Statisticians are increasingly posed with thought-provoking and even paradoxical questions, challenging our qualifications for entering the statistical paradises created by Big Data. By developing ...measures for data quality, this article suggests a framework to address such a question: “Which one should I trust more: a 1% survey with 60% response rate or a self-reported administrative dataset covering 80% of the population?” A 5-element Euler-formula-like identity shows that for any dataset of size n, probabilistic or not, the difference between the sample average X̅n
and the population average X̅N
is the product of three terms: (1) a data quality measure, ρR, X, the correlation between Xj
and the response/recording indicator Rj
; (2) a data quantity measure,
(
N
−
n
)
/
n
, where N is the population size; and (3) a problem difficulty measure, σX
, the standard deviation of X. This decomposition provides multiple insights: (I) Probabilistic sampling ensures high data quality by controlling ρR, X
at the level of N
−1/2; (II) When we lose this control, the impact of N is no longer canceled by ρR, X
, leading to a Law of Large Populations (LLP), that is, our estimation error, relative to the benchmarking rate 1/√n, increases with √N; and (III) the “bigness” of such Big Data (for population inferences) should be measured by the relative size f = n/N, not the absolute size n; (IV) When combining data sources for population inferences, those relatively tiny but higher quality ones should be given far more weights than suggested by their sizes.
Estimates obtained from the Cooperative Congressional Election Study (CCES) of the 2016 US presidential election suggest a ρR, X
≈ −0.005 for self-reporting to vote for Donald Trump. Because of LLP, this seemingly minuscule data defect correlation implies that the simple sample proportion of the self-reported voting preference for Trump from 1% of the US eligible voters, that is, n ≈ 2,300,000, has the same mean squared error as the corresponding sample proportion from a genuine simple random sample of size n ≈ 400, a 99.98% reduction of sample size (and hence our confidence). The CCES data demonstrate LLP vividly: on average, the larger the state’s voter populations, the further away the actual Trump vote shares from the usual 95% confidence intervals based on the sample proportions. This should remind us that, without taking data quality into account, population inferences with Big Data are subject to a Big Data Paradox: the more the data, the surer we fool ourselves.
This study investigates the socio-cultural experiences of Chinese international graduate students in a Canadian university. Specifically, this research explores the multiple challenges of their ...engagement in and out of the classroom as it relates to their language and culture. Qualitative data was collected by interviewing students and staff at the university. The findings show that Chinese international graduate students' experiences as passive learners and reduced engagement were disadvantaged in Canadian university classrooms. This is because active engagement is preferred in the Western-dominant ideology of student engagement in Canadian graduate schools. Implications from this study suggest that faculty and staff should deconstruct the Western dominant ways of the understanding of student engagement by empowering inclusivity and diversity of multiple languages and cultural identities. The study also provides some practical suggestions for the Chinese international graduate student population to better engage in Canadian graduate institutions and for educators and practitioners to better support Chinese international students in Canadian post-secondary schools.
This paper focuses on the phenomenon of “big data killing” implied in e-commerce and discusses how to take the government as the lead to coordinately supervise the price discrimination behavior of ...e-commerce companies towards loyal customers. First, the four-party evolutionary game model of the government regulatory department, e-commerce platform, e-commerce company, and consumer is built. Second, the stability of the strategy choice of each game subject is analyzed. On this basis, the evolutionary stable strategy in the system based on First Law of Lyapunov is explored. Finally, the influences of key elements on system evolution are simulated and analyzed by MATLAB2021. Results demonstrate that (1) the government supervision mechanism can effectively supervise the price discrimination of e-commerce company based on big data to loyal customers; (2) when the government chooses the strict supervision strategy, reducing the information supervision cost of the e-commerce platform and the strict supervision cost of the government enable the government and the e-commerce platform to coordinate supervision and make the e-commerce company incline to choose the nondifferential pricing strategy; (3) when the government chooses the loose supervision strategy, reducing the information supervision cost of the e-commerce platform and increasing the probability of consumer discovering differential pricing and the penalties for differential pricing of e-commerce company enable the e-commerce platform and consumer to coordinate supervision, and make the e-commerce company incline to choose the nondifferential pricing strategy. The results of this study can provide theoretical guidance for the government and companies to make beneficial strategic decisions in the development of e-commerce.
Severe acute pancreatitis (SAP) is an acute abdominal disease with the strong systemic inflammatory response, and rapidly progresses from a local pancreatic damage into multiple organ dysfunction. ...For many decades, the contributions of neutrophils to the pathology of SAP were traditionally thought to be the chemokine and cytokine cascades that accompany inflammation. In this review, we focus mainly on those recently recognized aspects of neutrophils in SAP processes. First, emerging evidence suggests that therapeutic interventions targeting neutrophils significantly lower tissue damage and protect against the occurrence of pancreatitis. Second, trypsin activation promotes the initial neutrophils recruitment into local pancreas, and subsequently neutrophils infiltration in turn triggers trypsin production. Finally, neutrophils have the unique ability to release neutrophil extracellular traps even in the absence of pathogens.
