Stair Step Research Articles

Elementary subtraction.

Four experiments examined performance on the 100 "basic facts" of subtraction and found a discontinuous "stair step" function for reaction times and errors beginning with 11 - n facts. Participants' immediate retrospective reports of nonretrieval showed the same pattern in Experiment 3. The degree to which elementary subtraction depends on working memory (WM) was examined in a dual-task paradigm in Experiment 4. The reconstructive processing used with larger basic facts was strongly associated with greater WM disruption, as evidenced by errors in the secondary task: this was especially the case for participants with lower WM spans. The results support the R. S. Siegler and E. Jenkins (1989) distribution of associations model, although discriminating among the alternative solution processes appears to be a serious challenge.

Synthesis and crystal structure of the two-dimensional coordination polymer catena(bis(μ3-iodo)-(μ 2-pyrazine)-di-copper(I))

The two-dimensional coordination polymer [Cu2i2(pyz)]n (where pyz = pyrazine) has been synthesized hydrothermally and structurally characterized by single crystal X-ray diffraction analysis. [Cu2i2(pyz)]n crystallizes in the space group P\({\bar 1}\) with a = 4.1759(4) A, b = 7.1281(7) A, c = 8.1279(8) A, α = 109.607(2)○, β = 101.769(2)○, γ = 96.676(2)○, and Z = 1. The sheet-like polymer is characterized by infinite “stair step” [Cu2i2]n double chains connected in two dimensions through bridging pyrazine ligands. The coordination environment about each copper is approximately tetrahedral having three Cu–I bonds and a single Cu–N bond.

Denucleation rates during Ostwald ripening: Distribution kinetics of unstable clusters

During Ostwald ripening in vapor–liquid or liquid–solid systems, unstable clusters, which are smaller than the critical nucleus size, rapidly disappear. This denucleation process is distinct from the reversible dissolution of stable clusters that are larger than the critical size but are more soluble than larger clusters because of the Gibbs–Thomson effect. Thus, ripening involves larger clusters growing, smaller clusters shrinking, and unstable clusters rapidly disintegrating. We show how the denucleation rate can be estimated based on the appropriate cluster distribution dynamics (population balance) equations. Monomer addition and dissociation from an unstable cluster occur at rates determined by the energy profile, which is formulated with classical nucleation concepts. Effectively, the cluster loses free energy as monomers dissociate, and falls down the energy stair steps. Numerical results for the distribution dynamics equations reveal the influence of the minimum number of dimensionless parameters, and demonstrate that denucleation is very fast compared to the ripening rate.

The effects of early rollback in total knee arthroplasty on stair stepping

We investigated the effects of early compared with late (ie, in flexion) rollback on quadriceps efficiency during stair stepping. We studied 10 patients with the IB II (Zimmer, Warsaw, IN) total knee arthroplasty (TKA), designed to enforce rollback at 73° of knee flexion; 9 patients with the Maxim PS (Biomet, Inc, Warsaw, IN) TKA, designed to enforce rollback between 20° and 30° of flexion; 8 patients with the TRAC PS (Biomet, Inc, Warsaw, IN) mobile bearing TKA, designed to enforce rollback at 8° of flexion; and 21 healthy control subjects during stair stepping. We measured the external knee flexion moments, which must be largely balanced by quadriceps force acting over the quadriceps lever arm, as indicators of quadriceps efficiency. The peak external knee flexion moment generated by the IB II patients during stair stepping was 12.4% and occurred at 65° of knee flexion. This moment was significantly less (P=.006) than the peak moment, 17.6%, generated by the healthy controls. Knee flexion for the IB II patients did not reach 73°, and rollback was not enforced until after the peak moment (ie, maximum demands on the quadriceps) had been attained. The peak moments generated by the TRAC PS patients, 14.2%, and Maxim patients, 14.8%, were not significantly different from that of the controls. These results suggest that early as compared with late rollback returns more normal quadriceps efficiency during stair stepping. Copyright 2002, Elsevier Science (USA). All rights reserved.

