Quantity Limits Research Articles

Per-customer quantity limit and price discrimination: Evidence from the U.S. residential mortgage market

Theoretically, if firms face a regulatory per-customer quantity limit, they should have an incentive to discriminatively charge high-demand customers higher prices and make them just willing to buy a quantity equal to the limit. In the U.S. residential mortgage industry, mortgages with origination balances above the conforming loan limits cannot be guaranteed by government-sponsored enterprises, which make lenders face a per-customer quantity limit. This paper finds that borrowers bunching at the limit pay higher interest rates due to price discrimination. This study rules out the alternative explanation that those borrowers are of higher risk (lending cost) than other borrowers.

Asymptotics in Spin-Boson Type Models

In this paper, we investigate a family of models for a qubit interacting with a bosonic field. More precisely, we find asymptotic limits of the Hamiltonian as the interaction strength tends to infinity. The main result has two applications. First of all, we show that any self-energy renormalisation scheme similar to that of the Nelson model does not converge for the three-dimensional Spin-Boson model. Secondly, we show that excited states exist in the massive Spin-Boson model for sufficiently large interaction strengths. We are also able to compute the asymptotic limit of many physical quantities.

OEC-cnn: a simple method for over-exposure correction in photographs

This work reports on convolutional neural network (CNN) performance on an image texture classification task as a function of linear image processing and number of training images. Detection performance of single and multi-layer CNNs (sCNN/mCNN) are compared to optimal observers. Performance is quantified by the area under the receiver operating characteristic (ROC) curve, also known as the AUC. For perfect detection AUC = 1.0 and AUC = 0.5 for guessing. The Ideal Observer (IO) maximizes AUC but is prohibitive in practice because it depends on high-dimensional image likelihoods. The IO performance is invariant to any fullrank, invertible linear image processing. This work demonstrates the existence of full-rank, invertible linear transforms that can degrade both sCNN and mCNN even in the limit of large quantities of training data. A subsequent invertible linear transform changes the images’ correlation structure again and can improve this AUC. Stationary textures sampled from zero mean and unequal covariance Gaussian distributions allow closed-form analytic expressions for the IO and optimal linear compression. Linear compression is a mitigation technique for high-dimension low sample size (HDLSS) applications. By definition, compression strictly decreases or maintains IO detection performance. For small quantities of training data, linear image compression prior to the sCNN architecture can increase AUC from 0.56 to 0.93. Results indicate an optimal compression ratio for CNN based on task difficulty, compression method, and number of training images.

Liquid-liquid chromatography in sample pretreatment for quantitative analysis of trace component in traditional Chinese medicines by conventional liquid chromatography

A method for sample pretreatment using liquid-liquid chromatography combined with a conventional liquid chromatography was developed for quantitative determination of trace chemical component in traditional Chinese medicine. The main effective component, wilforlide A, in the traditional Chinese medicinal herb Tripterygium wilfordii as well as in its Chinese patent medicine glycosides tablets was successfully determined after sample pretreatment by liquid-liquid chromatography. A biphasic solvent system n-hexane-ethyl acetate-ethanol-water (6:4:6:4, v/v) was screened for crude sample treatment by liquid-liquid chromatography. The collection time of eluted fractions containing target component could be well predicted using a continuous-stirred tank reactors model after determination of its retention time. Then, quantitative analysis of wilforlide A in Tripterygium wilfordii as well as in its tablets could be successfully determined by conventional reversed-phase high performance liquid chromatography with UV detector. Under the optimized conditions, the method showed good linearity (R2 = 0.9999) for wilforlide A in the range of 0.01 mg mL−1 −0.10 mg mL−1. The limit of detection and limit of quantity were 1.35 ng mL−1 and 4.50 ng mL−1, respectively. The average recovery rate, intra-day and inter-day precisions of wilforlide A were 96.43%, 0.67% and 1.14%, respectively. Compared with previous studies, the present method showed advantages of complete recovery of target component in the sample pretreatment and good repeatability.

