Serial Shifts Research Articles

Effect of serial night shifts on the cognitive, psychomotor, and moral performance of residents in the department of Emergency Medicine.

The objective was to study the effect of serial night shifts on the cognitive, psychomotor, and moral performance of emergency medicine residents of an academic Emergency Medicine Department. This prospective case-crossover study compared emergency medicine residents' sleep time, subjective sleepiness, cognitive function, moral judgment, and psychomotor skills after 5 consecutive days versus night shifts using sleep diaries, activity monitors, and multiple performance tests. Paired t-tests and Wilcoxon signed-rank tests were used to analyze data based on normality. Correlation analysis was done using Spearman's correlation test. Subgroup analysis was also performed to find any difference based on gender and year of residency. Twenty-seven emergency medicine residents participated (13 males, 48.1%). The distribution across residency years was as follows: 44.4% in their first year, 25.9% in their second year, and 29.6% in their third year. Following five consecutive night shifts, total sleep duration decreased significantly from 338.1 ± 67.8 to 307.4 ± 71.0 min (p < 0.001), while subjective sleepiness scores increased from 9.6 ± 3.3 to 13.6 ± 4.6. Psychomotor performance and reaction times did not significantly differ between night and day shifts. However, working memory declined, assessed by self-paced three-back test scores (median [IQR] 517.1 [471.9-546.7] vs. 457.6 [334.4-508.8]; p = 0.034) and interference test scores (445.5 ± 59.9 vs. 407.2 ± 56.8; p < 0.001), along with moral judgment (median [IQR] 19 [18-28] vs. 15 [11-21]; p = 0.010) after serial night shifts. No correlations existed between performance measures nor differences based on gender or residency year. Residents sleep less following night versus day shifts, reporting the highest sleepiness levels after 5 consecutive nights. Despite this, psychomotor performance and reaction times did not significantly differ. However, considerable reductions occurred in moral judgment, working memory, and interference test performance after serial night shifts.

Cerebral Autoregulation Assessment Using the Near Infrared Spectroscopy 'NIRS-Only' High Frequency Methodology in Critically Ill Patients: A Prospective Cross-Sectional Study.

Impairments in cerebral autoregulation (CA) are related to poor clinical outcome. Near infrared spectroscopy (NIRS) is a non-invasive technique applied to estimate CA. Our general purpose was to study the clinical feasibility of a previously published ‘NIRS-only’ CA methodology in a critically ill intensive care unit (ICU) population and determine its relationship with clinical outcome. Bilateral NIRS measurements were performed for 1–2 h. Data segments of ten-minutes were used to calculate transfer function analyses (TFA) CA estimates between high frequency oxyhemoglobin (oxyHb) and deoxyhemoglobin (deoxyHb) signals. The phase shift was corrected for serial time shifts. Criteria were defined to select TFA phase plot segments (segments) with ‘high-pass filter’ characteristics. In 54 patients, 490 out of 729 segments were automatically selected (67%). In 34 primary neurology patients the median (q1–q3) low frequency (LF) phase shift was higher in 19 survivors compared to 15 non-survivors (13° (6.3–35) versus 0.83° (−2.8–13), p = 0.0167). CA estimation using the NIRS-only methodology seems feasible in an ICU population using segment selection for more robust and consistent CA estimations. The ‘NIRS-only’ methodology needs further validation, but has the advantage of being non-invasive without the need for arterial blood pressure monitoring.

Method for investigating the error of a laser dynamic goniometer

A method for investigating the error of a laser dynamic goniometer by cross-calibration using a new calculation algorithm is proposed. The algorithm is based on the method of serial angle shifts of a polygon relative to ring laser of the goniometer. The results of using this algorithm for estimating the error of a laser dynamic goniometer are presented. The dominant source of error of this goniometer is determined ‒ the irregularity of the angular scale of the ring laser, which is caused by the slope of the scale to the axis of rotation of the goniometer spindle. Corrective corrections were calculated and introduced into the calculation algorithm, which allowed reducing the systematic error of the goniometer to 0.03″.

