Simultaneous performance of two tasks often leads to performance deficits in the component tasks. This effect, known as dual-task interference, is thought to be a proof of capacity limitation in ...cognition, and the lateral prefrontal cortex (LPFC) has been highlighted as its putative neural substrate. Here we recorded single-neuron activities in LPFC while monkeys performed dual tasks that required the simultaneous performance of a varying-load spatial attention task and a spatial memory task. We found that the performance of the monkeys exhibited dual-task interference, and prefrontal neuron activities showed a decreased ability to represent task-relevant information to a degree proportional to the increased demand of the concurrent counterpart task. The locus of the interference was shown to originate in the simultaneous, overloaded recruitment of the same LPFC neural population by the two tasks. These results provide direct neurophysiological evidence for, and constraints to, psychological models of dual-task interference and capacity limitation.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
We study the defining ideal of a numerical semigroup ring kH using the inverse polynomial attached to the Artinian ring kH/(th). We give a criterion for H to be symmetric or almost symmetric using ...the annihilator of the inverse system. Also we give characterizations of symmetric numerical semigroups with small multiplicity and give a new proof of Bresinsky's Theorem for symmetric semigroups generated by 4 elements.
Working memory (WM) provides the stability necessary for high-level cognition. Influential theories typically assume that WM depends on the persistence of stable neural representations, yet ...increasing evidence suggests that neural states are highly dynamic. Here we apply multivariate pattern analysis to explore the population dynamics in primate lateral prefrontal cortex (PFC) during three variants of the classic memory-guided saccade task (recorded in four animals). We observed the hallmark of dynamic population coding across key phases of a working memory task: sensory processing, memory encoding, and response execution. Throughout both these dynamic epochs and the memory delay period, however, the neural representational geometry remained stable. We identified two characteristics that jointly explain these dynamics: (1) time-varying changes in the subpopulation of neurons coding for task variables (i.e., dynamic subpopulations); and (2) time-varying selectivity within neurons (i.e., dynamic selectivity). These results indicate that even in a very simple memory-guided saccade task, PFC neurons display complex dynamics to support stable representations for WM.
Flexible, intelligent behavior requires the maintenance and manipulation of incoming information over various time spans. For short time spans, this faculty is labeled "working memory" (WM). Dominant models propose that WM is maintained by stable, persistent patterns of neural activity in prefrontal cortex (PFC). However, recent evidence suggests that neural activity in PFC is dynamic, even while the contents of WM remain stably represented. Here, we explored the neural dynamics in PFC during a memory-guided saccade task. We found evidence for dynamic population coding in various task epochs, despite striking stability in the neural representational geometry of WM. Furthermore, we identified two distinct cellular mechanisms that contribute to dynamic population coding.
Purpose
To elucidate the normative values of whole body sagittal alignment and balance of a healthy population in the standing position; and to clarify the relationship among the alignment, balance, ...health-related quality of life (HRQOL), and age.
Methods
Healthy Japanese adult volunteers
n
= 126, mean age 39.4 years (20–69), M/F = 30/96 with no history of spinal disease were enrolled in a cross-sectional cohort study. The Oswestry Disability Index (ODI) questionnaire was administered and subjects were scanned from the center of the acoustic meati (CAM) to the feet while standing on a force plate to determine the gravity line (GL), and the distance between CAM and GL (CAM–GL) was measured in the sagittal plane. Standard X-ray parameters were measured from the head to the lower extremities. ODI was compared among age groups stratified by decade. Correlations were investigated by simple linear regression analysis. Ideal lumbar lordosis was investigated using the least squares method.
Results
The present study yielded normative values for whole standing sagittal alignment including head and lower extremities in a cohort of 126 healthy adult volunteers, comparable to previous reports and thus a formula for ideal lumbar lordosis was deduced: LL = 32.9 + 0.60 × PI − 0.23 × age. There was a tendency of positive correlation between McGregor slope, thoracic kyphosis, PT, and age. SVA, T1 pelvic angle, sacrofemoral angle, knee flexion angle, and ankle flexion angle, but not CAM–GL, increased with age, suggesting that the spinopelvic alignment changes with age, but standing whole body alignment is compensated for to preserve a horizontal gaze. ODI tended to increase from the 40s in the domain of pain intensity, personal care, traveling, and total score. ODI weakly, but significantly positively correlated with age and PI–LL.
Conclusion
Whole body standing alignment even in healthy subjects gradually deteriorates with age, but is compensated to preserve a horizontal gaze. HRQOL is also affected by aging and spinopelvic malalignment.
The first author had shown earlier that for a standard graded ring R and a graded ideal I in characteristic p>0, with ℓ(R/I)<∞, there exists a compactly supported continuous function fR,I whose ...Riemann integral is the HK multiplicity eHK(R,I). We explore further some other invariants, namely the shape of the graph of fR,m (where m is the graded maximal ideal of R) and the maximum support (denoted as α(R,I)) of fR,I.