Sensitive colorimetric detection of Pb2+ by geometric field amplification and surface plasmon resonance visualization

Pb2+ is one of the major environmental pollutants, which can be visually detected by surface plasmon resonance of nanoparticles. Paper based analytical device, as a newly developed microfluidic detection platform, is featured in cost-effective and suitable for on-site analysis. In this paper, a sensitive and portable detection method for Pb2+ was proposed, in which Pb2+ was electrokinetically stacked on the paper fluidic channel by geometric field amplification effect and visualized online by glutathione-modified silver nanoparticles. Colorimetric quantification of the visualized stacking band was conducted by smart phone camera. To avoid unfavorable influence from pH change on the surface plasmon resonance visualization, field amplification effect was introduced by geometric design of the paper fluidic channel. The enriched Pb2+ was clearly visible on the paper substrate, and the stacking band intensity was about four orders of magnitude enhanced, comparing to the intensity without stacking. A linear response to Pb2+ was observed in the range of 0.3–7.0 μM (R2 = 0.997) with a limit of detection of 86 nM and a limit of quantity of 0.28 μM. The established method was used in the detection of Pb2+ from river and lake water samples, and the results were confirmed by atomic absorption spectroscopy method.

Per-Customer Quantity Limit and Price Discrimination: Evidence from the U.S. Residential Mortgage Market

Theoretically, if firms face a regulatory per-customer quantity limit, they should have an incentive to discriminatively charge high-demand customers higher prices and make them just willing to buy a quantity equal to the limit. In the U.S. residential mortgage industry, mortgages with origination balances above the conforming loan limits cannot be guaranteed by Government-Sponsored Enterprises, which make lenders face a per-customer quantity limit. This paper finds that borrowers bunching at the limit pay higher interest rates due to price discrimination. This study rules out the alternative explanation that those borrowers are of higher risk (lending cost) than other borrowers.

Freely Accessible Chemical Database Resources of Compounds for In Silico Drug Discovery.

In silico drug discovery has been proved to be a solidly established key component in early drug discovery. However, this task is hampered by the limitation of quantity and quality of compound databases for screening. In order to overcome these obstacles, freely accessible database resources of compounds have bloomed in recent years. Nevertheless, how to choose appropriate tools to treat these freely accessible databases is crucial. To the best of our knowledge, this is the first systematic review on this issue. The existed advantages and drawbacks of chemical databases were analyzed and summarized based on the collected six categories of freely accessible chemical databases from literature in this review. Suggestions on how and in which conditions the usage of these databases could be reasonable were provided. Tools and procedures for building 3D structure chemical libraries were also introduced. In this review, we described the freely accessible chemical database resources for in silico drug discovery. In particular, the chemical information for building chemical database appears as attractive resources for drug design to alleviate experimental pressure.

Multi-parameter adjustment for high-precision azimuthal intersection positioning

The traditional azimuthal intersection method is viable for situations with only two control stations but a simple height averaging is not rigorous because the intersections vary in their distances from the two stations. In order to obtain the high-precision azimuthal intersections, this study presented a multi-parameter adjustment method, together with the Earth curvature correction and the atmospheric refraction correction models. This method is robust with varied distances between the control stations and the targeted intersections, without limitation of station quantity.•Based on the traditional space intersection, a multi-parameter adjustment model is added into the data processing for high-precision 3D positioning.•Both the Earth curvature error correction model and the atmospheric error correction model are included in the multi-parameter adjustment model, so the intersected points are more accurate than traditional intersections.

Deep Learning From Limited Training Data: Novel Segmentation and Ensemble Algorithms Applied to Automatic Melanoma Diagnosis

Deep learning algorithms often require thousands of training instances to generalize well. The presented research demonstrates a novel algorithm, Predict-Evaluate-Correct K-fold (PECK), that trains ensembles to learn well from limited data. The PECK algorithm is used to train a deep ensemble on 153 non-dermoscopic lesion images, significantly outperforming prior publications and state-of-the-art methods trained and evaluated on the same dataset. The PECK algorithm merges deep convolutional neural networks with support vector machine and random forest classifiers to achieve an introspective learning method. Where the ensemble is organized hierarchically, deeper layers are provided not only more training folds, but also the predictions of previous layers. Subsequent classifiers then learn and correct the previous layer errors by training on the original data with injected predictions for new data folds. In addition to the PECK algorithm, a novel segmentation algorithm, Synthesis and Convergence of Intermediate Decaying Omnigradients (SCIDOG), is developed to accurately detect lesion contours in non-dermoscopic images, even in the presence of significant noise, hair, and fuzzy lesion boundaries. As SCIDOG is a non-learning algorithm, it is unhindered by data quantity limitations. The automatic and precise segmentations that SCIDOG produces allows for the extraction of 1,812 lesion features that quantify shape, color and texture. These morphological features are used in conjunction with convolutional neural network predictions for training the PECK ensemble. The combination of SCIDOG and PECK algorithms are used to diagnose melanomas and benign nevi through automatic digital image analysis on the MED-NODE dataset. Evaluated using 10-fold cross validation, the proposed methods achieve significantly increased diagnostic capability over the best prior methods.