How selective attention affects the detection of motion changes with peripheral vision in MOT

In sports, peripheral vision is expected to play an important role in tasks that demand distributed attention and motion-change detection. By using the Multiple-Object-Tracking (MOT) task, these demands were simulated in a well-controlled laboratory environment. Participants tracked four target out of ten moving objects (6 distractors) and pressed a button when one of the ten objects stopped. Detection rates for tracked targets were compared to detection rates of non-tracked distractors at eccentricities between 5° and 25°. The study's aim was to test how the location of attention affects peripheral motion detection. The results show a large attention effect because target stops were detected in 89 % and distractor stops only in 55 % of the trials. Distractor stops were more likely detected when they occurred closer to the fovea while target stops were detected at all eccentricities. That means, orienting attention at target objects facilitates the peripheral detection of their motion changes in monitoring tasks. Having distractors closer to the fovea increases the chance to also detect motion changes of unattended objects. On a theoretical level, results support a tracking mechanism with object-based attention, serial covert attention shifts and flexible but limited attentional resources. On a practical level, sports' experts should use their extensive knowledge to locate attention on most-relevant objects and reduce the eccentricity to other objects to detect motion changes of attended and unattended objects.

Existing Host Range Mutations Constrain Further Emergence of RNA Viruses.

RNA viruses are capable of rapid host shifting, typically due to a point mutation that confers expanded host range. As additional point mutations are necessary for further expansions, epistasis among host range mutations can potentially affect the mutational neighborhood and frequency of niche expansion. We mapped the mutational neighborhood of host range expansion using three genotypes of the double-stranded RNA (dsRNA) bacteriophage φ6 (wild type and two isogenic host range mutants) on the novel host Pseudomonas syringae pv. atrofaciens. Both Sanger sequencing of 50 P. syringae pv. atrofaciens mutant clones for each genotype and population Illumina sequencing revealed the same high-frequency mutations allowing infection of P. syringae pv. atrofaciens. Wild-type φ6 had at least nine different ways of mutating to enter the novel host, eight of which are in p3 (host attachment protein gene), and 13/50 clones had unchanged p3 genes. However, the two isogenic mutants had dramatically restricted neighborhoods: only one or two mutations, all in p3. Deep sequencing revealed that wild-type clones without mutations in p3 likely had changes in p12 (morphogenic protein), a region that was not polymorphic for the two isogenic host range mutants. Sanger sequencing confirmed that 10/13 of the wild-type φ6 clones had nonsynonymous mutations in p12, and 2 others had point mutations in p9 and p5. None of these genes had previously been associated with host range expansion in φ6. We demonstrate, for the first time, epistatic constraint in an RNA virus due to host range mutations themselves, which has implications for models of serial host range expansion.IMPORTANCE RNA viruses mutate rapidly and frequently expand their host ranges to infect novel hosts, leading to serial host shifts. Using an RNA bacteriophage model system (Pseudomonas phage φ6), we studied the impact of preexisting host range mutations on another host range expansion. Results from both clonal Sanger and Illumina sequencing show that extant host range mutations dramatically narrow the neighborhood of potential host range mutations compared to that of wild-type φ6. This research suggests that serial host-shifting viruses may follow a small number of molecular paths to enter additional novel hosts. We also identified new genes involved in φ6 host range expansion, expanding our knowledge of this important model system in experimental evolution.

Parseval Frames of Serial Shifts of a Function in Spaces of Trigonometric Polynomials

Abstract—We prove the criterion of existence of a Parseval frame of a priori given dimension in the space of trigonometric polynomials of the form TQ(x) = $${\sum\limits_{k \in Q} {cke} ^{ikx}}$$ consisting of serial shifts of a polynomial (ck ∈ C, where Q is a finite set of integer numbers). The form of a frame of serial shifts of one function is also indicated. The result is applied to some particular cases.

