Sahan, Ekrem; Maden, Orhan; Selçuk, Mehmet Timur

    2013-06-01

    latrogenic femoral pseudoaneurysm is a well-known vascular access site complication. Many invasive and noninvasive techniques have been proposed for the management of this relatively common complication. In this study, we aimed to evaluate efficiency and safety of stethoscope-guided compression as a novel noninvasive technique in the femoral pseudoaneurysm treatment. We prospectively included 29 consecutive patients with the diagnosis of femoral pseudoaneurysm who underwent coronary angiography. Patients with a clinical suspicion of femoral pseudoaneurysm were referred to colour Doppler ultrasound evaluation. The adult (large) side of the stethoscope was used to determine the location where the bruit was best heard. Then compression with the paediatric (small) side of the stethoscope was applied until the bruit could no longer be heard and compression was maintained for at least two sessions. Once the bruit disappeared, a 12-hour bed rest with external elastic compression was advised to the patients, in order to prevent disintegration of newly formed thrombosis. Mean pseudoaneurysm size was 1.7 +/- 0.4 cmx 3.0 +/- 0.9 cm and the mean duration of compression was 36.2 +/- 8.5 minutes.Twenty-six (89.6%) of these 29 patients were successfully treated with stethoscope-guided compression. In 18 patients (62%), the pseuodoaneurysms were successfully closed after 2 sessions of 15-minute compression. No severe complication was observed. Stethoscope-guided compression of femoral pseudoaneurysms is a safe and effective novel technique which requires less equipment and expertise than other contemporary methods.

  19. Percutaneous radiofrequency rhizotomy and neurovascular decompression of the trigeminal nerve for the treatment of facial pain Rizotomia percutânea por radiofreqüência e a descompressão neurovascular do nervo trigêmeo no tratamento das algias faciais

    Directory of Open Access Journals (Sweden)

    Manoel J. Teixeira

    2006-12-01

    Full Text Available OBJECTIVE: To determine the outcomes of 354 radiofrequency rhizotomies and 21 neurovascular decompressions performed as treatment for 367 facial pain patients (290 idiopathic trigeminal neuralgia, 52 symptomatic trigeminal neuralgia, 16 atypical facial pain, 9 post-herpetic neuralgia. METHOD: Clinical findings and surgery success rate were considered for evaluation. A scale of success rate was determined to classify patients, which considered pain relief and functional/sensorial deficits. RESULTS: Radiofrequency rhizotomy was performed in 273 patients with idiopathic trigeminal neuralgia and in all other patients, except for trigeminal neuropathy; neurovascular decompression was performed in 18 idiopathic trigeminal neuralgia patients; 100% idiopathic trigeminal neuralgia, 96.2% symptomatic trigeminal neuralgia, 37.5% atypical facial pain and 88.9% post-herpetic neuralgia had pain relief. CONCLUSION: Both techniques for idiopathic trigeminal neuralgia are usefull. Radiofrequency rhizotomy was also efficient to treat symptomatic facial pain, and post-herpetic facial pain, but is not a good technique for atypical facial pain.OBJETIVO: Determinar eficácia e achados pós-operatórios após 354 rizotomias por radiofreqüência e 21 descompressões neurovasculares como tratamento de 367 pacientes com dor facial (290 neuralgia idiopática do trigêmeo, 52 neuralgia sintomática do trigêmeo, 16 dor facial atípica, 9 neuralgia pós-herpética. MÉTODO: Achados clínicos e taxa de sucesso das cirurgias foram considerados para a avaliação. Uma escala avaliando alívio da dor e complicações sensoriais e funcionais foi utilizada para classificar os pacientes. RESULTADOS: A rizotomia por radiofreqüência foi realizada em 273 pacientes com neuralgia idiopática do trigêmeo e em todos os outros pacientes, exceto neuropatia trigeminal; descompressão neurovascular foi realizada em 18 pacientes com neuralgia idiopática do trigêmeo; 100% dos pacientes

  20. The "hierarchical" Scratch Collapse Test for identifying multilevel ulnar nerve compression.

    Science.gov (United States)

    Davidge, Kristen M; Gontre, Gil; Tang, David; Boyd, Kirsty U; Yee, Andrew; Damiano, Marci S; Mackinnon, Susan E

    2015-09-01

    The Scratch Collapse Test (SCT) is used to assist in the clinical evaluation of patients with ulnar nerve compression. The purpose of this study is to introduce the hierarchical SCT as a physical examination tool for identifying multilevel nerve compression in patients with cubital tunnel syndrome. A prospective cohort study (2010-2011) was conducted of patients referred with primary cubital tunnel syndrome. Five ulnar nerve compression sites were evaluated with the SCT. Each site generating a positive SCT was sequentially "frozen out" with a topical anesthetic to allow determination of both primary and secondary ulnar nerve entrapment points. The order or "hierarchy" of compression sites was recorded. Twenty-five patients (mean age 49.6 ± 12.3 years; 64 % female) were eligible for inclusion. The primary entrapment point was identified as Osborne's band in 80 % and the cubital tunnel retinaculum in 20 % of patients. Secondary entrapment points were also identified in the following order in all patients: (1) volar antebrachial fascia, (2) Guyon's canal, and (3) arcade of Struthers. The SCT is useful in localizing the site of primary compression of the ulnar nerve in patients with cubital tunnel syndrome. It is also sensitive enough to detect secondary compression points when primary sites are sequentially frozen out with a topical anesthetic, termed the hierarchical SCT. The findings of the hierarchical SCT are in keeping with the double crush hypothesis described by Upton and McComas in 1973 and the hypothesis of multilevel nerve compression proposed by Mackinnon and Novak in 1994.

  1. Neurovascular coupling protects neurons against hypoxic injury via inhibition of potassium currents by generation of nitric oxide in direct neuron and endothelium cocultures.

    Science.gov (United States)

    Wu, Kun-Wei; Kou, Zeng-Wei; Mo, Jia-Lin; Deng, Xu-Xu; Sun, Feng-Yan

    2016-10-15

    This study examined the effect of neuron-endothelial coupling on the survival of neurons after ischemia and the possible mechanism underlying that effect. Whole-cell patch-clamp experiments were performed on cortical neurons cultured alone or directly cocultured with brain microvascular endothelial cells (BMEC). Propidium iodide (PI) and NeuN staining were performed to examine neuronal death following oxygen and glucose deprivation (OGD). We found that the neuronal transient outward potassium currents (I A ) decreased in the coculture system, whereas the outward delayed-rectifier potassium currents (I K ) did not. Sodium nitroprusside, a NO donor, enhanced BMEC-induced I A inhibition and nitro-l-arginine methylester, a NOS inhibitor, partially prevented this inhibition. Moreover, the neurons directly cocultured with BMEC showed more resistance to OGD-induced injury compared with the neurons cultured alone, and that neuroprotective effect was abolished by treatment with NS5806, an activator of the I A . These results indicate that vascular endothelial cells assist neurons to prevent hypoxic injury via inhibiting neuronal I A by production of NO in the direct neuron-BMEC coculture system. These results further provide direct evidence of functional coupling between neurons and vascular endothelial cells. This study clearly demonstrates that vascular endothelial cells play beneficial roles in the pathophysiological processes of neurons after hypoxic injury, suggesting that the improvement of neurovascular coupling or functional remodeling may become an important therapeutic target for preventing brain injury. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

  2. A Pilot Study of Laparoscopic Doppler Ultrasound Probe to Map Arterial Vascular Flow within the Neurovascular Bundle during Robot-Assisted Radical Prostatectomy

    Directory of Open Access Journals (Sweden)

    Ketan K. Badani

    2013-01-01

    Full Text Available Purpose. To report on the feasibility of a new Laparoscopic Doppler ultrasound (LDU technology to aid in identifying and preserving arterial blood flow within the neurovascular bundle (NVB during robotic prostatectomy (RARP. Materials and Methods. Nine patients with normal preoperative potency and scheduled for a bilateral nerve-sparing procedure were prospectively enrolled. LDU was used to measure arterial flow at 6 anatomic locations alongside the prostate, and signal intensity was evaluated by 4 independent reviewers. Measurements were made before and after NVB dissection. Modifications in nerve-sparing procedure due to LDU use were recorded. Postoperative erectile function was assessed. Fleiss Kappa statistic was used to evaluate inter-rater agreement for each of the 12 measurements. Results. Analysis of Doppler signal intensity showed maintenance of flow in 80% of points assessed, a decrease in 16%, and an increase in 4%. Plane of NVB dissection was altered in 5 patients (56% on the left and in 4 patients (44% on the right. There was good inter-rater reliability for the 4 reviewers. Use of the probe did not significantly increase operative time or result in any complications. Seven (78% patients had recovery of erections at time of the 8-month follow-up visit. Conclusions. LDU is a safe, easy to use, and effective method to identify local vasculature and anatomic landmarks during RARP, and can potentially be used to achieve greater nerve preservation.

  3. Neurovascular Network Explorer 1.0: a database of 2-photon single-vessel diameter measurements with MATLAB(®) graphical user interface.

    Science.gov (United States)

    Sridhar, Vishnu B; Tian, Peifang; Dale, Anders M; Devor, Anna; Saisan, Payam A

    2014-01-01

    We present a database client software-Neurovascular Network Explorer 1.0 (NNE 1.0)-that uses MATLAB(®) based Graphical User Interface (GUI) for interaction with a database of 2-photon single-vessel diameter measurements from our previous publication (Tian et al., 2010). These data are of particular interest for modeling the hemodynamic response. NNE 1.0 is downloaded by the user and then runs either as a MATLAB script or as a standalone program on a Windows platform. The GUI allows browsing the database according to parameters specified by the user, simple manipulation and visualization of the retrieved records (such as averaging and peak-normalization), and export of the results. Further, we provide NNE 1.0 source code. With this source code, the user can database their own experimental results, given the appropriate data structure and naming conventions, and thus share their data in a user-friendly format with other investigators. NNE 1.0 provides an example of seamless and low-cost solution for sharing of experimental data by a regular size neuroscience laboratory and may serve as a general template, facilitating dissemination of biological results and accelerating data-driven modeling approaches.

  4. Magnetic compression into Brillouin flow

    International Nuclear Information System (INIS)

    Becker, R.

    1977-01-01

    The trajectories of beam edge electrons are calculated in the transition region between an electrostatic gun and an increasing magnetic field for various field shapes, transition length, and cathode fluxes, assuming that the resultant beam is of Brillouin flow type. The results give a good physical interpretation to the axial gradient of the magnetic field being responsible for the amount of magnetic compression and also for the proper injection conditions. Therefore it becomes possible to predict from the known characteristics of any fairly laminary electrostatic gun the necessary axial gradient of the magnetic field and the axial position of the gun with respect to the field build-up. (orig.) [de

  5. Antiproton compression and radial measurements

    CERN Document Server

    Andresen, G B; Bowe, P D; Bray, C C; Butler, E; Cesar, C L; Chapman, S; Charlton, M; Fajans, J; Fujiwara, M C; Funakoshi, R; Gill, D R; Hangst, J S; Hardy, W N; Hayano, R S; Hayden, M E; Humphries, A J; Hydomako, R; Jenkins, M J; Jorgensen, L V; Kurchaninov, L; Lambo, R; Madsen, N; Nolan, P; Olchanski, K; Olin, A; Page R D; Povilus, A; Pusa, P; Robicheaux, F; Sarid, E; Seif El Nasr, S; Silveira, D M; Storey, J W; Thompson, R I; Van der Werf, D P; Wurtele, J S; Yamazaki, Y

    2008-01-01

    Control of the radial profile of trapped antiproton clouds is critical to trapping antihydrogen. We report detailed measurements of the radial manipulation of antiproton clouds, including areal density compressions by factors as large as ten, achieved by manipulating spatially overlapped electron plasmas. We show detailed measurements of the near-axis antiproton radial profile, and its relation to that of the electron plasma. We also measure the outer radial profile by ejecting antiprotons to the trap wall using an octupole magnet.

  6. Capillary waves of compressible fluids

    International Nuclear Information System (INIS)

    Falk, Kerstin; Mecke, Klaus

    2011-01-01

    The interplay of thermal noise and molecular forces is responsible for surprising features of liquids on sub-micrometer lengths-in particular at interfaces. Not only does the surface tension depend on the size of an applied distortion and nanoscopic thin liquid films dewet faster than would be expected from hydrodynamics, but also the dispersion relation of capillary waves differ at the nanoscale from the familiar macroscopic behavior. Starting with the stochastic Navier-Stokes equation we study the coupling of capillary waves to acoustic surface waves which is possible in compressible fluids. We find propagating 'acoustic-capillary waves' at nanometer wavelengths where in incompressible fluids capillary waves are overdamped.

  7. Shock compression of diamond crystal

    OpenAIRE

    Kondo, Ken-ichi; Ahrens, Thomas J.

    1983-01-01

    Two shock wave experiments employing inclined mirrors have been carried out to determine the Hugoniot elastic limit (HEL), final shock state at 191 and 217 GPa, and the post-shock state of diamond crystal, which is shock-compressed along the intermediate direction between the and crystallographic axes. The HEL wave has a velocity of 19.9 ± 0.3 mm/µsec and an amplitude of 63 ± 28 GPa. An alternate interpretation of the inclined wedge mirror streak record suggests a ramp precursor wave and th...

  8. Atomic effect algebras with compression bases

    International Nuclear Information System (INIS)

    Caragheorgheopol, Dan; Tkadlec, Josef

    2011-01-01

    Compression base effect algebras were recently introduced by Gudder [Demonstr. Math. 39, 43 (2006)]. They generalize sequential effect algebras [Rep. Math. Phys. 49, 87 (2002)] and compressible effect algebras [Rep. Math. Phys. 54, 93 (2004)]. The present paper focuses on atomic compression base effect algebras and the consequences of atoms being foci (so-called projections) of the compressions in the compression base. Part of our work generalizes results obtained in atomic sequential effect algebras by Tkadlec [Int. J. Theor. Phys. 47, 185 (2008)]. The notion of projection-atomicity is introduced and studied, and several conditions that force a compression base effect algebra or the set of its projections to be Boolean are found. Finally, we apply some of these results to sequential effect algebras and strengthen a previously established result concerning a sufficient condition for them to be Boolean.

  9. Compressibility, turbulence and high speed flow

    CERN Document Server

    Gatski, Thomas B

    2013-01-01

    Compressibility, Turbulence and High Speed Flow introduces the reader to the field of compressible turbulence and compressible turbulent flows across a broad speed range, through a unique complimentary treatment of both the theoretical foundations and the measurement and analysis tools currently used. The book provides the reader with the necessary background and current trends in the theoretical and experimental aspects of compressible turbulent flows and compressible turbulence. Detailed derivations of the pertinent equations describing the motion of such turbulent flows is provided and an extensive discussion of the various approaches used in predicting both free shear and wall bounded flows is presented. Experimental measurement techniques common to the compressible flow regime are introduced with particular emphasis on the unique challenges presented by high speed flows. Both experimental and numerical simulation work is supplied throughout to provide the reader with an overall perspective of current tre...

  10. Excessive chest compression rate is associated with insufficient compression depth in prehospital cardiac arrest.

    Science.gov (United States)

    Monsieurs, Koenraad G; De Regge, Melissa; Vansteelandt, Kristof; De Smet, Jeroen; Annaert, Emmanuel; Lemoyne, Sabine; Kalmar, Alain F; Calle, Paul A

    2012-11-01

    BACKGROUND AND GOAL OF STUDY: The relationship between chest compression rate and compression depth is unknown. In order to characterise this relationship, we performed an observational study in prehospital cardiac arrest patients. We hypothesised that faster compressions are associated with decreased depth. In patients undergoing prehospital cardiopulmonary resuscitation by health care professionals, chest compression rate and depth were recorded using an accelerometer (E-series monitor-defibrillator, Zoll, U.S.A.). Compression depth was compared for rates 120/min. A difference in compression depth ≥0.5 cm was considered clinically significant. Mixed models with repeated measurements of chest compression depth and rate (level 1) nested within patients (level 2) were used with compression rate as a continuous and as a categorical predictor of depth. Results are reported as means and standard error (SE). One hundred and thirty-three consecutive patients were analysed (213,409 compressions). Of all compressions 2% were 120/min, 36% were 5 cm. In 77 out of 133 (58%) patients a statistically significant lower depth was observed for rates >120/min compared to rates 80-120/min, in 40 out of 133 (30%) this difference was also clinically significant. The mixed models predicted that the deepest compression (4.5 cm) occurred at a rate of 86/min, with progressively lower compression depths at higher rates. Rates >145/min would result in a depth compression depth for rates 80-120/min was on average 4.5 cm (SE 0.06) compared to 4.1 cm (SE 0.06) for compressions >120/min (mean difference 0.4 cm, Pcompression rates and lower compression depths. Avoiding excessive compression rates may lead to more compressions of sufficient depth. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  11. Dual compression is not an uncommon type of iliac vein compression syndrome.

    Science.gov (United States)

    Shi, Wan-Yin; Gu, Jian-Ping; Liu, Chang-Jian; Lou, Wen-Sheng; He, Xu

    2017-09-01

    Typical iliac vein compression syndrome (IVCS) is characterized by compression of left common iliac vein (LCIV) by the overlying right common iliac artery (RCIA). We described an underestimated type of IVCS with dual compression by right and left common iliac arteries (LCIA) simultaneously. Thirty-one patients with IVCS were retrospectively included. All patients received trans-catheter venography and computed tomography (CT) examinations for diagnosing and evaluating IVCS. Late venography and reconstructed CT were used for evaluating the anatomical relationship among LCIV, RCIA and LCIA. Imaging manifestations as well as demographic data were collected and evaluated by two experienced radiologists. Sole and dual compression were found in 32.3% (n = 10) and 67.7% (n = 21) of 31 patients respectively. No statistical differences existed between them in terms of age, gender, LCIV diameter at the maximum compression point, pressure gradient across stenosis, and the percentage of compression level. On CT and venography, sole compression was commonly presented with a longitudinal compression at the orifice of LCIV while dual compression was usually presented as two types: one had a lengthy stenosis along the upper side of LCIV and the other was manifested by a longitudinal compression near to the orifice of external iliac vein. The presence of dual compression seemed significantly correlated with the tortuous LCIA (p = 0.006). Left common iliac vein can be presented by dual compression. This type of compression has typical manifestations on late venography and CT.

  12. How Wage Compression Affects Job Turnover

    OpenAIRE

    Heyman, Fredrik

    2008-01-01

    I use Swedish establishment-level panel data to test Bertola and Rogerson’s (1997) hypothesis of a positive relation between the degree of wage compression and job reallocation. Results indicate that the effect of wage compression on job turnover is positive and significant in the manufacturing sector. The wage compression effect is stronger on job destruction than on job creation, consistent with downward wage rigidity. Further results include a strong positive relationship between the fract...

  13. Compressed Air Production Using Vehicle Suspension

    OpenAIRE

    Ninad Arun Malpure; Sanket Nandlal Bhansali

    2015-01-01

    Abstract Generally compressed air is produced using different types of air compressors which consumes lot of electric energy and is noisy. In this paper an innovative idea is put forth for production of compressed air using movement of vehicle suspension which normal is wasted. The conversion of the force energy into the compressed air is carried out by the mechanism which consists of the vehicle suspension system hydraulic cylinder Non-return valve air compressor and air receiver. We are co...

  14. Subband Coding Methods for Seismic Data Compression

    Science.gov (United States)

    Kiely, A.; Pollara, F.

    1995-01-01

    This paper presents a study of seismic data compression techniques and a compression algorithm based on subband coding. The compression technique described could be used as a progressive transmission system, where successive refinements of the data can be requested by the user. This allows seismologists to first examine a coarse version of waveforms with minimal usage of the channel and then decide where refinements are required. Rate-distortion performance results are presented and comparisons are made with two block transform methods.

