269 research outputs found
What are Current Best Approaches Companies are Using for Performance Management for Wage Employees?
Academic journals mainly focus on performance management for white-collar employees and lack resources on best practices for wage employees. In response, we have consulted with two renowned professors at the ILR School for advice and also interviewed an HR manager at GE Aviation to find out how leading firms manage performance of hourly-wage workers in practice by probing into three major components of how they 1) approach goal-setting, 2) manage the performance evaluation process, and 3) align performance results with other HR programs
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Terahertz Polarimetric Imaging
Imaging in the terahertz (THz) regime (0.1-10 THz) has shown grown interest over the past couple decades. While the THz imaging field is maturing, little work has been done imaging at these frequencies using polarization as a contrast mechanism. The polarization state of light as it interacts with different media contains additional information such as surface features, birefringence, and diattentuation. In this thesis, a polarization sensitive THz single-pixel imaging system is demonstrated using a recently developed THz quantum-cascade external cavity surface emitting laser (QC-VECSEL). The QC-VECSEL provides a high power THz laser output with good beam quality, features that are ideal for single-pixel imaging. The polarization sensitive images are acquired by using a fast rotating polarizer as an analyzer. This modulates the polarization state of the image, allowing for lock-in detection. Additionally, comparisons between past imaging systems are made to spotlight specific improvements achieved in this work
Circumnuclear gas in radio AGN revealed by molecular absorption
Active galactic nuclei (AGN) are among the most powerful energy sources in the Universe. The radio jet outflows triggered by AGN activity are supposed to play an important role in galaxy formation and evolution. However, our knowledge about the different types of radio jets and their influence on their host galaxies (i.e., radio jet feedback) is still limited. As a matter reservoir in the vicinity of the central engine, the circumnuclear gas is the key to study different accretion environments and the process of radio jet feedback in radio AGN. Although radio AGN tend to be gas-poor and distant, observations of molecular absorption lines against bright continuum radio jets facilitate the detection of this circumnuclear gas, independent from their cosmological distance. Moreover, spectral line VLBI observations towards molecular absorption lines provide a unique tool to study the small-scale (<pc) structure of the circumnuclear gas, which might be related to AGN fueling and feedback processes. By taking such advantages, this thesis aims to shed more light on the physical connection between the central portions of radio jets and their surrounding medium in radio AGN. The first chapter of this thesis briefly introduces the current understanding of AGN and touches on some remaining open questions. Chapter 2 briefly describes relevant observing tools for absorption line studies and principles of radio observations. Chapter 3 presents attempts to find molecular absorption lines towards 41 radio AGN with the 100-m Effelsberg and 30-m IRAM single dish telescopes. Although strong radio frequency interference and standing waves in the observed spectra resulted in a rather low detection rate, we detected molecular absorption in 3 AGN, and the 22 GHz H2O maser line in 2 AGN. Diagnostics using the molecular absorption and maser lines show different kinematics of the circumnuclear gas in the Seyfert galaxy NGC3079 and in the radio-loud AGN NGC1052. As a new approach to overcome technical hindrances from single-dish absorption studies, an interferometric absorption line study was conducted using the NOEMA interferometer. These results are presented in Chapter 4. The copious molecular absorption lines detected in 3C 293 and 4C 31.04 demonstrate the excellence of the interferometric array in absorption line observations towards radio AGN with bright continuum jets. In particular, the physical and chemical properties constrained by the detected molecular absorption lines better clarify the physical origin of the obscuring gas, and provide a diagnostics of radio jet feedback on the circumnuclear gas in the restarted (3C 293) and young (4C 31.04) radio AGN. In order to reach even smaller angular and spatial scales of the circumnuclear gas in radio AGN, high-resolution Very Long Baseline Interferometry (VLBI) observations were conducted towards OH absorption lines. Chapter 5 presents VLBI observations towards OH absorption lines at 6 GHz in the Seyfert galaxy NGC 3079 using the European VLBI Network (EVN). The still putative radio jet feedback was confirmed by the detection of spatially resolved OH absorption lines on the continuum jets. The blue-shifted OH absorption on the propagating jet component indicates jet-ISM interaction and a resultant molecular outflow at a distance of a few pc from the central engine. An increasing jet luminosity and decelerated