TY  - JOUR
A1  - Dipaola, Mariangela
A1  - Pavan, Esteban E.
A1  - Cattaneo, Andrea
A1  - Frazzitta, Giuseppe
A1  - Pezzoli, Gianni
A1  - Cavallari, Paolo
A1  - Frigo, Carlo A.
A1  - Isaias, Ioannis U.
T1  - Mechanical Energy Recovery during Walking in Patients with Parkinson Disease
JF  - PLoS ONE
N2  - The mechanisms of mechanical energy recovery during gait have been thoroughly investigated in healthy subjects, but never described in patients with Parkinson disease (PD). The aim of this study was to investigate whether such mechanisms are preserved in PD patients despite an altered pattern of locomotion. We consecutively enrolled 23 PD patients (mean age 64±9 years) with bilateral symptoms (H&Y ≥II) if able to walk unassisted in medication-off condition (overnight suspension of all dopaminergic drugs). Ten healthy subjects (mean age 62±3 years) walked both at their ‘preferred’ and ‘slow’ speeds, to match the whole range of PD velocities. Kinematic data were recorded by means of an optoelectronic motion analyzer. For each stride we computed spatio-temporal parameters, time-course and range of motion (ROM) of hip, knee and ankle joint angles. We also measured kinetic (Wk), potential (W\(_{p}\)), total (W\(_{totCM}\)) energy variations and the energy recovery index (ER). Along with PD progression, we found a significant correlation of W\(_{totCM}\) and W\(_{p}\) with knee ROM and in particular with knee extension in terminal stance phase. W\(_{k}\) and ER were instead mainly related to gait velocity. In PD subjects, the reduction of knee ROM significantly diminished both W\(_{p}\) and W\(_{totCM}\). Rehabilitation treatments should possibly integrate passive and active mobilization of knee to prevent a reduction of gait-related energetic components.
KW  - Parkinson disease
KW  - mechanical energy
KW  - kinematics
KW  - velocity
KW  - hip
KW  - gait analysis
KW  - walking
KW  - knees
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-179739
VL  - 11
IS  - 6
ER  - 
TY  - JOUR
A1  - Zaho, Huaying
A1  - Ghirlando, Rodolfo
A1  - Alfonso, Carlos
A1  - Arisaka, Fumio
A1  - Attali, Ilan
A1  - Bain, David L.
A1  - Bakhtina, Marina M.
A1  - Becker, Donald F.
A1  - Bedwell, Gregory J.
A1  - Bekdemir, Ahmet
A1  - Besong, Tabot M. D.
A1  - Birck, Catherine
A1  - Brautigam, Chad A.
A1  - Brennerman, William
A1  - Byron, Olwyn
A1  - Bzowska, Agnieszka
A1  - Chaires, Jonathan B.
A1  - Chaton, Catherine T.
A1  - Coelfen, Helmbut
A1  - Connaghan, Keith D.
A1  - Crowley, Kimberly A.
A1  - Curth, Ute
A1  - Daviter, Tina
A1  - Dean, William L.
A1  - Diez, Ana I.
A1  - Ebel, Christine
A1  - Eckert, Debra M.
A1  - Eisele, Leslie E.
A1  - Eisenstein, Edward
A1  - England, Patrick
A1  - Escalante, Carlos
A1  - Fagan, Jeffrey A.
A1  - Fairman, Robert
A1  - Finn, Ron M.
A1  - Fischle, Wolfgang
A1  - Garcia de la Torre, Jose
A1  - Gor, Jayesh
A1  - Gustafsson, Henning
A1  - Hall, Damien
A1  - Harding, Stephen E.
A1  - Hernandez Cifre, Jose G.
A1  - Herr, Andrew B.
A1  - Howell, Elizabeth E.
A1  - Isaac, Richard S.
A1  - Jao, Shu-Chuan
A1  - Jose, Davis
A1  - Kim, Soon-Jong
A1  - Kokona, Bashkim
A1  - Kornblatt, Jack A.
A1  - Kosek, Dalibor
A1  - Krayukhina, Elena
A1  - Krzizike, Daniel
A1  - Kusznir, Eric A.