  15. Compressibility of the protein-water interface

    Science.gov (United States)

    Persson, Filip; Halle, Bertil

    2018-06-01

    The compressibility of a protein relates to its stability, flexibility, and hydrophobic interactions, but the measurement, interpretation, and computation of this important thermodynamic parameter present technical and conceptual challenges. Here, we present a theoretical analysis of protein compressibility and apply it to molecular dynamics simulations of four globular proteins. Using additively weighted Voronoi tessellation, we decompose the solution compressibility into contributions from the protein and its hydration shells. We find that positively cross-correlated protein-water volume fluctuations account for more than half of the protein compressibility that governs the protein's pressure response, while the self correlations correspond to small (˜0.7%) fluctuations of the protein volume. The self compressibility is nearly the same as for ice, whereas the total protein compressibility, including cross correlations, is ˜45% of the bulk-water value. Taking the inhomogeneous solvent density into account, we decompose the experimentally accessible protein partial compressibility into intrinsic, hydration, and molecular exchange contributions and show how they can be computed with good statistical accuracy despite the dominant bulk-water contribution. The exchange contribution describes how the protein solution responds to an applied pressure by redistributing water molecules from lower to higher density; it is negligibly small for native proteins, but potentially important for non-native states. Because the hydration shell is an open system, the conventional closed-system compressibility definitions yield a pseudo-compressibility. We define an intrinsic shell compressibility, unaffected by occupation number fluctuations, and show that it approaches the bulk-water value exponentially with a decay "length" of one shell, less than the bulk-water compressibility correlation length. In the first hydration shell, the intrinsic compressibility is 25%-30% lower than in

  16. Eccentric crank variable compression ratio mechanism

    Science.gov (United States)

    Lawrence, Keith Edward [Kobe, JP; Moser, William Elliott [Peoria, IL; Roozenboom, Stephan Donald [Washington, IL; Knox, Kevin Jay [Peoria, IL

    2008-05-13

    A variable compression ratio mechanism for an internal combustion engine that has an engine block and a crankshaft is disclosed. The variable compression ratio mechanism has a plurality of eccentric disks configured to support the crankshaft. Each of the plurality of eccentric disks has at least one cylindrical portion annularly surrounded by the engine block. The variable compression ratio mechanism also has at least one actuator configured to rotate the plurality of eccentric disks.

  17. Computer calculations of compressibility of natural gas

    Energy Technology Data Exchange (ETDEWEB)

    Abou-Kassem, J.H.; Mattar, L.; Dranchuk, P.M

    An alternative method for the calculation of pseudo reduced compressibility of natural gas is presented. The method is incorporated into the routines by adding a single FORTRAN statement before the RETURN statement. The method is suitable for computer and hand-held calculator applications. It produces the same reduced compressibility as other available methods but is computationally superior. Tabular definitions of coefficients and comparisons of predicted pseudo reduced compressibility using different methods are presented, along with appended FORTRAN subroutines. 7 refs., 2 tabs.

  18. Compressibility of the protein-water interface.

    Science.gov (United States)

    Persson, Filip; Halle, Bertil

    2018-06-07

    The compressibility of a protein relates to its stability, flexibility, and hydrophobic interactions, but the measurement, interpretation, and computation of this important thermodynamic parameter present technical and conceptual challenges. Here, we present a theoretical analysis of protein compressibility and apply it to molecular dynamics simulations of four globular proteins. Using additively weighted Voronoi tessellation, we decompose the solution compressibility into contributions from the protein and its hydration shells. We find that positively cross-correlated protein-water volume fluctuations account for more than half of the protein compressibility that governs the protein's pressure response, while the self correlations correspond to small (∼0.7%) fluctuations of the protein volume. The self compressibility is nearly the same as for ice, whereas the total protein compressibility, including cross correlations, is ∼45% of the bulk-water value. Taking the inhomogeneous solvent density into account, we decompose the experimentally accessible protein partial compressibility into intrinsic, hydration, and molecular exchange contributions and show how they can be computed with good statistical accuracy despite the dominant bulk-water contribution. The exchange contribution describes how the protein solution responds to an applied pressure by redistributing water molecules from lower to higher density; it is negligibly small for native proteins, but potentially important for non-native states. Because the hydration shell is an open system, the conventional closed-system compressibility definitions yield a pseudo-compressibility. We define an intrinsic shell compressibility, unaffected by occupation number fluctuations, and show that it approaches the bulk-water value exponentially with a decay "length" of one shell, less than the bulk-water compressibility correlation length. In the first hydration shell, the intrinsic compressibility is 25%-30% lower than

  19. Thermal compression modulus of polarized neutron matter

    International Nuclear Information System (INIS)

    Abd-Alla, M.

    1990-05-01

    We applied the equation of state for pure polarized neutron matter at finite temperature, calculated previously, to calculate the compression modulus. The compression modulus of pure neutron matter at zero temperature is very large and reflects the stiffness of the equation of state. It has a little temperature dependence. Introducing the spin excess parameter in the equation of state calculations is important because it has a significant effect on the compression modulus. (author). 25 refs, 2 tabs

  20. Cosmological Particle Data Compression in Practice

    Science.gov (United States)

    Zeyen, M.; Ahrens, J.; Hagen, H.; Heitmann, K.; Habib, S.

    2017-12-01

    In cosmological simulations trillions of particles are handled and several terabytes of unstructured particle data are generated in each time step. Transferring this data directly from memory to disk in an uncompressed way results in a massive load on I/O and storage systems. Hence, one goal of domain scientists is to compress the data before storing it to disk while minimizing the loss of information. To prevent reading back uncompressed data from disk, this can be done in an in-situ process. Since the simulation continuously generates data, the available time for the compression of one time step is limited. Therefore, the evaluation of compression techniques has shifted from only focusing on compression rates to include run-times and scalability.In recent years several compression techniques for cosmological data have become available. These techniques can be either lossy or lossless, depending on the technique. For both cases, this study aims to evaluate and compare the state of the art compression techniques for unstructured particle data. This study focuses on the techniques available in the Blosc framework with its multi-threading support, the XZ Utils toolkit with the LZMA algorithm that achieves high compression rates, and the widespread FPZIP and ZFP methods for lossy compressions.For the investigated compression techniques, quantitative performance indicators such as compression rates, run-time/throughput, and reconstruction errors are measured. Based on these factors, this study offers a comprehensive analysis of the individual techniques and discusses their applicability for in-situ compression. In addition, domain specific measures are evaluated on the reconstructed data sets, and the relative error rates and statistical properties are analyzed and compared. Based on this study future challenges and directions in the compression of unstructured cosmological particle data were identified.

  1. Compressive Strength of Cometary Surfaces Derived from Radar Observations

    Science.gov (United States)

    ElShafie, A.; Heggy, E.

    2014-12-01

    Landing on a comet nucleus and probing it, mechanically using harpoons, penetrometers and drills, and electromagnetically using low frequency radar waves is a complex task that will be tackled by the Rosetta mission for Comet 67P/Churyumov-Gerasimenko. The mechanical properties (i.e. density, porosity and compressive strength) and the electrical properties (i.e. the real and imaginary parts of the dielectric constant) of the comet nucleus, constrain both the mechanical and electromagnetic probing capabilities of Rosetta, as well as the choice of landing site, the safety of the landing, and subsurface data interpretation. During landing, the sounding radar data that will be collected by Rosetta's CONSERT experiment can be used to probe the comet's upper regolith layer by assessing its dielectric properties, which are then inverted to retrieve the surface mechanical properties. These observations can help characterize the mechanical properties of the landing site, which will optimize the operation of the anchor system. In this effort, we correlate the mechanical and electrical properties of cometary analogs to each other, and derive an empirical model that can be used to retrieve density, porosity and compressive strength from the dielectric properties of the upper regolith inverted from CONSERT observations during the landing phase. In our approach we consider snow as a viable cometary material analog due to its low density and its porous nature. Therefore, we used the compressive strength and dielectric constant measurements conducted on snow at a temperature of 250 K and a density range of 0.4-0.9 g/cm3 in order to investigate the relation between compressive strength and dielectric constant under cometary-relevant density range. Our results suggest that compressive strength increases linearly as function of the dielectric constant over the observed density range mentioned above. The minimum and maximum compressive strength of 0.5 and 4.5 MPa corresponded to a

  2. Hyperelastic Material Properties of Mouse Skin under Compression.

    Directory of Open Access Journals (Sweden)

    Yuxiang Wang

    Full Text Available The skin is a dynamic organ whose complex material properties are capable of withstanding continuous mechanical stress while accommodating insults and organism growth. Moreover, synchronized hair cycles, comprising waves of hair growth, regression and rest, are accompanied by dramatic fluctuations in skin thickness in mice. Whether such structural changes alter skin mechanics is unknown. Mouse models are extensively used to study skin biology and pathophysiology, including aging, UV-induced skin damage and somatosensory signaling. As the skin serves a pivotal role in the transfer function from sensory stimuli to neuronal signaling, we sought to define the mechanical properties of mouse skin over a range of normal physiological states. Skin thickness, stiffness and modulus were quantitatively surveyed in adult, female mice (Mus musculus. These measures were analyzed under uniaxial compression, which is relevant for touch reception and compression injuries, rather than tension, which is typically used to analyze skin mechanics. Compression tests were performed with 105 full-thickness, freshly isolated specimens from the hairy skin of the hind limb. Physiological variables included body weight, hair-cycle stage, maturity level, skin site and individual animal differences. Skin thickness and stiffness were dominated by hair-cycle stage at young (6-10 weeks and intermediate (13-19 weeks adult ages but by body weight in mature mice (26-34 weeks. Interestingly, stiffness varied inversely with thickness so that hyperelastic modulus was consistent across hair-cycle stages and body weights. By contrast, the mechanics of hairy skin differs markedly with anatomical location. In particular, skin containing fascial structures such as nerves and blood vessels showed significantly greater modulus than adjacent sites. Collectively, this systematic survey indicates that, although its structure changes dramatically throughout adult life, mouse skin at a given

  3. Compressed Data Structures for Range Searching

    DEFF Research Database (Denmark)

    Bille, Philip; Gørtz, Inge Li; Vind, Søren Juhl

    2015-01-01

    matrices and web graphs. Our contribution is twofold. First, we show how to compress geometric repetitions that may appear in standard range searching data structures (such as K-D trees, Quad trees, Range trees, R-trees, Priority R-trees, and K-D-B trees), and how to implement subsequent range queries...... on the compressed representation with only a constant factor overhead. Secondly, we present a compression scheme that efficiently identifies geometric repetitions in point sets, and produces a hierarchical clustering of the point sets, which combined with the first result leads to a compressed representation...

  4. Energy Conservation In Compressed Air Systems

    International Nuclear Information System (INIS)

    Yusuf, I.Y.; Dewu, B.B.M.

    2004-01-01

    Compressed air is an essential utility that accounts for a substantial part of the electricity consumption (bill) in most industrial plants. Although the general saying Air is free of charge is not true for compressed air, the utility's cost is not accorded the rightful importance due to its by most industries. The paper will show that the cost of 1 unit of energy in the form of compressed air is at least 5 times the cost electricity (energy input) required to produce it. The paper will also provide energy conservation tips in compressed air systems

  5. Study of CSR longitudinal bunch compression cavity

    International Nuclear Information System (INIS)

    Yin Dayu; Li Peng; Liu Yong; Xie Qingchun

    2009-01-01

    The scheme of longitudinal bunch compression cavity for the Cooling Storage Ring (CSR)is an important issue. Plasma physics experiments require high density heavy ion beam and short pulsed bunch,which can be produced by non-adiabatic compression of bunch implemented by a fast compression with 90 degree rotation in the longitudinal phase space. The phase space rotation in fast compression is initiated by a fast jump of the RF-voltage amplitude. For this purpose, the CSR longitudinal bunch compression cavity, loaded with FINEMET-FT-1M is studied and simulated with MAFIA code. In this paper, the CSR longitudinal bunch compression cavity is simulated and the initial bunch length of 238 U 72+ with 250 MeV/u will be compressed from 200 ns to 50 ns.The construction and RF properties of the CSR longitudinal bunch compression cavity are simulated and calculated also with MAFIA code. The operation frequency of the cavity is 1.15 MHz with peak voltage of 80 kV, and the cavity can be used to compress heavy ions in the CSR. (authors)

  6. Memory hierarchy using row-based compression

    Science.gov (United States)

    Loh, Gabriel H.; O'Connor, James M.

    2016-10-25

    A system includes a first memory and a device coupleable to the first memory. The device includes a second memory to cache data from the first memory. The second memory includes a plurality of rows, each row including a corresponding set of compressed data blocks of non-uniform sizes and a corresponding set of tag blocks. Each tag block represents a corresponding compressed data block of the row. The device further includes decompression logic to decompress data blocks accessed from the second memory. The device further includes compression logic to compress data blocks to be stored in the second memory.

  7. Comparing biological networks via graph compression

    Directory of Open Access Journals (Sweden)

    Hayashida Morihiro

    2010-09-01

    Full Text Available Abstract Background Comparison of various kinds of biological data is one of the main problems in bioinformatics and systems biology. Data compression methods have been applied to comparison of large sequence data and protein structure data. Since it is still difficult to compare global structures of large biological networks, it is reasonable to try to apply data compression methods to comparison of biological networks. In existing compression methods, the uniqueness of compression results is not guaranteed because there is some ambiguity in selection of overlapping edges. Results This paper proposes novel efficient methods, CompressEdge and CompressVertices, for comparing large biological networks. In the proposed methods, an original network structure is compressed by iteratively contracting identical edges and sets of connected edges. Then, the similarity of two networks is measured by a compression ratio of the concatenated networks. The proposed methods are applied to comparison of metabolic networks of several organisms, H. sapiens, M. musculus, A. thaliana, D. melanogaster, C. elegans, E. coli, S. cerevisiae, and B. subtilis, and are compared with an existing method. These results suggest that our methods can efficiently measure the similarities between metabolic networks. Conclusions Our proposed algorithms, which compress node-labeled networks, are useful for measuring the similarity of large biological networks.

  8. Compression therapy after ankle fracture surgery

    DEFF Research Database (Denmark)

    Winge, R; Bayer, L; Gottlieb, H

    2017-01-01

    PURPOSE: The main purpose of this systematic review was to investigate the effect of compression treatment on the perioperative course of ankle fractures and describe its effect on edema, pain, ankle joint mobility, wound healing complication, length of stay (LOS) and time to surgery (TTS). The aim...... undergoing surgery, testing either intermittent pneumatic compression, compression bandage and/or compression stocking and reporting its effect on edema, pain, ankle joint mobility, wound healing complication, LOS and TTS. To conclude on data a narrative synthesis was performed. RESULTS: The review included...

  9. Compressed Sensing with Rank Deficient Dictionaries

    DEFF Research Database (Denmark)

    Hansen, Thomas Lundgaard; Johansen, Daniel Højrup; Jørgensen, Peter Bjørn

    2012-01-01

    In compressed sensing it is generally assumed that the dictionary matrix constitutes a (possibly overcomplete) basis of the signal space. In this paper we consider dictionaries that do not span the signal space, i.e. rank deficient dictionaries. We show that in this case the signal-to-noise ratio...... (SNR) in the compressed samples can be increased by selecting the rows of the measurement matrix from the column space of the dictionary. As an example application of compressed sensing with a rank deficient dictionary, we present a case study of compressed sensing applied to the Coarse Acquisition (C...

  10. Compressive failure with interacting cracks

    International Nuclear Information System (INIS)

    Yang Guoping; Liu Xila

    1993-01-01

    The failure processes in concrete and other brittle materials are just the results of the propagation, coalescence and interaction of many preexisting microcracks or voids. To understand the real behaviour of the brittle materials, it is necessary to bridge the gap from the relatively matured one crack behaviour to the stochastically distributed imperfections, that is, to concern the crack propagation and interaction of microscopic mechanism with macroscopic parameters of brittle materials. Brittle failure in compression has been studied theoretically by Horii and Nemat-Nasser (1986), in which a closed solution was obtained for a preexisting flaw or some special regular flaws. Zaitsev and Wittmann (1981) published a paper on crack propagation in compression, which is so-called numerical concrete, but they did not take account of the interaction among the microcracks. As for the modelling of the influence of crack interaction on fracture parameters, many studies have also been reported. Up till now, some researcher are working on crack interaction considering the ratios of SIFs with and without consideration of the interaction influences, there exist amplifying or shielding effects of crack interaction which are depending on the relative positions of these microcracks. The present paper attempts to simulate the whole failure process of brittle specimen in compression, which includes the complicated coupling effects between the interaction and propagation of randomly distributed or other typical microcrack configurations step by step. The lengths, orientations and positions of microcracks are all taken as random variables. The crack interaction among many preexisting random microcracks is evaluated with the help of a simple interaction matrix (Yang and Liu, 1991). For the subcritically stable propagation of microcracks in mixed mode fracture, fairly known maximum hoop stress criterion is adopted to compute branching lengths and directions at each tip of the crack

  11. Blind compressive sensing dynamic MRI

    Science.gov (United States)

    Lingala, Sajan Goud; Jacob, Mathews

    2013-01-01

    We propose a novel blind compressive sensing (BCS) frame work to recover dynamic magnetic resonance images from undersampled measurements. This scheme models the dynamic signal as a sparse linear combination of temporal basis functions, chosen from a large dictionary. In contrast to classical compressed sensing, the BCS scheme simultaneously estimates the dictionary and the sparse coefficients from the undersampled measurements. Apart from the sparsity of the coefficients, the key difference of the BCS scheme with current low rank methods is the non-orthogonal nature of the dictionary basis functions. Since the number of degrees of freedom of the BCS model is smaller than that of the low-rank methods, it provides improved reconstructions at high acceleration rates. We formulate the reconstruction as a constrained optimization problem; the objective function is the linear combination of a data consistency term and sparsity promoting ℓ1 prior of the coefficients. The Frobenius norm dictionary constraint is used to avoid scale ambiguity. We introduce a simple and efficient majorize-minimize algorithm, which decouples the original criterion into three simpler sub problems. An alternating minimization strategy is used, where we cycle through the minimization of three simpler problems. This algorithm is seen to be considerably faster than approaches that alternates between sparse coding and dictionary estimation, as well as the extension of K-SVD dictionary learning scheme. The use of the ℓ1 penalty and Frobenius norm dictionary constraint enables the attenuation of insignificant basis functions compared to the ℓ0 norm and column norm constraint assumed in most dictionary learning algorithms; this is especially important since the number of basis functions that can be reliably estimated is restricted by the available measurements. We also observe that the proposed scheme is more robust to local minima compared to K-SVD method, which relies on greedy sparse coding

  12. Mechanical vapor compression Desalination plant at Trombay

    International Nuclear Information System (INIS)

    Adak, A.K.; Kishore, G.; Srivastava, V.K.; Tewari, P.K.

    2007-01-01

    Desalination plants based on Mechanical Vapour Compression (MVC) technology are inherently the most thermodynamically efficient. The thermodynamic efficiency of the MVC process is derived from the application of the heat pump principle. A single unit of two-effect MVC desalination pilot plant of capacity 50 m3/day has recently been commissioned at Trombay, Mumbai. The desalination unit is very compact and unique of its kind in the seawater desalination technologies and is being operated by using electricity only. Horizontal tube thin film spray desalination evaporators are used for efficient heat transfer. It is suitable for a site, where feed water is highly saline and condenser cooling water is absent and where a thermal heat source is not available. The unit produces high quality water, nearly demineralized (DM) quality directly from seawater. There is no need of polishing unit and product water can be utilized directly as make up of boiler feed and for other high quality process water requirements in the industries. This paper includes the design and highlights the technical features of this unit. (author)

  13. Simulation of compression engine powered by Biofuels

    International Nuclear Information System (INIS)

    Hamdan, M.A.; Khalil, Runa Haj

    2010-01-01

    The present work describes a theoretical investigation concerning the performance of a four strokes compression engine, which is powered by alternative fuels in the form of diesel-ethanol and diesel-ether mixtures, the properties of which were sited from literature. The amount of each alcohol added was 5%, 10% and 15% by volume. The engine speed during the experimental work was within the range from 1000 to 4000 rpm, with engine was set at full throttle opening and hence the engine was operating under full load conditions. Several parameters were calculated namely: engine torque, brake mean effective pressure, brake power, specific fuel consumption and the thermal efficiency, this was carried out using DIESEL-RK software. It was found that the engine is of highest thermal efficiency when it is powered by a 15% ethanol-diesel blend, wile it is of minimum thermal efficiency when it is powered by pure diesel fuel. Further, it was found that both the thermal efficiency of the engine and the specific fuel consumption increases with the percentage of either ethanol or ether in the fuel blend. However, the power was found to decrease with the amount of either ethanol or ether in the fuel blends.

  14. Simultaneous display of MRA and MPR in detecting vascular compression for trigeminal neuralgia or hemifacial spasm: comparison with oblique sagittal views of MRI

    International Nuclear Information System (INIS)

    Arbab, A.S.; Aoki, S.; Yoshikawa, T.; Kumagai, H.; Araki, T.; Nishiyama, Y.; Nagaseki, Y.; Nukui, H.