The speed of voluntary and priority-driven shifts of visual attention.

The question how fast spatial attention moves between different visual objects remains debated. We used electrophysiological measures to determine the speed of voluntary and visually guided shifts of attention. Participants shifted attention from a known benchmark object (T1) to a benchmark-defined target object (T2) in tasks where these shifts had to be controlled endogenously and tasks where they could be guided by visible stimulus attributes (target features or arrow cues). To track the speed of these attention shifts, we measured event-related potential (ERP) markers of attentional object selection (N2pc components). The N2pc to T1 emerged earlier than the N2pc to T2, confirming the presence of serial attention shifts. N2pc onset differences between T1 and T2 revealed that shifts guided by target features were triggered within 50 ms, whereas voluntary movements of attention took substantially longer (150 ms). Attention shifts signaled by arrow cues were initiated within about 100 ms. Results show that genuinely voluntary shifts of attention are slower than shifts that are guided by cues or target features, but can still be initiated more rapidly than has previously been assumed. They also demonstrate that EEG markers can track different types of serial attentional selection processes with high temporal precision. (PsycINFO Database Record

Sensitivity to meter in auditory feedback during music performance.

Performance of a complex sequential task, such as speech or music, occurs simultaneously with its perceived outcome, known as auditory feedback. The importance of auditory feedback to the fluency of performance is demonstrated by the disruptive effects of altered auditory feedback (AAF). For instance, it has been know for decades that sequence production (in music and speech) can be disrupted by delayed auditory feedback (DAF), a slight asynchrony between actions and resulting sounds (for reviews see Finney, 1999; Howell, 2004; Pfordresher, 2006; Yates, 1963). Fluency in performance clearly relies on temporal coordination between planned actions and concurrent sounds. It is less clear whether performance relies on the content of auditory feedback, which in a musical context refers to the pitches associated with individual notes.For some time, it appeared as though performance may not rely on feedback content. For instance, Howell and Archer (1984) found that disruption from DAF was unchanged when speech feedback was converted to an amplitude-modulated square-wave tone. Finney (1997) further demonstrated that pianists' performances of Bach inventions did not suffer when pitch content was altered in a random-like way. These observations are consistent with Howell's claim that DAF effects result from displacement of auditory rhythms, relative to the rhythmic coordination of actions (Howell, 2001, 2004; Howell, Powell, & Khan, 1983; Howell & Sackin, 2002).However, Pfordresher (2003) introduced an AAF manipulation of pitch content that can disrupt production, referred to as a serial shift. In contrast to other manipulations of content, serial shifts involve presenting pitches from a planned melody (i.e., a sequence of actions that are associated with a sequence of anticipated pitch events) at an alternate serial position. For instance, a lag-1 serial shift causes the feedback pitch heard at each keypress to match what the performer produced at the previous keypress. As such the feedback melody is serially shifted relative to the planned melody. Serial shifts lead to increased pitch errors in performance, while sparing produced timing (Pfordresher, 2003), can disrupt performance of both pianists and nonpianists (Pfordresher, 2005), can lead to disruption of music performance via keyboard or singing (Pfordresher & Mantell, 2012), and can also disrupt the accuracy of speech production (Pruitt & Pfordresher, 2015). It is important to note that serial shifts are distinct from traditional DAF, even though serial shifts may refer to previous events. For instance, hearing serially shifted pitches from future positions also disrupts performance (Pfordresher & Palmer, 2006).Although the effect of serial shifts does demonstrate sensitivity to pitch content, this effect alone does not rule out the possibility that their disruptive effect is to some extent based on rhythmic relationships between perception and action. It has often been observed that the patterning of pitch content can convey rhythmic information through melodic accents (Cooper & Meyer, 1960; Ellis & Jones, 2009; Jones, 1987), including breaks or pivots in the melodic contour (for examples, see Handel, 1989, p. 398), and the use of parallelism in broader pitch patterns (Acevedo, Temperley, & Pfordresher, 2014; Deutsch & Feroe, 1981; Steedman, 1977; Temperley & Bartlette, 2002).We adopted these features to create stimuli for the present study. Notation for the four melodies we used are shown in Figure 1 along with their meter, represented as a grid. Metrical accents are associated with positions that have higher columns of X's above them. Melodies were created to match either a binary (4/4) or a ternary (3/4) metrical structure. The first binary melody (Figure IA) used breaks in the melodic contour to signal metrical boundaries, whereas the second binary melody includes a recurring pattern structure based on an alternating melodic contour that is inverted in the second measure. …