A1  - Kwon, Hyewon
A1  - Larson, Adam
A1  - Laue, Thomas M.
A1  - Le Roy, Aline
A1  - Leech, Andrew P.
A1  - Lilie, Hauke
A1  - Luger, Karolin
A1  - Luque-Ortega, Juan R.
A1  - Ma, Jia
A1  - May, Carrie A.
A1  - Maynard, Ernest L.
A1  - Modrak-Wojcik, Anna
A1  - Mok, Yee-Foong
A1  - Mücke, Norbert
A1  - Nagel-Steger, Luitgard
A1  - Narlikar, Geeta J.
A1  - Noda, Masanori
A1  - Nourse, Amanda
A1  - Obsil, Thomas
A1  - Park, Chad K
A1  - Park, Jin-Ku
A1  - Pawelek, Peter D.
A1  - Perdue, Erby E.
A1  - Perkins, Stephen J.
A1  - Perugini, Matthew A.
A1  - Peterson, Craig L.
A1  - Peverelli, Martin G.
A1  - Piszczek, Grzegorz
A1  - Prag, Gali
A1  - Prevelige, Peter E.
A1  - Raynal, Bertrand D. E.
A1  - Rezabkova, Lenka
A1  - Richter, Klaus
A1  - Ringel, Alison E.
A1  - Rosenberg, Rose
A1  - Rowe, Arthur J.
A1  - Rufer, Arne C.
A1  - Scott, David J.
A1  - Seravalli, Javier G.
A1  - Solovyova, Alexandra S.
A1  - Song, Renjie
A1  - Staunton, David
A1  - Stoddard, Caitlin
A1  - Stott, Katherine
A1  - Strauss, Holder M.
A1  - Streicher, Werner W.
A1  - Sumida, John P.
A1  - Swygert, Sarah G.
A1  - Szczepanowski, Roman H.
A1  - Tessmer, Ingrid
A1  - Toth, Ronald T.
A1  - Tripathy, Ashutosh
A1  - Uchiyama, Susumu
A1  - Uebel, Stephan F. W.
A1  - Unzai, Satoru
A1  - Gruber, Anna Vitlin
A1  - von Hippel, Peter H.
A1  - Wandrey, Christine
A1  - Wang, Szu-Huan
A1  - Weitzel, Steven E
A1  - Wielgus-Kutrowska, Beata
A1  - Wolberger, Cynthia
A1  - Wolff, Martin
A1  - Wright, Edward
A1  - Wu, Yu-Sung
A1  - Wubben, Jacinta M.
A1  - Schuck, Peter
T1  - A Multilaboratory Comparison of Calibration Accuracy and the Performance of External References in Analytical Ultracentrifugation
JF  - PLoS ONE
N2  - Analytical ultracentrifugation (AUC) is a first principles based method to determine absolute sedimentation coefficients and buoyant molar masses of macromolecules and their complexes, reporting on their size and shape in free solution. The purpose of this multi-laboratory study was to establish the precision and accuracy of basic data dimensions in AUC and validate previously proposed calibration techniques. Three kits of AUC cell assemblies containing radial and temperature calibration tools and a bovine serum albumin (BSA) reference sample were shared among 67 laboratories, generating 129 comprehensive data sets. These allowed for an assessment of many parameters of instrument performance, including accuracy of the reported scan time after the start of centrifugation, the accuracy of the temperature calibration, and the accuracy of the radial magnification. The range of sedimentation coefficients obtained for BSA monomer in different instruments and using different optical systems was from 3.655 S to 4.949 S, with a mean and standard deviation of (4.304\(\pm\)0.188) S (4.4%). After the combined application of correction factors derived from the external calibration references for elapsed time, scan velocity, temperature, and radial magnification, the range of s-values was reduced 7-fold with a mean of 4.325 S and a 6-fold reduced standard deviation of \(\pm\)0.030 S (0.7%). In addition, the large data set provided an opportunity to determine the instrument-to-instrument variation of the absolute radial positions reported in the scan files, the precision of photometric or refractometric signal magnitudes, and the precision of the calculated apparent molar mass of BSA monomer and the fraction of BSA dimers. These results highlight the necessity and effectiveness of independent calibration of basic AUC data dimensions for reliable quantitative studies.