    2000-01-01

    A new technique, simultaneous display of magnetic resonance angiography (MRA) and multiplanar reconstruction (MPR), was performed by a workstation to identify the involved vessels in patients with trigeminal neuralgia (TN) or hemifacial spasm (HFS), and the results were compared with those of oblique sagittal MRI technique. Twelve patients with either HFS or TN were prospectively assessed by simultaneous display of MRA and MPR, and oblique sagittal techniques, to point out the neurovascular compression and to identify the involved vessels. Three-dimensional (3D) time-of-flight (TOF) spoiled gradient-echo (SPGR) images were acquired to create MRA and MPR. Oblique sagittal views were also created and displayed on films. A total of 15 vessels in 12 patients were identified as compressing vessels during surgery. Simultaneous display of MRA and MPR technique pointed out the presence of vessels at and/or around root entry/exit zone (REZ) in all 12 patients, but proper identification by the name of the individual vessel was correct in 13 of 15 cases. However, oblique sagittal technique indicated the presence of vessels at and/or around REZ in 11 patients, but only 8 of 14 vessels were correctly identified. Our new method, simultaneous display of MRA-MPR, facilitated correct identification of the involved vessels compared with the oblique sagittal view method. (orig.)

  15. Membrane filtration device for studying compression of fouling layers in membrane bioreactors.

    Directory of Open Access Journals (Sweden)

    Mads Koustrup Jørgensen

    Full Text Available A filtration devise was developed to assess compressibility of fouling layers in membrane bioreactors. The system consists of a flat sheet membrane with air scouring operated at constant transmembrane pressure to assess the influence of pressure on resistance of fouling layers. By fitting a mathematical model, three model parameters were obtained; a back transport parameter describing the kinetics of fouling layer formation, a specific fouling layer resistance, and a compressibility parameter. This stands out from other on-site filterability tests as model parameters to simulate filtration performance are obtained together with a characterization of compressibility. Tests on membrane bioreactor sludge showed high reproducibility. The methodology's ability to assess compressibility was tested by filtrations of sludges from membrane bioreactors and conventional activated sludge wastewater treatment plants from three different sites. These proved that membrane bioreactor sludge showed higher compressibility than conventional activated sludge. In addition, detailed information on the underlying mechanisms of the difference in fouling propensity were obtained, as conventional activated sludge showed slower fouling formation, lower specific resistance and lower compressibility of fouling layers, which is explained by a higher degree of flocculation.

  16. Fragment separator momentum compression schemes

    Energy Technology Data Exchange (ETDEWEB)

    Bandura, Laura, E-mail: bandura@anl.gov [Facility for Rare Isotope Beams (FRIB), 1 Cyclotron, East Lansing, MI 48824-1321 (United States); National Superconducting Cyclotron Lab, Michigan State University, 1 Cyclotron, East Lansing, MI 48824-1321 (United States); Erdelyi, Bela [Argonne National Laboratory, Argonne, IL 60439 (United States); Northern Illinois University, DeKalb, IL 60115 (United States); Hausmann, Marc [Facility for Rare Isotope Beams (FRIB), 1 Cyclotron, East Lansing, MI 48824-1321 (United States); Kubo, Toshiyuki [RIKEN Nishina Center, RIKEN, Wako (Japan); Nolen, Jerry [Argonne National Laboratory, Argonne, IL 60439 (United States); Portillo, Mauricio [Facility for Rare Isotope Beams (FRIB), 1 Cyclotron, East Lansing, MI 48824-1321 (United States); Sherrill, Bradley M. [National Superconducting Cyclotron Lab, Michigan State University, 1 Cyclotron, East Lansing, MI 48824-1321 (United States)

    2011-07-21

    We present a scheme to use a fragment separator and profiled energy degraders to transfer longitudinal phase space into transverse phase space while maintaining achromatic beam transport. The first order beam optics theory of the method is presented and the consequent enlargement of the transverse phase space is discussed. An interesting consequence of the technique is that the first order mass resolving power of the system is determined by the first dispersive section up to the energy degrader, independent of whether or not momentum compression is used. The fragment separator at the Facility for Rare Isotope Beams is a specific application of this technique and is described along with simulations by the code COSY INFINITY.

  17. Fragment separator momentum compression schemes

    International Nuclear Information System (INIS)

    Bandura, Laura; Erdelyi, Bela; Hausmann, Marc; Kubo, Toshiyuki; Nolen, Jerry; Portillo, Mauricio; Sherrill, Bradley M.

    2011-01-01

    We present a scheme to use a fragment separator and profiled energy degraders to transfer longitudinal phase space into transverse phase space while maintaining achromatic beam transport. The first order beam optics theory of the method is presented and the consequent enlargement of the transverse phase space is discussed. An interesting consequence of the technique is that the first order mass resolving power of the system is determined by the first dispersive section up to the energy degrader, independent of whether or not momentum compression is used. The fragment separator at the Facility for Rare Isotope Beams is a specific application of this technique and is described along with simulations by the code COSY INFINITY.

  18. Lossless Compression of Digital Images

    DEFF Research Database (Denmark)

    Martins, Bo

    Presently, tree coders are the best bi-level image coders. The currentISO standard, JBIG, is a good example.By organising code length calculations properly a vast number of possible models (trees) can be investigated within reasonable time prior to generating code.A number of general-purpose coders...... version that is substantially faster than its precursorsand brings it close to the multi-pass coders in compression performance.Handprinted characters are of unequal complexity; recent work by Singer and Tishby demonstrates that utilizing the physiological process of writing one can synthesize cursive.......The feature vector of a bitmap initially constitutes a lossy representation of the contour(s) of the bitmap. The initial feature space is usually too large but can be reduced automatically by use ofa predictive code length or predictive error criterion....

  19. Compressive creep of silicon nitride

    International Nuclear Information System (INIS)

    Silva, C.R.M. da; Melo, F.C.L. de; Cairo, C.A.; Piorino Neto, F.

    1990-01-01

    Silicon nitride samples were formed by pressureless sintering process, using neodymium oxide and a mixture of neodymium oxide and yttrio oxide as sintering aids. The short term compressive creep behaviour was evaluated over a stress range of 50-300 MPa and temperature range 1200 - 1350 0 C. Post-sintering heat treatments in nitrogen with a stepwise decremental variation of temperature were performed in some samples and microstructural analysis by X-ray diffraction and transmission electron microscopy showed that the secondary crystalline phase which form from the remnant glass are dependent upon composition and percentage of aditives. Stress exponent values near to unity were obtained for materials with low glass content suggesting grain boundary diffusion accommodation processes. Cavitation will thereby become prevalent with increase in stress, temperature and decrease in the degree of crystallization of the grain boundary phase. (author) [pt

  20. Right brachial angiography with compression

    International Nuclear Information System (INIS)

    Ruggiero, G.; Dalbuono, S.; Tampieri, D.

    1982-01-01

    A technique for performing right brachial anigography by compressing the right anterior-inferior part of the neck is proposed, as a result of studying the left carotid circulation without puncturing the left carotid artery. A success was obtained in about 75% of cases. The success of the technique depends mainly on the anatomical nature of the innominate artery. When the technique is successful both left carotid arteries in the neck and their intracranial branches can be satisfactorily visualized. In some cases visualization of the left vertebral artery was also otbained. Attention is drawn also on the increased diagnostic possibilities of studying the vessels in the neck with a greater dilution of the contrast medium. (orig.)

  1. Shock compression of geological materials

    International Nuclear Information System (INIS)

    Kirk, S; Braithwaite, C; Williamson, D; Jardine, A

    2014-01-01

    Understanding the shock compression of geological materials is important for many applications, and is particularly important to the mining industry. During blast mining the response to shock loading determines the wave propagation speed and resulting fragmentation of the rock. The present work has studied the Hugoniot of two geological materials; Lake Quarry Granite and Gosford Sandstone. For samples of these materials, the composition was characterised in detail. The Hugoniot of Lake Quarry Granite was predicted from this information as the material is fully dense and was found to be in good agreement with the measured Hugoniot. Gosford Sandstone is porous and undergoes compaction during shock loading. Such behaviour is similar to other granular material and we show how it can be described using a P-a compaction model.

  2. Modeling Compressed Turbulence with BHR

    Science.gov (United States)

    Israel, Daniel

    2011-11-01

    Turbulence undergoing compression or expansion occurs in systems ranging from internal combustion engines to supernovae. One common feature in many of these systems is the presence of multiple reacting species. Direct numerical simulation data is available for the single-fluid, low turbulent Mach number case. Wu, et al. (1985) compared their DNS results to several Reynolds-averaged Navier-Stokes models. They also proposed a three-equation k - ɛ - τ model, in conjunction with a Reynolds-stress model. Subsequent researchers have proposed alternative corrections to the standard k - ɛ formulation. Here we investigate three variants of the BHR model (Besnard, 1992). BHR is a model for multi-species variable-density turbulence. The three variants are the linear eddy-viscosity, algebraic-stress, and full Reynolds-stress formulations. We then examine the predictions of the model for the fluctuating density field for the case of variable-density turbulence.

  3. Nuclear transmutation by flux compression

    International Nuclear Information System (INIS)

    Seifritz, W.

    2001-01-01

    A new idea for the transmutation of minor actinides, long (and even short) lived fission products is presented. It is based an the property of neutron flux compression in nuclear (fast and/or thermal) reactors possessing spatially non-stationary critical masses. An advantage factor for the burn-up fluence of the elements to be transmuted in the order of magnitude of 100 and more is obtainable compared with the classical way of transmutation. Three typical examples of such transmuters (a subcritical ringreactor with a rotating reflector, a sub-critical ring reactor with a rotating spallation source, the socalled ''pulsed energy amplifier'', and a fast burn-wave reactor) are presented and analysed with regard to this purpose. (orig.) [de

  4. A New Approach for Fingerprint Image Compression

    Energy Technology Data Exchange (ETDEWEB)

    Mazieres, Bertrand

    1997-12-01

    The FBI has been collecting fingerprint cards since 1924 and now has over 200 million of them. Digitized with 8 bits of grayscale resolution at 500 dots per inch, it means 2000 terabytes of information. Also, without any compression, transmitting a 10 Mb card over a 9600 baud connection will need 3 hours. Hence we need a compression and a compression as close to lossless as possible: all fingerprint details must be kept. A lossless compression usually do not give a better compression ratio than 2:1, which is not sufficient. Compressing these images with the JPEG standard leads to artefacts which appear even at low compression rates. Therefore the FBI has chosen in 1993 a scheme of compression based on a wavelet transform, followed by a scalar quantization and an entropy coding : the so-called WSQ. This scheme allows to achieve compression ratios of 20:1 without any perceptible loss of quality. The publication of the FBI specifies a decoder, which means that many parameters can be changed in the encoding process: the type of analysis/reconstruction filters, the way the bit allocation is made, the number of Huffman tables used for the entropy coding. The first encoder used 9/7 filters for the wavelet transform and did the bit allocation using a high-rate bit assumption. Since the transform is made into 64 subbands, quite a lot of bands receive only a few bits even at an archival quality compression rate of 0.75 bit/pixel. Thus, after a brief overview of the standard, we will discuss a new approach for the bit-allocation that seems to make more sense where theory is concerned. Then we will talk about some implementation aspects, particularly for the new entropy coder and the features that allow other applications than fingerprint image compression. Finally, we will compare the performances of the new encoder to those of the first encoder.

  5. A theoretical alternative intraosseous infusion site in severely hypovolemic children

    Directory of Open Access Journals (Sweden)

    Nkhensani Mogale

    2015-07-01

    Full Text Available Background: Studies have shown that the venous system tends to collapse during hypovolemic shock. The use of the bone marrow space for infusions is an effective alternative, with the tibial insertion site being the norm. Objectives: This study was conducted to determine a quick intraosseous infusion method that could be an alternative to the tibial route in neonates during emergency situations. Method: A sample of 30 neonatal cadavers was dissected to explore a possible alternative to the tibial insertion site. The needle was inserted in the superolateral aspect of the humerus. The needle infusion site was then dissected to determine possible muscular and neurovascular damage that might occur during the administration of this procedure, with the greatest concern being the posterior circumflex humeral artery and axillary nerve exiting the quadrangular space. The distance of the needle insertion site was measured in relation to the soft tissue aswell as to bony landmarks. Results: The calculated 95% confidence interval shows that the needle can be safely inserted into the intraosseous tissue at the greater tubercle of the humerus 9.5 mm – 11.1 mm from the acromion. This is about a little finger’s width from the acromioclavicular joint. Conclusion: Anatomically, the described site is suggested to offer a safe alternative access point for emergency infusion in severely hypovolemic newborns and infants, without the risk of damage to any anatomical structures.

  6. Site Features

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset consists of various site features from multiple Superfund sites in U.S. EPA Region 8. These data were acquired from multiple sources at different times...

  7. Compression of Short Text on Embedded Systems

    DEFF Research Database (Denmark)

    Rein, S.; Gühmann, C.; Fitzek, Frank

    2006-01-01

    The paper details a scheme for lossless compression of a short data series larger than 50 bytes. The method uses arithmetic coding and context modelling with a low-complexity data model. A data model that takes 32 kBytes of RAM already cuts the data size in half. The compression scheme just takes...

  8. Recoil Experiments Using a Compressed Air Cannon

    Science.gov (United States)

    Taylor, Brett

    2006-01-01

    Ping-Pong vacuum cannons, potato guns, and compressed air cannons are popular and dramatic demonstrations for lecture and lab. Students enjoy them for the spectacle, but they can also be used effectively to teach physics. Recently we have used a student-built compressed air cannon as a laboratory activity to investigate impulse, conservation of…

  9. Rupture of esophagus by compressed air.

    Science.gov (United States)

    Wu, Jie; Tan, Yuyong; Huo, Jirong

    2016-11-01

    Currently, beverages containing compressed air such as cola and champagne are widely used in our daily life. Improper ways to unscrew the bottle, usually by teeth, could lead to an injury, even a rupture of the esophagus. This letter to editor describes a case of esophageal rupture caused by compressed air.

  10. Normalized compression distance of multisets with applications

    NARCIS (Netherlands)

    Cohen, A.R.; Vitányi, P.M.B.

    Pairwise normalized compression distance (NCD) is a parameter-free, feature-free, alignment-free, similarity metric based on compression. We propose an NCD of multisets that is also metric. Previously, attempts to obtain such an NCD failed. For classification purposes it is superior to the pairwise

  11. Spectral Compressive Sensing with Polar Interpolation

    DEFF Research Database (Denmark)

    Fyhn, Karsten; Dadkhahi, Hamid; F. Duarte, Marco

    2013-01-01

    . In this paper, we introduce a greedy recovery algorithm that leverages a band-exclusion function and a polar interpolation function to address these two issues in spectral compressive sensing. Our algorithm is geared towards line spectral estimation from compressive measurements and outperforms most existing...

  12. Compression and fast retrieval of SNP data.

    Science.gov (United States)

    Sambo, Francesco; Di Camillo, Barbara; Toffolo, Gianna; Cobelli, Claudio

    2014-11-01

    The increasing interest in rare genetic variants and epistatic genetic effects on complex phenotypic traits is currently pushing genome-wide association study design towards datasets of increasing size, both in the number of studied subjects and in the number of genotyped single nucleotide polymorphisms (SNPs). This, in turn, is leading to a compelling need for new methods for compression and fast retrieval of SNP data. We present a novel algorithm and file format for compressing and retrieving SNP data, specifically designed for large-scale association studies. Our algorithm is based on two main ideas: (i) compress linkage disequilibrium blocks in terms of differences with a reference SNP and (ii) compress reference SNPs exploiting information on their call rate and minor allele frequency. Tested on two SNP datasets and compared with several state-of-the-art software tools, our compression algorithm is shown to be competitive in terms of compression rate and to outperform all tools in terms of time to load compressed data. Our compression and decompression algorithms are implemented in a C++ library, are released under the GNU General Public License and are freely downloadable from http://www.dei.unipd.it/~sambofra/snpack.html. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  13. Dynamic compression and sound quality of music

    NARCIS (Netherlands)

    Lieshout, van R.A.J.M.; Wagenaars, W.M.; Houtsma, A.J.M.; Stikvoort, E.F.

    1984-01-01

    Amplitude compression is often used to match the dynamic: range of music to a particular playback situation in order to ensure, e .g ., continuous audibility in a noisy environment or unobtrusiveness if the music is intended as a quiet background. Since amplitude compression is a nonlinear process,

  14. Subjective evaluation of dynamic compression in music

    NARCIS (Netherlands)

    Wagenaars, W.M.; Houtsma, A.J.M.; Lieshout, van R.A.J.M.

    1986-01-01

    Amplitude compression is often used to match the dynamic range of music to a particular playback situation so as to ensure continuous audibility in a noisy environment. Since amplitude compression is a nonlinear process, it is potentially very damaging to sound quality. Three physical parameters of

  15. Mammography parameters: compression, dose, and discomfort

    International Nuclear Information System (INIS)

    Blanco, S.; Di Risio, C.; Andisco, D.; Rojas, R.R.; Rojas, R.M.

    2017-01-01

    Objective: To confirm the importance of compression in mammography and relate it to the discomfort expressed by the patients. Materials and methods: Two samples of 402 and 268 mammographies were obtained from two diagnostic centres that use the same mammographic equipment, but different compression techniques. The patient age range was from 21 to 50 years old. (authors) [es

  16. Hardware compression using common portions of data

    Science.gov (United States)

    Chang, Jichuan; Viswanathan, Krishnamurthy

    2015-03-24

    Methods and devices are provided for data compression. Data compression can include receiving a plurality of data chunks, sampling at least some of the plurality of data chunks extracting a common portion from a number of the plurality of data chunks based on the sampling, and storing a remainder of the plurality of data chunks in memory.

  17. High Compressive Stresses Near the Surface of the Sierra Nevada, California

    Science.gov (United States)

    Martel, S. J.; Logan, J. M.; Stock, G. M.

    2012-12-01

    Observations and stress measurements in granitic rocks of the Sierra Nevada, California reveal strong compressive stresses parallel to the surface of the range at shallow depths. New overcoring measurements show high compressive stresses at three locations along an east-west transect through Yosemite National Park. At the westernmost site (west end of Tenaya Lake), the mean compressive stress is 1.9. At the middle site (north shore of Tenaya Lake) the mean compressive stress is 6.8 MPa. At the easternmost site (south side of Lembert Dome) the mean compressive stress is 3.0 MPa. The trend of the most compressive stress at these sites is within ~30° of the strike of the local topographic surface. Previously published hydraulic fracturing measurements by others elsewhere in the Sierra Nevada indicate surface-parallel compressive stresses of several MPa within several tens of meters of the surface, with the stress magnitudes generally diminishing to the west. Both the new and the previously published compressive stress magnitudes are consistent with the presence of sheeting joints (i.e., "exfoliation joints") in the Sierra Nevada, which require lateral compressive stresses of several MPa to form. These fractures are widespread: they are distributed in granitic rocks from the north end of the range to its southern tip and across the width of the range. Uplift along the normal faults of the eastern escarpment, recently measured by others at ~1-2 mm/yr, probably contributes to these stresses substantially. Geodetic surveys reveal that normal faulting flexes a range concave upwards in response to fault slip, and this flexure is predicted by elastic dislocation models. The topographic relief of the eastern escarpment of the Sierra Nevada is 2-4 km, and since alluvial fill generally buries the bedrock east of the faults, the offset of granitic rocks is at least that much. Compressive stresses of several MPa are predicted by elastic dislocation models of the range front

  18. The auriculotemporal nerve in etiology of migraine headaches: compression points and anatomical variations.

    Science.gov (United States)

    Chim, Harvey; Okada, Haruko C; Brown, Matthew S; Alleyne, Brendan; Liu, Mengyuan T; Zwiebel, Samantha; Guyuron, Bahman

    2012-08-01

    The auriculotemporal nerve has been identified as one of the peripheral trigger sites for migraine headaches. However, its distal course is poorly mapped following emergence from the parotid gland. In addition, a reliable anatomical landmark for locating the potential compression points along the course of the nerve during surgery has not been sufficiently described. Twenty hemifaces on 10 fresh cadavers were dissected to trace the course of the auriculotemporal nerve from the inferior border of the zygomatic arch to its termination in the temporal scalp. The compression points were mapped and the distances were measured from the most anterosuperior point of the external auditory meatus, which was used as a fixed anatomical landmark. Three potential compression points along the course of the auriculotemporal nerve were identified. Compression points 1 and 2 corresponded to preauricular fascial bands. Compression point 1 was centered 13.1±5.9 mm anterior and 5.0±7.0 mm superior to the most anterosuperior point of the external auditory meatus, whereas compression point 2 was centered at 11.9±6.0 mm anterior and 17.2±10.4 mm superior to the most anterosuperior point of the external auditory meatus. A significant relationship was found between the auriculotemporal nerve and superficial temporal artery (compression point 3) in 80 percent of hemifaces, with three patterns of interaction: a single site of artery crossing over the nerve (62.5 percent), a helical intertwining relationship (18.8 percent), and nerve crossing over the artery (18.8 percent). Findings from this cadaver study provide information relevant to the operative localization of potential compression points along the auriculotemporal nerve.