Enhancing the prebiotic effect of cellulose biopolymer in the gut by physical structuring via particle size manipulation.

Cellulose is generally recognised as dietary fibre with no limit of permissible quantity in food, and its consumption may modulate digesta content and impact positively on the gastrointestinal physiology and gut microflora. However, cellulose in its native form possessed inherent undesirable physical properties, making it unattractive for food applications. Here, we postulate that by changing cellulose size to nanometric scale, its prebiotic effect would be altered and fermented differently in contrast with micro size cellulose by the gut microbiome and promote the yield of metabolites such as short chain fatty acids (SCFAs). Using faecal matter from three healthy human donors as microbial source, in vitro fermentation of variable size fractions of cellulose from the same were fermented under anaerobic conditions, and SCFAs as well Bifidobacterium selectively isolated and analysed. The increase in production of acetate (194%), butyrate (224%) and propionate (211%) after 24h of fermentation was significantly promoted by the size reduction and revealed size-dependent relationship as exemplified R2 values >0.83. Consequently, gavaging rats with nanometric size cellulose (125nm) significantly (p<0.05) increased these SCFAs yields as well Bifidobacterium counts in contrast with both control and the micro scale size cellulose. Therefore, engineered nanocellulose might have beneficial physiological impact on the gut with improved prebiotic effect.

A statistical model of the impact of online rumors on the information quantity of online public opinion

Current studies have considered the upper growth limit of the information quantity of online public opinion, although the effect of online rumors on the upper growth limit has not been considered. This study aims to identify the key parameters in a model of online rumors that affect the upper growth limit. First, the logistic population growth model is introduced to analyze the mechanism underlying the impact of online rumors on the information quantity of online public opinion. Second, the theory of differential equations is employed to build an influence rule between the two models. Third, we perform a numerical simulation to explore the development trend of the information quantity of online public opinion under the control of three parameters: rumor input rate, rumor conversion rate and rumor refutation rate. This paper defined the key factors for assessing how online public opinions are affected by online rumors, determined the influence strength of parameters under different online public opinion modes, better described the abnormal growth pattern of online public opinion, and provided a theoretical basis for online public opinion prediction and rumor control research.

Tracking Mercury in Individual Tetrahymena Using a Capillary Single-Cell Inductively Coupled Plasma Mass Spectrometry Online System.

As a kind of unicellular eukaryotic protozoa, Tetrahymena is located at the bottom of the aquatic food webs and plays an essential role in the bioaccumulation of mercury (Hg). To track Hg in individual Tetrahymena, a capillary single-cell inductively coupled plasma mass spectrometry (ICPMS) online system was developed. The experimental and instrumental conditions were optimized to ensure the signal detected was the Hg uptake in individual Tetrahymena. Moreover, a quantitative method was established and validated by detecting Hg2+ standard solutions. The limit of quantity was calculated to be approximately 3.8 × 10-15 g Hg/cell, and the detection limit for Hg2+ exposure of Tetrahymena was 0.05 μg/L. By using the proposed method, we found the peak became wider with increasing of exposure concentrations, indicating the accumulated Hg by different Tetrahymena varied greatly, and the difference was more significant at higher exposure concentration. This novel method has the advantages of high sensitivity and real-time detection in individual Tetrahymena, and it could be widely used for further tracking the accumulation of mercury and other metals at the single cell level.

Effective extraction of fluorescent brightener 52 from foods by in situ formation of hydrophobic deep eutectic solvent

Fluorescent brightener 52 (FWA52) is a coumarin-based compound, and it is difficult to degrade owing to its high chemical stability. Up to now, several methods have been developed to extract and determine FWAs, but toxic, volatile and harmful organic solvents are often used. In this paper, a novel method for the extraction and analysis of FWA52 is proposed for the first time by in situ formation of hydrophobic deep eutectic solvent (DES) with parabens in aqueous solution. The effects of paraben structure, solution pH, system temperature, extractant dosage and initial FWA52 concentration on the extraction recovery were investigated systematically. It is shown that FWA52 can be extracted by 2-ethylhexyl 4-hydroxybenzoate at ultra-trace level (0.05 μg/L FWA52) at room temperature without using harmful organic solvents, and various coexisting inorganic ions and organic compounds have little effect on the extraction efficiency. Based on these results, a novel and simple strategy is developed for the accurate determination of FWA52 in water. It is found that under the optimal experimental conditions, the linear range of this method is 0.20~25 μg/L (R2 = 0.9995), and the detection limit and the quantity limit are 0.045 μg/L and 0.20 μg/L respectively. This method has been successfully applied for the determination of FWA52 in actual food samples and food contact materials, such as noodles, fish balls, mushroom and paper cups, with a recovery from 82 to 113% and a relative standard deviation (RSD) from 4.7 to 9.9%. In addition, the separation mechanism was investigated by FT-IR and 1H NMR, and was discussed from strong hydrogen bonding between FWA52 and 2-ethylhexyl 4-hydroxybenzoate and the formation of corresponding DES.