KW  - fluorescence-detected sedimentation
KW  - size exclusion chromatography
KW  - field flow fractionation
KW  - spinco ultracentrifuge
KW  - aggregation
KW  - bead models
KW  - velocity
KW  - hydrodynamics
KW  - biopharmaceuticals
KW  - proteins
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-151903
VL  - 10
IS  - 5
ER  - 
TY  - JOUR
A1  - Isaias, Ioannis Ugo
A1  - Dipaola, Mariangela
A1  - Michi, Marlies
A1  - Marzegan, Alberto
A1  - Volkmann, Jens
A1  - Rodocanachi Roidi, Mariana L.
A1  - Frigo, Carlo Albino
A1  - Cavallari, Paolo
T1  - Gait Initiation in Children with Rett Syndrome
JF  - PLoS ONE
N2  - Rett syndrome is an X-linked neurodevelopmental condition mainly characterized by loss of spoken language and a regression of purposeful hand use, with the development of distinctive hand stereotypies, and gait abnormalities. Gait initiation is the transition from quiet stance to steady-state condition of walking. The associated motor program seems to be centrally mediated and includes preparatory adjustments prior to any apparent voluntary movement of the lower limbs. Anticipatory postural adjustments contribute to postural stability and to create the propulsive forces necessary to reach steady-state gait at a predefined velocity and may be indicative of the effectiveness of the feedforward control of gait. In this study, we examined anticipatory postural adjustments associated with gait initiation in eleven girls with Rett syndrome and ten healthy subjects. Muscle activity (tibialis anterior and soleus muscles), ground reaction forces and body kinematic were recorded. Children with Rett syndrome showed a distinctive impairment in temporal organization of all phases of the anticipatory postural adjustments. The lack of appropriate temporal scaling resulted in a diminished impulse to move forward, documented by an impairment in several parameters describing the efficiency of gait start: length and velocity of the first step, magnitude and orientation of centre of pressure-centre of mass vector at the instant of (swing-)toe off. These findings were related to an abnormal muscular activation pattern mainly characterized by a disruption of the synergistic activity of antagonistic pairs of postural muscles. This study showed that girls with Rett syndrome lack accurate tuning of feedforward control of gait.
KW  - syndrome
KW  - ankles  
KW  - biological locomotion
KW  - kinematics
KW  - rett
KW  - soleus muscles
KW  - walking
KW  - velocity
KW  - children
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-119789
SN  - 1932-6203
VL  - 9
IS  - 4
ER  - 
TY  - THES
A1  - Hagendorf, Annika
T1  - Untersuchungen zum Strömungsverhalten in einer Spiralstrahlmühle mittels Druckmessungen
T1  - Investigations on the flow in a spiral jet mill by pressure measurements
N2  - Der Untersuchung des Strömungsverhaltens in einer Spiralstrahlmühle kommt auf Grund ihrer Komplexität besondere Bedeutung zu. Seit der Entwicklung der Strahlmühlen wird versucht, die Abläufe während des Zerkleinerungsprozesses genau zu beobachten und zu analysieren. Als Kontrollinstrument der Betriebszustände in der Mühle hat sich die Aufzeichnung des statischen Drucks etabliert. Der statische Druck ist auf gleichem Radius unabhängig von der Position des Druckaufnehmers und damit auch unabhängig vom Einfluss der Treibstrahlen über der Wandschicht fast konstant. Weitere Untersuchungen über dem Radius der Mahlkammer bringen den Beweis, dass die aufgenommene radiale Druckkennlinie vom äußeren Mahlkammerrand in Richtung des Kammermittelpunktes abfällt. Die Aufnahme des zur Geschwindigkeitsberechnung benötigten Gesamtdrucks erfolgt über ein Pitot-Rohr. Dazu muss zunächst ein für die Mühle geeignetes Pitot-Rohr