First- and second-order transformational apparent motion rely on common shape representations.

When one figure is replaced with another that overlaps its spatial location, observers perceive an illusory, continuous shape change of the original object, a phenomenon known as transformational apparent motion (TAM). The current study investigated the extent to which TAM depends on a common, high-level shape representation that is independent of the shape-defining attribute. Specifically, we tested whether TAM is perceived similarly for both first- and second-order objects, defined by luminance and texture contrast, respectively. A compelling motion percept was observed in second-order TAM displays that was comparable to that seen in first-order TAM displays. Importantly, TAM for both stimulus classes showed the same pattern over a range of stimulus onset asynchronies. These results support the high-level shape account, indicating that TAM is driven by segmentation mechanisms that rely on high-level shape information rather than low-level visual characteristics.

Newer fluoroquinolones for treating respiratory infection: do they mask tuberculosis?

Possible masking of tuberculosis (TB) in treatment of community-acquired respiratory infection by newer fluoroquinolones has not been examined in randomised controlled trials. We undertook a randomised, open-label controlled trial involving adults with community-acquired pneumonia or infective exacerbation of bronchiectasis encountered in government chest clinics in Hong Kong. 427 participants were assigned by random permutated blocks of 20 to receive either amoxicillin clavulanate (n = 212) or moxifloxacin (n = 215). Participants were followed for 1 yr for active pulmonary TB. Excluding three participants with positive baseline culture, 13 developed active pulmonary TB: 10 (4.8%) out of 210 were given amoxicillin clavulanate, and three (1.4%) out of 214 were given moxifloxacin. The difference was significant by both proportion and time-to-event analysis. Post hoc analysis showed a significant decrease in the proportion with active pulmonary TB from 4.8% to 2.4% and 0% among participants given amoxicillin clavulanate (n = 210), moxifloxacin for predominantly 5 days (n = 127) and 10 days (n = 87), respectively. The log rank test for trend also showed a significant difference between the three subgroups. Regression models reaffirmed the linear effect; the adjusted odds ratio (95% confidence interval) of active pulmonary TB after moxifloxacin exposure up to predominantly 10 days was 0.3 (0.1-0.9). Newer fluoroquinolones appear to mask active pulmonary TB.

Review of on-line and near real-time spectroscopic monitoring of processes relevant to nuclear material management.

Spectroscopic chemometric based on-line monitoring of used nuclear fuel (UNF) reprocessing solutions and characterization of legacy nuclear waste (LNW) stored at Hanford is discussed in this manuscript. Utilizing on-line and near real-time monitoring, as opposed to traditional off-line monitoring, can significantly reduce the cost, risk and improve the efficiency of characterizing UNF and LNW processing streams. Specifically, this manuscript will highlight the benefits of spectroscopy-based monitoring approaches, which generally include the ability to collect data non-destructively. Furthermore, significant literature precedence supports the use of various real-time analysis methods, including chemometric analysis, that enable near-instantaneous conversion of spectroscopic data into information useable by process operators. This approach can accurately quantify and qualify nuclear material in near-real time enabling immediate condition characterization and potential diversion detection within UNF reprocessing streams and LNW. The ability to be applied in a real reprocessing plant and in an actual Hanford waste tank/transfer pipe has been demonstrated by applying this technique to accurately quantify analytes in real UNF streams and LNW samples. The future development of spectroscopy-based on-line monitoring is also discussed in this manuscript.

Differences Between the East and the West in Managing Advanced-Stage Non-small Cell Lung Cancer.

Lung cancer is a common cancer associated with high mortality rates worldwide. Unfortunately, it usually presents at a late stage, precluding the chance of curative therapy. The discovery of oncogenic driver mutations in patients with non-small cell lung cancer over the past 20 years has led to new molecular targeted therapies that have dramatically improved treatment efficacy and quality of life. New generations of therapy that target the drug-resistant mutations have also quickly evolved, benefiting patients who are refractory or intolerant to first-line targeted therapy. Eastern patients, from Southeast Asia, Japan and China, are known to have a higher incidence of epidermal growth factor receptor mutation. Therefore, compared with the West, more patients would benefit from these recent advances. In contrast, survival of patients without driver mutations has benefited from advances in novel therapeutics, including the immune checkpoint inhibitors. The current review aims to highlight the recent developments in the management of advanced-stage non-small cell lung cancer and to compare the differences in clinical practice between Eastern and Western countries.

