We demonstrate the creation of entangled, spin-squeezed states using a collective, or joint, measurement and real-time feedback. The pseudospin state of an ensemble of N=5×10^{4} laser-cooled ^{87}Rb ...atoms is deterministically driven to a specified population state with angular resolution that is a factor of 5.5(8) 7.4(6) dB in variance below the standard quantum limit for unentangled atoms-comparable to the best enhancements using only unitary evolution. Without feedback, conditioning on the outcome of the joint premeasurement, we directly observe up to 59(8) times 17.7(6) dB improvement in quantum phase variance relative to the standard quantum limit for N=4×10^{5} atoms. This is one of the largest reported entanglement enhancements to date in any system.
Disaggregation of conventional soil surveys has been identified as a potential source for much of the next generation of model-ready digital soil spatial data. This process aims to apportion vector ...soil surveys into raster (gridded) representations of the component soils that are often aggregated together in map unit designs. Most soil surveys are published with some description of the soil–landscape relationships that distinguish component soils within map units. We used these descriptions found in the Soil Survey Geographic (SSURGO) database of Webster and Pocahontas Counties in West Virginia, USA, to build a set of representative training areas for all soil components by using 1-arc second digital elevation data and derived geomorphic indices. These training areas were then used in classification tree ensembles with a more extensive environmental database to transform the original SSURGO map into a gridded soil series map. We created underlying prediction frequency surfaces from the models that can be used for creating continuous representations of soil class and property distributions.
Disaggregation models matched training sets in 71%–74% of pixels and matched components in original SSURGO map units in 56%–65% of the study area. We evaluated both the original SSURGO data and our models using 87 independent pedons not used in model building. Validation pedons matched components in SSURGO map units at 39% of sites, but in map units that only included one named component (as opposed to multiple soils that could be matched to validation pedons) only 27% of the sites matched. Disaggregation predictions matched validation pedon classes 22–24% of the time using nearest neighbor spatial matches, and these rates increased to 39–44% for correct predictions within a 60-meter radius of the pedon. To characterize uncertainty, we compared relative ensemble prediction frequency (probability) of final hardened model classes at validation sites. Sites with correct predictions had generally higher prediction frequencies; which lead us to use them to create an uncertainty model. Uncertainty was calculated by determining the rate of correct predictions at validation sites within different intervals of prediction frequencies using nearest neighbor validation results. We were able to discern four uncertainty classes with values of 7%, 18%, 20% and 43%, which we called “ground truth probabilities”. We present the methods to create these models as a specific example of how disaggregation techniques may be used to aid in updating national soil survey inventories.
•Conventional soil maps were disaggregated with no new field observations.•Higher resolution disaggregated maps had equivalent accuracy to original soil maps.•Uncertainty was characterized spatially for updated map.•Repeatable methodology for updating and harmonizing conventional soil maps.
The choice of the firm's market environment is one of the fundamental decisions of firm founders. We study the pre-entry generation of founders' market choice sets by investigating their search for ...market opportunities in which the firm's technological resources, as embodied in a product or service, can be commercialized. Analyzing data collected through personal interviews with founders of 496 technology ventures, we find that founding teams with more diverse industry experience and more diverse external knowledge sourcing relationships identify not only a larger number of but, in particular, more varied (distant) market opportunities. However, the extent to which strategic variety of such opportunities is identified depends on the founders' technological expertise, whereas technological expertise is less relevant in identification of the number of opportunities. Furthermore, by showing that the extent and nature of the firm's pre-entry opportunity set has a significant effect on the likelihood of subsequent firm diversification, we document how initial constraints in founders' choice sets can have a lasting impact on the growth potential that the new firm exploits over time. We discuss the implications of our findings for the literatures on organizational learning and innovation, entrepreneurship, as well as the strategy literature examining firm growth, diversification, and value creation.