angefertigt werden. Das Pitot-Rohr mit einer Kopflänge von 13 mm und einem Verhältnis von Innendurchmesser zu Außendurchmesser von 0,73 liefert in Vergleichsmessungen die höchsten Gesamtdruckwerte und wird daher für die weiteren Versuche eingesetzt. Um den Innenraum der Mühle so vollständig wie möglich zu erfassen, werden wesentliche Einflussgrößen, wie Messposition und Eintauchtiefe des Pitot-Rohres sowie definierte radiale Positionen in der Mahlkammer schrittweise variiert. Dabei erfolgt jeweils die Ermittlung des optimalen Anströmwinkels des Pitot-Rohres. Versuche mit unterschiedlichen Eintauchtiefen des Pitot-Rohres in die Mahlkammer zeigen ebenfalls einen Druckanstieg, sobald das Messrohr in Nähe der Treibstrahldüsen ausgerichtet wird. Je weiter sich das Rohr von der Treibstrahldüse entfernt, desto niedriger sind aufgenommener Gesamtdruck und die daraus resultierende Geschwindigkeit. Die berechneten Geschwindigkeitswerte lassen sich mit Hilfe des Programms MATLAB® graphisch in Strömungsprofilen darstellen. So können besonders übersichtlich Richtung und Geschwindigkeit der lokalen Strömung in Abhängigkeit vom Radius der Mahlkammer und Position des Pitot-Rohres veranschaulicht werden. Von großer Bedeutung sind die Treibstrahlebenen sowie angrenzende Bereiche ober- bzw. unterhalb der Treibstrahlebenen, da hier ein symmetrisches Strömungsverhalten beobachtet werden kann. Diese Symmetrie wird jedoch in den nachfolgenden Ebenen, bedingt durch das Tauchrohr, durchbrochen. Der charakteristische Verlauf einer Spiralströmung kann mit Hilfe der durchgeführten Druckmessungen bestätigt werden. Das geläufige “Drei-Ebenen-Modell“ von Kürten und Rumpf zur Darstellung der Strömungsverläufe in der Strahlmühle kann an Hand der gewonnenen Erkenntnisse nicht bestätigt werden. Die vermuteten Rückströmungen lassen sich trotz Ausrichtung des Pitot-Rohres in verschiedenen Eintauchtiefen sowie an veränderten Positionen der Mahlkammer nicht beobachten. Für die Versuche mit Pulverbeladung der Mühle ist es notwendig, zunächst einen konstanten Feststoffdurchsatz zu bestimmen, bei dem stabile Betriebsbedingungen der Strahlmühle gewährleistet sind. Dazu werden Mahlvorgänge mit veränderter Förderrate des Gutes durchgeführt. Es zeigt sich, dass bei einer Förderrate von 3,49 g/min die statischen Druck- und damit Strömungsverhältnisse über eine Messdauer von 10 Minuten stabil sind. Mit dieser Einstellung werden anschließend statische Druckverläufe in Abhängigkeit von der Position des Druckaufnehmers aufgezeichnet. Ein Einfluss der Treibstrahlen auf die statischen Druckwerte ist auch hier nicht erkennbar, wie bereits in den Untersuchungen ohne Feststoffbeladung bewiesen. Die Bestimmung der Partikelgrößenverteilung und Auswertung mittels RRSB-Netz dient dabei zur Überprüfung eines erfolgreichen Zerkleinerungsprozesses. Je höher der angelegte Mahldruck, desto feinkörniger und enger verteilt ist das erhaltene Mahlprodukt. Die Aufzeichnung des Gesamtdrucks bei Feststoffbeladung verläuft hingegen nicht erfolgreich. Durch die Ausrichtung in Strömungsrichtung setzt sich das Pitot-Rohr schnell mit Pulverpartikeln zu, die sich trotz regelmäßiger Freiblasstöße nicht entfernen lassen. Es treten starke Druckschwankungen und zahlreiche Strömungsinstabilitäten auf, die eine reproduzierbare Gesamtdruckerfassung selbst über eine kurze Messdauer und damit eine genaue Berechnung der Geschwindigkeit nicht erlauben. Zusammenfassend lässt sich festhalten, dass die Messungen mittels Pitot-Rohr eine geeignete Methode zur Ermittlung des Gesamtdrucks in reinen Gasströmungen darstellen. Aus diesen Messergebnissen kann der Strömungsverlauf in der Luftstrahlmühle wiedergegeben werden, der dem einer Spiralströmung exakt entspricht.