Modified Stepladder Lip Flap in Secondary Oral Commissure Reconstruction

In this paper we describe our experience using a two-stage reconstruction procedure in 24 patients who underwent ablative buccal cancer resection. In the first stage, cheek defects were reconstructed using free radial forearm flap in 10 of the patients, and free anterolateral thigh flap in 14 of the patients. Modified stepladder lip flap for oral commissure reconstruction followed in the second stage. The modified stepladder lip flap is different from the traditional stair step flap in that each step of the flap consists of different components of tissue. The first step is a full-thickness layer comprising skin, orbicularis oris muscle and mucosa. The second step is a partial-thickness layer comprising skin, subcutaneous fat and partially split orbicularis oris muscle. The third step is a dermis layer. The 24 patients in the study (all male, with a mean age of 51 years old) were followed up for at least 6 months after the second stage commissure reconstruction. Prior to commissure reconstruction, all had symptoms of oral incompetence (saliva drooling and food/liquid expulsion), and all obtained adequate oral competence after surgery. Nine patients resumed a regular diet, 8 patients had a semi-solid diet and 7 patients had a soft diet after surgery. Six of the patients developed mild microstomia postoperatively though did not have difficulty with dietary intake. All the patients were satisfied with their postoperative appearance. Postoperative scar contracture did not occur in any of the patients. Using this technique, continuity and function of the orbicularis oris muscle can be restored, and satisfactory cosmetic and functional results can be achieved.

Delayed onset of quadriceps activity and altered knee joint kinematics during stair stepping in individuals with knee osteoarthritis

Hinman RS, Bennell KL, Metcalf BR, Crossley KM. Delayed onset of quadriceps activity and altered knee joint kinematics during stair stepping in individuals with knee osteoarthritis. Arch Phys Med Rehabil 2002;83:1080-6. Objective: To determine if the electromyographic onset of vastus lateralis and kinematic knee joint motion in individuals with knee osteoarthritis (OA) differs from that of asymptomatic persons, during the task of stair stepping. Design: Cross-sectional. Setting: University laboratory in Australia. Participants: Twenty-five participants with symptomatic knee OA and 33 asymptomatic controls. Interventions: Not applicable. Main Outcome Measures: Surface electromyography to determine the onset of vastus lateralis activity. Two-dimensional kinematic analysis of sagittal plane knee motion during stance phase of stair ascent and descent. Results: Participants with knee OA showed delayed onset of vastus lateralis activity during stair descent (P<.05) but not ascent. Both groups displayed a similar total range of knee motion. However, during stair descent, participants with OA had less knee flexion during early stance (P<.05) than controls. Conclusion: Individuals with knee OA display altered quadriceps function and knee joint kinematics during stair descent. These impairments may have implications for force attenuation across the knee joint and warrant future investigation. © 2002 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation

N-Channel Field-Effect Transistors from Blends of Conjugated Polymers

We report the first field-effect transistors from blends of conjugated polymers and the determination of the field-effect mobility of electrons as a function of blend composition. It is found that the field-effect electron mobility (μe) in a series of 12 binary blends of poly(benzobisimidazobenzophenanthroline) (BBL, μe = 5 × 10-4 cm2/Vs) and poly(p-phenylene-2,6-benzobisthiazole) (PBZT, μe = 2 × 10-7 cm2/Vs) has a novel “stair step” dependence on composition. The electron mobility is relatively high (5 × 10-5 cm2/Vs) and constant over a wide blend composition range (x = 0.05−0.6, wt fraction of PBZT). At higher concentration of the lower-mobility component, the electron mobility falls exponentially with composition. The results suggest that thin film transistors with relatively high mobility may be realized in blends of conjugated polymers if one of the components has a sufficiently high mobility. The observed “stair step” electron mobility dependence on blend composition is not explained by current theories of hopping transport.

THERAPEUTIC PATELLAR TAPING CHANGES THE TIMING OF VASTII MUSCLE ACTIVATION IN PEOPLE WITH PATELLOFEMORAL PAIN

PURPOSE: Despite clinical success and research evidence that patellar taping reduces patellofemoral pain (PFP), its mechanism of action is largely unknown. It is possible that patellar taping changes the relationship between the onset of the medial and lateral vastii in people with PFP. The aim of this study was to compare the effect of therapeutic tape, control tape and no tape, on the EMG onset of vastus medialis oblique (VMO) and vastus lateralis (VL) in a stair stepping task using a randomised within-subject design in participants with and without PFP. METHODS: 10 subjects (3m, 7f) diagnosed with PFP on the basis of clinical examination by an experienced musculoskeletal physiotherapist and 12 asymptomatic controls (4m, 8f) were recruited. Surface electrodes were placed over the muscle bellies of VMO and VL. EMG onsets of VMO and VL were assessed during the concentric and eccentric phases of a stair stepping task. Each subject was tested under all three test conditions in a randomised order. RESULTS: In the subjects with PFP the application of therapeutic patellar tape was found to alter the temporal characteristics of VMO and VL activation (earlier onset of VMO) whereas control tape had no effect. In contrast, there was no change in the EMG onset of VMO and VL with the application of either control or therapeutic tape to the knee in asymptomatic subjects. Additionally therapeutic taping in the PFP group resulted in significantly less pain during stair stepping compared with pain in both the control and no tape conditions. There was no difference in pain between the no tape and control taped condition. DISCUSSION: These results provide the first evidence that application of therapeutic tape to the patella changes the relative temporal activity of the vastii in people with PFP. Since therapeutic tape led to an earlier onset of VMO compared with VL, this may have a positive effect on patellar tracking.