Think Thrice, It's Alright: Mad Men's "The Wheel" and the Future Study of Television Narratives

This article discusses three strategies that TV shows have increasingly employed in recent years to produce what Jason Mittell, in an essay that marked the beginning of his thoughts on the issue, has called "narrative complexity": unreliable narration, counterfictional scenarios, and ellipses and anachronological narration. It uses the last minutes of "The Wheel," the final episode of the first season of AMC's Mad Men (2007–15), as its primary example. More specifically, this article proposes three different interpretations of the final moments of that episode. These readings have in common that they underline one of Mittell's central claims, namely that serial television shifts comprehension processes toward conscious hypotheses in what he describes as "operational aesthetic." However, the article will also assume a broader perspective throughout and demonstrate that the three interpretations it develops are instances of more widely spread phenomena that merit far more attention than a single article can provide. Thus, the article offers, on the one hand, a close reading of an episode of Mad Men against the background of the early seasons of the show, but, on the other, it also identifies three topics for further fruitful research on television narrative more generally.

The Speed of Serial Attention Shifts in Visual Search: Evidence from the N2pc Component.

Finding target objects among distractors in visual search display is often assumed to be based on sequential movements of attention between different objects. However, the speed of such serial attention shifts is still under dispute. We employed a search task that encouraged the successive allocation of attention to two target objects in the same search display and measured N2pc components to determine how fast attention moved between these objects. Each display contained one digit in a known color (fixed-color target) and another digit whose color changed unpredictably across trials (variable-color target) together with two gray distractor digits. Participants' task was to find the fixed-color digit and compare its numerical value with that of the variable-color digit. N2pc components to fixed-color targets preceded N2pc components to variable-color digits, demonstrating that these two targets were indeed selected in a fixed serial order. The N2pc to variable-color digits emerged approximately 60 msec after the N2pc to fixed-color digits, which shows that attention can be reallocated very rapidly between different target objects in the visual field. When search display durations were increased, thereby relaxing the temporal demands on serial selection, the two N2pc components to fixed-color and variable-color targets were elicited within 90 msec of each other. Results demonstrate that sequential shifts of attention between different target locations can operate very rapidly at speeds that are in line with the assumptions of serial selection models of visual search.

Marked Increases in Alpha Power Over the Left Prefrontal Region During Days Following Shift Work: A Case Report

Quantitative electroencephalographic (QEEG) measurements were completed for a 35 year old of paramedic following two to five days of shift change and rest periods. The most conspicuous and reliable change was a marked increase (factor of 5) in power within the alpha band over the left prefrontal region and, to a lesser degree, increased power within the low-beta band over the right parietal region during the test periods after no work days. These results indicate that regions of cerebral cortices associated with self-monitoring and spatial vigilance are most affected by a schedule that involves serial shifts in sleep schedule but that the structure of employment may attenuate the most significant changes that occur after days of rest. These results are consistent with previous observations that changing sleep and work schedules affect the activity of regions of the human brain that are essential for awareness of spatial content and reasoning.

Optimization Algorithm Analysis for FIR Filter by FPGA

The article introduces essential method to realize the high accuracy and velocity FIR filter by FPGA. Proposes the FIR filter optimization scheme design of serial shifts based on FPGA. Avoided the shortcoming of the traditional parallel algorithm module taking the massive hardware resources . And give 11-order and 8-bits low pass filter design as the specific research object. Realized the partial functions which the traditional numeral FIR filter cannot.May adjusts the filter exponent number conveniently and suits different application.