Management of patients admitted with pneumothorax: a multi-centre study of the practice and outcomes in Hong Kong.

OBJECTIVE: To examine the management practice of pneumothorax in hospitalised patients in Hong Kong, especially the choice of drainage options and their success rates, as well as the factors associated with procedural failures. DESIGN: Retrospective study. SETTING: Multi-centre study involving 12 public hospitals in Hong Kong. PATIENTS: All adult patients admitted as an emergency in the year 2004 with a discharge diagnosis of 'pneumothorax' were included. Data on the management and outcomes of the various types of pneumothoraces were collected from their case records. RESULTS: Altogether these patients had 1091 episodes (476 primary spontaneous pneumothoraces, 483 secondary spontaneous pneumothoraces, 87 iatrogenic pneumothoraces, and 45 traumatic pneumothoraces). Conservative treatment was offered in 182 (17%) episodes, which were more common among patients with small primary spontaneous pneumothoraces (71%). Simple aspiration was performed to treat 122 (11%) of such episodes, and had a success rate of 15%. Aspiration failure was associated with having a pneumothorax of size 2 cm or larger (odds ratio=3.7; 95% confidence interval, 1.2-11.5; P=0.03) and a smoking history (4.1; 1.2-14.3; P=0.03). Intercostal tube drainage was employed in 890 (82%) episodes, with a success rate of 77%. Failure of intercostal tube drainage was associated with application of suction (odds ratio=4.1; 95% confidence interval, 2.8-5.9; P<0.001) and presence of any tube complications (1.55; 1.0-2.3; P=0.03). Small-bore catheters (<14 French) were used in 12 (1%) of the episodes only. Tube complications were encountered in 214 (24%) episodes. CONCLUSION: Notwithstanding recommendations from international guidelines, simple aspiration and intercostal tube drainage with small-bore catheters were not commonly employed in the management of hospitalised patients with the various types of pneumothoraces in Hong Kong.

Characteristics of false-negative ThinPrep cervical smears in women with high-grade squamous intraepithelial lesions.

OBJECTIVE: To examine the cellular characteristics and other possible factors affecting the correct prediction of ThinPrep cervical smears from patients with high-grade squamous intraepithelial lesions. DESIGN: Retrospective study. SETTING: Private anatomical pathology service, Hong Kong. PATIENTS: Patients (n=98) with biopsy-confirmed high-grade squamous intraepithelial lesion of the uterine cervix encountered between 2004 and 2006. MAIN OUTCOME MEASURES: Correct prediction of the cervical ThinPrep Papanicolaou tests. RESULTS: There were no significant differences in age, hormonal status, degree of inflammation, and the presence or absence of endocervical/metaplastic cells between the true-positive and false-negative groups. There was a significant difference in the number of abnormal cells present and the screening time between the two groups. Approximately 79% (34/43) false-negative smears had 100 or less abnormal cells, while only 11% (5/45) true-positive smears had 100 or less abnormal cells (P<0.001). The true-positive smears were also more likely to contain koilocytic cells and abnormal cells with hyperchromatic nuclei. CONCLUSIONS: The number of abnormal cells present, the presence or absence of koilocytic cells, and the presence or absence of abnormal cells with nuclear hyperchromasia appeared to be independent factors affecting the correct prediction of smears from patients with high-grade squamous intraepithelial lesions.

Grouping inhibits motion fading by giving rise to virtual trackable features.

After prolonged viewing of a slowly drifting or rotating pattern under strict fixation, the pattern appears to slow down and then momentarily stop. The authors show that grouping can slow down the process of "motion fading," suggesting that cortical configural form analysis interacts with the computation of motion signals during motion fading. The authors determined that grouping slows motion fading because it can give rise to trackable features, such as virtual contour terminators not present in the image, that possess stronger motion signals than would occur in the absence of such trackable features. That a continuously rotating stimulus will eventually be perceived to stop, despite the presence of such trackable features, suggests that the motion-from-form system itself can be fatigued. The finding that stationary form can remain visible even after the motion signal has faded suggests that the neural bases of motion visibility and form visibility arise from different neuronal populations.