jet motion show the impact of jet-ISM interaction on jet evolution. Chapter 6 presents High Sensitivity Array (HSA) and EVN observations towards two distinct radio-loud AGN Cygnus A and NGC 4261. The 6 GHz and 13 GHz excited OH absorption lines were searched to test the unified scheme and different accretion environments in Cygnus A (HERG and FR II) and NGC 4261 (LERG and FR I). The 13 GHz OH absorption lines detected in front of the jet, but not on the counter-jet in CygnusA contradict the classical scenario of an obscuring torus, which covers the counter-jet, but not the jet. The red-shifted and compact OH cloud in front of the jet might indicate fueling gas falling into the central engine. In contrast to this, no OH absorption was seen in NGC 4261 despite previous detection of 6 GHz OH absorption. Several scenarios are discussed to explain the lack of OH absorption in NGC 4261. Chapter 7 summarizes the implications of molecular absorption line studies towards radio AGN from the ongoing work and addresses some remaining questions. The absorption studies presented in this thesis provide new insights on the circumnuclear gas in the observed radio AGN, constraining their physical and chemical properties down to sub-parsec scales and near the jet-launching region. With planned imaging arrays of higher sensitivity and extended spectral coverage, future absorption line VLBI studies have a great potential to reveal even more details on the physical and geometrical properties of the circumnuclear gas and on the interaction between inflow and outflow of matter within the central regions of radio galaxies
Eigenvector space model to capture features of documents
Eigenvectors are a special set of vectors associated with a linear system of equations. Because of the special property of eigenvector, it has been used a lot for computer vision area. When the eigenvector is applied to information retrieval field, it is possible to obtain properties of documents data corpus. To capture properties of given documents, this paper conducted simple experiments to prove the eigenvector is also possible to use in document analysis. For the experiment, we use short abstract document of Wikipedia provided by DBpedia as a document corpus. To build an original square matrix, the most popular method named tf-idf measurement will be used. After calculating the eigenvectors of original matrix, each vector will be plotted into 3D graph to find what the eigenvector means in document processing.
Audio-Visual Spatial Integration and Recursive Attention for Robust Sound Source Localization
The objective of the sound source localization task is to enable machines to
detect the location of sound-making objects within a visual scene. While the
audio modality provides spatial cues to locate the sound source, existing
approaches only use audio as an auxiliary role to compare spatial regions of
the visual modality. Humans, on the other hand, utilize both audio and visual
modalities as spatial cues to locate sound sources. In this paper, we propose
an audio-visual spatial integration network that integrates spatial cues from
both modalities to mimic human behavior when detecting sound-making objects.
Additionally, we introduce a recursive attention network to mimic human
behavior of iterative focusing on objects, resulting in more accurate attention
regions. To effectively encode spatial information from both modalities, we
propose audio-visual pair matching loss and spatial region alignment loss. By
utilizing the spatial cues of audio-visual modalities and recursively focusing
objects, our method can perform more robust sound source localization.
Comprehensive experimental results on the Flickr SoundNet and VGG-Sound Source
datasets demonstrate the superiority of our proposed method over existing
approaches. Our code is available at: https://github.com/VisualAIKHU/SIRA-SSLComment: Camera-Ready, ACM MM 202
Task Agnostic Restoration of Natural Video Dynamics
In many video restoration/translation tasks, image processing operations are
na\"ively extended to the video domain by processing each frame independently,
disregarding the temporal connection of the video frames. This disregard for
the temporal connection often leads to severe temporal inconsistencies.
State-Of-The-Art (SOTA) techniques that address these inconsistencies rely on
the availability of unprocessed videos to implicitly siphon and utilize
consistent video dynamics to restore the temporal consistency of frame-wise
processed videos which often jeopardizes the translation effect. We propose a
general framework for this task that learns to infer and utilize consistent
motion dynamics from inconsistent videos to mitigate the temporal flicker while
preserving the perceptual quality for both the temporally neighboring and
relatively distant frames without requiring the raw videos at test time. The
proposed framework produces SOTA results on two benchmark datasets, DAVIS and
videvo.net, processed by numerous image processing applications. The code and
the trained models are available at
\url{https://github.com/MKashifAli/TARONVD}
Printed Receive Coils with High Acoustic Transparency for Magnetic Resonance Guided Focused Ultrasound.