Evolution of the TRICARE Pharmacy Benefit: A Decade of Change.

TRICARE is the military's health plan that provides coverage to 9.4 million active duty and retired uniformed services personnel and their family members. The TRICARE pharmacy benefit has undergone many changes in the last decade. These changes include assigning newly approved drugs to nonformulary status after regulatory approval, the addition of weight loss medications to the benefit, channel management point-of-service requirements for some medications, and copay increases. Several initiatives have resulted in significant cost avoidance to the Department of Defense (DoD). The purpose of this article is to discuss the changes to the TRICARE pharmacy benefit, describe the continual challenges, and estimate cost savings associated with implementation of these changes. DoD implemented its 3-tier Uniform Formulary in 2005. Since then, many changes have been enacted, including more extensive use of prior authorization, step therapy, and quantity limits; coverage of over-the-counter medications; the retail refund program; coverage of vaccines and smoking cessation agents; mandatory mail/military treatment facility requirements; rapid review and initial nonformulary status for newly approved innovator drugs; revisions to the compounded drug benefit; initial deployment of a new medical record system; coverage of weight loss medications; and the ability to exclude medications from the Uniform Formulary. Although the TRICARE pharmacy benefit has evolved significantly, the focus remains on the beneficiaries, with an overall goal of providing integrated, affordable, and high quality health services for the Military Health System. Challenges for the future include maximizing clinical effectiveness in the face of rising pharmaceutical costs and cost avoidance, while supporting the needs of TRICARE beneficiaries. DISCLOSURES: No outside funding supported this study. The authors declare no conflicts of interest, real or apparent, and no financial interests in any company, product, or service mentioned in this program, including grants, employment, gifts, stock holdings, and honoraria. The information discussed here represents the views of the authors and does not necessarily reflect the views of the Defense Health Agency (DHA), the Department of Defense (DoD), or the Departments of the Army, Navy, and Air Force. The authors have nothing to disclose that presents a potential conflict of interest.

Obtaining Genome Sequences of Mutualistic Bacteria in Single Microcystis Colonies.

Cells of Microcystis are associated with heterotrophic bacteria and organized in colonies in natural environment, which are basic elements in the mass occurrence of cyanobacterial species. Analyzing these colonies by using metagenomics is helpful to understand species composition and relationship. Meanwhile, the difference in population abundance among Microcystis colonies could be used to recover genome bins from metagenome assemblies. Herein, we designed a pipeline to obtain high-quality genomes of mutualistic bacteria from single natural Microcystis colonies. Single colonies were lysed, and then amplified by using multiple displacement amplification to overcome the DNA quantity limit. A two-step assembly was performed after sequencing and scaffolds were grouped into putative bins based on their differential-coverage among species. We analyzed six natural colonies of three prevailing Microcystis species from Lake Taihu. Clustering results proved that colonies of the same species were similar in the microbial community composition. Eight putative population genome bins with wide bacterial diversity and different GC content were identified based on coverage difference among colonies. At the phylum level, proteobacteria was the most abundant besides cyanobacteria. Six of the population bins were further refined into nearly complete genomes (completeness > 90%).

Embedded Hardware Artificial Neural Network Control for Global and Real-Time Imbalance Current Suppression of Parallel Connected IGBTs

A global and real-time control with embedded hardware artificial neural network (ANN) for imbalance current suppression of parallel connected insulated gate bipolar transistors (IGBTs) is first proposed in this paper. This method focuses on control strategy and control execution. The former one is realized by porting the ANN-based PID (ANN-PID) strategy in the control loop to yield the real-time and adaptive characteristics without IGBT quantity limitation. The latter one is realized by designing the IGBT gate quantity of charge regulator (GQR) to execute the command from ANN-PID controller. The evaluation of ANN-PID algorithm results 0.023% mean error in IGBT current control that reveals the feasibility of the proposed method. A full prototype with FPGA-based hardware accelerator for ANN-PID computing, including the designed GQR circuit, has been built for realization and qualification in a buck converter with parallel connected IGBTs. The experimental results show that the performance of the proposed method in imbalance current suppression is improved about 3.5–5.5 times as the load increase from low to high with the advantage of immunity to load change and the current imbalance can be suppressed within 4%.