  19. Insertion profiles of 4 headless compression screws.

    Science.gov (United States)

    Hart, Adam; Harvey, Edward J; Lefebvre, Louis-Philippe; Barthelat, Francois; Rabiei, Reza; Martineau, Paul A

    2013-09-01

    In practice, the surgeon must rely on screw position (insertion depth) and tactile feedback from the screwdriver (insertion torque) to gauge compression. In this study, we identified the relationship between interfragmentary compression and these 2 factors. The Acutrak Standard, Acutrak Mini, Synthes 3.0, and Herbert-Whipple implants were tested using a polyurethane foam scaphoid model. A specialized testing jig simultaneously measured compression force, insertion torque, and insertion depth at half-screw-turn intervals until failure occurred. The peak compression occurs at an insertion depth of -3.1 mm, -2.8 mm, 0.9 mm, and 1.5 mm for the Acutrak Mini, Acutrak Standard, Herbert-Whipple, and Synthes screws respectively (insertion depth is positive when the screw is proud above the bone and negative when buried). The compression and insertion torque at a depth of -2 mm were found to be 113 ± 18 N and 0.348 ± 0.052 Nm for the Acutrak Standard, 104 ± 15 N and 0.175 ± 0.008 Nm for the Acutrak Mini, 78 ± 9 N and 0.245 ± 0.006 Nm for the Herbert-Whipple, and 67 ± 2N, 0.233 ± 0.010 Nm for the Synthes headless compression screws. All 4 screws generated a sizable amount of compression (> 60 N) over a wide range of insertion depths. The compression at the commonly recommended insertion depth of -2 mm was not significantly different between screws; thus, implant selection should not be based on compression profile alone. Conically shaped screws (Acutrak) generated their peak compression when they were fully buried in the foam whereas the shanked screws (Synthes and Herbert-Whipple) reached peak compression before they were fully inserted. Because insertion torque correlated poorly with compression, surgeons should avoid using tactile judgment of torque as a proxy for compression. Knowledge of the insertion profile may improve our understanding of the implants, provide a better basis for comparing screws, and enable the surgeon to optimize compression. Copyright

  20. Biomechanical Comparison of External Fixation and Compression Screws for Transverse Tarsal Joint Arthrodesis.

    Science.gov (United States)

    Latt, L Daniel; Glisson, Richard R; Adams, Samuel B; Schuh, Reinhard; Narron, John A; Easley, Mark E

    2015-10-01

    Transverse tarsal joint arthrodesis is commonly performed in the operative treatment of hindfoot arthritis and acquired flatfoot deformity. While fixation is typically achieved using screws, failure to obtain and maintain joint compression sometimes occurs, potentially leading to nonunion. External fixation is an alternate method of achieving arthrodesis site compression and has the advantage of allowing postoperative compression adjustment when necessary. However, its performance relative to standard screw fixation has not been quantified in this application. We hypothesized that external fixation could provide transverse tarsal joint compression exceeding that possible with screw fixation. Transverse tarsal joint fixation was performed sequentially, first with a circular external fixator and then with compression screws, on 9 fresh-frozen cadaveric legs. The external fixator was attached in abutting rings fixed to the tibia and the hindfoot and a third anterior ring parallel to the hindfoot ring using transverse wires and half-pins in the tibial diaphysis, calcaneus, and metatarsals. Screw fixation comprised two 4.3 mm headless compression screws traversing the talonavicular joint and 1 across the calcaneocuboid joint. Compressive forces generated during incremental fixator foot ring displacement to 20 mm and incremental screw tightening were measured using a custom-fabricated instrumented miniature external fixator spanning the transverse tarsal joint. The maximum compressive force generated by the external fixator averaged 186% of that produced by the screws (range, 104%-391%). Fixator compression surpassed that obtainable with screws at 12 mm of ring displacement and decreased when the tibial ring was detached. No correlation was found between bone density and the compressive force achievable by either fusion method. The compression across the transverse tarsal joint that can be obtained with a circular external fixator including a tibial ring exceeds that

  1. Optimisation algorithms for ECG data compression.

    Science.gov (United States)

    Haugland, D; Heber, J G; Husøy, J H

    1997-07-01

    The use of exact optimisation algorithms for compressing digital electrocardiograms (ECGs) is demonstrated. As opposed to traditional time-domain methods, which use heuristics to select a small subset of representative signal samples, the problem of selecting the subset is formulated in rigorous mathematical terms. This approach makes it possible to derive algorithms guaranteeing the smallest possible reconstruction error when a bounded selection of signal samples is interpolated. The proposed model resembles well-known network models and is solved by a cubic dynamic programming algorithm. When applied to standard test problems, the algorithm produces a compressed representation for which the distortion is about one-half of that obtained by traditional time-domain compression techniques at reasonable compression ratios. This illustrates that, in terms of the accuracy of decoded signals, existing time-domain heuristics for ECG compression may be far from what is theoretically achievable. The paper is an attempt to bridge this gap.

  2. Mathematical transforms and image compression: A review

    Directory of Open Access Journals (Sweden)

    Satish K. Singh

    2010-07-01

    Full Text Available It is well known that images, often used in a variety of computer and other scientific and engineering applications, are difficult to store and transmit due to their sizes. One possible solution to overcome this problem is to use an efficient digital image compression technique where an image is viewed as a matrix and then the operations are performed on the matrix. All the contemporary digital image compression systems use various mathematical transforms for compression. The compression performance is closely related to the performance by these mathematical transforms in terms of energy compaction and spatial frequency isolation by exploiting inter-pixel redundancies present in the image data. Through this paper, a comprehensive literature survey has been carried out and the pros and cons of various transform-based image compression models have also been discussed.

  3. Sudden viscous dissipation in compressing plasma turbulence

    Science.gov (United States)

    Davidovits, Seth; Fisch, Nathaniel

    2015-11-01

    Compression of a turbulent plasma or fluid can cause amplification of the turbulent kinetic energy, if the compression is fast compared to the turnover and viscous dissipation times of the turbulent eddies. The consideration of compressing turbulent flows in inviscid fluids has been motivated by the suggestion that amplification of turbulent kinetic energy occurred on experiments at the Weizmann Institute of Science Z-Pinch. We demonstrate a sudden viscous dissipation mechanism whereby this amplified turbulent kinetic energy is rapidly converted into thermal energy, which further increases the temperature, feeding back to further enhance the dissipation. Application of this mechanism in compression experiments may be advantageous, if the plasma can be kept comparatively cold during much of the compression, reducing radiation and conduction losses, until the plasma suddenly becomes hot. This work was supported by DOE through contract 67350-9960 (Prime # DOE DE-NA0001836) and by the DTRA.

  4. Exploring compression techniques for ROOT IO

    Science.gov (United States)

    Zhang, Z.; Bockelman, B.

    2017-10-01

    ROOT provides an flexible format used throughout the HEP community. The number of use cases - from an archival data format to end-stage analysis - has required a number of tradeoffs to be exposed to the user. For example, a high “compression level” in the traditional DEFLATE algorithm will result in a smaller file (saving disk space) at the cost of slower decompression (costing CPU time when read). At the scale of the LHC experiment, poor design choices can result in terabytes of wasted space or wasted CPU time. We explore and attempt to quantify some of these tradeoffs. Specifically, we explore: the use of alternate compressing algorithms to optimize for read performance; an alternate method of compressing individual events to allow efficient random access; and a new approach to whole-file compression. Quantitative results are given, as well as guidance on how to make compression decisions for different use cases.

  5. Stress analysis of shear/compression test

    International Nuclear Information System (INIS)

    Nishijima, S.; Okada, T.; Ueno, S.

    1997-01-01

    Stress analysis has been made on the glass fiber reinforced plastics (GFRP) subjected to the combined shear and compression stresses by means of finite element method. The two types of experimental set up were analyzed, that is parallel and series method where the specimen were compressed by tilted jigs which enable to apply the combined stresses, to the specimen. Modified Tsai-Hill criterion was employed to judge the failure under the combined stresses that is the shear strength under the compressive stress. The different failure envelopes were obtained between the two set ups. In the parallel system the shear strength once increased with compressive stress then decreased. On the contrary in the series system the shear strength decreased monotonicly with compressive stress. The difference is caused by the different stress distribution due to the different constraint conditions. The basic parameters which control the failure under the combined stresses will be discussed

  6. Interactive computer graphics applications for compressible aerodynamics

    Science.gov (United States)

    Benson, Thomas J.

    1994-01-01

    Three computer applications have been developed to solve inviscid compressible fluids problems using interactive computer graphics. The first application is a compressible flow calculator which solves for isentropic flow, normal shocks, and oblique shocks or centered expansions produced by two dimensional ramps. The second application couples the solutions generated by the first application to a more graphical presentation of the results to produce a desk top simulator of three compressible flow problems: 1) flow past a single compression ramp; 2) flow past two ramps in series; and 3) flow past two opposed ramps. The third application extends the results of the second to produce a design tool which solves for the flow through supersonic external or mixed compression inlets. The applications were originally developed to run on SGI or IBM workstations running GL graphics. They are currently being extended to solve additional types of flow problems and modified to operate on any X-based workstation.

  7. The impact of chest compression rates on quality of chest compressions - a manikin study.

    Science.gov (United States)

    Field, Richard A; Soar, Jasmeet; Davies, Robin P; Akhtar, Naheed; Perkins, Gavin D

    2012-03-01

    Chest compressions are often performed at a variable rate during cardiopulmonary resuscitation (CPR). The effect of compression rate on other chest compression quality variables (compression depth, duty-cycle, leaning, performance decay over time) is unknown. This randomised controlled cross-over manikin study examined the effect of different compression rates on the other chest compression quality variables. Twenty healthcare professionals performed 2 min of continuous compressions on an instrumented manikin at rates of 80, 100, 120, 140 and 160 min(-1) in a random order. An electronic metronome was used to guide compression rate. Compression data were analysed by repeated measures ANOVA and are presented as mean (SD). Non-parametric data was analysed by Friedman test. At faster compression rates there were significant improvements in the number of compressions delivered (160(2) at 80 min(-1) vs. 312(13) compressions at 160 min(-1), P<0.001); and compression duty-cycle (43(6)% at 80 min(-1) vs. 50(7)% at 160 min(-1), P<0.001). This was at the cost of a significant reduction in compression depth (39.5(10)mm at 80 min(-1) vs. 34.5(11)mm at 160 min(-1), P<0.001); and earlier decay in compression quality (median decay point 120 s at 80 min(-1) vs. 40s at 160 min(-1), P<0.001). Additionally not all participants achieved the target rate (100% at 80 min(-1) vs. 70% at 160 min(-1)). Rates above 120 min(-1) had the greatest impact on reducing chest compression quality. For Guidelines 2005 trained rescuers, a chest compression rate of 100-120 min(-1) for 2 min is feasible whilst maintaining adequate chest compression quality in terms of depth, duty-cycle, leaning, and decay in compression performance. Further studies are needed to assess the impact of the Guidelines 2010 recommendation for deeper and faster chest compressions. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  8. Isostatic compression of buffer blocks. Middle scale

    International Nuclear Information System (INIS)

    Ritola, J.; Pyy, E.

    2012-01-01

    Manufacturing of buffer components using isostatic compression method has been studied in small scale in 2008 (Laaksonen 2010). These tests included manufacturing of buffer blocks using different bentonite materials and different compression pressures. Isostatic mould technology was also tested, along with different methods to fill the mould, such as vibration and partial vacuum, as well as a stepwise compression of the blocks. The development of manufacturing techniques has continued with small-scale (30 %) blocks (diameter 600 mm) in 2009. This was done in a separate project: Isostatic compression, manufacturing and testing of small scale (D = 600 mm) buffer blocks. The research on the isostatic compression method continued in 2010 in a project aimed to test and examine the isostatic manufacturing process of buffer blocks at 70 % scale (block diameter 1200 to 1300 mm), and the aim was to continue in 2011 with full-scale blocks (diameter 1700 mm). A total of nine bentonite blocks were manufactured at 70 % scale, of which four were ring-shaped and the rest were cylindrical. It is currently not possible to manufacture full-scale blocks, because there is no sufficiently large isostatic press available. However, such a compression unit is expected to be possible to use in the near future. The test results of bentonite blocks, produced with an isostatic pressing method at different presses and at different sizes, suggest that the technical characteristics, for example bulk density and strength values, are somewhat independent of the size of the block, and that the blocks have fairly homogenous characteristics. Water content and compression pressure are the two most important properties determining the characteristics of the compressed blocks. By adjusting these two properties it is fairly easy to produce blocks at a desired density. The commonly used compression pressure in the manufacturing of bentonite blocks is 100 MPa, which compresses bentonite to approximately

  9. Isostatic compression of buffer blocks. Middle scale

    Energy Technology Data Exchange (ETDEWEB)

    Ritola, J.; Pyy, E. [VTT Technical Research Centre of Finland, Espoo (Finland)

    2012-01-15

    Manufacturing of buffer components using isostatic compression method has been studied in small scale in 2008 (Laaksonen 2010). These tests included manufacturing of buffer blocks using different bentonite materials and different compression pressures. Isostatic mould technology was also tested, along with different methods to fill the mould, such as vibration and partial vacuum, as well as a stepwise compression of the blocks. The development of manufacturing techniques has continued with small-scale (30 %) blocks (diameter 600 mm) in 2009. This was done in a separate project: Isostatic compression, manufacturing and testing of small scale (D = 600 mm) buffer blocks. The research on the isostatic compression method continued in 2010 in a project aimed to test and examine the isostatic manufacturing process of buffer blocks at 70 % scale (block diameter 1200 to 1300 mm), and the aim was to continue in 2011 with full-scale blocks (diameter 1700 mm). A total of nine bentonite blocks were manufactured at 70 % scale, of which four were ring-shaped and the rest were cylindrical. It is currently not possible to manufacture full-scale blocks, because there is no sufficiently large isostatic press available. However, such a compression unit is expected to be possible to use in the near future. The test results of bentonite blocks, produced with an isostatic pressing method at different presses and at different sizes, suggest that the technical characteristics, for example bulk density and strength values, are somewhat independent of the size of the block, and that the blocks have fairly homogenous characteristics. Water content and compression pressure are the two most important properties determining the characteristics of the compressed blocks. By adjusting these two properties it is fairly easy to produce blocks at a desired density. The commonly used compression pressure in the manufacturing of bentonite blocks is 100 MPa, which compresses bentonite to approximately

  10. Fast lossless compression via cascading Bloom filters.

    Science.gov (United States)

    Rozov, Roye; Shamir, Ron; Halperin, Eran

    2014-01-01

    Data from large Next Generation Sequencing (NGS) experiments present challenges both in terms of costs associated with storage and in time required for file transfer. It is sometimes possible to store only a summary relevant to particular applications, but generally it is desirable to keep all information needed to revisit experimental results in the future. Thus, the need for efficient lossless compression methods for NGS reads arises. It has been shown that NGS-specific compression schemes can improve results over generic compression methods, such as the Lempel-Ziv algorithm, Burrows-Wheeler transform, or Arithmetic Coding. When a reference genome is available, effective compression can be achieved by first aligning the reads to the reference genome, and then encoding each read using the alignment position combined with the differences in the read relative to the reference. These reference-based methods have been shown to compress better than reference-free schemes, but the alignment step they require demands several hours of CPU time on a typical dataset, whereas reference-free methods can usually compress in minutes. We present a new approach that achieves highly efficient compression by using a reference genome, but completely circumvents the need for alignment, affording a great reduction in the time needed to compress. In contrast to reference-based methods that first align reads to the genome, we hash all reads into Bloom filters to encode, and decode by querying the same Bloom filters using read-length subsequences of the reference genome. Further compression is achieved by using a cascade of such filters. Our method, called BARCODE, runs an order of magnitude faster than reference-based methods, while compressing an order of magnitude better than reference-free methods, over a broad range of sequencing coverage. In high coverage (50-100 fold), compared to the best tested compressors, BARCODE saves 80-90% of the running time while only increasing space

  11. External pneumatic intermittent compression for treatment of dependent pregnancy edema.

    Science.gov (United States)

    Jacobs, M K; McCance, K L; Stewart, M L

    1982-01-01

    A portable external pneumatic intermittent compression (EPIC) device has been successful in reducing peripheral edema. This study explored the effectiveness of EPIC for treating dependent pregnancy edema. In the study, 42 healthy pregnant women received EPIC for 30 minutes at 40 torr while in the left lateral recumbent position: Group One with mid-thigh boots, and Group Two with below-knee boots. Prior to compression, descriptive data were gathered, leg circumference measurements made, and surface skin temperatures recorded for three sites per leg. Vital signs were taken and pedal edema subjectively indexed. Following compression, circumferences, skin temperatures, vital signs, and edema indices were rerecorded. Three volumes were calculated for each leg using a mathematical model of leg segments as conical frustum units. Mean volume reductions for each leg were significant. The mid-thigh-length boots produced greater mean volume decreases. The volume decrease for calf, lower leg, and foot frustum units were significant. EPIC holds promise as a useful treatment for dependent pregnancy edema.

  12. Site decontamination

    International Nuclear Information System (INIS)

    Bicker, A.E.

    1981-01-01

    Among the several DOE sites that have been radiologically decontaminated under the auspices of the Nevada Operations Office are three whose physical characteristics are unique. These are the Tatum Dome Test Site (TDTS) near Hattiesburg, Mississippi; a location of mountainous terrain (Pahute Mesa) on the Nevada Test Site; and the GNOME site near Carlsbad, New Mexico. In each case the contamination, the terrain, and the climate conditions were different. This presentation includes a brief description of each site, the methods used to perform radiological surveys, the logistics required to support the decontamination (including health physics and sample analysis), and the specific techniques used to reduce or remove the contamination

  13. Magnetic resonance imaging of malignant extradural tumors with acute spinal cord compression

    International Nuclear Information System (INIS)

    Lien, H.H.; Blomlie, V.; Heimdal, K.; Norwegian Radium Hospital, Oslo; Norwegian Radium Hospital, Oslo

    1990-01-01

    Thirty-six cancer patients with extradural spinal metastatic disease and acute symptoms of spinal cord compression underwent magnetic resonance (MR) imaging at 1.5 T. Cord involvement was found in all 36, 7 of whom had lesions at 2 different sites. Vertebral metastases in addition to those corresponding to the cord compressions were detected in 27 patients, and 18 of these had widespread deposits. MR displayed the extent of the tumors in the craniocaudal and lateral directions. The ability to identify multiple sites of cord and vertebral involvement and to delineate tumor accurately makes MR the examination of choice in cancer patients with suspected spinal cord compression. It obviates the need for myelography and postmyelography CT in this group of patients. (orig.)

  14. Site organization and site arrangement

    International Nuclear Information System (INIS)

    Boissonnet, B.; Macqueron, J.F.

    1976-01-01

    The present paper deals with criteria for the choice of a production unit or power plant site, the organization and development of a site in terms of its particular characteristics and takes into account personnel considerations in site organizations as well as the problem of integrating the architecture into the environment. (RW) [de

  15. New thermodynamical systems. Alternative of compression-absorption; Nouveaux systemes thermodynamiques. Alternative de la compression-absorption

    Energy Technology Data Exchange (ETDEWEB)

    Feidt, M.; Brunin, O.; Lottin, O.; Vidal, J.F. [Universite Henri Poincare Nancy, 54 - Vandoeuvre-les-Nancy (France); Hivet, B. [Electricite de France, 77 - Moret sur Loing (France)

    1996-12-31

    This paper describes a 5 years joint research work carried out by Electricite de France (EdF) and the ESPE group of the LEMTA on compression-absorption heat pumps. It shows how a thermodynamical model of machinery, completed with precise exchanger-reactor models, allows to simulate and dimension (and eventually optimize) the system. A small power prototype has been tested and the first results are analyzed with the help of the models. A real scale experiment in industrial sites is expected in the future. (J.S.) 20 refs.