In case R is a domain of dimension d≥2, we prove that (R,m) is a regular ring if and only if fR,m has a symmetry fR,m(x)=fR,m(d−x), for all x.
If R is strongly F-regular on the punctured spectrum then we prove that the F-threshold cI(m) coincides with α(R,I).
As a consequence, if R is a two dimensional domain and I is generated by homogeneous elements of the same degree, then we have (1) a formula for the F-threshold cI(m) in terms of the minimum strong Harder-Narasimhan slope of the syzygy bundle and (2) a well defined notion of the F-threshold cI(m) in characteristic 0.
This characterisation readily computes cI(n)(m), for the set of all irreducible plane trinomials kx,y,z/(h), where m=(x,y,z) and I(n)=(xn,yn,zn).
Emergence of thermoresponsive and reversible color changes at low temperature is a challenging target. In general, it is not easy to induce sufficient dynamic motion of rigid molecules including ...chromophore at a lower temperature. The present work shows unusually low‐temperature color‐change properties originating from the dynamic motion of rigid conjugated polymer in solid state. The layered composites of polydiacetylene (PDA) and guest l‐arginine (L‐Arg) (PDA‐(L‐Arg)) exhibit temperature‐responsive gradual color changes with reversibility in the range of 123–333 K in solid crystalline state. The dynamic properties are induced by gradual and reversible distortion of the π‐conjugated main chain in response to temperature. The tuned flexibility of the layered structure facilitates motion of the rigid π‐conjugated molecule at low temperature. The PDA‐(L‐Arg)‐coated substrates are applied to visualization and quantification of 2D and 3D temperature distributions generated by cooling with liquid nitrogen. These thermographic devices afford to image lower temperature range than typical infrared thermography. The present work indicates potentials of layered architectures with tunable flexibility for emergence of dynamic properties.
Layered conjugated polymer exhibits thermoresponsive and reversible color changes at unusual low‐temperature range even in the solid crystalline state consisting of rigid macromolecules. The tuned flexibility of the layered structure plays an important role for emergence of the dynamic motion. The properties afford to 2D and 3D thermographic imaging temperature range much lower than typical infrared thermography.
Hilbert-Kunz density function for graded domains Trivedi, Vijaylaxmi; Watanabe, Kei-Ichi
Journal of pure and applied algebra,
February 2022, 2022-02-00, Letnik:
226, Številka:
2
Journal Article
Recenzirano
Odprti dostop
We prove the existence of HK density function for a graded pair (R,I), where R is an N-graded domain of finite type over a perfect field and I⊂R is a graded ideal of finite colength. This generalizes ...our earlier result where one proves the existence of such a function for a pair (R,I), where, in addition R is standard graded.
Other properties of the HK density functions also hold for the graded pairs: for example, it is a multiplicative function for Segre products, its maximum support is the F-threshold of an m-primary ideal provided ProjR is smooth, it has a closed formula when either I is generated by a system of parameters or R is of dimension two.
As one of the consequences we show that if G is a finite group scheme acting linearly on a polynomial ring R of dimension d then the HK density function fRG,mG, of the pair (RG,mG), is a piecewise polynomial function of degree d−1.
We also compute the HK density functions for (RG,mG), where G⊂SL2(k) is a finite group acting linearly on the ring kX,Y.
We study the behavior of various properties of commutative Noetherian rings under Segre products, with a special focus on properties in positive prime characteristic defined using the Frobenius ...endomorphism. Specifically, we construct normal graded rings of finite Frobenius representation type that are not Cohen-Macaulay.
We study almost symmetric numerical semigroups and semigroup rings. We describe a characteristic property of the minimal free resolution of the semigroup ring of an almost symmetric numerical ...semigroup. For almost symmetric semigroups generated by four elements we will give a structure theorem by using the “row-factorization matrices”, introduced by Moscariello. As a result, we give a simpler proof of Komeda’s structure theorem of pseudo-symmetric numerical semigroups generated by four elements. Row-factorization matrices are also used to study shifted families of numerical semigroups.
Measurement of friction force is important for safety, security, and health. Excessive friction force causes degradation of materials and biological bodies. For example, tooth enamel and gums are ...damaged by strong toothbrushing force. However, friction force is not easily measured by conventional materials and devices. Here, we proposed design strategies of a paper-based device for measurement of friction force. Toothbrushing force, a model of weak friction force, is the measurement target in the present work. Soft layered composites of polydiacetylene (PDA) and interlayer guest macromolecules were designed and synthesized to achieve a visible color change in response to weak friction force. A data-scientific approach assisted in the selection of the interlayer guest molecule to control the stimuli responsivity of the layered PDA. The guest polyethyleneimine (PEI) formed soft layered composites exhibiting a color change in response to weak friction force. The paper-based device of the layered PDA/PEI composite showed a gradual color change from blue to red in response to the strength and number of the applied friction force. As a model case, toothbrushing force was measured using the paper-based device. The present work shows new design strategies of molecules and materials toward measurement of a wide variety of friction forces.
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