21 research outputs found
Smooth pursuit operates over perceived not physical positions of the double-drift stimulus
The double-drift illusion produces a large deviation in perceived direction that strongly dissociates physical position from perceived position. Surprisingly, saccades do not seem to be affected by the illusion (Lisi & Cavanagh, 2015). When targeting a double-drift stimulus, the saccade system is driven by retinal rather than perceived position. Here, using paired double-drift targets, we test whether the smooth pursuit system is driven by perceived or physical position. Participants (n = 7) smoothly pursued the inferred midpoint (Steinbach, 1976) between two horizontally aligned Gabor patches that were separated by 20° and moving on parallel, oblique paths. On the first half of each trial, the Gabors’ internal textures were static while both drifted obliquely downward. On the second half of each trial, while the envelope moved obliquely upward, the internal texture drifted orthogonally to the envelope's motion, producing a large perceived deviation from the downward path even though the upward and downward trajectories always followed the same physical path but in opposite directions. We find that smooth pursuit eye movements accurately followed the nonillusory downward path of the midpoint between the two Gabors, but then followed the illusory rather than the physical trajectory on the upward return. Thus, virtual targets for smooth pursuit are derived from perceived rather than retinal coordinates
Oscillations, Intercellular Coupling, and Insulin Secretion in Pancreatic β Cells
Insulin is a potent metabolic regulator that is released by pancreatic beta-cells, which respond to body glucose concentrations. Here the authors explain the physiological basis of insulin release
Diagnostic and prognostic value of QRS duration and QTc interval in patients with suspected myocardial infarction
Background: While prolongation of QRS duration and QTc interval during acute myocardial infarction (AMI) has been reported in animals, limited data is available for these readily available electrocardiography (ECG) markers in humans.
Methods: Diagnostic and prognostic value of QRS duration and QTc interval in patients with suspected AMI in a prospective diagnostic multicentre study were prospectively assessed. Digital 12-lead ECGs were recorded at presentation. QRS duration and QTc interval were automatically calculated in a blinded fashion. Final diagnosis was adjudicated by two independent cardiologists. The prognostic endpoint was all-cause mortality during 24 months of follow-up.
Results: Among 4042 patients, AMI was the final diagnosis in 19% of patients. Median QRS duration and median QTc interval were significantly greater in patients with AMI compared to those with other final diagnoses (98 ms [IQR 88–108] vs. 94 ms [IQR 86–102] and 436 ms [IQR 414–462] vs. 425 ms [IQR 407–445], p < 0.001 for both comparisons). The diagnostic value of both ECG signatures however was only modest (AUC 0.56 and 0.60). Cumulative mortality rates after 2 years were 15.9% vs. 5.6% in patients with a QRS > 120 ms compared to a QRS duration ≤ 120 ms (p < 0.001), and 11.4% vs. 4.3% in patients with a QTc > 440 ms compared to a QRS duration ≤ 440 ms (p < 0.001). After adjustment for age and important ECG and clinical parameters, the QTc interval but not QRS duration remained an independent predictor of mortality.