Rotating dotted ellipses: motion perception driven by grouped figural rather than local dot motion signals.

UNLABELLED: Unlike the motion of a continuous contour, the motion of a single dot is unambiguous and immune to the aperture problem. Here we exploit this fact to explore the conditions under which unambiguous local motion signals are used to drive global percepts of an ellipse undergoing rotation. In previous work, we have shown that a thin, high aspect ratio ellipse will appear to rotate faster than a lower aspect ratio ellipse even when the two in fact rotate at the same angular velocity [Caplovitz, G. P., Hsieh, P. -J., & Tse, P. U. (2006) Mechanisms underlying the perceived angular velocity of a rigidly rotating object. Vision Research, 46(18), 2877-2893]. In this study we examined the perceived speed of rotation of ellipses defined by a virtual contour made up of evenly spaced dots. RESULTS: Ellipses defined by closely spaced dots exhibit the speed illusion observed with continuous contours. That is, thin dotted ellipses appear to rotate faster than fat dotted ellipses when both rotate at the same angular velocity. This illusion is not observed if the dots defining the ellipse are spaced too widely apart. A control experiment ruled out low spatial frequency "blurring" as the source of the illusory percept. CONCLUSION: Even in the presence of local motion signals that are immune to the aperture problem, the global percept of an ellipse undergoing rotation can be driven by potentially ambiguous motion signals arising from the non-local form of the grouped ellipse itself. Here motion perception is driven by emergent motion signals such as those of virtual contours constructed by grouping procedures. Neither these contours nor their emergent motion signals are present in the image.

Illusory color mixing upon perceptual fading and filling-in does not result in 'forbidden colors'.

A retinally stabilized object readily undergoes perceptual fading. It is commonly believed that the color of the apparently vanished object is filled in with the color of the background because the features of the filled-in area are determined by features located outside the stabilized boundary. Crane, H. D., & Piantanida, T. P. (1983) (On seeing reddish green and yellowish blue. Science, 221, 1078-1080) reported that the colors that are perceived upon full or partial perceptual fading can be 'forbidden' in the sense that they violate color opponency theory. For example, they claimed that their subjects could perceive "reddish greens" and "yellowish blues." Here we use visual stimuli composed of spatially alternating stripes of two different colors to investigate the characteristics of color mixing during perceptual filling-in, and to determine whether 'forbidden colors' really occur. Our results show that (1) the filled-in color is not solely determined by the background color, but can be the mixture of the background and the foreground color; (2) apparent color mixing can occur even when the two colors are presented to different eyes, implying that color mixing during filling-in is in part a cortical phenomenon; and (3) perceived colors are not 'forbidden colors' at all, but rather intermediate colors.

The infinite regress illusion reveals faulty integration of local and global motion signals.

We report a new visual illusion, where a global shape appears to continually move away from fixation, even though it remains a fixed distance from fixation. The illusion occurs because local motion signals within the object indicate motion away from fixation, and are incorrectly attributed by the visual system to the motion trajectory of the global object. A simple weighted vector summation of global and local motion signals, while a reasonable first approximation, cannot fully account for our data. We show that the faster the local motion signal, the more it biases judgments of global motion direction. We propose that local and global motion signals are summed non-linearly for this stimulus because as local motion speed increases, moving luminance blobs are visible for less time, affording less time to inhibit inappropriate component motion signals. This effect reveals the degree to which the visual system can incorrectly combine local and global motion signals belonging to a single object.

Stimulus factors affecting illusory rebound motion.