Long term assessment of factors affecting nitrifying bacteria communities and N-removal in a full-scale biological process treating high strength hazardous wastewater

Over a 3year period, interactions between nitrifying bacterial communities and the operational parameters of a full-scale wastewater treatment plant were analyzed to assess their impact on nitrification performance. Throughout the study period, nitrification fluctuated while Nitrosomonas europaea and Nitrosomonas nitrosa, the two major ammonia oxidizing bacteria (AOB) communities, showed resistance to changes in operational and environmental conditions. Nitrobacter populations mostly exceeded those of Nitrospira within nitrite oxidizing bacteria (NOB). Meanwhile, principal component analysis (PCA) results revealed that a close association between Nitrobacter and nitrite concentration as well as a direct correlation between the quantity of AOB and influent SCN− concentration. The serial shifts of data points over time showed that the nitrification of a full-scale treatment plant has been gradually suppressed by the influence of influent COD and phenol concentrations.

Attention shifts or volatile representations: What causes binding deficits in visual working memory?

The current study tested two hypotheses of feature binding memory: The attention hypothesis, which suggests that attention is needed to maintain feature bindings in visual working memory (VWM) and the volatile representation hypothesis, which suggests that feature bindings in memory are volatile and easily overwritten, but do not require sustained attention. Experiment 1 tested the attention hypothesis by measuring shifts of overt attention during the study array of a change detection task; serial shifts of attention did not disrupt feature bindings. Experiments 2 and 3 encouraged encoding of more volatile (Experiment 2) or durable (Experiment 3) representations during the study array. Binding change detection performance was impaired in Experiment 2, but not in Experiment 3, suggesting that binding performance is impaired when encoding supports a less durable memory representation. Together, these results suggest that although feature bindings may be volatile and easily overwritten, attention is not required to maintain feature bindings in VWM.

Intentional subitizing: Exploring the role of automaticity in enumeration

Subitizing is traditionally described as the rapid, preattentive and automatic enumeration of up to four items. Counting, by contrast, describes the enumeration of larger sets of items and requires slower serial shifts of attention. Although recent research has called into question the preattentive nature of subitizing, whether or not numerosities in the subitizing range can be automatically accessed is yet to be empirically tested. In the current study, participants searched for two pre-defined digits in a circular visual-search array. Distractor dots of various set sizes were placed at the centre of the array. Despite the relevance of the distractor numerosities to the target detection task, the distractors did not influence target detection, thereby suggesting that their numerosities were not automatically accessed in Experiment 1. In Experiment 2, participants were explicitly instructed to enumerate the distractor dots. Here, congruent and incongruent distractor numerosities influenced the target detection task, thereby revealing that the distractor dots were capable of generating interference. Experiment 3 ensured that dots were attended by asking participants to detect the luminance of dots. Data confirmed that subitizing was not automatic. The present study also supported the alleged discontinuity between the subitizing and counting ranges because an examination of reaction time gradients in Experiment 2 found the counting gradient to be significantly steeper than the subitizing gradient. In sum, the results suggest that subitizing is a distinct but non-automatic style of enumeration.

Eye movements in a sequential scanning task: Evidence for distributed processing

Current models of eye movement control are derived from theories assuming serial processing of single items or from theories based on parallel processing of multiple items at a time. This issue has persisted because most investigated paradigms generated data compatible with both serial and parallel models. Here, we study eye movements in a sequential scanning task, where stimulus n indicates the position of the next stimulus n + 1. We investigate whether eye movements are controlled by sequential attention shifts when the task requires serial order of processing. Our measures of distributed processing in the form of parafoveal-on-foveal effects, long-range modulations of target selection, and skipping saccades provide evidence against models strictly based on serial attention shifts. We conclude that our results lend support to parallel processing as a strategy for eye movement control.