  16. Prefrontal white matter pathology in air pollution exposed Mexico City young urbanites and their potential impact on neurovascular unit dysfunction and the development of Alzheimer's disease

    Energy Technology Data Exchange (ETDEWEB)

    Calderón-Garcidueñas, Lilian, E-mail: lilian.calderon-garciduenas@umontana.edu [The University of Montana, Missoula, MT 59812 (United States); Universidad del Valle de México, Mexico City 04850, México (Mexico); Reynoso-Robles, Rafael [Instituto Nacional de Pediatría, Mexico City 04530 México (Mexico); Vargas- Martínez, Javier [Universidad del Valle de México, Mexico City 04850, México (Mexico); Gómez-Maqueo-Chew, Aline [Universidad del Valle de México, Hermosillo, Sonora 83299, México (Mexico); Pérez-Guillé, Beatriz [Instituto Nacional de Pediatría, Mexico City 04530 México (Mexico); Mukherjee, Partha S. [Mathematics Department, Boise State University, Boise, ID (United States); Torres-Jardón, Ricardo [Centro de Ciencias de la Atmósfera, Universidad Nacional Autónoma de México, Mexico City 04310, México (Mexico); Perry, George [College of Sciences, University of Texas at San Antonio, San Antonio, TX (United States); Gónzalez-Maciel, Angélica [Instituto Nacional de Pediatría, Mexico City 04530 México (Mexico)

    2016-04-15

    Millions of urban children are chronically exposed to high concentrations of air pollutants, i.e., fine particulate matter (PM{sub 2.5}) and ozone, associated with increased risk for Alzheimer's disease. Compared with children living with clear air those in Mexico City (MC) exhibit systemic, brain and intrathecal inflammation, low CSF Aβ{sub 42,} breakdown of the BBB, attention and short-term memory deficits, prefrontal white matter hyperintensities, damage to epithelial and endothelial barriers, tight junction and neural autoantibodies, and Alzheimer and Parkinson's hallmarks. The prefrontal white matter is a target of air pollution. We examined by light and electron microscopy the prefrontal white matter of MC dogs (n: 15, age 3.17±0.74 years), children and teens (n: 34, age: 12.64±4.2 years) versus controls. Major findings in MC residents included leaking capillaries and small arterioles with extravascular lipids and erythrocytes, lipofuscin in pericytes, smooth muscle and endothelial cells (EC), thickening of cerebrovascular basement membranes with small deposits of amyloid, patchy absence of the perivascular glial sheet, enlarged Virchow–Robin spaces and nanosize particles (20–48 nm) in EC, basement membranes, axons and dendrites. Tight junctions, a key component of the neurovascular unit (NVU) were abnormal in MC versus control dogs (χ{sup 2}<0.0001), and white matter perivascular damage was significantly worse in MC dogs (p=0.002). The integrity of the NVU, an interactive network of vascular, glial and neuronal cells is compromised in MC young residents. Characterizing the early NVU damage and identifying biomarkers of neurovascular dysfunction may provide a fresh insight into Alzheimer pathogenesis and open opportunities for pediatric neuroprotection. - Highlights: • The prefrontal white matter is a target of air pollution. • Tight junctions, key neurovascular unit elements, are abnormal in young urbanites. • Identifying

  17. Shock compression profiles in ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Grady, D.E.; Moody, R.L.

    1996-03-01

    An investigation of the shock compression properties of high-strength ceramics has been performed using controlled planar impact techniques. In a typical experimental configuration, a ceramic target disc is held stationary, and it is struck by plates of either a similar ceramic or by plates of a well-characterized metal. All tests were performed using either a single-stage propellant gun or a two-stage light-gas gun. Particle velocity histories were measured with laser velocity interferometry (VISAR) at the interface between the back of the target ceramic and a calibrated VISAR window material. Peak impact stresses achieved in these experiments range from about 3 to 70 GPa. Ceramics tested under shock impact loading include: Al{sub 2}O{sub 3}, AlN, B{sub 4}C, SiC, Si{sub 3}N{sub 4}, TiB{sub 2}, WC and ZrO{sub 2}. This report compiles the VISAR wave profiles and experimental impact parameters within a database-useful for response model development, computational model validation studies, and independent assessment of the physics of dynamic deformation on high-strength, brittle solids.

  18. Rapid reconnection in compressible plasma

    International Nuclear Information System (INIS)

    Heyn, M.F.; Semenov, V.S.

    1996-01-01

    A study of set-up, propagation, and interaction of non-linear and linear magnetohydrodynamic waves driven by magnetic reconnection is presented. The source term of the waves generated by magnetic reconnection is obtained explicitly in terms of the initial background conditions and the local reconnection electric field. The non-linear solution of the problem found earlier, serves as a basis for formulation and extensive investigation of the corresponding linear initial-boundary value problem of compressible magnetohydrodynamics. In plane geometry, the Green close-quote s function of the problem is obtained and its properties are discussed. For the numerical evaluation it turns out that a specific choice of the integration contour in the complex plane of phase velocities is much more effective than the convolution with the real Green close-quote s function. Many complex effects like intrinsic wave coupling, anisotropic propagation characteristics, generation of surface and side wave modes in a finite beta plasma are retained in this analysis. copyright 1996 American Institute of Physics

  19. The Compressed Baryonic Matter experiment

    Directory of Open Access Journals (Sweden)

    Seddiki Sélim

    2014-04-01

    Full Text Available The Compressed Baryonic Matter (CBM experiment is a next-generation fixed-target detector which will operate at the future Facility for Antiproton and Ion Research (FAIR in Darmstadt. The goal of this experiment is to explore the QCD phase diagram in the region of high net baryon densities using high-energy nucleus-nucleus collisions. Its research program includes the study of the equation-of-state of nuclear matter at high baryon densities, the search for the deconfinement and chiral phase transitions and the search for the QCD critical point. The CBM detector is designed to measure both bulk observables with a large acceptance and rare diagnostic probes such as charm particles, multi-strange hyperons, and low mass vector mesons in their di-leptonic decay. The physics program of CBM will be summarized, followed by an overview of the detector concept, a selection of the expected physics performance, and the status of preparation of the experiment.

  20. Composite Techniques Based Color Image Compression

    Directory of Open Access Journals (Sweden)

    Zainab Ibrahim Abood

    2017-03-01

    Full Text Available Compression for color image is now necessary for transmission and storage in the data bases since the color gives a pleasing nature and natural for any object, so three composite techniques based color image compression is implemented to achieve image with high compression, no loss in original image, better performance and good image quality. These techniques are composite stationary wavelet technique (S, composite wavelet technique (W and composite multi-wavelet technique (M. For the high energy sub-band of the 3rd level of each composite transform in each composite technique, the compression parameters are calculated. The best composite transform among the 27 types is the three levels of multi-wavelet transform (MMM in M technique which has the highest values of energy (En and compression ratio (CR and least values of bit per pixel (bpp, time (T and rate distortion R(D. Also the values of the compression parameters of the color image are nearly the same as the average values of the compression parameters of the three bands of the same image.

  1. Tokamak plasma variations under rapid compression

    International Nuclear Information System (INIS)

    Holmes, J.A.; Peng, Y.K.M.; Lynch, S.J.

    1980-04-01

    Changes in plasmas undergoing large, rapid compressions are examined numerically over the following range of aspect ratios A:3 greater than or equal to A greater than or equal to 1.5 for major radius compressions of circular, elliptical, and D-shaped cross sections; and 3 less than or equal to A less than or equal to 6 for minor radius compressions of circular and D-shaped cross sections. The numerical approach combines the computation of fixed boundary MHD equilibria with single-fluid, flux-surface-averaged energy balance, particle balance, and magnetic flux diffusion equations. It is found that the dependences of plasma current I/sub p/ and poloidal beta anti β/sub p/ on the compression ratio C differ significantly in major radius compressions from those proposed by Furth and Yoshikawa. The present interpretation is that compression to small A dramatically increases the plasma current, which lowers anti β/sub p/ and makes the plasma more paramagnetic. Despite large values of toroidal beta anti β/sub T/ (greater than or equal to 30% with q/sub axis/ approx. = 1, q/sub edge/ approx. = 3), this tends to concentrate more toroidal flux near the magnetic axis, which means that a reduced minor radius is required to preserve the continuity of the toroidal flux function F at the plasma edge. Minor radius compressions to large aspect ratio agree well with the Furth-Yoshikawa scaling laws

  2. Compression experiments on the TOSKA tokamak

    International Nuclear Information System (INIS)

    Cima, G.; McGuire, K.M.; Robinson, D.C.; Wootton, A.J.

    1980-10-01

    Results from minor radius compression experiments on a tokamak plasma in TOSCA are reported. The compression is achieved by increasing the toroidal field up to twice its initial value in 200μs. Measurements show that particles and magnetic flux are conserved. When the initial energy confinement time is comparable with the compression time, energy gains are greater than for an adiabatic change of state. The total beta value increases. Central beta values approximately 3% are measured when a small major radius compression is superimposed on a minor radius compression. Magnetic field fluctuations are affected: both the amplitude and period decrease. Starting from low energy confinement times, approximately 200μs, increases in confinement times up to approximately 1 ms are measured. The increase in plasma energy results from a large reduction in the power losses during the compression. When the initial energy confinement time is much longer than the compression time, the parameter changes are those expected for an adiabatic change of state. (author)

  3. Highly Efficient Compression Algorithms for Multichannel EEG.

    Science.gov (United States)

    Shaw, Laxmi; Rahman, Daleef; Routray, Aurobinda

    2018-05-01

    The difficulty associated with processing and understanding the high dimensionality of electroencephalogram (EEG) data requires developing efficient and robust compression algorithms. In this paper, different lossless compression techniques of single and multichannel EEG data, including Huffman coding, arithmetic coding, Markov predictor, linear predictor, context-based error modeling, multivariate autoregression (MVAR), and a low complexity bivariate model have been examined and their performances have been compared. Furthermore, a high compression algorithm named general MVAR and a modified context-based error modeling for multichannel EEG have been proposed. The resulting compression algorithm produces a higher relative compression ratio of 70.64% on average compared with the existing methods, and in some cases, it goes up to 83.06%. The proposed methods are designed to compress a large amount of multichannel EEG data efficiently so that the data storage and transmission bandwidth can be effectively used. These methods have been validated using several experimental multichannel EEG recordings of different subjects and publicly available standard databases. The satisfactory parametric measures of these methods, namely percent-root-mean square distortion, peak signal-to-noise ratio, root-mean-square error, and cross correlation, show their superiority over the state-of-the-art compression methods.

  4. Cloud Optimized Image Format and Compression

    Science.gov (United States)

    Becker, P.; Plesea, L.; Maurer, T.

    2015-04-01

    Cloud based image storage and processing requires revaluation of formats and processing methods. For the true value of the massive volumes of earth observation data to be realized, the image data needs to be accessible from the cloud. Traditional file formats such as TIF and NITF were developed in the hay day of the desktop and assumed fast low latency file access. Other formats such as JPEG2000 provide for streaming protocols for pixel data, but still require a server to have file access. These concepts no longer truly hold in cloud based elastic storage and computation environments. This paper will provide details of a newly evolving image storage format (MRF) and compression that is optimized for cloud environments. Although the cost of storage continues to fall for large data volumes, there is still significant value in compression. For imagery data to be used in analysis and exploit the extended dynamic range of the new sensors, lossless or controlled lossy compression is of high value. Compression decreases the data volumes stored and reduces the data transferred, but the reduced data size must be balanced with the CPU required to decompress. The paper also outlines a new compression algorithm (LERC) for imagery and elevation data that optimizes this balance. Advantages of the compression include its simple to implement algorithm that enables it to be efficiently accessed using JavaScript. Combing this new cloud based image storage format and compression will help resolve some of the challenges of big image data on the internet.

  5. Diagnostic value of MRI for nerve root compression due to lumbar canal stenosis. Clinical and anatomic study

    International Nuclear Information System (INIS)

    Seki, Michihiro; Kikuchi, Shinichi; Kageyama, Kazuhiro; Katakura, Toshihiko; Suzuki, Kenji

    1995-01-01

    Magnetic resonance imaging (MRI) was undertaken in 26 patients with surgically proven nerve root compression due to lumbar canal stenosis. The findings on coronary images were compared with those of selective radiculography to assess the diagnostic ability of MRI to determine the site of nerve root compression. Intermission and partial defect, which reflect nerve root compression, were seen in only 5 (19.2%) of 26 nerve roots on MRI, as compared with 20 (76.9%) on radiculography. Thus MRI alone was difficult to diagnose nerve root compression due to lumbar canal stenosis. Furthermore, the optimum angle of coronary views was determined in 13 cadavers. Para-sagittal views were found to be optimal for the observation of the whole running of the nerve root. Three-dimensional MRI was found to have a potential to diagnose nerve root compression in the intervertebral foramen and the distal part of the intervertebral foramen. (N.K.)

  6. The Effect of Inhomogeneous Compression on Water Transport in the Cathode of a Proton Exchange Membrane Fuel Cell

    DEFF Research Database (Denmark)

    Olesen, Anders Christian; Berning, Torsten; Kær, Søren Knudsen

    2012-01-01

    A three-dimensional, multicomponent, two-fluid model developed in the commercial CFD package CFX 13 (ANSYS Inc.) is used to investigate the effect of porous media compression on water transport in a proton exchange membrane fuel cell (PEMFC). The PEMFC model only consist of the cathode channel, gas....... Furthermore, the presence of irreducible liquid water is taken into account. In order to account for compression, porous media morphology variations are specified based on the gas diffusion layer (GDL) through-plane strain and intrusion which are stated as a function of compression. These morphology...... variations affect gas and liquid water transport, and hence liquid water distribution and the risk of blocking active sites. Hence, water transport is studied under GDL compression in order to investigate the qualitative effects. Two simulation cases are compared; one with and one without compression....

  7. ERGC: an efficient referential genome compression algorithm.

    Science.gov (United States)

    Saha, Subrata; Rajasekaran, Sanguthevar

    2015-11-01

    Genome sequencing has become faster and more affordable. Consequently, the number of available complete genomic sequences is increasing rapidly. As a result, the cost to store, process, analyze and transmit the data is becoming a bottleneck for research and future medical applications. So, the need for devising efficient data compression and data reduction techniques for biological sequencing data is growing by the day. Although there exists a number of standard data compression algorithms, they are not efficient in compressing biological data. These generic algorithms do not exploit some inherent properties of the sequencing data while compressing. To exploit statistical and information-theoretic properties of genomic sequences, we need specialized compression algorithms. Five different next-generation sequencing data compression problems have been identified and studied in the literature. We propose a novel algorithm for one of these problems known as reference-based genome compression. We have done extensive experiments using five real sequencing datasets. The results on real genomes show that our proposed algorithm is indeed competitive and performs better than the best known algorithms for this problem. It achieves compression ratios that are better than those of the currently best performing algorithms. The time to compress and decompress the whole genome is also very promising. The implementations are freely available for non-commercial purposes. They can be downloaded from http://engr.uconn.edu/∼rajasek/ERGC.zip. rajasek@engr.uconn.edu. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  8. Modelling for Fuel Optimal Control of a Variable Compression Engine

    OpenAIRE

    Nilsson, Ylva

    2007-01-01

    Variable compression engines are a mean to meet the demand on lower fuel consumption. A high compression ratio results in high engine efficiency, but also increases the knock tendency. On conventional engines with fixed compression ratio, knock is avoided by retarding the ignition angle. The variable compression engine offers an extra dimension in knock control, since both ignition angle and compression ratio can be adjusted. The central question is thus for what combination of compression ra...

  9. Site operations

    International Nuclear Information System (INIS)

    House, W.B.; Ebenhack, D.G.

    1989-01-01

    This chapter is a discussion of the management and operations practices used at the Barnwell Waste Management Facility in Barnwell, SC. The following topics are discussed: (1) Waste receiving and inspection, including manifest and certificates of compliance, radiological surveys, disposition of nonconforming items, and decontamination and disposition of secondary waste streams; (2) Waste disposal, including Title 10 CFR 61 requirements, disposal area evaluations, shipment offloading, container emplacement, and radiation protection; (3) Trench closure, including trench backfilling, trench capping, and permanent markers; (4) Site maintenance and stabilization, including trench maintenance, surface water management, and site closure activities; (5) Site monitoring programs, including operational monitoring, and environmental monitoring program; (6) Personnel training and qualifications, including basic training program, safety training program, special skills training, and physical qualifications; (7) Records management, including waste records, personnel training records, personnel dosimetry records, site monitoring records, trench qualification and construction records, and site drawings and stabilization records; (8) Site security; (9) Emergency response plans; and (10) Quality assurance

  10. Survived ileocecal blowout from compressed air.

    Science.gov (United States)

    Weber, Marco; Kolbus, Frank; Dressler, Jan; Lessig, Rüdiger

    2011-03-01

    Industrial accidents with compressed air entering the gastro-intestinal tract often run fatally. The pressures usually over-exceed those used by medical applications such as colonoscopy and lead to vast injuries of the intestines with high mortality. The case described in this report is of a 26-year-old man who was harmed by compressed air that entered through the anus. He survived because of fast emergency operation. This case underlines necessity of explicit instruction considering hazards handling compressed air devices to maintain safety at work. Further, our observations support the hypothesis that the mucosa is the most elastic layer of the intestine wall.

  11. Radial and axial compression of pure electron

    International Nuclear Information System (INIS)

    Park, Y.; Soga, Y.; Mihara, Y.; Takeda, M.; Kamada, K.

    2013-01-01

    Experimental studies are carried out on compression of the density distribution of a pure electron plasma confined in a Malmberg-Penning Trap in Kanazawa University. More than six times increase of the on-axis density is observed under application of an external rotating electric field that couples to low-order Trivelpiece-Gould modes. Axial compression of the density distribution with the axial length of a factor of two is achieved by controlling the confining potential at both ends of the plasma. Substantial increase of the axial kinetic energy is observed during the axial compression. (author)

  12. Plant for compacting compressible radioactive waste

    International Nuclear Information System (INIS)

    Baatz, H.; Rittscher, D.; Lueer, H.J.; Ambros, R.

    1983-01-01

    The waste is filled into auxiliary barrels made of sheet steel and compressed with the auxiliary barrels into steel jackets. These can be stacked in storage barrels. A hydraulic press is included in the plant, which has a horizontal compression chamber and a horizontal pressure piston, which works against a counter bearing slider. There is a filling and emptying device for the pressure chamber behind the counter bearing slider. The auxiliary barrels can be introduced into the compression chamber by the filling and emptying device. The pressure piston also pushes out the steel jackets formed, so that they are taken to the filling and emptying device. (orig./HP) [de

  13. Compressed Gas Safety for Experimental Fusion Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Lee C. Cadwallader

    2004-09-01

    Experimental fusion facilities present a variety of hazards to the operators and staff. There are unique or specialized hazards, including magnetic fields, cryogens, radio frequency emissions, and vacuum reservoirs. There are also more general industrial hazards, such as a wide variety of electrical power, pressurized air, and cooling water systems in use, there are crane and hoist loads, working at height, and handling compressed gas cylinders. This paper outlines the projectile hazard assoicated with compressed gas cylinders and mthods of treatment to provide for compressed gas safety. This information should be of interest to personnel at both magnetic and inertial fusion experiments.

  14. Logarithmic compression methods for spectral data

    Science.gov (United States)

    Dunham, Mark E.

    2003-01-01

    A method is provided for logarithmic compression, transmission, and expansion of spectral data. A log Gabor transformation is made of incoming time series data to output spectral phase and logarithmic magnitude values. The output phase and logarithmic magnitude values are compressed by selecting only magnitude values above a selected threshold and corresponding phase values to transmit compressed phase and logarithmic magnitude values. A reverse log Gabor transformation is then performed on the transmitted phase and logarithmic magnitude values to output transmitted time series data to a user.