Medium and long-term power quantity check and adjustment method based on power quantity margin

Medium and long-term power trade is increasing, and the adjustable margin of power grid is reducing. Therefore, medium and long-term power quantity security check is necessary. Firstly, a power quantity margin model is constructed, and power quantity constraints and the future state grid model are considered. The power quantity limits of principal parts such as unit and line section are calculated, and quantity adjustment method is given.Then the medium and long-term power quantity check and adjustment are realized through the correlation coefficient matrix. Finally, the actual provincial power grid is taken as an example to verify the effectiveness of the proposed model and method. Through the calculation of the quantity margin by power, the verification of medium and long-term transactions and the control of the safety margin of the power grid are realized.

Introduction of New Tensile Specimen Geometry for Property Evaluation in Stamped Parts

Abstract Reliable tensile data are crucial in the automotive design process, particularly for the implementation of new Advanced High Strength Steel grades that can be used in new intricate shapes. The property evaluation of specific subsections of a complex part, such as a metal stamping, requires deviation from standard-sized specimens because of material quantity limitations which force the use of smaller specimens. A new tensile geometry is introduced for testing regions within parts that were previously difficult to characterize. However, the specimen size effect is not consistent between different steels, as demonstrated for this new geometry herein. Tensile property measurements taken with noncontact extensometers from specimens of three different sizes from three different sheet steels showed varying material responses to changes in specimen geometry.

Syringe Quantity Limitations: Syringe Exchange Program Participant Health Behavior and Satisfaction

Syringe exchange programs (SEPs) increase participation in drug abuse treatment, reduce drug risk behavior, and may effectively lower rates of Human Immunodeficiency Virus (HIV) and Hepatitis C (HCV) infections. This study evaluated participant-identified barriers to access, self-reported health behaviors, and participant satisfaction with the quantity of syringes provided through a SEP located in Northern Colorado. Using a cross-sectional survey design, a non-probability sample of 40 SEP participants participated in the study. A majority of participants (77.5%) reported that they were receiving enough syringes. There was no significant relationship between satisfaction with number of syringes received and quantity of syringes not returned to the SEP. Results reveal several gaps in prevention efforts. The study presents suggestions for program improvement.

Ultrasound guided surgery under Dilutional Local Anaesthesia and no sedation in breast cancer patients

BackgroundBreast cancer surgery under local anaesthesia (LA) can be challenging due to limitation of dose and quantity of anaesthetic agent that can be used safely. Elderly patients with breast cancer and with multiple co-morbidities are often prevented from having a standard treatment as they are considered unfit for general anaesthesia. We describe a technique of surgery under local anaesthesia without sedation that employs dilution to generate large volumes of LA and infiltration under ultrasound guidance. MethodsWe present a case series by a single surgeon of breast cancer patients who underwent surgery under LA. 40 mls of 1% lignocaine with 1:200,000 adrenaline was diluted with 160 mls of normal saline to make a total of 200 mls, resulting in dilution to a concentration of 0.2% lignocaine. Radioactive isotope having been injected before patient's arrival in theatre, 1 ml of diluted anaesthetic solution is used with 2 mls of 2.5% patent blue to inject in the sub-areolar space. Local anaesthetic is infiltrated at operative site under ultrasound guidance using a long echogenic needle. ResultsA total of 71 patients with breast cancer underwent surgery under the LA between September 2015 and October 2018. 64 (90%) patients had wide local excisions and 7 (10%) had mastectomies. All had axillary surgery, 65 (91.5%) had dual technique sentinel lymph node biopsy as a day case and 6 (8.5%) patients had axillary clearance. 8 patients had re excision (12.5%). All patients had ‘0′ pain score and no postoperative analgesia was required in recovery. Local anaesthetic used did not exceed the maximum safe dose in any of the cases. One patient returned to theatre for postoperative wound bleeding. No other postoperative complication was observed. ConclusionUltrasound guided infiltration allows accurate placement of large volume of diluted local anaesthetic solution safely and provides effective anaesthesia.