Hemispheric asymmetries in visual search

We conducted two visual search experiments, and found that target-detection accuracy and speed were better when the target was projected to the right hemisphere in the feature search condition and better when the target was projected to the left hemisphere in the feature-conjunction search condition. We propose that the highly efficient, so-called parallel search performance characteristic of feature search is enabled by a broadly distributed, global view of the visual field, and the right hemisphere is more efficient than the left in such global processing. On the other hand, the less-efficient performance characteristic of conjunction search (demonstrated by the set-size effect) involves serial shifts of focused attention, and the left hemisphere is more efficient than the right in such localised attentional processing. We suggest that hemispheric asymmetries observed in visual search are related to the attentional demands of the task, and that we adjust our attentional distribution to fit task difficulty. When the target is very distinct, a global, low-resolution attentional distribution is sufficient, and enables parallel search; but a localised, narrow-aperture attentional distribution is sometimes necessary to find targets that either require feature binding, or are very similar to other “distractor” stimuli in terms of compositional attributes.

Preview fixation duration modulates identical and semantic preview benefit in Chinese reading

Semantic preview benefit from parafoveal words is critical for proposals of distributed lexical processing during reading. Semantic preview benefit has been demonstrated for Chinese reading with the boundary paradigm in which unrelated or semantically related previews of a target word N + 1 are replaced by the target word once the eyes cross an invisible boundary located after word N (Yan et al., 2009); for the target word in position N + 2, only identical compared to unrelated-word preview led to shorter fixation times on the target word (Yan et al., in press). A reanalysis of these data reveals that identical and semantic preview benefits depend on preview duration (i.e., the fixation duration on the preboundary word). Identical preview benefit from word N + 1 increased with preview duration. The identical preview benefit was also significant for N + 2, but did not significantly interact with preview duration. The previously reported semantic preview benefit from word N + 1 was mainly due to single- or first-fixation durations following short previews. We discuss implications for notions of serial attention shifts and parallel distributed processing of words during reading.

Robust Selectivity to Two-Object Images in Human Visual Cortex

We can recognize objects in complex images in a fraction of a second. Neuronal responses in macaque areas V4 and inferior temporal cortex to preferred stimuli are typically suppressed by the addition of other objects within the receptive field (see, however, [16, 17]). How can this suppression be reconciled with rapid visual recognition in complex scenes? Certain "special categories" could be unaffected by other objects, but this leaves the problem unsolved for other categories. Another possibility is that serial attentional shifts help ameliorate the problem of distractor objects. Yet, psychophysical studies, scalp recordings, and neurophysiological recordings suggest that the initial sweep of visual processing contains a significant amount of information. We recorded intracranial field potentials in human visual cortex during presentation of flashes of two-object images. Visual selectivity from temporal cortex during the initial approximately 200 ms was largely robust to the presence of other objects. We could train linear decoders on the responses to isolated objects and decode information in two-object images. These observations are compatible with parallel, hierarchical, and feed-forward theories of rapid visual recognition and may provide a neural substrate to begin to unravel rapid recognition in natural scenes.

Parafoveal load of word N+1 modulates preprocessing effectiveness of word N+2 in Chinese reading.

Preview benefits (PBs) from two words to the right of the fixated one (i.e., word N + 2) and associated parafoveal-on-foveal effects are critical for proposals of distributed lexical processing during reading. This experiment examined parafoveal processing during reading of Chinese sentences, using a boundary manipulation of N + 2-word preview with low- and high-frequency words N + 1. The main findings were (a) an identity PB for word N + 2 that was (b) primarily observed when word N + 1 was of high frequency (i.e., an interaction between frequency of word N + 1 and PB for word N + 2), and (c) a parafoveal-on-foveal frequency effect of word N + 1 for fixation durations on word N. We discuss implications for theories of serial attention shifts and parallel distributed processing of words during reading.