  15. An efficient compression scheme for bitmap indices

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Kesheng; Otoo, Ekow J.; Shoshani, Arie

    2004-04-13

    When using an out-of-core indexing method to answer a query, it is generally assumed that the I/O cost dominates the overall query response time. Because of this, most research on indexing methods concentrate on reducing the sizes of indices. For bitmap indices, compression has been used for this purpose. However, in most cases, operations on these compressed bitmaps, mostly bitwise logical operations such as AND, OR, and NOT, spend more time in CPU than in I/O. To speedup these operations, a number of specialized bitmap compression schemes have been developed; the best known of which is the byte-aligned bitmap code (BBC). They are usually faster in performing logical operations than the general purpose compression schemes, but, the time spent in CPU still dominates the total query response time. To reduce the query response time, we designed a CPU-friendly scheme named the word-aligned hybrid (WAH) code. In this paper, we prove that the sizes of WAH compressed bitmap indices are about two words per row for large range of attributes. This size is smaller than typical sizes of commonly used indices, such as a B-tree. Therefore, WAH compressed indices are not only appropriate for low cardinality attributes but also for high cardinality attributes.In the worst case, the time to operate on compressed bitmaps is proportional to the total size of the bitmaps involved. The total size of the bitmaps required to answer a query on one attribute is proportional to the number of hits. These indicate that WAH compressed bitmap indices are optimal. To verify their effectiveness, we generated bitmap indices for four different datasets and measured the response time of many range queries. Tests confirm that sizes of compressed bitmap indices are indeed smaller than B-tree indices, and query processing with WAH compressed indices is much faster than with BBC compressed indices, projection indices and B-tree indices. In addition, we also verified that the average query response time

  16. How compressible is recombinant battery separator mat?

    Energy Technology Data Exchange (ETDEWEB)

    Pendry, C. [Hollingsworth and Vose, Postlip Mills Winchcombe (United Kingdom)

    1999-03-01

    In the past few years, the recombinant battery separator mat (RBSM) for valve-regulated lead/acid (VRLA) batteries has become the focus of much attention. Compression, and the ability of microglass separators to maintain a level of `springiness` have helped reduce premature capacity loss. As higher compressions are reached, we need to determine what, if any, damage can be caused during the assembly process. This paper reviews the findings when RBSM materials, with different surface areas, are compressed under forces up to 500 kPa in the dry state. (orig.)

  17. Physics Based Modeling of Compressible Turbulance

    Science.gov (United States)

    2016-11-07

    AFRL-AFOSR-VA-TR-2016-0345 PHYSICS -BASED MODELING OF COMPRESSIBLE TURBULENCE PARVIZ MOIN LELAND STANFORD JUNIOR UNIV CA Final Report 09/13/2016...on the AFOSR project (FA9550-11-1-0111) entitled: Physics based modeling of compressible turbulence. The period of performance was, June 15, 2011...by ANSI Std. Z39.18 Page 1 of 2FORM SF 298 11/10/2016https://livelink.ebs.afrl.af.mil/livelink/llisapi.dll PHYSICS -BASED MODELING OF COMPRESSIBLE

  18. Combined Sparsifying Transforms for Compressive Image Fusion

    Directory of Open Access Journals (Sweden)

    ZHAO, L.

    2013-11-01

    Full Text Available In this paper, we present a new compressive image fusion method based on combined sparsifying transforms. First, the framework of compressive image fusion is introduced briefly. Then, combined sparsifying transforms are presented to enhance the sparsity of images. Finally, a reconstruction algorithm based on the nonlinear conjugate gradient is presented to get the fused image. The simulations demonstrate that by using the combined sparsifying transforms better results can be achieved in terms of both the subjective visual effect and the objective evaluation indexes than using only a single sparsifying transform for compressive image fusion.

  19. Evolution Of Nonlinear Waves in Compressing Plasma

    International Nuclear Information System (INIS)

    Schmit, P.F.; Dodin, I.Y.; Fisch, N.J.

    2011-01-01

    Through particle-in-cell simulations, the evolution of nonlinear plasma waves is examined in one-dimensional collisionless plasma undergoing mechanical compression. Unlike linear waves, whose wavelength decreases proportionally to the system length L(t), nonlinear waves, such as solitary electron holes, conserve their characteristic size Δ during slow compression. This leads to a substantially stronger adiabatic amplification as well as rapid collisionless damping when L approaches Δ. On the other hand, cessation of compression halts the wave evolution, yielding a stable mode.

  20. Compressive Load Resistance Characteristics of Rice Grain

    OpenAIRE

    Sumpun Chaitep; Chaiy R. Metha Pathawee; Pipatpong Watanawanyoo

    2008-01-01

    Investigation was made to observe the compressive load property of rice gain both rough rice and brown grain. Six rice varieties (indica and japonica) were examined with the moisture content at 10-12%. A compressive load with reference to a principal axis normal to the thickness of the grain were conducted at selected inclined angles of 0°, 15°, 30°, 45°, 60° and 70°. The result showed the compressive load resistance of rice grain based on its characteristic of yield s...

  1. Evolution Of Nonlinear Waves in Compressing Plasma

    Energy Technology Data Exchange (ETDEWEB)

    P.F. Schmit, I.Y. Dodin, and N.J. Fisch

    2011-05-27

    Through particle-in-cell simulations, the evolution of nonlinear plasma waves is examined in one-dimensional collisionless plasma undergoing mechanical compression. Unlike linear waves, whose wavelength decreases proportionally to the system length L(t), nonlinear waves, such as solitary electron holes, conserve their characteristic size {Delta} during slow compression. This leads to a substantially stronger adiabatic amplification as well as rapid collisionless damping when L approaches {Delta}. On the other hand, cessation of compression halts the wave evolution, yielding a stable mode.

  2. Seneca Compressed Air Energy Storage (CAES) Project

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2012-11-30

    Compressed Air Energy Storage (CAES) is a hybrid energy storage and generation concept that has many potential benefits especially in a location with increasing percentages of intermittent wind energy generation. The objectives of the NYSEG Seneca CAES Project included: for Phase 1, development of a Front End Engineering Design for a 130MW to 210 MW utility-owned facility including capital costs; project financials based on the engineering design and forecasts of energy market revenues; design of the salt cavern to be used for air storage; draft environmental permit filings; and draft NYISO interconnection filing; for Phase 2, objectives included plant construction with a target in-service date of mid-2016; and for Phase 3, objectives included commercial demonstration, testing, and two-years of performance reporting. This Final Report is presented now at the end of Phase 1 because NYSEG has concluded that the economics of the project are not favorable for development in the current economic environment in New York State. The proposed site is located in NYSEG’s service territory in the Town of Reading, New York, at the southern end of Seneca Lake, in New York State’s Finger Lakes region. The landowner of the proposed site is Inergy, a company that owns the salt solution mining facility at this property. Inergy would have developed a new air storage cavern facility to be designed for NYSEG specifically for the Seneca CAES project. A large volume, natural gas storage facility owned and operated by Inergy is also located near this site and would have provided a source of high pressure pipeline quality natural gas for use in the CAES plant. The site has an electrical take-away capability of 210 MW via two NYSEG 115 kV circuits located approximately one half mile from the plant site. Cooling tower make-up water would have been supplied from Seneca Lake. NYSEG’s engineering consultant WorleyParsons Group thoroughly evaluated three CAES designs and concluded that any

  3. Extreme compression for extreme conditions: pilot study to identify optimal compression of CT images using MPEG-4 video compression.

    Science.gov (United States)

    Peterson, P Gabriel; Pak, Sung K; Nguyen, Binh; Jacobs, Genevieve; Folio, Les

    2012-12-01

    This study aims to evaluate the utility of compressed computed tomography (CT) studies (to expedite transmission) using Motion Pictures Experts Group, Layer 4 (MPEG-4) movie formatting in combat hospitals when guiding major treatment regimens. This retrospective analysis was approved by Walter Reed Army Medical Center institutional review board with a waiver for the informed consent requirement. Twenty-five CT chest, abdomen, and pelvis exams were converted from Digital Imaging and Communications in Medicine to MPEG-4 movie format at various compression ratios. Three board-certified radiologists reviewed various levels of compression on emergent CT findings on 25 combat casualties and compared with the interpretation of the original series. A Universal Trauma Window was selected at -200 HU level and 1,500 HU width, then compressed at three lossy levels. Sensitivities and specificities for each reviewer were calculated along with 95 % confidence intervals using the method of general estimating equations. The compression ratios compared were 171:1, 86:1, and 41:1 with combined sensitivities of 90 % (95 % confidence interval, 79-95), 94 % (87-97), and 100 % (93-100), respectively. Combined specificities were 100 % (85-100), 100 % (85-100), and 96 % (78-99), respectively. The introduction of CT in combat hospitals with increasing detectors and image data in recent military operations has increased the need for effective teleradiology; mandating compression technology. Image compression is currently used to transmit images from combat hospital to tertiary care centers with subspecialists and our study demonstrates MPEG-4 technology as a reasonable means of achieving such compression.

  4. Characterization of focal muscle compression under impact loading

    Science.gov (United States)

    Butler, B. J.; Sory, D. R.; Nguyen, T.-T. N.; Proud, W. G.; Williams, A.; Brown, K. A.

    2017-01-01

    In modern wars over 70% of combat wounds are to the extremities. These injuries are characterized by disruption and contamination of the limb soft tissue envelope. The extent of this tissue trauma and contamination determine the outcome of the extremity injury. In military injury, common post-traumatic complications at amputation sites include heterotopic ossification (formation of bone in soft tissue), and severe soft tissue and bone infections. We are currently developing a model of soft tissue injury that recreates pathologies observed in combat injuries. Here we present characterization of a controlled focal compression of the rabbit flexor carpi ulnaris (FCU) muscle group. The FCU was previously identified as a suitable site for studying impact injury because its muscle belly can easily be mobilized from the underlying bone without disturbing anatomical alignment in the limb. We show how macroscopic changes in tissue organization, as visualized using optical microscopy, can be correlated with data from temporally resolved traces of loading conditions.

  5. Researches on the CAES (Compressed Air Energy Storage) system

    Energy Technology Data Exchange (ETDEWEB)

    Shin Hee Soon; Kang, Sang Soo; Kwon, Kwang Soo [Korea Institute of Geology Mining and Materials, Taejon (Korea)] [and others

    1998-12-01

    CAES which is called as a compressed air energy storage was firstly developed at Huntorf, German in 1978. The capacity of that system was 290 MW, and it can be treated as a first commercial power plant. CAES has a lot of merits, such as saving the unit price of power generation, averaging the peak demand, improvement of maintenance, enlarging the benefit of dynamic use. According to the literature survey, the unlined rock cavern should be proposed to be a reasonable storing style as a method of compressed air storage in Korea. In this study, the most important techniques were evaluated through the investigation of the foreign construction case studies, especially on the unlined rock caverns in hard rock mass. We decided the hill of the Korea Institute of Geology, Mining and materials as CAES site. If we construct the underground spaces in this site, the demand for electricity nearby Taejon should be considered. So we could determine the capacity of the power plant as a 350 MW. This capacity needs a underground space of 200,000 m{sup 3}, and we can conclude 4 parallel tunnels through the numerical studies. Design parameters were achieved from 300 m depth boring job and image processing job. Moreover the techniques for determination of joint characteristics from the images could be obtained. Blasting pattern was designed on the underground spaces, and automatic gas control system and thermomechanical characteristics on caverns were also studied. (author). 51 refs., 79 tabs., 114 figs.

  6. Compression and archiving of digital images

    International Nuclear Information System (INIS)

    Huang, H.K.

    1988-01-01

    This paper describes the application of a full-frame bit-allocation image compression technique to a hierarchical digital image archiving system consisting of magnetic disks, optical disks and an optical disk library. The digital archiving system without the compression has been in clinical operation in the Pediatric Radiology for more than half a year. The database in the system consists of all pediatric inpatients including all images from computed radiography, digitized x-ray films, CT, MR, and US. The rate of image accumulation is approximately 1,900 megabytes per week. The hardware design of the compression module is based on a Motorola 68020 microprocessor, A VME bus, a 16 megabyte image buffer memory board, and three Motorola digital signal processing 56001 chips on a VME board for performing the two-dimensional cosine transform and the quantization. The clinical evaluation of the compression module with the image archiving system is expected to be in February 1988

  7. Pulse power applications of flux compression generators

    International Nuclear Information System (INIS)

    Fowler, C.M.; Caird, R.S.; Erickson, D.J.; Freeman, B.L.

    1981-01-01

    Characteristics are presented for two different types of explosive driven flux compression generators and a megavolt pulse transformer. Status reports are given for rail gun and plasma focus programs for which the generators serve as power sources

  8. Compressibility, turbulence and high speed flow

    CERN Document Server

    Gatski, Thomas B

    2009-01-01

    This book introduces the reader to the field of compressible turbulence and compressible turbulent flows across a broad speed range through a unique complimentary treatment of both the theoretical foundations and the measurement and analysis tools currently used. For the computation of turbulent compressible flows, current methods of averaging and filtering are presented so that the reader is exposed to a consistent development of applicable equation sets for both the mean or resolved fields as well as the transport equations for the turbulent stress field. For the measurement of turbulent compressible flows, current techniques ranging from hot-wire anemometry to PIV are evaluated and limitations assessed. Characterizing dynamic features of free shear flows, including jets, mixing layers and wakes, and wall-bounded flows, including shock-turbulence and shock boundary-layer interactions, obtained from computations, experiments and simulations are discussed. Key features: * Describes prediction methodologies in...

  9. Efficiency of Compressed Air Energy Storage

    DEFF Research Database (Denmark)

    Elmegaard, Brian; Brix, Wiebke

    2011-01-01

    The simplest type of a Compressed Air Energy Storage (CAES) facility would be an adiabatic process consisting only of a compressor, a storage and a turbine, compressing air into a container when storing and expanding when producing. This type of CAES would be adiabatic and would if the machines...... were reversible have a storage efficiency of 100%. However, due to the specific capacity of the storage and the construction materials the air is cooled during and after compression in practice, making the CAES process diabatic. The cooling involves exergy losses and thus lowers the efficiency...... of the storage significantly. The efficiency of CAES as an electricity storage may be defined in several ways, we discuss these and find that the exergetic efficiency of compression, storage and production together determine the efficiency of CAES. In the paper we find that the efficiency of the practical CAES...

  10. Compression Behavior of High Performance Polymeric Fibers

    National Research Council Canada - National Science Library

    Kumar, Satish

    2003-01-01

    Hydrogen bonding has proven to be effective in improving the compressive strength of rigid-rod polymeric fibers without resulting in a decrease in tensile strength while covalent crosslinking results in brittle fibers...

  11. Large Eddy Simulation for Compressible Flows

    CERN Document Server

    Garnier, E; Sagaut, P

    2009-01-01

    Large Eddy Simulation (LES) of compressible flows is still a widely unexplored area of research. The authors, whose books are considered the most relevant monographs in this field, provide the reader with a comprehensive state-of-the-art presentation of the available LES theory and application. This book is a sequel to "Large Eddy Simulation for Incompressible Flows", as most of the research on LES for compressible flows is based on variable density extensions of models, methods and paradigms that were developed within the incompressible flow framework. The book addresses both the fundamentals and the practical industrial applications of LES in order to point out gaps in the theoretical framework as well as to bridge the gap between LES research and the growing need to use it in engineering modeling. After introducing the fundamentals on compressible turbulence and the LES governing equations, the mathematical framework for the filtering paradigm of LES for compressible flow equations is established. Instead ...

  12. optimizing compressive strength characteristics of hollow building

    African Journals Online (AJOL)

    eobe

    Keywords: hollow building Blocks, granite dust, sand, partial replacement, compressive strength. 1. INTRODUCTION ... exposed to extreme climate. The physical ... Sridharan et al [13] conducted shear strength studies on soil-quarry dust.

  13. Embedment of Chlorpheniramine Maleate in Directly Compressed ...

    African Journals Online (AJOL)

    chlorpheniramine maleate (CPM) from its matrix tablets prepared by direct compression. Methods: Different ratios of compritol and kollidon SR (containing 50 % matrix component) in 1:1, 1:2, ... Magnesium stearate and hydrochloric acid were.

  14. FRC translation into a compression coil

    International Nuclear Information System (INIS)

    Chrien, R.E.

    1985-01-01

    Several features of the problem of FRC translation into a compression coil are considered. First, the magnitude of the guide field is calculated and found to exceed that which would be applied to a flux conserver. Second, energy conservation is applied to FRC translation from a flux conserver into a compression coil. It is found that a significant temperature decrease is required for translation to be energetically possible. The temperature change depends on the external inductance in the compression circuit. An analogous case is that of a compression region composed of a compound magnet; in this case the temperature change depends on the ratio of inner and outer coil radii. Finally, the kinematics of intermediate translation states are calculated using an ''abrupt transition'' model. It is found, in this model, that the FRC must overcome a potential hill during translation, which requires a small initial velocity

  15. Adiabatic Liquid Piston Compressed Air Energy Storage

    DEFF Research Database (Denmark)

    Petersen, Tage; Elmegaard, Brian; Pedersen, Allan Schrøder

    the system. The compression leads to a significant increase in temperature, and the heat generated is dumped into the ambient. This energy loss results in a low efficiency of the system, and when expanding the air, the expansion leads to a temperature drop reducing the mechanical output of the expansion......), but no such units are in operation at present. The CAES system investigated in this project uses a different approach to avoid compression heat loss. The system uses a pre-compressed pressure vessel full of air. A liquid is pumped into the bottom of the vessel when charging and the same liquid is withdrawn through......-CAES system is significantly higher than existing CAES systems due to a low or nearly absent compression heat loss. Furthermore, pumps/turbines, which use a liquid as a medium, are more efficient than air/gas compressors/turbines. In addition, the demand for fuel during expansion does not occur. •The energy...

  16. Compressive multi-mode superresolution display

    KAUST Repository

    Heide, Felix

    2014-01-01

    Compressive displays are an emerging technology exploring the co-design of new optical device configurations and compressive computation. Previously, research has shown how to improve the dynamic range of displays and facilitate high-quality light field or glasses-free 3D image synthesis. In this paper, we introduce a new multi-mode compressive display architecture that supports switching between 3D and high dynamic range (HDR) modes as well as a new super-resolution mode. The proposed hardware consists of readily-available components and is driven by a novel splitting algorithm that computes the pixel states from a target high-resolution image. In effect, the display pixels present a compressed representation of the target image that is perceived as a single, high resolution image. © 2014 Optical Society of America.

  17. Compressive properties of sandwiches with functionally graded ...

    Indian Academy of Sciences (India)

    319–328. c Indian Academy of Sciences. Compressive properties ... †Mechanical Engineering, National Institute of Technology Karnataka, Surathkal, India .... spheres) which might aid in building FG composites is not explored ... Sample code.

  18. The Distinction of Hot Herbal Compress, Hot Compress, and Topical Diclofenac as Myofascial Pain Syndrome Treatment.

    Science.gov (United States)

    Boonruab, Jurairat; Nimpitakpong, Netraya; Damjuti, Watchara

    2018-01-01

    This randomized controlled trial aimed to investigate the distinctness after treatment among hot herbal compress, hot compress, and topical diclofenac. The registrants were equally divided into groups and received the different treatments including hot herbal compress, hot compress, and topical diclofenac group, which served as the control group. After treatment courses, Visual Analog Scale and 36-Item Short Form Health survey were, respectively, used to establish the level of pain intensity and quality of life. In addition, cervical range of motion and pressure pain threshold were also examined to identify the motional effects. All treatments showed significantly decreased level of pain intensity and increased cervical range of motion, while the intervention groups exhibited extraordinary capability compared with the topical diclofenac group in pressure pain threshold and quality of life. In summary, hot herbal compress holds promise to be an efficacious treatment parallel to hot compress and topical diclofenac.

  19. High-quality compressive ghost imaging

    Science.gov (United States)

    Huang, Heyan; Zhou, Cheng; Tian, Tian; Liu, Dongqi; Song, Lijun

    2018-04-01

    We propose a high-quality compressive ghost imaging method based on projected Landweber regularization and guided filter, which effectively reduce the undersampling noise and improve the resolution. In our scheme, the original object is reconstructed by decomposing of regularization and denoising steps instead of solving a minimization problem in compressive reconstruction process. The simulation and experimental results show that our method can obtain high ghost imaging quality in terms of PSNR and visual observation.

  20. Bond graph modeling of centrifugal compression systems

    OpenAIRE

    Uddin, Nur; Gravdahl, Jan Tommy

    2015-01-01

    A novel approach to model unsteady fluid dynamics in a compressor network by using a bond graph is presented. The model is intended in particular for compressor control system development. First, we develop a bond graph model of a single compression system. Bond graph modeling offers a different perspective to previous work by modeling the compression system based on energy flow instead of fluid dynamics. Analyzing the bond graph model explains the energy flow during compressor surge. Two pri...

  1. Prechamber Compression-Ignition Engine Performance

    Science.gov (United States)

    Moore, Charles S; Collins, John H , Jr

    1938-01-01

    Single-cylinder compression-ignition engine tests were made to investigate the performance characteristics of prechamber type of cylinder head. Certain fundamental variables influencing engine performance -- clearance distribution, size, shape, and direction of the passage connecting the cylinder and prechamber, shape of prechamber, cylinder clearance, compression ratio, and boosting -- were independently tested. Results of motoring and of power tests, including several typical indicator cards, are presented.