Stimulus attributes that influence a recently reported illusion called "illusory rebound motion" (IRM; [Hsieh, P.-J., Caplovitz, G. P., & Tse, P. U. (2005). Illusory rebound motion and the motion continuity heuristic. Vision Research, 45, 2972-2985.]) are described. When a bar alternates between two different colors, IRM can be observed to traverse the bar as if the color were shooting back and forth like the opening and closing of a zipper, even though each color appears in fact all at once. Here, we tested IRM over dynamic squares or disks defined by random dot or checkerboard textures to show that (1) IRM can be perceived in the absence of first-order motion-energy (or when the direction of net first-order motion-energy is ambiguous); (2) the direction of IRM is multistable and can change spontaneously or be changed volitionally; and (3) the perceived frequency of IRM is affected by several factors such as the contours of the stimulus, stimulus texture, and motion-energy.

Microsaccade directions do not predict directionality of illusory brightness changes of overlapping transparent surfaces.

Tse (2005) recently introduced a new class of illusory brightness changes where shifts of attention lead to shifts in perceived brightness across overlapping, transparent figures, under conditions of visual fixation. In the absence of endogenous attentional shifts, illusory brightness changes appear to shift from figure to figure spontaneously, much as occurs in other multistable phenomena. The goal of the present research is to determine whether fixational microsaccades are correlated with perceived brightness changes. It has recently been demonstrated that microsaccades can reveal the direction of covert attentional shifts either toward (Engbert, R. & Kliegl, R. (2003). Microsaccades uncover the orientation of covert attention. Vision Research, 43, 1035-1045; Hafed, Z. M. & Clark, J. J. (2002). Microsaccades as an overt measure of covert attention shifts. Vision Research, 42(22), 2533-2545) or away from (Rolfs, M., Engbert, R., & Kliegl, R. (2004). Microsaccade orientation supports attentional enhancement opposite a peripheral cue: commentary on Tse, Sheinberg, and Logothetis (2003). Psychological Science, 15(10), 705-707) a peripheral cue under certain circumstances. Others (Horwitz, G. D. & Albright, T. D. (2003). Short-latency fixational saccades induced by luminance increments. Journal of Neurophysiology, 90(2), 1333-1339; Tse, P. U., Sheinberg, D. L., & Logothetis, N. K. (2002). Fixational eye movements are not affected by abrupt onsets that capture attention. Vision Research, 42, 1663-1669; Tse, P. U., Sheinberg, D. L., & Logothetis, N. K. (2004). The distribution of microsaccade directions need not reveal the location of attention. Psychological Science, 15(10), 708-710) found no change in the distribution of microsaccade directions as a function of where attention is allocated, although changes in the rate of microsaccades were observed in all of these studies in response to the onset of attentional reallocation. It is therefore possible that the distribution of microsaccade directions will change as a function of which figure is perceived to darken, or that changes in this distribution predict which figure will subsequently darken. We find no correlation between this distribution and which figure undergoes the effect, and therefore conclude that microsaccade directionality is not influenced by and does not influence which figure undergoes the effect. Moreover, the directions of microsaccades that occur immediately prior to a perceptual switch are not correlated with the perceived position of the figure that undergoes the effect. However, we do find that the rate of microsaccades decreases upon a perceptual switch, signifying an attentional shift coincident with the perceptual shift. We conclude that microsaccade directionality does not determine, predict, or cause which figure will subsequently be perceived to undergo an illusory brightness change.

Mechanisms underlying the perceived angular velocity of a rigidly rotating object.

The perceived angular velocity of an ellipse undergoing a constant rate of rotation will vary as its aspect ratio is changed. Specifically, a "fat" ellipse with a low aspect ratio will in general be perceived to rotate more slowly than a "thin" ellipse with a higher aspect ratio. Here we investigate this illusory underestimation of angular velocity in the domain where ellipses appear to be rotating rigidly. We characterize the relationship between aspect ratio and perceived angular velocity under luminance and non-luminance-defined conditions. The data are consistent with two hypotheses concerning the construction of rotational motion percepts. The first hypothesis is that perceived angular velocity is determined by low-level component-motion (i.e., motion-energy) signals computed along the ellipse's contour. The second hypothesis is that relative maxima of positive contour curvature are treated as non-component, form-based "trackable features" (TFs) that contribute to the visual system's construction of the motion percept. Our data suggest that perceived angular velocity is driven largely by component signals, but is modulated by the motion signals of trackable features, such as corners and regions of high contour curvature.

