1,493 research outputs found
On Expressivity and Trainability of Quadratic Networks
Inspired by the diversity of biological neurons, quadratic artificial neurons
can play an important role in deep learning models. The type of quadratic
neurons of our interest replaces the inner-product operation in the
conventional neuron with a quadratic function. Despite promising results so far
achieved by networks of quadratic neurons, there are important issues not well
addressed. Theoretically, the superior expressivity of a quadratic network over
either a conventional network or a conventional network via quadratic
activation is not fully elucidated, which makes the use of quadratic networks
not well grounded. Practically, although a quadratic network can be trained via
generic backpropagation, it can be subject to a higher risk of collapse than
the conventional counterpart. To address these issues, we first apply the
spline theory and a measure from algebraic geometry to give two theorems that
demonstrate better model expressivity of a quadratic network than the
conventional counterpart with or without quadratic activation. Then, we propose
an effective and efficient training strategy referred to as ReLinear to
stabilize the training process of a quadratic network, thereby unleashing the
full potential in its associated machine learning tasks. Comprehensive
experiments on popular datasets are performed to support our findings and
evaluate the performance of quadratic deep learning
Density alteration in non-physiological cells
In the present study an important phenomenon of cells was discovered: the change of intracellular density in cell's response to drug and environmental factors. For convenience, this phenomenon is named as "density alteration in non-physiological cells" ( DANCE). DANCE was determined by discontinuous sucrose gradient centrifugation (DSGC), in which cells were separated into several bands. The number and position of the bands in DSGC varied with the change of cell culture conditions, drugs, and physical process, indicating that cell's response to these factors was associated with alteration of intracellular density. Our results showed that the bands of cells were molecularly different from each other, such as the expression of some mRNAs. For most cells tested, intracellular density usually decreased when the cells were in bad conditions, in presence of drugs, or undergoing pathological changes. However, unlike other tissue cells, brain cells showed increased intracellular density in 24 hrs after the animal death. In addition, DANCE was found to be related to drug resistance, with higher drug-resistance in cells of lower intracellular density. Further study found that DANCE also occurred in microorganisms including bacteria and fungus, suggesting that DANCE might be a sensitive and general response of cells to drugs and environmental change. The mechanisms for DANCE are not clear. Based on our study the following causes were hypothesized: change of metabolism mode, change of cell membrane function, and pathological change. DANCE could be important in medical and biological sciences. Study of DANCE might be helpful to the understanding of drug resistance, development of new drugs, separation of new subtypes from a cell population, forensic analysis, and importantly, discovery of new physiological or pathological properties of cells
3,4-Dihydroxyphenethyl acetate
In the title compound, C10H12O4, the dihedral angle between the acetate group and the aromatic ring is 20.47 (10)°. In the crystal, molecules are linked by O—H⋯O hydrogen bonds, forming [001] chains. Weak C—H⋯O interactions consolidate the packing
Effects of acute ammonia exposure and post-exposure recovery on nonspecific immunity in Clam Cyclina sinensis
This study aimed to assess the toxicity of ammonia on clam Cyclina sinensis and the post-exposure recovery. With increased exposure to TAN, the alkaline phosphatase (AKP) activities after exposure showed a trend of growing initially and subsequently decreasing, whereas the AKP activities after post-exposure recovery showed an increasing trend. The AKP activities after post-exposure recovery were significantly higher than those in control. The acid phosphatase (ACP) activities in T1 and T2 after post-exposure recovery were higher than those in the control, whereas the ACP activities in T3, T4, and T5 after post-exposure recovery were significantly higher than those in the control. The lysozyme (LZM) activities in T1 and T2 after exposure were significantly higher than those in control, whereas the LZM activities in T3, T4, and T5 after exposure were significantly lower than those in the control. Overall, ACP and LZM in the clams exposed to a low level of TAN (≤ 40 mg/L) can recover to the normal levels completely. However, a 48h recovery period scarcely seems adequate to compensate for AKP, ACP, and LZM activities in the clams exposed to a high level of TAN (> 40 mg/L)
Identifying the physical origin of gamma-ray bursts with supervised machine learning
The empirical classification of gamma-ray bursts (GRBs) into long and short
GRBs based on their durations is already firmly established. This empirical
classification is generally linked to the physical classification of GRBs
originating from compact binary mergers and GRBs originating from massive star
collapses, or Type I and II GRBs, with the majority of short GRBs belonging to
Type I and the majority of long GRBs belonging to Type II. However, there is a
significant overlap in the duration distributions of long and short GRBs.
Furthermore, some intermingled GRBs, i.e., short-duration Type II and
long-duration Type I GRBs, have been reported. A multi-parameter classification
scheme of GRBs is evidently needed. In this paper, we seek to build such a
classification scheme with supervised machine learning methods, chiefly
XGBoost. We utilize the GRB Big Table and Greiner's GRB catalog and divide the
input features into three subgroups: prompt emission, afterglow, and host
galaxy. We find that the prompt emission subgroup performs the best in
distinguishing between Type I and II GRBs. We also find the most important
distinguishing feature in prompt emission to be T_{90}, hardness ratio, and
fluence. After building the machine learning model, we apply it to the
currently unclassified GRBs to predict their probabilities of being either GRB
class, and we assign the most probable class of each GRB to be its possible
physical class.Comment: 23 pages, 8 tables, 11 figures, accepted for publication by ApJ. Full
version of Table 5 is available as ancillary materia
1-{(1Z)-1-[6-(4-Chlorophenoxy)hexyloxy]-1-(2,4-difluorophenyl)prop-1-en-2-yl}-1H-1,2,4-triazol-4-ium nitrate
In the title compound, C23H25ClF2N3O2
+·NO3
−, the triazole ring makes dihedral angles of 60.9 (4) and 25.0 (3)° with the 6-chlorophenyl and 2,4-difluorophenyl rings, respectively. The molecule adopts a Z configuration about the C=C double bond. In the crystal, the cations and anions are linked by N—H⋯O hydrogen bonds and weak C—H⋯O interactions
Effects of methylphenidate on attentional set-shifting in a genetic model of attention-deficit/hyperactivity disorder
Abstract Background Although deficits of attentional set-shifting have been reported in individuals with attention deficit/hyperactivity disorder (ADHD), it is rarely examined in animal models. Methods This study compared spontaneously hypertensive rats (SHRs; a genetic animal model of ADHD) and Wistar-Kyoto (WKY) and Sprague-Dawley (SD) rats (normoactive control strains), on attentional set-shifting task (ASST) performance. Furthermore, the dose-effects of methylphenidate (MPH) on attentional set-shifting of SHR were investigated. In experiment 1, ASST procedures were conducted in SHR, WKY and SD rats of 8 each at the age of 5 weeks. Mean latencies at the initial phase, error types and numbers, and trials to criteria at each stage were recorded. In experiment 2, 24 SHR rats were randomly assigned to 3 groups of 8 each-- MPH-L (lower dose), MPH-H (higher dose), and SHR-vehicle groups. From 3 weeks, they were administered 2.5 mg/kg or 5 mg/kg MPH or saline respectively for 14 consecutive days. All rats were tested in the ASST at the age of 5 weeks. Results The SHRs generally exhibited poorer performance on ASST than the control WKY and SD rats. Significant strain effects on mean latency [F (2, 21) = 639.636, p p p p p Conclusions The SHR may be impaired in discrimination learning, reversal learning and attentional set-shifting. Our study provides evidence that MPH may improve the SHR's performance on attentional set-shifting and lower dose is more effective than higher dose.</p
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