In magnetic resonance guided focused ultrasound (MRgFUS) therapy sound waves are focused through the body to selectively ablate difficult to access lesions and tissues. A magnetic resonance imaging (MRI) scanner non-invasively tracks the temperature increase throughout the tissue to guide the therapy. In clinical MRI, tightly fitted hardware comprised of multichannel coil arrays are required to capture high quality images at high spatiotemporal resolution. Ablating tissue requires a clear path for acoustic energy to travel but current array materials scatter and attenuate acoustic energy. As a result coil arrays are placed outside of the transducer, clear of the beam path, compromising imaging speed, resolution, and temperature accuracy of the scan. Here we show that when coil arrays are fabricated by additive manufacturing (i.e., printing), they exhibit acoustic transparency as high as 89.5%. This allows the coils to be placed in the beam path increasing the image signal to noise ratio (SNR) five-fold in phantoms and volunteers. We also characterize printed coil materials properties over time when submerged in the water required for acoustic coupling. These arrays offer high SNR and acceleration capabilities, which can address current challenges in treating head and abdominal tumors allowing MRgFUS to give patients better outcomes
The distribution of cyanobacterial toxins in Korean lakes
Cyanobacterial blooms in eutrophic lakes often produce algal toxins causing death of livestock, wild animals, and fish. In this work, phytoplankton communities were examined for the appearance of toxic species. The occurrence of toxic bloom was examined with mouse bioassay. Phytoplankton were collected in late summer at the surface of 6 middlestream reservoirs(Soyang, Chungju, Daechong, Jangsung, Hapchon, Jinyang, Okjung), an estuarine reservoir(Yongsan), and a coastal lagoon(Yonglang). Algal cells were freeze-dried for the use in mouse bioassay and chemical analysis. The occurrence of toxic bloom was examined with mouse bioassay and the content of two cyanobacterial hepatotoxins, microcystin-RR and -LR, that are known to be most common in freshwater algae were analyzed with HPLC. In all the study lakes cyanobacteria were dominant phytoplankton. The dominant species implied the possibility of toxin production(Microcystis, Anabaena etc.). In L. Soyang and Chungju, dominant species were Anabaena and Oscillatoria, respectively. In L. Jangsung and Daechong, Anabaena and Microcystis appeared together. Test of toxicity by mouse bioassay showed lethal effect for L. Yonglang, L. Hapchon, L. Yongsan, L. Jangsung. L. Yonglang showed strong lethal effect. Microcystin-LR and -RR both were detected in L. Hapchon, L. Jangsung and L. Yonglang, and microcystin-LR was detected in L. Yongsan, -RR was detected in L. Daechong, L. Chungju, and L. Soyang.Article信州大学理学部附属諏訪臨湖実験所報告 9: 169-174(1995)departmental bulletin pape
Effects of Branching on Conformation, Crystallization, and Self-Assembly of Polymers
The central feature of bottlebrush polymers is the stiffening of the main-chain (MC) due to side-chain side-chain (SC-SC) repulsion, amplified by densely grafting long SCs, particularly in good solvent conditions. The expectation of stiffening has led most prior studies to refer to bottlebrush polymers as "worm-like," "cylindrical" or a "self-avoiding walk (SAW) of superblobs". However, there is no direct evidence of stiffening of the main-chain and measurements of the overall segment distribution of the whole molecule have failed to discriminate between competing models. Here, we provide a set of measurements of the main-chain conformation (neutron scattering in a solvent that is contrast matched to the side chains) together with the overall conformation of the bottlebrush as a whole (light, X-ray, and neutron scattering) under conditions that highlight SC-SC repulsion: the side-chains are relatively long compared to prior literature, the concentration of bottlebrushes is low, and the solvent quality is good. Surprisingly, the main-chain has a conformation that does not conform to any prior models: all three main-chain lengths examined showed a window of length scales in which the scattering power increased less than linearly with length scale. In particular, the MC conformation is not worm-like. Direct observation of the main-chain conformation and the overall conformation discriminates among models more powerfully than the overall conformation alone. Inspired by the Paturej-Rubinstein tension blob model, we examined a conceptual model in which tension of the MC accumulates with distance from the ends of the MC and found that it can capture the salient features of both the MC- and whole bottlebrush scattering more gradually than previous theoretical models predicted. The conceptual model also explains our observation of a substantial increase in anisometry with increasing MC length, opposite to a worm-like chain. The results indicate that synthetically accessible bottlebrushes are not fractals; they cannot have self-similar (fractal) conformation because each increase in main-chain length accesses greater side-chain crowding than any of its shorter siblings. We expanded the work to understand the behavior in θ conditions and shorter side-chains expected to have reduced tension as well as the behavior at different concentrations.
In addition, we characterized the interplay of self-assembly and polymer crystallization through analysis of three representative bottlebrush copolymer systems. Our results revealed a surprising number of unexpected behaviors ranging from unexpected morphologies, control of thermal properties even to complete suppression of phase transitions, and control of the orientation of crystal stem with respect to the morphological interface, which highlights the potential of the bottlebrush architecture.</p
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