Illusory motion induced by the offset of stationary luminance-defined gradients.

An illusory motion induced by the offset of a stationary gradient stimulus is characterized. When a gradient stimulus, whose luminance contrast ranges gradually from white on one side to black on the other, is made to disappear all at once so that only the uniform white background remains visible, illusory motion is perceived. This motion lasts approximately 700 ms, as if the stimulus moves from the low to the high luminance contrast side. This gradient-offset induced motion does not occur for equiluminant color-defined gradient offsets, suggesting that it relies mainly on the magnocellular pathway. Our data are consistent with the hypothesis that this illusion is caused by the decay of the gradient afterimage.

Risk factors of long bone fracture in non-ambulatory cerebral palsy children.

OBJECTIVES: To identify the risk factors for long bone fractures in non-ambulatory cerebral palsy children. DESIGN. Case-control study. SETTING: A residential rehabilitation centre in Hong Kong. PATIENTS: The fracture group comprised 19 (13 male, 6 female) cerebral palsy children aged 4 years 5 months to 18 years 11 months (mean, 10 years; standard deviation, 3 years 9 months), who had their first long bone fracture during the period June 1992 to May 2001 inclusive. The control group was composed of 90 (46 male, 44 female) concomitant cerebral palsy residents aged 6 years 1 month to 16 years 11 months (mean, 9 years 11 months; standard deviation, 2 years 4 months) with no history of long bone fracture. MAIN OUTCOME MEASURES: Presence of features considered relevant to the risk of fracture, namely: anthropometry, feeding practice, orthopaedic surgery and duration of postoperative immobilisation, extremity contracture, anti-epileptic medications, and general health status in the 12 months prior to the fracture. RESULTS: Of the 19 fracture episodes, 18 occurred in the femur and one in the tibia/fibula. Multivariate analysis revealed that weight for age Z scores (adjusted odds ratio=0.41, 95% confidence interval, 0.19-0.86) and recent postoperative immobilisation (weeks) [adjusted odds ratio=1.35, 95% confidence interval, 0.97-1.89] were independent predictors for fracture occurrence. CONCLUSION: Early intervention targeting these risk factors may reduce the fracture risk in non-ambulatory cerebral palsy children.

Nissen fundoplication and gastrostomy in severely neurologically impaired children with gastroesophageal reflux.

OBJECTIVES: To study the effect of Nissen fundoplication and gastrostomy in severely neurologically impaired children. DESIGN: Prospective observational study. SETTING: Developmental Disabilities Unit of a regional medical centre in Hong Kong. PATIENTS: Children with severe neurological impairment and gastroesophageal reflux who were institutionalised between 1999 and 2004 inclusive. MAIN OUTCOME MEASURES: Incidence of vomiting, gastro-intestinal bleeding, and pneumonia in the baseline year and consecutive years following surgery; 24-hour oesophageal pH monitoring; recurrence rate (determined by 24-hour oesophageal monitoring); body weight; complications of surgery; and mortality. RESULTS: Twenty children, with a mean age at surgery of 8.5 (standard deviation, 3.5) years, were recruited. Nissen fundoplication was performed in nine children and 11 children underwent laparoscopic fundoplication. Children were monitored for 1.3 to 5.7 years (median, 3.5 years) after surgery. The incidence of vomiting and gastro-intestinal bleeding was significantly decreased following surgery (P < 0.001 and P = 0.001, respectively; Friedman's test). There was no difference between the preoperative and postoperative incidence of pneumonia (P = 0.973, Friedman's test). The median reflux index was reduced from 5.7% to 0.15% after surgery but six (30%) patients had recurrent gastroesophageal reflux. The mean body weight was 17.4 kg (standard deviation, 4.7 kg) at baseline and 22.8 kg (standard deviation, 4.4 kg) at the end of follow-up (P < 0.05, Student's t test). One patient had mild dumping syndrome soon after fundoplication. One patient had one episode of intestinal obstruction. Four patients died 1.9 to 5.0 years following surgery due to respiratory disease. CONCLUSION: Our results indicate that in severely neurologically impaired children with gastroesophageal reflux, vomiting, gastro-intestinal bleeding, and reflux indices based on 24-hour oesophageal pH monitoring were significantly reduced following fundoplication and gastrostomy. The incidence of pneumonia was unchanged. The recurrence rate of reflux was 30% and mortality rate was 20%.