  2. NRGC: a novel referential genome compression algorithm.

    Science.gov (United States)

    Saha, Subrata; Rajasekaran, Sanguthevar

    2016-11-15

    Next-generation sequencing techniques produce millions to billions of short reads. The procedure is not only very cost effective but also can be done in laboratory environment. The state-of-the-art sequence assemblers then construct the whole genomic sequence from these reads. Current cutting edge computing technology makes it possible to build genomic sequences from the billions of reads within a minimal cost and time. As a consequence, we see an explosion of biological sequences in recent times. In turn, the cost of storing the sequences in physical memory or transmitting them over the internet is becoming a major bottleneck for research and future medical applications. Data compression techniques are one of the most important remedies in this context. We are in need of suitable data compression algorithms that can exploit the inherent structure of biological sequences. Although standard data compression algorithms are prevalent, they are not suitable to compress biological sequencing data effectively. In this article, we propose a novel referential genome compression algorithm (NRGC) to effectively and efficiently compress the genomic sequences. We have done rigorous experiments to evaluate NRGC by taking a set of real human genomes. The simulation results show that our algorithm is indeed an effective genome compression algorithm that performs better than the best-known algorithms in most of the cases. Compression and decompression times are also very impressive. The implementations are freely available for non-commercial purposes. They can be downloaded from: http://www.engr.uconn.edu/~rajasek/NRGC.zip CONTACT: rajasek@engr.uconn.edu. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  3. Signal compression in radar using FPGA

    OpenAIRE

    Escamilla Hemández, Enrique; Kravchenko, Víctor; Ponomaryov, Volodymyr; Duchen Sánchez, Gonzalo; Hernández Sánchez, David

    2010-01-01

    We present the hardware implementation of radar real time processing procedures using a simple, fast technique based on FPGA (Field Programmable Gate Array) architecture. This processing includes different window procedures during pulse compression in synthetic aperture radar (SAR). The radar signal compression processing is realized using matched filter, and classical and novel window functions, where we focus on better solution for minimum values of sidelobes. The proposed architecture expl...

  4. Compressive sensing based algorithms for electronic defence

    CERN Document Server

    Mishra, Amit Kumar

    2017-01-01

    This book details some of the major developments in the implementation of compressive sensing in radio applications for electronic defense and warfare communication use. It provides a comprehensive background to the subject and at the same time describes some novel algorithms. It also investigates application value and performance-related parameters of compressive sensing in scenarios such as direction finding, spectrum monitoring, detection, and classification.

  5. Does the quality of chest compressions deteriorate when the chest compression rate is above 120/min?

    Science.gov (United States)

    Lee, Soo Hoon; Kim, Kyuseok; Lee, Jae Hyuk; Kim, Taeyun; Kang, Changwoo; Park, Chanjong; Kim, Joonghee; Jo, You Hwan; Rhee, Joong Eui; Kim, Dong Hoon

    2014-08-01

    The quality of chest compressions along with defibrillation is the cornerstone of cardiopulmonary resuscitation (CPR), which is known to improve the outcome of cardiac arrest. We aimed to investigate the relationship between the compression rate and other CPR quality parameters including compression depth and recoil. A conventional CPR training for lay rescuers was performed 2 weeks before the 'CPR contest'. CPR anytime training kits were distributed to respective participants for self-training on their own in their own time. The participants were tested for two-person CPR in pairs. The quantitative and qualitative data regarding the quality of CPR were collected from a standardised check list and SkillReporter, and compared by the compression rate. A total of 161 teams consisting of 322 students, which includes 116 men and 206 women, participated in the CPR contest. The mean depth and rate for chest compression were 49.0±8.2 mm and 110.2±10.2/min. Significantly deeper chest compression depths were noted at rates over 120/min than those at any other rates (47.0±7.4, 48.8±8.4, 52.3±6.7, p=0.008). Chest compression depth was proportional to chest compression rate (r=0.206, pcompression including chest compression depth and chest recoil by chest compression rate. Further evaluation regarding the upper limit of the chest compression rate is needed to ensure complete full chest wall recoil while maintaining an adequate chest compression depth. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  6. Using Costal Chondrocytes to Engineer Articular Cartilage with Applications of Passive Axial Compression and Bioactive Stimuli.

    Science.gov (United States)

    Huwe, Le W; Sullan, Gurdeep K; Hu, Jerry C; Athanasiou, Kyriacos A

    2018-03-01

    Generating neocartilage with suitable mechanical integrity from a cell source that can circumvent chondrocyte scarcity is indispensable for articular cartilage regeneration strategies. Costal chondrocytes of the rib eliminate donor site morbidity in the articular joint, but it remains unclear how neocartilage formed from these cells responds to mechanical loading, especially if the intent is to use it in a load-bearing joint. In a series of three experiments, this study sought to determine efficacious parameters of passive axial compressive stimulation that would enable costal chondrocytes to synthesize mechanically robust cartilage. Experiment 1 determined a suitable time window for stimulation by its application during either the matrix synthesis phase, the maturation phase, or during both phases of the self-assembling process. The results showed that compressive stimulation at either time was effective in increasing instantaneous moduli by 92% and 87% in the synthesis and maturation phases, respectively. Compressive stimulation during both phases did not further improve properties beyond a one-time stimulation. The magnitude of passive axial compression was examined in Experiment 2 by applying 0, 3.3, 5.0, or 6.7 kPa stresses to the neocartilage. Unlike 6.7 kPa, both 3.3 and 5.0 kPa significantly increased neocartilage compressive properties by 42% and 48% over untreated controls, respectively. Experiment 3 examined how the passive axial compression regimen developed from the previous phases interacted with a bioactive regimen (transforming growth factor [TGF]-β1, chondroitinase ABC, and lysyl oxidase-like 2). Passive axial compression significantly improved the relaxation modulus compared with bioactive treatment alone. Furthermore, a combined treatment of compressive and bioactive stimulation improved the tensile properties of neocartilage 2.6-fold compared with untreated control. The ability to create robust articular cartilage from passaged costal

  7. The relationship between central motor conduction time and spinal cord compression in patients with cervical spondylotic myelopathy.

    Science.gov (United States)

    Rikita, T; Tanaka, N; Nakanishi, K; Kamei, N; Sumiyoshi, N; Kotaka, S; Adachi, N; Ochi, M

    2017-04-01

    Retrospective study. Few studies have reported a relationship between central motor conduction time (CMCT), which evaluates corticospinal function, and degree of spinal cord compression in patients with myelopathy. Thus, there is no consensus on predicting the degree of prolonged CMCT on the basis of the degree of spinal cord compression. If a correlation exists between CMCT and spinal cord compression, then spinal cord compression may be a useful noninvasive clinical indicator of corticospinal function. Therefore, this study evaluated the relationship between CMCT and cervical spinal cord compression measured by magnetic resonance imaging (MRI) in patients with cervical spondylotic myelopathy (CSM). Hiroshima University Hospital in Japan. We studied 33 patients undergoing laminoplasty. Patients exhibited significant cervical spinal cord compression on both MRI and intraoperative electrophysiological examination. We assessed transcranial magnetic stimulation measurement of CMCT; spinal cord compression parameters such as area, lateral diameter, anteroposterior diameter and flattening of the spinal cord at the lesion site and C2/3 levels on MRI; and pre- versus postoperative Japanese Orthopaedic Association (JOA) scores. Correlations between CMCT and flattening as well as anteroposterior diameter of the spinal cord at the lesion level were observed. Strong correlations between CMCT and the ratio of the flattening and anteroposterior diameter parameters at the lesion level to that at the C2/3 level were also observed. Measurement of spinal cord compression may be useful for the evaluation of corticospinal function as a proxy for CMCT in patients with CSM.

  8. Compressibility characteristics of Sabak Bernam Marine Clay

    Science.gov (United States)

    Lat, D. C.; Ali, N.; Jais, I. B. M.; Baharom, B.; Yunus, N. Z. M.; Salleh, S. M.; Azmi, N. A. C.

    2018-04-01

    This study is carried out to determine the geotechnical properties and compressibility characteristics of marine clay collected at Sabak Bernam. The compressibility characteristics of this soil are determined from 1-D consolidation test and verified by existing correlations by other researchers. No literature has been found on the compressibility characteristics of Sabak Bernam Marine Clay. It is important to carry out this study since this type of marine clay covers large coastal area of west coast Malaysia. This type of marine clay was found on the main road connecting Klang to Perak and the road keeps experiencing undulation and uneven settlement which jeopardise the safety of the road users. The soil is indicated in the Generalised Soil Map of Peninsular Malaysia as a CLAY with alluvial soil on recent marine and riverine alluvium. Based on the British Standard Soil Classification and Plasticity Chart, the soil is classified as a CLAY with very high plasticity (CV). Results from laboratory test on physical properties and compressibility parameters show that Sabak Bernam Marine Clay (SBMC) is highly compressible, has low permeability and poor drainage characteristics. The compressibility parameters obtained for SBMC is in a good agreement with other researchers in the same field.

  9. A review on compressed pattern matching

    Directory of Open Access Journals (Sweden)

    Surya Prakash Mishra

    2016-09-01

    Full Text Available Compressed pattern matching (CPM refers to the task of locating all the occurrences of a pattern (or set of patterns inside the body of compressed text. In this type of matching, pattern may or may not be compressed. CPM is very useful in handling large volume of data especially over the network. It has many applications in computational biology, where it is useful in finding similar trends in DNA sequences; intrusion detection over the networks, big data analytics etc. Various solutions have been provided by researchers where pattern is matched directly over the uncompressed text. Such solution requires lot of space and consumes lot of time when handling the big data. Various researchers have proposed the efficient solutions for compression but very few exist for pattern matching over the compressed text. Considering the future trend where data size is increasing exponentially day-by-day, CPM has become a desirable task. This paper presents a critical review on the recent techniques on the compressed pattern matching. The covered techniques includes: Word based Huffman codes, Word Based Tagged Codes; Wavelet Tree Based Indexing. We have presented a comparative analysis of all the techniques mentioned above and highlighted their advantages and disadvantages.

  10. Efficient predictive algorithms for image compression

    CERN Document Server

    Rosário Lucas, Luís Filipe; Maciel de Faria, Sérgio Manuel; Morais Rodrigues, Nuno Miguel; Liberal Pagliari, Carla

    2017-01-01

    This book discusses efficient prediction techniques for the current state-of-the-art High Efficiency Video Coding (HEVC) standard, focusing on the compression of a wide range of video signals, such as 3D video, Light Fields and natural images. The authors begin with a review of the state-of-the-art predictive coding methods and compression technologies for both 2D and 3D multimedia contents, which provides a good starting point for new researchers in the field of image and video compression. New prediction techniques that go beyond the standardized compression technologies are then presented and discussed. In the context of 3D video, the authors describe a new predictive algorithm for the compression of depth maps, which combines intra-directional prediction, with flexible block partitioning and linear residue fitting. New approaches are described for the compression of Light Field and still images, which enforce sparsity constraints on linear models. The Locally Linear Embedding-based prediction method is in...

  11. Compressing bitmap indexes for faster search operations

    International Nuclear Information System (INIS)

    Wu, Kesheng; Otoo, Ekow J.; Shoshani, Arie

    2002-01-01

    In this paper, we study the effects of compression on bitmap indexes. The main operations on the bitmaps during query processing are bitwise logical operations such as AND, OR, NOT, etc. Using the general purpose compression schemes, such as gzip, the logical operations on the compressed bitmaps are much slower than on the uncompressed bitmaps. Specialized compression schemes, like the byte-aligned bitmap code(BBC), are usually faster in performing logical operations than the general purpose schemes, but in many cases they are still orders of magnitude slower than the uncompressed scheme. To make the compressed bitmap indexes operate more efficiently, we designed a CPU-friendly scheme which we refer to as the word-aligned hybrid code (WAH). Tests on both synthetic and real application data show that the new scheme significantly outperforms well-known compression schemes at a modest increase in storage space. Compared to BBC, a scheme well-known for its operational efficiency, WAH performs logical operations about 12 times faster and uses only 60 percent more space. Compared to the uncompressed scheme, in most test cases WAH is faster while still using less space. We further verified with additional tests that the improvement in logical operation speed translates to similar improvement in query processing speed

  12. Compressing bitmap indexes for faster search operations

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Kesheng; Otoo, Ekow J.; Shoshani, Arie

    2002-04-25

    In this paper, we study the effects of compression on bitmap indexes. The main operations on the bitmaps during query processing are bitwise logical operations such as AND, OR, NOT, etc. Using the general purpose compression schemes, such as gzip, the logical operations on the compressed bitmaps are much slower than on the uncompressed bitmaps. Specialized compression schemes, like the byte-aligned bitmap code(BBC), are usually faster in performing logical operations than the general purpose schemes, but in many cases they are still orders of magnitude slower than the uncompressed scheme. To make the compressed bitmap indexes operate more efficiently, we designed a CPU-friendly scheme which we refer to as the word-aligned hybrid code (WAH). Tests on both synthetic and real application data show that the new scheme significantly outperforms well-known compression schemes at a modest increase in storage space. Compared to BBC, a scheme well-known for its operational efficiency, WAH performs logical operations about 12 times faster and uses only 60 percent more space. Compared to the uncompressed scheme, in most test cases WAH is faster while still using less space. We further verified with additional tests that the improvement in logical operation speed translates to similar improvement in query processing speed.

  13. Optimization of Error-Bounded Lossy Compression for Hard-to-Compress HPC Data

    Energy Technology Data Exchange (ETDEWEB)

    Di, Sheng; Cappello, Franck

    2018-01-01

    Since today’s scientific applications are producing vast amounts of data, compressing them before storage/transmission is critical. Results of existing compressors show two types of HPC data sets: highly compressible and hard to compress. In this work, we carefully design and optimize the error-bounded lossy compression for hard-tocompress scientific data. We propose an optimized algorithm that can adaptively partition the HPC data into best-fit consecutive segments each having mutually close data values, such that the compression condition can be optimized. Another significant contribution is the optimization of shifting offset such that the XOR-leading-zero length between two consecutive unpredictable data points can be maximized. We finally devise an adaptive method to select the best-fit compressor at runtime for maximizing the compression factor. We evaluate our solution using 13 benchmarks based on real-world scientific problems, and we compare it with 9 other state-of-the-art compressors. Experiments show that our compressor can always guarantee the compression errors within the user-specified error bounds. Most importantly, our optimization can improve the compression factor effectively, by up to 49% for hard-tocompress data sets with similar compression/decompression time cost.

  14. MR imaging of spondylolytic spondylolisthesis: changes of intervertebral foramen and nerve root compression

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ji Hyung [Ajou Univ. College of Medicine, Seoul (Korea, Republic of); Chung, Tae Sub; Kim, Young Soo [Yonsei Univ. College of Medicine, Seoul (Korea, Republic of)

    1999-08-01

    To evaluate the factors affecting intervertebral foramen stenosis and nerve root compression in spondylolytic spondylolisthesis. We investigated 120 intervertebral foramina of 60 patients with spondylolytic spondylolisthesis who had undergone lumbar MRI. A retrospective review of their MR images revealed the degree of intervertebral foramen stenosis and causes of nerve root compression. The relationship between disk height diminution following spondylolysis and degree of intervertebral foramen stenosis was also evaluated. Forty eight of 60 patients showed a similar degree of intervertebral foramen stenosis, and in 12 patients the degree of stenosis was different. In 110 intervertebral foramina, stenosis of both the superior and inferior compartments of intervertebral foramina was demonstrated. In 37 of 120 cases (30.8%), stenosis was mild ; in 44 of 120 (36.7%) it was modcrate, and in 29 of 120 (24.2%) it was severe. Stenosis of the inferior compartment was demonstrated in ten of 120 intervertebral foramina (8.3%). Nerve root compression was caused by posterior bulging of the intervertebral disk (65/120), descent of the pedicle (51/120), an isthmic bony segment above the site of spondylolytic (44/120), a bony spur formed at a spondylolytic site (11/120), and fibrocartilaginous callus at a spondylolytic site (5/48). In all cases there was degenerative change of the intervertebral disk at the affected level. There was no relationship between degree of disk height diminution and degree of intervertebral foramen stenosis (p > 0.05). The degree of intervertebral foramen stenosis and causes of nerve root compression in spondylolytic spondylolisthesis are variable, and MRI demonstrates them precisely. There was no positive relationship between degree of nerve root compression at an intervertebral foramen and degree of spondylolysis and degeneration of an intervertebral foramen. The degree of nerve root compression is believed to be another criterion for describing

  15. MR imaging of spondylolytic spondylolisthesis: changes of intervertebral foramen and nerve root compression

    International Nuclear Information System (INIS)

    Kim, Ji Hyung; Chung, Tae Sub; Kim, Young Soo

    1999-01-01

    To evaluate the factors affecting intervertebral foramen stenosis and nerve root compression in spondylolytic spondylolisthesis. We investigated 120 intervertebral foramina of 60 patients with spondylolytic spondylolisthesis who had undergone lumbar MRI. A retrospective review of their MR images revealed the degree of intervertebral foramen stenosis and causes of nerve root compression. The relationship between disk height diminution following spondylolysis and degree of intervertebral foramen stenosis was also evaluated. Forty eight of 60 patients showed a similar degree of intervertebral foramen stenosis, and in 12 patients the degree of stenosis was different. In 110 intervertebral foramina, stenosis of both the superior and inferior compartments of intervertebral foramina was demonstrated. In 37 of 120 cases (30.8%), stenosis was mild ; in 44 of 120 (36.7%) it was modcrate, and in 29 of 120 (24.2%) it was severe. Stenosis of the inferior compartment was demonstrated in ten of 120 intervertebral foramina (8.3%). Nerve root compression was caused by posterior bulging of the intervertebral disk (65/120), descent of the pedicle (51/120), an isthmic bony segment above the site of spondylolytic (44/120), a bony spur formed at a spondylolytic site (11/120), and fibrocartilaginous callus at a spondylolytic site (5/48). In all cases there was degenerative change of the intervertebral disk at the affected level. There was no relationship between degree of disk height diminution and degree of intervertebral foramen stenosis (p > 0.05). The degree of intervertebral foramen stenosis and causes of nerve root compression in spondylolytic spondylolisthesis are variable, and MRI demonstrates them precisely. There was no positive relationship between degree of nerve root compression at an intervertebral foramen and degree of spondylolysis and degeneration of an intervertebral foramen. The degree of nerve root compression is believed to be another criterion for describing

  16. Compression behavior of Fe-Si-H alloys

    Science.gov (United States)

    Tagawa, S.; Ohta, K.; Hirose, K.; Ohishi, Y.

    2015-12-01

    Although the light elements in the Earth's core are still enigmatic, hydrogen has recently been receiving much attention. Planetary formation theory suggested that a large amount of water, much more than is in the oceans, could have been brought to the Earth during its accretion. Hydrogen is a strong siderophile element and could be incorporated into the core as a consequence of a reaction between water and molten iron in a magma ocean [Okuchi, 1997 Science]. Nevertheless, the effect of hydrogen on the property of iron is not well known so far. Here, we have experimentally examined the compression behavior of hcp Fe0.88Si0.12Hx (6.5 wt.% Si) at two different hydrogen concentrations (x = 0.7 and 0.9). Fe0.88Si0.12 foil was loaded into a diamond-anvil cell, and then liquid hydrogen was introduced to a sample chamber below 20 K. Hydrogenation occurred upon thermal annealing below 1500 K at 25-62 GPa, and hcp Fe0.88Si0.12Hx was obtained as a single phase. Unlike the Fe-H alloy, hydrogen did not fully occupy the octahedral sites even under hydrogen-saturated conditions. Two compression curves, one from 25 to 136 GPa, and the other from 62 to 128 GPa, were obtained at room temperature. While the effect of hydrogen on the compressibility of iron has been controversial in earlier experimental studies [Hirao et al., 2004 GRL; Pépin et al., 2014 PRL], our data indicate that the compressibility of Fe0.88Si0.12Hx alloy does not change with changing hydrogen content from x = 0 to 0.9. Such compression behavior observed is consistent with the recent ab initio calculations for hcp Fe-H alloys by Caracas[2015 GRL]. The extrapolation of present data to the outer core pressure and temperature range, assuming thermal expansivity is the same as that for iron and there is no density difference between solid and liquid, shows that the density of Fe0.88Si0.12H0.3 matches the PREM in the whole outer core within 1%.