COMPARISON OF SINGLE‐PHASE AND HIGH‐FREQUENCY GENERATORS FOR X‐RAY UNITS

The purpose of this study was to compare characteristics and performances between single-phase (SP) and high-frequency (HF) generators for x-ray units dedicated to veterinary radiology practice. A 30-kW SP and a 30-kW high HF generator connected to a rotating anode x-ray tube were used for the study. Source-film distance, screen/film combination, and film processing were kept the same during the experiment. The mAs value yielding a similar film optical density of a stair step phantom, as assessed by a densitometer and a similar dose, as assessed by a solid state detector, was estimated for different kVp values. The ratio of the mAs used with the SP generator to the equivalent mAs used with the HF generator to produce similar film density or radiation dose was calculated. Subject contrast was measured for different kVp values as the relative difference in film optical density between two steps of the phantom. The waveform of the tube current was recorded for the two generators using an oscilloscope. Motion artifact was produced on a lateral radiograph of a canine tarsus using the two generators. Reproducibility was assessed by comparing the variances of film density measurements made on the central step of the phantom on 10 consecutive images produced with the two generators. mAs ratios (SP/HF) to obtain similar film optical density ranged from 2 (for 90kVp) to 2.5 (for 70 kVp), and mAs ratios to obtain similar radiation dose ranged from 1.2 (for 100 kVp) to 1.4 (for 70 kVp). Image contrast was slightly higher for the SP than for the HF generator. Current waveform for the SP generator was half-sinusoidal and it was almost continuous for the HF generator. Motion artifact appeared as blur for the HF generator and as several regularly placed images of the subject for the SP generator. Reproducibility was significantly better for the HF than for the SP generator (P = 0.047). It was concluded that the HF generator was approximately two times more efficient, had a better reproducibility, and produced images with a lower contrast than the SP generator. Motion artifact appears differently due to different current waveform.

Phase-controlled stair-step decay of autoionizing radial wave packets

The time-dependent survival probabilities of autoionizing $4pNd$ wave packets in calcium have been measured. Femtosecond laser pulses induce sequential isolated-core excitations of singly excited $4sNd$ radial wave packets to create and probe the nonstationary doubly excited states. Stair step rather than exponential decay of the wave packets is observed. Moreover, we show that the autoionization lifetime can be varied by a factor of five by adjusting the relative phases of the constituent eigenstates in the packet. The stair-step decay structure and its dependence on the wave packet phase is interpreted using an intuitive time-domain picture. The experimental results are in excellent agreement with a K-matrix based, 28-channel quantum-defect theory calculation as well as with an approximate two-channel formulation.

慢性期の小脳失調症患者に対して水中歩行訓練を行い良好な結果を得た１例

The specific effect of general dynamic water exercise in 41 year-old woman with chronic cerebellar ataxia induced by meningitis was observed. She was conservatively treated and took bed rest for two weeks, and she suffered from severe dynamic and static ataxia. And exercise under weight-bearing and bandage pressure and Frenkel exercise was applied for nine months. However her disability was not improved. And then she took a 30-minute walking practice in water twice weekly. After that training of 3 months, dramatic improvements in trunk balance and walking speed were demonstrated. She could stand up and walk by herself. The FIM scores for walking, stair stepping and transfer also improved. We suggested that walking practice in water could contribute to improve her ataxia.

Analgesic effect of etidronate on degenerative joint disease

In the present study, 80 patients with degenerative joint disease, spondylosis deformans, and/or osteoarthritis of the knee with back or joint pain, especially on movement and strain, were randomly divided into four groups. Group A received no etidronate, while groups B, C and D received 66, 133 and 200 mg/day etidronate, respectively, for 12 months. Every 3 months, after evaluating subjective pain on a visual rating scale (VRS), skin impedance was measured with subjects in a quiet sitting position and with the application of various strains on the spine and knee, including standing up from quiet sitting on a chair, bending forward to flex the spine, squatting to flex the knee, walking 20 paces on a flat floor, ascending 10 stair steps and descending 10 stair steps. A dose related improvement of subjective pain on the VRS with a parallel decrease in the percentage fall in skin impedance was noted. The intra-individual coefficients of variation (CV) of L1-L4 bone mineral density (BMD) on dual-energy X-ray absorptiometry were calculated as a possible index for spondylotic changes before and after treatment as an indication of spondylotic deformity, because no established method is yet available to evaluate such changes objectively. A dose-related decrease in CV of BMD was also noted, parallel to the analgesic effect.