Targeted protein degraders such as PROTACs and molecular glues are a rapidly emerging therapeutic modality within industry and academia. Degraders possess unique mechanisms of action that lead to the ...removal of specific proteins by co-opting the cell's natural degradation mechanisms
via
induced proximity. Their optimisation thus far has often been largely empirical, requiring the synthesis and screening of a large number of analogues. In addition, the synthesis and development of degraders is often challenging, leading to lengthy optimisation campaigns to deliver candidate-quality compounds. This review highlights how the synthesis of degraders has evolved in recent years, in particular focusing on means of applying high-throughput chemistry and screening approaches to expedite these timelines, which we anticipate to be valuable in shaping the future of degrader optimisation campaigns.
In this review we highlight how the synthesis of degraders has evolved in recent years, in particular the application of high-throughput chemistry and screening approaches such as D2B and DEL technologies to expedite discovery timelines.
We have investigated the electronic relaxation dynamics of gas-phase piperidine (a secondary aliphatic amine) using time-resolved photoelectron imaging. Following 200 nm excitation, spectrally sharp ...and highly anisotropic photoelectron data reveal ultrafast (60 fs) internal conversion between the initially excited 3p
x
Rydberg state and the lower-lying 3s Rydberg state, mediated by the evolution of nσ* valence character along the 3p
x
N-C bond. This behaviour is in good agreement with previously reported findings for several tertiary aliphatic amines. In contrast to the these systems, however, much broader photoelectron signals exhibiting only very small angular anisotropy and two distinct decay timescales (180 fs and 1.7 ps) were also observed. As confirmed by our supporting calculations, this is attributable to nσ* valence character now evolving along the N-H stretching coordinate within the 3s Rydberg state as the molecule starts dissociating to yield H atom photoproducts in conjunction with ground state piperidinyl radicals. By analogy with systems such as ammonia and morpholine, we conclude this event may occur either promptly or, alternatively,
via
a "frustrated" process where the system repeatedly traverses the upper cone of a conical intersection with the ground state until the required region of phase space is sampled to facilitate non-adiabatic population transfer. Our findings reveal the role of several different nuclear coordinate motions in driving stepwise internal conversion across multiple potential energy surfaces and the distinct photoionization signatures that are associated with these processes.
Time-resolved photoelectron spectroscopy reveals distinct ionization signatures of Rydberg-to-valence state evolution in the secondary aliphatic amine piperidine.
The biologic implications of delayed parenthood have been blamed for a major public health crisis in the United States, that includes high rates of neonatal morbidity and mortality (NMM). The ...objective of this study was to evaluate the risk of parent age on NMM and to provide results that can serve as a starting point for more specific mediation modeling.
Data containing approximately 15,000,000 birth records were obtained from the United States Natality database for the years 2014 to 2018. A Bayesian modeling approach was used to estimate the both the total effect and the risk adjusted for confounding between parent ages and for mediation by chromosomal disorders including Down syndrome. Outcomes included intra-hospital death and nine measures of neonatal morbidity.
For paternal age, seven NMM (preterm birth, very preterm birth, low Apgar score, treatment with antibiotics, treatment with surfactant, prolonged ventilation, intra-hospital death) had U-shaped risk patterns, two NMM (small for gestational age, admission to neonatal intensive care) had J-shaped risk patterns, one NMM (seizures) was not significantly related to paternal age. For maternal age, three NMM (low Apgar score, treatment with antibiotics and intra-hospital death) had U-shaped risk patterns, four NMM (preterm delivery, very preterm delivery, admission to neonatal intensive care, treatment with surfactant) had J-shaped risk patterns, one NMM (small for gestational age) had a risk declining with age, one NMM (prolonged ventilation) had a risk increasing with age and one NMM (seizures) was not significantly related to maternal age.
Both advancing maternal and paternal ages had U- or J-shaped risk patterns for neonatal morbidity and mortality.