  17. Compressed air as a source of inhaled oxidants in intensive care units.

    Science.gov (United States)

    Thibeault, D W; Rezaiekhaligh, M H; Ekekezie, I; Truog, W E

    1999-01-01

    3) We recommend that all compressed air methods using tap water have charcoal filters at the compression site and the gases be assessed periodically for oxidants.

  18. Superfund Sites

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This layer represents active Superfund Sites published by the Environmental Protection Agency (EPA). These data were extracted from the Superfund Enterprise...

  19. Site development

    International Nuclear Information System (INIS)

    Noack, J.

    1975-01-01

    The subject of this paper is a general view over all necessary considerations to develop the site after it has been chosen and before starting with the construction of a nuclear power plant. (orig./RW) [de

  20. Site selection

    International Nuclear Information System (INIS)

    Olsen, C.W.

    1983-07-01

    The conditions and criteria for selecting a site for a nuclear weapons test at the Nevada Test Site are summarized. Factors considered are: (1) scheduling of drill rigs, (2) scheduling of site preparation (dirt work, auger hole, surface casing, cementing), (3) schedule of event (when are drill hole data needed), (4) depth range of proposed W.P., (5) geologic structure (faults, Pz contact, etc.), (6) stratigraphy (alluvium, location of Grouse Canyon Tuff, etc.), (7) material properties (particularly montmorillonite and CO 2 content), (8) water table depth, (9) potential drilling problems (caving), (10) adjacent collapse craters and chimneys, (11) adjacent expended but uncollapsed sites, (12) adjacent post-shot or other small diameter holes, (13) adjacent stockpile emplacement holes, (14) adjacent planned events (including LANL), (15) projected needs of Test Program for various DOB's and operational separations, and (16) optimal use of NTS real estate

  1. 30 CFR 57.13020 - Use of compressed air.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Use of compressed air. 57.13020 Section 57... MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Compressed Air and Boilers § 57.13020 Use of compressed air. At no time shall compressed air be directed toward a...

  2. 30 CFR 56.13020 - Use of compressed air.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Use of compressed air. 56.13020 Section 56... MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Compressed Air and Boilers § 56.13020 Use of compressed air. At no time shall compressed air be directed toward a person...

  3. 30 CFR 77.412 - Compressed air systems.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Compressed air systems. 77.412 Section 77.412... for Mechanical Equipment § 77.412 Compressed air systems. (a) Compressors and compressed-air receivers... involving the pressure system of compressors, receivers, or compressed-air-powered equipment shall not be...

  4. Adiabatic liquid piston compressed air energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Petersen, Tage [Danish Technological Institute, Aarhus (Denmark); Elmegaard, B. [Technical Univ. of Denmark. DTU Mechanical Engineering, Kgs. Lyngby (Denmark); Schroeder Pedersen, A. [Technical Univ. of Denmark. DTU Energy Conversion, Risoe Campus, Roskilde (Denmark)

    2013-01-15

    This project investigates the potential of a Compressed Air Energy Storage system (CAES system). CAES systems are used to store mechanical energy in the form of compressed air. The systems use electricity to drive the compressor at times of low electricity demand with the purpose of converting the mechanical energy into electricity at times of high electricity demand. Two such systems are currently in operation; one in Germany (Huntorf) and one in the USA (Macintosh, Alabama). In both cases, an underground cavern is used as a pressure vessel for the storage of the compressed air. Both systems are in the range of 100 MW electrical power output with several hours of production stored as compressed air. In this range, enormous volumes are required, which make underground caverns the only economical way to design the pressure vessel. Both systems use axial turbine compressors to compress air when charging the system. The compression leads to a significant increase in temperature, and the heat generated is dumped into the ambient. This energy loss results in a low efficiency of the system, and when expanding the air, the expansion leads to a temperature drop reducing the mechanical output of the expansion turbines. To overcome this, fuel is burned to heat up the air prior to expansion. The fuel consumption causes a significant cost for the storage. Several suggestions have been made to store compression heat for later use during expansion and thereby avoid the use of fuel (so called Adiabatic CAES units), but no such units are in operation at present. The CAES system investigated in this project uses a different approach to avoid compression heat loss. The system uses a pre-compressed pressure vessel full of air. A liquid is pumped into the bottom of the vessel when charging and the same liquid is withdrawn through a turbine when discharging. In this case, the liquid works effectively as a piston compressing the gas in the vessel, hence the name &apos

  5. Processing of mixed-waste compressed-gas cylinders on the Oak Ridge Reservation

    International Nuclear Information System (INIS)

    Morris, M.I.; Conley, T.B.; Osborne-Lee, I.W.

    1998-03-01

    To comply with restrictions on the storage of old compressed gas cylinders, the environmental management organization of Lockheed Martin Energy Systems must dispose of several thousand kilograms of compressed gases stored on the Oak Ridge Reservation (ORR) because the cylinders cannot be taken off-site for disposal in their current configuration. In the ORR Site Treatment Plan, a milestone is cited that requires repackaging and shipment off-site of 21 cylinders by September 30, 1997. A project was undertaken to first evaluate and then either recontainerize or neutralize these cylinders using a transportable compressed gas recontainerization skid (TCGRS), which was developed by Integrated Environmental Services of Atlanta. The transportable system can: (1) sample, analyze, and identify at the site the chemical and radiological content of each cylinder, even those with inoperable valves; (2) breach cylinders, when necessary, to release their contents into a containment chamber; and (3) either neutralize the gas or liquid contents within the containment chamber or transfer the gas or liquids to a new cylinder. The old cylinders and cylinder fragments were disposed of and the gases neutralized or transferred to new cylinders for transportation off-site for disposal. The entire operation to process the 21 cylinders took place in only 5 days once the system was approved for operation. The system performed as expected and can now be used to process the potentially thousands of more cylinders located across the US Department of Energy (DOE) complex that have not yet been declared surplus

  6. A comparative experimental study on engine operating on premixed charge compression ignition and compression ignition mode

    Directory of Open Access Journals (Sweden)

    Bhiogade Girish E.

    2017-01-01

    Full Text Available New combustion concepts have been recently developed with the purpose to tackle the problem of high emissions level of traditional direct injection Diesel engines. A good example is the premixed charge compression ignition combustion. A strategy in which early injection is used causing a burning process in which the fuel burns in the premixed condition. In compression ignition engines, soot (particulate matter and NOx emissions are an extremely unsolved issue. Premixed charge compression ignition is one of the most promising solutions that combine the advantages of both spark ignition and compression ignition combustion modes. It gives thermal efficiency close to the compression ignition engines and resolves the associated issues of high NOx and particulate matter, simultaneously. Premixing of air and fuel preparation is the challenging part to achieve premixed charge compression ignition combustion. In the present experimental study a diesel vaporizer is used to achieve premixed charge compression ignition combustion. A vaporized diesel fuel was mixed with the air to form premixed charge and inducted into the cylinder during the intake stroke. Low diesel volatility remains the main obstacle in preparing premixed air-fuel mixture. Exhaust gas re-circulation can be used to control the rate of heat release. The objective of this study is to reduce exhaust emission levels with maintaining thermal efficiency close to compression ignition engine.

  7. Modeling the mechanical and compression properties of polyamide/elastane knitted fabrics used in compression sportswear

    NARCIS (Netherlands)

    Maqsood, Muhammad

    2016-01-01

    A compression sportswear fabric should have excellent stretch and recovery properties in order to improve the performance of the sportsman. The objective of this study was to investigate the effect of elastane linear density and loop length on the stretch, recovery, and compression properties of the

  8. Compression Characteristics of Solid Wastes as Backfill Materials

    OpenAIRE

    Meng Li; Jixiong Zhang; Rui Gao

    2016-01-01

    A self-made large-diameter compression steel chamber and a SANS material testing machine were chosen to perform a series of compression tests in order to fully understand the compression characteristics of differently graded filling gangue samples. The relationship between the stress-deformation modulus and stress-compression degree was analyzed comparatively. The results showed that, during compression, the deformation modulus of gangue grew linearly with stress, the overall relationship bet...

  9. Developing a dynamic control system for mine compressed air networks

    OpenAIRE

    Van Heerden, S.W.; Pelzer, R.; Marais, J.H.

    2014-01-01

    Mines in general, make use of compressed air systems for daily operational activities. Compressed air on mines is traditionally distributed via compressed air ring networks where multiple shafts are supplied with compressed air from an integral system. These compressed air networks make use of a number of compressors feeding the ring from various locations in the network. While these mines have sophisticated control systems to control these compressors, they are not dynamic systems. Compresso...

  10. Results of subscale MTF compression experiments

    Science.gov (United States)

    Howard, Stephen; Mossman, A.; Donaldson, M.; Fusion Team, General

    2016-10-01

    In magnetized target fusion (MTF) a magnetized plasma torus is compressed in a time shorter than its own energy confinement time, thereby heating to fusion conditions. Understanding plasma behavior and scaling laws is needed to advance toward a reactor-scale demonstration. General Fusion is conducting a sequence of subscale experiments of compact toroid (CT) plasmas being compressed by chemically driven implosion of an aluminum liner, providing data on several key questions. CT plasmas are formed by a coaxial Marshall gun, with magnetic fields supported by internal plasma currents and eddy currents in the wall. Configurations that have been compressed so far include decaying and sustained spheromaks and an ST that is formed into a pre-existing toroidal field. Diagnostics measure B, ne, visible and x-ray emission, Ti and Te. Before compression the CT has an energy of 10kJ magnetic, 1 kJ thermal, with Te of 100 - 200 eV, ne 5x1020 m-3. Plasma was stable during a compression factor R0/R >3 on best shots. A reactor scale demonstration would require 10x higher initial B and ne but similar Te. Liner improvements have minimized ripple, tearing and ejection of micro-debris. Plasma facing surfaces have included plasma-sprayed tungsten, bare Cu and Al, and gettering with Ti and Li.

  11. Lightweight SIP/SDP compression scheme (LSSCS)

    Science.gov (United States)

    Wu, Jian J.; Demetrescu, Cristian

    2001-10-01

    In UMTS new IP based services with tight delay constraints will be deployed over the W-CDMA air interface such as IP multimedia and interactive services. To integrate the wireline and wireless IP services, 3GPP standard forum adopted the Session Initiation Protocol (SIP) as the call control protocol for the UMTS Release 5, which will implement next generation, all IP networks for real-time QoS services. In the current form the SIP protocol is not suitable for wireless transmission due to its large message size which will need either a big radio pipe for transmission or it will take far much longer to transmit than the current GSM Call Control (CC) message sequence. In this paper we present a novel compression algorithm called Lightweight SIP/SDP Compression Scheme (LSSCS), which acts at the SIP application layer and therefore removes the information redundancy before it is sent to the network and transport layer. A binary octet-aligned header is added to the compressed SIP/SDP message before sending it to the network layer. The receiver uses this binary header as well as the pre-cached information to regenerate the original SIP/SDP message. The key features of the LSSCS compression scheme are presented in this paper along with implementation examples. It is shown that this compression algorithm makes SIP transmission efficient over the radio interface without losing the SIP generality and flexibility.

  12. Compressed Air/Vacuum Transportation Techniques

    Science.gov (United States)

    Guha, Shyamal

    2011-03-01

    General theory of compressed air/vacuum transportation will be presented. In this transportation, a vehicle (such as an automobile or a rail car) is powered either by compressed air or by air at near vacuum pressure. Four version of such transportation is feasible. In all versions, a ``c-shaped'' plastic or ceramic pipe lies buried a few inches under the ground surface. This pipe carries compressed air or air at near vacuum pressure. In type I transportation, a vehicle draws compressed air (or vacuum) from this buried pipe. Using turbine or reciprocating air cylinder, mechanical power is generated from compressed air (or from vacuum). This mechanical power transferred to the wheels of an automobile (or a rail car) drives the vehicle. In type II-IV transportation techniques, a horizontal force is generated inside the plastic (or ceramic) pipe. A set of vertical and horizontal steel bars is used to transmit this force to the automobile on the road (or to a rail car on rail track). The proposed transportation system has following merits: virtually accident free; highly energy efficient; pollution free and it will not contribute to carbon dioxide emission. Some developmental work on this transportation will be needed before it can be used by the traveling public. The entire transportation system could be computer controlled.

  13. Compressing Aviation Data in XML Format

    Science.gov (United States)

    Patel, Hemil; Lau, Derek; Kulkarni, Deepak

    2003-01-01

    Design, operations and maintenance activities in aviation involve analysis of variety of aviation data. This data is typically in disparate formats making it difficult to use with different software packages. Use of a self-describing and extensible standard called XML provides a solution to this interoperability problem. XML provides a standardized language for describing the contents of an information stream, performing the same kind of definitional role for Web content as a database schema performs for relational databases. XML data can be easily customized for display using Extensible Style Sheets (XSL). While self-describing nature of XML makes it easy to reuse, it also increases the size of data significantly. Therefore, transfemng a dataset in XML form can decrease throughput and increase data transfer time significantly. It also increases storage requirements significantly. A natural solution to the problem is to compress the data using suitable algorithm and transfer it in the compressed form. We found that XML-specific compressors such as Xmill and XMLPPM generally outperform traditional compressors. However, optimal use of Xmill requires of discovery of optimal options to use while running Xmill. This, in turn, depends on the nature of data used. Manual disc0ver.y of optimal setting can require an engineer to experiment for weeks. We have devised an XML compression advisory tool that can analyze sample data files and recommend what compression tool would work the best for this data and what are the optimal settings to be used with a XML compression tool.

  14. Iris Recognition: The Consequences of Image Compression

    Directory of Open Access Journals (Sweden)

    Bishop DanielA

    2010-01-01

    Full Text Available Iris recognition for human identification is one of the most accurate biometrics, and its employment is expanding globally. The use of portable iris systems, particularly in law enforcement applications, is growing. In many of these applications, the portable device may be required to transmit an iris image or template over a narrow-bandwidth communication channel. Typically, a full resolution image (e.g., VGA is desired to ensure sufficient pixels across the iris to be confident of accurate recognition results. To minimize the time to transmit a large amount of data over a narrow-bandwidth communication channel, image compression can be used to reduce the file size of the iris image. In other applications, such as the Registered Traveler program, an entire iris image is stored on a smart card, but only 4 kB is allowed for the iris image. For this type of application, image compression is also the solution. This paper investigates the effects of image compression on recognition system performance using a commercial version of the Daugman iris2pi algorithm along with JPEG-2000 compression, and links these to image quality. Using the ICE 2005 iris database, we find that even in the face of significant compression, recognition performance is minimally affected.

  15. Iris Recognition: The Consequences of Image Compression

    Science.gov (United States)

    Ives, Robert W.; Bishop, Daniel A.; Du, Yingzi; Belcher, Craig

    2010-12-01

    Iris recognition for human identification is one of the most accurate biometrics, and its employment is expanding globally. The use of portable iris systems, particularly in law enforcement applications, is growing. In many of these applications, the portable device may be required to transmit an iris image or template over a narrow-bandwidth communication channel. Typically, a full resolution image (e.g., VGA) is desired to ensure sufficient pixels across the iris to be confident of accurate recognition results. To minimize the time to transmit a large amount of data over a narrow-bandwidth communication channel, image compression can be used to reduce the file size of the iris image. In other applications, such as the Registered Traveler program, an entire iris image is stored on a smart card, but only 4 kB is allowed for the iris image. For this type of application, image compression is also the solution. This paper investigates the effects of image compression on recognition system performance using a commercial version of the Daugman iris2pi algorithm along with JPEG-2000 compression, and links these to image quality. Using the ICE 2005 iris database, we find that even in the face of significant compression, recognition performance is minimally affected.

  16. Wave energy devices with compressible volumes.

    Science.gov (United States)

    Kurniawan, Adi; Greaves, Deborah; Chaplin, John

    2014-12-08

    We present an analysis of wave energy devices with air-filled compressible submerged volumes, where variability of volume is achieved by means of a horizontal surface free to move up and down relative to the body. An analysis of bodies without power take-off (PTO) systems is first presented to demonstrate the positive effects a compressible volume could have on the body response. Subsequently, two compressible device variations are analysed. In the first variation, the compressible volume is connected to a fixed volume via an air turbine for PTO. In the second variation, a water column separates the compressible volume from another volume, which is fitted with an air turbine open to the atmosphere. Both floating and bottom-fixed, axisymmetric, configurations are considered, and linear analysis is employed throughout. Advantages and disadvantages of each device are examined in detail. Some configurations with displaced volumes less than 2000 m 3 and with constant turbine coefficients are shown to be capable of achieving 80% of the theoretical maximum absorbed power over a wave period range of about 4 s.

  17. Lagrangian statistics in compressible isotropic homogeneous turbulence

    Science.gov (United States)

    Yang, Yantao; Wang, Jianchun; Shi, Yipeng; Chen, Shiyi

    2011-11-01

    In this work we conducted the Direct Numerical Simulation (DNS) of a forced compressible isotropic homogeneous turbulence and investigated the flow statistics from the Lagrangian point of view, namely the statistics is computed following the passive tracers trajectories. The numerical method combined the Eulerian field solver which was developed by Wang et al. (2010, J. Comp. Phys., 229, 5257-5279), and a Lagrangian module for tracking the tracers and recording the data. The Lagrangian probability density functions (p.d.f.'s) have then been calculated for both kinetic and thermodynamic quantities. In order to isolate the shearing part from the compressing part of the flow, we employed the Helmholtz decomposition to decompose the flow field (mainly the velocity field) into the solenoidal and compressive parts. The solenoidal part was compared with the incompressible case, while the compressibility effect showed up in the compressive part. The Lagrangian structure functions and cross-correlation between various quantities will also be discussed. This work was supported in part by the China's Turbulence Program under Grant No.2009CB724101.

  18. The compressed word problem for groups

    CERN Document Server

    Lohrey, Markus

    2014-01-01

    The Compressed Word Problem for Groups provides a detailed exposition of known results on the compressed word problem, emphasizing efficient algorithms for the compressed word problem in various groups. The author presents the necessary background along with the most recent results on the compressed word problem to create a cohesive self-contained book accessible to computer scientists as well as mathematicians. Readers will quickly reach the frontier of current research which makes the book especially appealing for students looking for a currently active research topic at the intersection of group theory and computer science. The word problem introduced in 1910 by Max Dehn is one of the most important decision problems in group theory. For many groups, highly efficient algorithms for the word problem exist. In recent years, a new technique based on data compression for providing more efficient algorithms for word problems, has been developed, by representing long words over group generators in a compres...

  19. Compression evaluation of surgery video recordings retaining diagnostic credibility (compression evaluation of surgery video)

    Science.gov (United States)

    Duplaga, M.; Leszczuk, M. I.; Papir, Z.; Przelaskowski, A.

    2008-12-01

    Wider dissemination of medical digital video libraries is affected by two correlated factors, resource effective content compression that directly influences its diagnostic credibility. It has been proved that it is possible to meet these contradictory requirements halfway for long-lasting and low motion surgery recordings at compression ratios close to 100 (bronchoscopic procedures were a case study investigated). As the main supporting assumption, it has been accepted that the content can be compressed as far as clinicians are not able to sense a loss of video diagnostic fidelity (a visually lossless compression). Different market codecs were inspected by means of the combined subjective and objective tests toward their usability in medical video libraries. Subjective tests involved a panel of clinicians who had to classify compressed bronchoscopic video content according to its quality under the bubble sort algorithm. For objective tests, two metrics (hybrid vector measure and hosaka Plots) were calculated frame by frame and averaged over a whole sequence.

  20. Two divergent paths: compression vs. non-compression in deep venous thrombosis and post thrombotic syndrome

    Directory of Open Access Journals (Sweden)

    Eduardo Simões Da Matta

    Full Text Available Abstract Use of compression therapy to reduce the incidence of postthrombotic syndrome among patients with deep venous thrombosis is a controversial subject and there is no consensus on use of elastic versus inelastic compression, or on the levels and duration of compression. Inelastic devices with a higher static stiffness index, combine relatively small and comfortable pressure at rest with pressure while standing strong enough to restore the “valve mechanism” generated by plantar flexion and dorsiflexion of the foot. Since the static stiffness index is dependent on the rigidity of the compression system and the muscle strength within the bandaged area, improvement of muscle mass with muscle-strengthening programs and endurance training should be encouraged. Therefore, in the acute phase of deep venous thrombosis events, anticoagulation combined with inelastic compression therapy can reduce the extension of the thrombus. Notwithstanding, prospective studies evaluating the effectiveness of inelastic therapy in deep venous thrombosis and post-thrombotic syndrome are needed.