A new strategy for applying the parabolic equation to a penetrable rough surface

The range-dependent parabolic equation (PE) propagates an auxiliary field that roughly corresponds to the square root of the downrange flux. At the ocean bottom, the interface is broken into stair steps, and this auxiliary field is conserved at the vertical interfaces. Because of its success in matching benchmark solutions, this method is widely used to model standard propagation problems in underwater acoustics. However, when the interface is rough at the wavelength scale, the physics of the problem changes, and the standard approach ceases to be practicable. This talk presents a new approach specifically designed to handle this important problem. The Foldy–Wouthuysen transformation generates the PE for this auxiliary field, complete with a full suite of boundary conditions. In the discrete problem, the boundary conditions are used to evaluate the Hamiltonian on the interface, and the result is used to perform the next downrange step. At lowest order, the new theory streamlines the stair step method, and frees it from ad hoc impositions such as those spawned by the density jump at the ocean bottom. The approach also systematically provides higher-order corrections. [Work supported by ONR.]

Delayed onset of electromyographic activity of vastus medialis obliquus relative to vastus lateralis in subjects with patellofemoral pain syndrome

Cowan SM, Bennell KL, Hodges PW, Crossley KM, McConnell J. Delayed onset of electromyographic activity of vastus medialis obliquus relative to vastus lateralis in subjects with patellofemoral pain syndrome. Arch Phys Med Rehabil 2001;82:183-9. Objective: To determine whether electromyographic (EMG) onsets of vastus medialis obliquus (VMO) and vastus lateralis (VL) are altered in the presence of patellofemoral pain syndrome (PFPS) during the functional task of stair stepping. Design: Cross-sectional. Setting: University laboratory. Patients: Thirty-three subjects with PFPS and 33 asymptomatic controls. Interventions: Subjects ascended and descended a set of stairs—2 steps, each 20-cm high—at usual stair-stepping pace. EMG readings of VMO and VL taken on middle stair during step up (concentric contraction) and step down (eccentric contraction). Main Outcome Measures: Relative difference in onset of surface EMG activity of VMO compared with VL during a stair-stepping task. EMG onsets were determined by using a computer algorithm and were verified visually. Results: In the PFPS population, the EMG onset of VL occurred before that of VMO in both the step up and step down phases of the stair-stepping task (p <.05). In contrast, no such differences occurred in the onsets of EMG activity of VMO and VL in either phase of the task for the control subjects. Conclusion: This finding supports the hypothesized relationship between changes in the timing of activity of the vastimuscles and PFPS. This finding provides theoretical rationale to support physiotherapy treatment commonly used in the management of PFPS.

地下鉄駅舎における探索歩行時の注視に関する研究

Visual search at subway stations, while subjects transfer or find the exit, were discussed and compared with way-finding in a small maze. The fixation durations on signs and ceiling were distributed from shorter to longer duration. However, durations on the floor were shorter. The fixation movement patterns on signs were repetitive and concentrated. Slanting fixations were not only beyond the occluding edge of the wall, but also beyond column, pedestrians, a stair step and ceiling. After the entire path was learned, number of fixations on the wall, column, and sign decreased, and those on the floor, ceiling, and pedestrians increased.

Full Wave Analysis of Rounded Ends Iris and Its Application in Coupling

An accurate analysis of the rounded ends iris using the mode matching technique is presented. Stair steps are used to approximate the curved ends of the iris to simplify the modeling procedure. The characteristic equation of the iris can be obtained by matching the boundaries between the rectangular stair steps. By applying the cascading procedure, the reflection coefficient of the coupling structure can be obtained. From the phase variation of the reflection coefficient and circuit theory, resonant frequency and input/output coupling of the structure are accurately determined. The coupling by the iris between a rectangular waveguide and a resonator is calculated and compared to the approximate method. The results are also compared to the finite element method (HFSS) and shown to be in good agreement.