N2  - Investigations of the flow in a spiral jet mill demand particular importance due to its complexity. Since the development of these mills began, numerous studies have aimed at improving understanding of flow processes during particle comminution. Monitoring the static pressure represents a well suitable method of controlling operating conditions in the mill. easily be calculated using the “compressible Bernoulli Equation”. Several experiments indicate that the static pressure remains nearly constant over the same jet mill radius and is dependent neither on the position of the pressure transducer nor on the influence of the jets. Further investigations of the static pressure against the radius prove the pressure decreases from circumferential radii towards the middle of the milling chamber, as expected for spiral jet streams. Recording total pressure values for subsequent calculating flow velocities requires a pitot tube. Accordingly, an appropriate pitot tube for the jet mill has to be constructed. The pitot tube with a tip length of 13 mm and a ratio of inner to outer diameter of 0,73 provides the highest total pressure data in comparative tests. Hence it will be used in the following research. Evaluating the total pressure in inner planes of the jet mill as completely as possible, essential parameters such as position and immersion depth of the pitot tube as well as defined radii of the milling chamber are varied step by step. At each measuring point the optimal direction angle of the probe has to be explored carefully. Experiments run with different immersion depths of the pitot tube in the milling chamber also show pressure data increasing when the probe is aligned near the jet nozzles. The further the probe is removed from the jet nozzle the lower are the monitored total pressure and the resultant velocity. With the help of the program MATLAB® the calculated velocity data are visualised graphically as stream profiles. Thus direction and velocity of the local flow can be illustrated particularly clearly subject to the radius of the milling chamber as well as to the position of the pitot tube. Appearing of symmetric flow properties the nozzle plane itself as well as following planes above and below this plane, respectively, demand great importance. Because of the classification tube this symmetric flow behaviour cannot further be detected in adjacent planes. These pressure measurements apparently confirm the typical profile of a spiral jet stream. Based on the measured data, the common “Drei-Ebenen-Modell” by Kürten and Rumpf describing flow processes in a jet mill cannot be confirmed. The backstreaming in the jet nozzle plane proposed in this model is not observable not even by placing the probe at different immersion depths and modified positions in the milling chamber. It is then necessary to establish a constant feed rate guarantying stable flow conditions while loading the jet mill with solid material. To this end several comminution processes are carried out with varying powder supply at different settings. Over a period of 10 minutes a feeding rate of 3,49 g/min leads distinctly to stable pressure and resultant stream conditions. With this setting all further static pressure profiles are recorded while the position of the pressure transducer is varied. An influence of the jet nozzles on the static pressure values does not become apparent as already demonstrated in preceding tests without feed. When the milling gas pressure is raised, the static pressure at circumferential radii also increases linearly. Hereby the determination of particle size distributions and analysis by the use of a RRBS-Netz serves as a check for successful grinding processes. Comparing as well location and dispersion parameters as medians of the ground material indicates that the higher the adjusted milling gas pressure is, the finer and tighter-distributed is the received comminution product. In contrast to these static pressure measurements, it is not possible to monitor total pressure profiles without difficulties. Aligning the pitot tube directly into the gas-solid stream causes fast blocking of the probe´s tip with fine particles. In spite of pulsating air blasts the pitot tube cannot be freed from this clogging. Neither an increase of the milling gas pressure nor the purgation gas pulsing for shortened-time intervals have cleaning effects on the probe. The appearance of enormous pressure fluctuations and high flow instabilities do not enable reproducible measurements of the total pressure even over a short length of time nor of correct calculations of local velocities. All in all the pitot tube represents an appropriate method of evaluating total pressure values without particle load. The measured data render stream profiles for every plane of the jet mill, each corresponding exactly to a spiral stream profile.
KW  - Spiralstrahlmühle
KW  - Pitot-Rohr
KW  - Strömung
KW  - Spiralstrahlmühle
KW  - Pitot-Rohr
KW  - Strömungsverhalten
KW  - Druck
KW  - Geschwindigkeit
KW  - spiral jet mill
KW  - pitot tube
KW  - flow
KW  - pressure
KW  - velocity
Y1  - 2006
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-19804
ER  -