We have observed the assembly of the staphylococcal pore-forming toxin α-hemolysin using single-molecule fluorescence imaging. Surprisingly, assembly from the monomer to the complete heptamer is ...extremely rapid, occurring in <5 ms. No lower order oligomeric intermediates are detected. Monte Carlo simulation of our experiment shows that assembly is diffusion limited, and pore formation is dependent on the stability of intermediate species. There are close similarities between bacterial pore-forming toxins, such as staphylococcal α-hemolysin, the anthrax protective antigen, and the cholesterol-dependent cytolysins, and their eukaryotic analogs, such as the complement pore membrane attack complex and perforin domain. The assembly mechanism we have observed for α-hemolysin provides a simple model that aids our understanding of these important pore formers.
Herein, we propose a quantum enhanced interferometric protocol for gravimetry and force sensing using cold atoms in an optical lattice supported by a standing-wave cavity. By loading the atoms in ...partially delocalized Wannier-Stark states, it is possible to cancel the undesirable inhomogeneities arising from the mismatch between the lattice and cavity fields and to generate spin squeezed states via a uniform one-axis twisting model. The quantum enhanced sensitivity of the states is combined with the subsequent application of a compound pulse sequence that allows us to separate atoms by several lattice sites. This, together with the capability to load small atomic clouds in the lattice at micrometric distances from a surface, make our setup ideal for sensing short-range forces. We show that for arrays of 104 atoms, our protocol can reduce the required averaging time by a factor of 10 compared to unentangled lattice-based interferometers after accounting for primary sources of decoherence.
Recent experimental evidence suggests that the perception of temporal intervals is influenced by the temporal context in which they are presented. A longstanding example is the time-order-error, ...wherein the perception of two intervals relative to one another is influenced by the order in which they are presented. Here, we test whether the perception of temporal intervals in an absolute judgment task is influenced by the preceding temporal context. Human subjects participated in a temporal bisection task with no anchor durations (partition method). Intervals were demarcated by a Gaussian blob (visual condition) or burst of white noise (auditory condition) that persisted for one of seven logarithmically spaced sub-second intervals. Crucially, the order in which stimuli were presented was first-order counterbalanced, allowing us to measure the carryover effect of every successive combination of intervals. The results demonstrated a number of distinct findings. First, the perception of each interval was biased by the prior response, such that each interval was judged similarly to the preceding trial. Second, the perception of each interval was also influenced by the prior interval, such that perceived duration shifted away from the preceding interval. Additionally, the effect of decision bias was larger for visual intervals, whereas auditory intervals engendered greater perceptual carryover. We quantified these effects by designing a biologically-inspired computational model that measures noisy representations of time against an adaptive memory prior while simultaneously accounting for uncertainty, consistent with a Bayesian heuristic. We found that our model could account for all of the effects observed in human data. Additionally, our model could only accommodate both carryover effects when uncertainty and memory were calculated separately, suggesting separate neural representations for each. These findings demonstrate that time is susceptible to similar carryover effects as other basic stimulus attributes, and that the brain rapidly adapts to temporal context.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Interacting with others in the environment requires that we perceive and recognize their movements and actions. Neuroimaging and neuropsychological studies have indicated that a number of brain ...regions, particularly the superior temporal sulcus, are involved in a number of processes essential for action recognition, including the processing of biological motion and processing the intentions of actions. We review the behavioral and neuroimaging evidence suggesting that while some aspects of action recognition might be rapid and effective, they are not necessarily automatic. Attention is particularly important when visual information about actions is degraded or ambiguous, or if competing information is present. We present evidence indicating that neural responses associated with the processing of biological motion are strongly modulated by attention. In addition, behavioral and neuroimaging evidence shows that drawing inferences from the actions of others is attentionally demanding. The role of attention in action observation has implications for everyday social interactions and workplace applications that depend on observing, understanding and interpreting actions.
► We review the role of attention in action observation. ► Attention is needed when displays of human actions are degraded, or contain noise or competing stimuli. ► The neuroergonomic implications of these findings are discussed.
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