The test–retest reliability of the onset of concentric and eccentric vastus medialis obliquus and vastus lateralis electromyographic activity in a stair stepping task

Study design: Test–retest reliability using a repeated measures design. Objectives: The aim of this study was to evaluate the test–retest reliability of measurement of onsets of electromyographic (EMG) activity of vastus medialis oblique (VMO) and vastus lateralis (VL) during a stair stepping task. Background: Differences in the timing of onset of VMO and VL have been hypothesized to contribute to patellofemoral pain syndrome. However, no studies have investigated the reliability of the EMG onset of VL and VMO using a direct measure of EMG onset timing. Methods and measures: Ten asymptomatic subjects were assessed by the same examiner on two occasions one week apart. The relative difference in the timing of onset of EMG activity of VMO and VL was quantified by subtracting VMO EMG onset from that of VL. Results: The difference in EMG onsets during the concentric task (step up) had an intraclass correlation coefficient (ICC) of 0·91 with a standard error of measurement of 6·20 ms (95% CL 12·20ms). The difference in EMG onsets during the eccentric task (step down) had an ICC of 0·96 with a standard error of measurement of 5·90ms (95% CL 11·56ms). Conclusions: The results indicate that in a normal population a difference of greater than 12·20ms in the concentric and 11·56ms in the eccentric phase of stair stepping would be required to demonstrate a significant difference in EMG onsets of VMO and VL between groups. Further research is required to determine the degree of measurement error in a population with specific pathologies.

Coordination polymers of copper(I) halides.

A total of 21 complexes of CuX (X = Cl, Br, I) with bridging ligand (B = 4,4'-dipyridyl (Bpy), pyrazine (Pyz), quinoxaline (Quin), phenazine (Phz), 1,4-diazabicyclo[2.2.2]octane (DABCO), and hexamethylenetetramine (HMTA)) have been synthesized. The products show two stoichiometries: [CuXB] (type 1) and [(CuX)2B] (type 2). Both types can be obtained for B = Bpy, depending on the conditions of preparation. In these cases, the type 2 stoichiometry is the kinetic product. Type 2 complexes only are found for B = Pyz (X = I), Quin, Phz, DABCO, and HMTA. Type 1 complexes form for Pyz (X = Cl, Br). Thermogravimetic analyses of the complexes reveal the general decomposition trend: 1 --> 2 --> [(CuX)2B(1/2)] --> CuX. The X-ray crystal structure of [CuBr(Pyz)] (type 1) features copper atoms bridged by Br and Pyz, forming 2D sheets of fused rectangular Cu4Br2(Pyz)2 units. The X-ray structure of [(CuI)2(Quin)] (type 2) shows 2D layers composed of [Cu2I2]infinity "stair step" chains which are cross-linked by Quin ligands. A total of 16 complexes of CuXL (L = P(OPh)3) with bridging ligand (B = those above and 1,4-dimethylpiperazine (DMP)) have also been prepared. All of these products, except those of HMTA, are of type 3 formulation, [(CuXL)2B]. The HMTA products have the formula [CuX(HMTA)], type 4. Thermal decomposition of the type 3 and 4 complexes occurs with initial loss of B, L, or both. The X-ray structures of [(CuBrL)2(Bpy)] and [(CuBrL)2(Pyz)] (type 3) reveal 1D chains formed from rhomboidal (LCu)2Br2 units linked by the B ligand. The type 4 structure of [CuBrL(HMTA)] is shown by X-ray to be a simple halide-bridged dimer.

The effects of the rotating-hinge total knee replacement on gait and stair stepping

We studied 7 younger and 5 older patients who had rotating-hinge total knee replacements, 10 patients who had semiconstrained total knee replacements, and 8 younger and 11 older healthy control subjects to determine the effects of the rotating-hinge device on gait and stair stepping. The younger patients with the rotating-hinge device had few significant differences from the younger control subjects during gait or stair stepping. Theolder patients with the rotating-hinge device had several significant differences from both the older control subjects and subjects with the semiconstrained device during gait and stair stepping. Nevertheless, the proportions of older patients with the 2 devices who were able to perform the step on activity for the highest step were the same.

Abstract

The reflection coefficient of sloping solid walls was developed theoretically and verified experimentally. In the theoretical derivation, a sloping solid wall was simulated by an N-step staircase. In this circumstance, each stair step would raise a sub-reflected wave, and N stairs would raise N sub-reflected waves. Then the reflected wave from the staircase was assumed to be a superposition of these N sub-reflected waves. As a result, letting N approach infinity would make the reflected wave from the staircase become equivalent to the reflected wave from the sloping solid wall. Practically, a number of steps rather than infinity was selected for N when the reflection coefficient of the sloping wall was calculated. After the appropriate N number was selected, reflection coefficients of sloping walls with varied wall slopes were calculated under different wave conditions. Results showed that the reflection coefficient is closely related to the incident wave period and the wall slope for h/L 0.5, the reflection coefficient is merely a function of wall slope. To verify theoretical calculations, experimental tests were performed and compared with theoretical results. Agreement between theory and experiment is good.