Conclusions: Prolongation of QRS duration > 120 ms and QTc interval > 440 ms predict mortality in patients with suspected AMI, but do not add diagnostic value
Screaming 'Black' Murder: Crime Fiction and the Construction of Ethnic Identities
A significant segment of crime fiction is concerned with the representation of ethnic identities and may to some extent be considered paradigmatic of the participation of literary texts in discourses on race and minorities. This article explores constructions of ethnic identities in American, British, and South African crime fiction from the 1920s to the early twenty-first century. In particular, the focus will be on such texts in which the ethno-cultural identity of the detective gives special prominence not only to the ethnic particularity of the fictional character itself and of its environs but frequently also to that of its author. Main texts discussed are Rudolph Fisher’s The Conjure Man Dies (1932), Earl Derr Biggers’ The House Without a Key (1925) and The Black Camel (1929), Walter Mosley’s Devil in a Blue Dress (1990) and Little Scarlet (2004) as well as James McClure’s The Gooseberry Fool (1974) and Patrick Neate’s City of Tiny Lights (2005). It is argued that all of these texts have a distinct subversive potential of which the construction of ethnic identities becomes the main vehicle because these identities are the products and the catalysts of the conflicts negotiated in ethnic crime fiction and correlating to ‘reality’
Robust Asynchronous Indoor Localization Using Led Lighting
We propose a low-cost system for indoor self-localization of mobile devices using modulated LED ceiling lamps that are fully autonomous and broadcast their identifiers without any synchronization. The proposed self-localization method is designed to handle this lack of synchronization as well as the possibility of blocked line-of-sight connections or severe attenuation in real-world environments. This robustness is achieved by applying a suitable Bayesian signal model and by taking into account the inherent sparsity in detecting the concurrently visible lamps. The proposed estimator of the location approximates optimal Bayesian estimation while maintaining low complexity. Simulation results confirm a significant gain in performance compared to a classical matched-filter approach
The magnitude of the Double-Drift illusion is lessened by a reference object with high positional certainty
MAECHLER et al.: VLSI DESIGN OF APPROXIMATE MESSAGE PASSING FOR SIGNAL RESTORATION AND COMPRESSIVE SENSING 1 VLSI Design of Approximate Message Passing for Signal Restoration and Compressive Sensing
Abstract—Sparse signal recovery finds use in a variety of practical applications, such as signal and image restoration and the recovery of signals acquired by compressive sensing. In this paper, we present two generic VLSI architectures that implement the approximate message passing (AMP) algorithm for sparse signal recovery. The first architecture, referred to as AMP-M, employs parallel multiply-accumulate units and is suitable for recovery problems based on unstructured (e.g., random) matrices. The second architecture, referred to as AMP-T, takes advantage of fast linear transforms, which arise in many real-world applications. To demonstrate the effectiveness of both architectures, we present corresponding VLSI and FPGA implementation results for an audio restoration application. We show that AMP-T is superior to AMP-M with respect to silicon area, throughput, and power consumption, whereas AMP-M offers more flexibility. Index Terms—Approximate message passing (AMP), compressive sensing, fast discrete cosine transform, field-programmable gate array (FPGA), ℓ1-norm minimization, signal restoration, sparse signal recovery, very-large scale integration (VLSI). I
Circulating 1,5-anhydroglucitol as a biomarker of ß-cell mass independent of a diabetes phenotype in human subjects
CONTEXT: During an asymptomatic pre-diabetic state, the functional ß-cell mass decreases up to a critical threshold triggering diabetes and related symptoms. To date, there are no reliable readouts able to capture in vivo a potential drop of the ß-cell mass. OBJECTIVE: Beside its use as a short-term marker of glycemic control, the deoxyhexose 1,5-anhydroglucitol was identified in rodents as a circulating biomarker of the functional ß-cell mass already in the asymptomatic prediabetic stage. The present study investigated the putative corresponding relevance of circulating 1,5-anhydroglucitol in different human cohorts. METHODS: We analyzed clinical and blood parameters in patients with established type 2 diabetes and subjects considered at high risk of developing diabetes, as well as patients with no history of diabetes scheduled for pancreaticoduodenectomy. RESULTS: Circulating 1,5-anhydroglucitol was reduced in type 2 diabetic patients, negatively correlating with fasting plasma glucose (p<0.0001) and HbA1c (p<0.0001). In healthy subjects, 1,5-AG levels positively correlated with body mass index (p=0.004) and HOMA%S (p<0.03) and was particularly high in nondiabetic obese individuals, potential accounting for compensatory ß-cell expansion. Patients with no history of diabetes undergoing pancreaticoduodenectomy exhibited a 50% reduction of circulating 1,5-anhydroglucitol levels following surgery leading to an acute loss of their ß-cell mass (p=0.002), regardless their glucose tolerance status. CONCLUSION: In summary, plasma concentration of 1,5-anhydroglucitol follows the ß-cell mass and its non-invasive monitoring may alert about the loss of ß-cells in subjects at risk for diabetes, an event that cannot be captured by other clinical parameters of glycemic control
Circulating 1,5-anhydroglucitol as a biomarker of ß-cell mass independent of a diabetes phenotype in human subjects
Context: During an asymptomatic pre-diabetic state, the functional ß-cell mass decreases up to a critical threshold triggering diabetes and related symptoms. To date, there are no reliable readouts able to capture in vivo a potential drop of the ß-cell mass.
