Bow Test Research Articles

Pseudo-spontaneous nystagmus in lateral semicircular canal benign paroxysmal positional vertigo: Correlation with bow and lean test in a pitch plane.

ObjectivesWe investigated the incidence and characteristics of pseudo-spontaneous nystagmus (PSN) in benign paroxysmal positional vertigo involving the lateral semicircular canal (LC-BPPV) and evaluated the correlation between PSN and the bow and lean test.MethodsWe examined nystagmus in the sitting position using video-oculography goggles in 131 LC-BPPV patients. The positioning test and bow and lean test were also performed. Patients were divided into canalolithiasis and cupulolithiasis groups according to the character of nystagmus. In each group, the incidence and direction of PSN, correlation with the bow and lean test, and treatment outcome were analyzed.ResultsPSN was observed in 25 cases (19.1%) in LC-BPPV patients, 7 of which were canalolithiasis and 18 of which were cupulolithiasis (p = 0.098). Of the 25 patients with PSN, 21 (84%) exhibited nystagmus consistent with the lean test whereas 4 (16%) exhibited nystagmus consistent with the bow test. In patients with PSN, nystagmus was observed in the bow and lean test in all cases (23/23), but in patients without PSN, no nystagmus was observed in 13 cases (13/87) in the bow and lean test (p = 0.048). The number of barbecue maneuvers performed until the end of treatment was 1.4 ± 0.7 in patients with PSN and 1.4 ± 0.9 in those without PSN (p = 0.976).ConclusionWe identified PSN in patients with LC-BPPV irrelevant of subtype. Moreover, all patients with PSN showed nystagmus in the bow and lean test. The direction of PSN was mostly consistent with that of the lean test (21/25, 84%). The presence of PSN was not related to the treatment outcome in this study.

Marble bowing: comparative studies of three different public building facades

The veneer cladding of the Oeconomicum (OEC, Göttingen), the State Theatre of Darmstadt (STD, Darmstadt) and of the State and University Library (SUB, Göttingen) is characterised by pronounced bowing after a short time of exposure. Direct comparison of bowing data related to measurements from 2000 to 2003 at the SUB clearly show that the amplitude in bowing had significantly increased. The bowing is different in intensity and orientation (concave, convex). The cladding material (Peccia marble, Rosa Estremoz marble and Carrara marble) are different in lattice preferred orientation, grain size distribution and grain interlocking. Depending on the bowing, panels may show cracks mostly initiated at the dowels. The percentage of visible cracks and breakouts increases with the amplitude of bowing except for the STD. Repetitive heating–cooling under dry conditions leads to considerable inelastic residual strain only after the first or second thermal cycle. The residual strain continuously increases again if water is present, whereby the moisture content after a thermal cycle has a certain impact on the decay rate. The water-enhanced thermal dilatation strongly correlates with the deterioration rate obtained from the laboratory bow test. Detailed petrophysical investigations provide evidence that with increasing bowing a decrease of mechanical properties (flexural strength or breaking load at dowel hole) occur. Marble degradation is also connected with the increase in porosity and a general shift of the maximum pore radii to larger pore sizes. On-site damage analyses were combined with laboratory tests of the bowing potential to constrain factors that may influence the risk failure. The experimental bowing data clearly demonstrate that after 40 heating cycles combined with the effect of moisture a certain impact on the decay rate is observed. In the case of demounted panels the bowing tests show that already strongly deformed panels from the building exhibit a lower bowing potential than those with lower amplitudes of bowing. This is not the general case for all marble types. Finally, the artificial bowing causes a significant reduction of the flexural strength and the breaking load at the dowel hole. The strength loss of the experimentally aged claddings combined with on-site damage analyses led to conclusions concerning risk assessment and the predicted lifetime of the investigated marble claddings.

The Influence of the Climatic Factors on the Decay of Marbles: an Experimental Study

Stone decay is affected by the influence of climatic factors. In particular marble degradation, that could be expressed by decohesion and /or bowing, is mainly due to the action of temperature and water (rains and relative humidity). In this work non destructive and destructive tests have been performed to evaluate the decay of marble slabs subjected both to natural exposition and to artificial ageing tests (Lab - Bow test). Measurements of Ultrasonic Pulse Velocities (UPV) and bowing have been executed periodically on marble slabs exposed for a period of four years as preliminary field tests. On the base of this work an integrated test methodology to monitoring and previewing the behaviour of faA§ade slabs have been set up. The methodology has been applied on the marble faA§ade of modern building of centre Italy and consists of in situ and laboratory tests. In laboratory a destructive test (flexural strength) has been added to the non destructive tests to evaluate the decay before and after cycles of an ageing test. The results of the analysis, show an evaluative trend of the decay, though it changes its slope after 25 cycles of the ageing test. Moreover this work confirms the effectiveness of the employed non destructive tests and their god correlation with the mechanical tests.

The combined effect of moisture and temperature on the anomalous expansion behaviour of marble

Three calcitic marble types often used as cladding material and different in lattice preferred orientation (texture), grain shape preferred orientation, grain size distribution and grain interlocking are investigated to study the combined effect of thermal cycles (day-night) and moisture on the decay of marble, particularly on the bowing phenomenon. Repetitive heating-cooling under dry conditions leads to considerable inelastic residual strain only in the first thermal cycle. The residual strain continuously increases again if water is present, whereby the moisture content after a thermal cycle has a certain impact on the decay rate. The water-enhanced thermal dilatation strongly correlates with the deterioration rate obtained from the laboratory bow test. All applied approaches reveal that the texture in combination with the grain shape preferred orientation control the intensity and anisotropy of marble deterioration, thus, the cutting direction of facade panels has to be considered in terms of durability. On-site analysis from building facades confirm the laboratory results such as the bowing tendency of different marbles, directional dependence, relevance of moisture content during cyclical heating and the loss of strength due to environmental impact.

The bow test for the subacromial impingement syndrome

Because of the biomechanics of the glenohumeral joint, impairment of rotator cuff function leads to cranial migration of the humeral head, impinging the greater tubercle against the coraco-acromial arch and irritating the subacromial bursa. When bursal irritation has become established, active elevation of the arm against gravity will cause pain within an arc of motion. When a patient with a painful arc is asked to bend forward and let the arm hang, the same arc will become painless. This noninvasive clinical test called the "bow test" is a simple means by which subacromial impingement can be clinically identified as the source of pain in the painful arc of shoulder motion.