Breakage of intramedullary femoral guide rod during total knee arthroplasty: a case report.

We report a rare complication during primary total knee arthroplasty. An intramedullary femoral guide rod was broken during insertion. The broken part jammed into the isthmus of the femur. An initial attempt to push the broken rod via the proximal femur by a guide wire to the distal femur was unsuccessful because the broken rod was lodged in the isthmus. Ultimately, the isthmus was opened using a flexible 9-mm end-cutting reamer, and the broken rod was pushed down to the distal femoral entry site in an antegrade fashion under image intensification. Selecting a more medial entry site on the intercondylar notch with a smaller valgus cutting angle and using a shorter guide rod can avoid such a breakage.

Illusory rebound motion and the motion continuity heuristic.

A new motion illusion, "illusory rebound motion" (IRM), is described. IRM is qualitatively similar to illusory line motion (ILM). ILM occurs when a bar is presented shortly after an initial stimulus such that the bar appears to move continuously away from the initial stimulus. IRM occurs when a second bar of a different color is presented at the same location as the first bar within a certain delay after ILM, making this second bar appear to move in the opposite direction relative to the preceding direction of ILM. Three plausible accounts of IRM are considered: a shifting attentional gradient model, a motion aftereffect (MAE) model, and a heuristic model. Results imply that IRM arises because of a heuristic about how objects move in the environment: In the absence of countervailing evidence, motion trajectories are assumed to continue away from the location where an object was last seen to move.

Arthroscopic procedures for the treatment of anterior shoulder instability: local experiences.

OBJECTIVE: To review the outcomes of arthroscopic stabilisation procedures for the treatment of recurrent anterior shoulder dislocation. DESIGN: Retrospective study. SETTING: Regional hospital, Hong Kong. PATIENTS: Patients receiving arthroscopic stabilisation procedures for recurrent anterior shoulder dislocation between 1999 and 2003. MAIN OUTCOME MEASURES: Functional outcomes including pain, range of motion, and activity level were assessed using the Constant score. Intra-operative findings were also discussed. RESULTS: A total of 18 arthroscopic stabilisation procedures were performed for the treatment of recurrent shoulder instability. Two cases converted to open procedures were excluded from this review. The overall outcomes were good and seven patients reported a full recovery. Fourteen out of 16 patients reported minimal or no pain, and the mean Constant score was 80. There were no cases of re-dislocation and no major complication was noted. CONCLUSION: All the reviewed patients had a satisfactory functional recovery. Therefore, we believe that the use of arthroscopic stabilisation procedure can produce a favourable outcome for appropriate shoulder pathologies.

Investigation of the use of drained blood reinfusion after total knee arthroplasty: a prospective randomised controlled study.

PURPOSE: To compare the use of a blood salvage and reinfusion system with standard allogeneic blood transfusion after total knee arthroplasty--a procedure associated with significant postoperative blood loss. METHODS: Between June 2002 and May 2004, 60 patients undergoing total knee arthroplasty were randomly allocated into a reinfusion group (n = 26) or a control group (n = 34). Patients in the reinfusion group had their blood reinfused from drains within 6 hours of surgery. Both groups received allogeneic blood transfusions according to specified transfusion criteria if the haemoglobin level fell below 90 g/l, or in the presence of severe anaemic symptoms. Haemoglobin levels and drain output were recorded daily for 3 consecutive days after surgery. RESULTS: There was no significant difference between the 2 groups in demographic data, drain output, total blood loss, and mean postoperative haemoglobin levels. Significantly more allogeneic blood was required by the control group than by the reinfusion group (p = 0.022). CONCLUSION: Postoperative reinfusion of drained blood reduced the need for blood transfusion after total knee arthroplasty, while having an effect on postoperative haemoglobin level equivalent to standard allogeneic blood transfusion.