Objective: Beside its use as a short-term marker of glycemic control, the deoxyhexose 1,5-anhydroglucitol was identified in rodents as a circulating biomarker of the functional ß-cell mass already in the asymptomatic prediabetic stage. The present study investigated the putative corresponding relevance of circulating 1,5-anhydroglucitol in different human cohorts.
Methods: We analyzed clinical and blood parameters in patients with established type 2 diabetes and subjects considered at high risk of developing diabetes, as well as patients with no history of diabetes scheduled for pancreaticoduodenectomy.
Results: Circulating 1,5-anhydroglucitol was reduced in type 2 diabetic patients, negatively correlating with fasting plasma glucose (p<0.0001) and HbA1c (p<0.0001). In healthy subjects, 1,5-AG levels positively correlated with body mass index (p=0.004) and HOMA%S (p<0.03) and was particularly high in nondiabetic obese individuals, potential accounting for compensatory ß-cell expansion. Patients with no history of diabetes undergoing pancreaticoduodenectomy exhibited a 50% reduction of circulating 1,5-anhydroglucitol levels following surgery leading to an acute loss of their ß-cell mass (p=0.002), regardless their glucose tolerance status.
Conclusion: In summary, plasma concentration of 1,5-anhydroglucitol follows the ß-cell mass and its non-invasive monitoring may alert about the loss of ß-cells in subjects at risk for diabetes, an event that cannot be captured by other clinical parameters of glycemic control.</p
Incremental diagnostic and prognostic value of the QRS-T angle, a 12-lead ECG marker quantifying heterogeneity of depolarization and repolarization, in patients with suspected non-ST-elevation myocardial infarction.
BACKGROUND
The value of the 12-lead ECG in the diagnosis of non-ST-elevation myocardial infarction (NSTEMI) is limited due to insufficient sensitivity and specificity of standard ECG criteria. The QRS-T angle reflects depolarization-repolarization heterogeneity and might assist in detecting patients with a NSTEMI (diagnosis) as well as predicting patients with an increased mortality risk (prognosis).
METHODS
We prospectively enrolled 2705 consecutive patients with symptoms suggestive of NSTEMI. The QRS-T angle was automatically derived from the standard 10 s 12-lead ECG recorded at presentation to the ED. Patients were followed up for all-cause mortality for 2 years.
RESULTS
NSTEMI was the final diagnosis in 15% (n = 412) of patients. QRS-T angles were significantly greater in patients with NSTEMI compared to those without (p < 0.001). The use of the QRS-T angle in addition to standard ECG criteria indicative of ischemia improved the diagnostic accuracy for NSTEMI as quantified by the area under the ROC curve from 0.68 to 0.72 (p < 0.001). An algorithm for the combined use of standard ECG criteria and the QRS-T angle improved the sensitivity of the ECG for NSTEMI from 45% to 78% and the specificity from 86% to 91% (p < 0.001 for both comparisons). The 2-year survival rates were 98%, 97% and 87% according to QRS-T angle tertiles (p < 0.001).
CONCLUSION
In patients with suspected NSTEMI, the QRS-T angle derived from the standard 12-lead ECG provides incremental diagnostic accuracy on top of standard ECG criteria indicative of ischemia, and independently predicts all-cause mortality during 2 years of follow-up