The catalytic conversion of dinitrogen (N2) into ammonia under ambient conditions represents one of the Holy Grails in sustainable chemistry. As a potential alternative to the Haber–Bosch process, ...the electrochemical reduction of N2 to NH3 is attractive owing to its renewability and flexibility, as well as its sustainability for producing and storing value‐added chemicals from the abundant feedstock of water and nitrogen on earth. However, owing to the kinetically complex and energetically challenging N2 reduction reaction (NRR) process, NRR electrocatalysts with high catalytic activity and high selectivity are rare. In this contribution, as a proof‐of‐concept, we demonstrate that both the NH3 yield and faradaic efficiency (FE) under ambient conditions can be improved by modification of the hematite nanostructure surface. Introducing more oxygen vacancies to the hematite surface renders an improved performance in NRR, which leads to an average NH3 production rate of 0.46 μg h−1 cm−2 and an NH3 FE of 6.04 % at −0.9 V vs. Ag/AgCl in 0.10 m KOH electrolyte. The durability of the electrochemical system was also investigated. A surprisingly high average NH3 production rate of 1.45 μg h−1 cm−2 and a NH3 FE of 8.28 % were achieved after the first 1 h chronoamperometry test. This is among the highest FEs reported so far for non‐precious‐metal catalysts that use a polymer‐electrolyte‐membrane cell and is much higher than the FE of precious‐metal catalysts (e.g., Ru/C) under comparable reaction conditions. However, the NH3 yield and the FE dropped to 0.29 μg h−1 cm−2 and 2.74 %, respectively, after 16 h of chronoamperometry tests, which indicates poor durability of the system. Our results demonstrate the important role that the surface states of transition‐metal oxides have in promoting electrocatalytic NRR under ambient conditions. This work may spur interest towards the rational design of electrocatalysts as well as electrochemical systems for NRR, with emphasis on the issue of stability.
A sustainable alternative to the Haber–Bosch process: The introduction of oxygen vacancies into hematite (α‐Fe2O3) nanorods promotes the electrocatalytic synthesis of ammonia from N2 and water at room temperature and atmospheric pressure (see picture). A higher concentration of surface oxygen vacancies leads to both improved NH3 yield and a large NH3 faradaic efficiency.
Developing an autonomous room temperature self‐healing supramolecular polyurethane (PU) with toughness and stiffness remains a great challenge. Herein, a novel concept that utilizes a T‐shaped chain ...extender with double amide hydrogen bonds in a side chain to extend PU prepolymers to construct highly stiff and tough supramolecular PU with integrated functions is reported. Mobile side‐chain H‐bonds afford a large flexibility to modulate the stiffness of the PUs ranging from highly stiff and tough elastomer (105.87 MPa Young's modulus, 27 kJ m−2 tearing energy), to solvent‐free hot‐melt adhesive, and coating. The dynamic side‐chain multiple H‐bonds afford an autonomous self‐healability at room temperature (25 °C). Due to the rapid reconstruction of hydrogen bonds, this PU adhesive demonstrates a high adhesion strength, fast curing, reusability, long‐term adhesion, and excellent low‐temperature resistance. Intriguingly, the PU emits intrinsic blue fluorescence presumably owing to the aggregation‐induced emission of tertiary amine domains induced by side‐chain H‐bonds. The PU is explored as a counterfeit ink coated on the predesigned pattern, which is visible‐light invisible and UV‐light visible. This work represents a universal and facile approach to fabricate supertough supramolecular PU with tailorable functions by chain extension of PU prepolymers with multiple H‐bonding chain extenders.
A multiple H‐bonding chain extender carrying two amides in the side chain is reacted with a polyurethane (PU) prepolymer to construct a supramolecular thermoplastic PU. Mobile side‐chain H‐bonds afford room temperature autonomous healability, allowing for flexible modulation of PU properties ranging from highly stiff and tough elastomer to solvent‐free hot‐melt adhesive. The PU emitting blue fluorescence is harnessed as a counterfeit coating.
Non‐small‐cell lung cancer (NSCLC), with its aggressive biological behavior, is one of the most diagnosed cancers. Tumor‐associated inflammatory cells play important roles in the interaction between ...chronic inflammation and lung cancer, however the mechanisms involved are far from defined. In the present study, by developing an orthotopic NSCLC mouse model based on chronic inflammation, we proved that an inflammatory microenvironment accelerated the growth of orthotopic xenografts in vivo. Tumor‐associated macrophages, the most abundant population of inflammatory cells, were identified. Treatment with macrophage‐conditioned medium (MCM) promoted the growth and migration of NSCLC cells. Using bioinformatics analysis, we identified downregulated PP2Ac expression in NSCLC cells upon treatment with MCM. We further confirmed that this downregulation was executed in an NF‐κB pathway‐dependent manner. As IκB kinase (IKK) has been proved to be a substrate of PP2Ac, inhibition on PP2Ac could result in amplification of NF‐κB pathway signaling. Overexpression of PP2Ac, or the dominant‐negative forms of IKK or IκB, attenuated the acceleration of growth and metastasis by MCM. Using bioinformatics analysis, we further identified that CXCL1 and COL6A1 could be downstream of NF‐κB/PP2Ac pathway. Luciferase assay and ChIP assay further confirmed the location of response elements on the promoter regions of CXCL1 and COL6A1. Elevated CXCL1 facilitated angiogenesis, whereas upregulated COL6A1 promoted proliferation and migration.
Tumor‐associated macrophages, the prominent type of inflammatory cells in non‐small‐cell lung cancer, can promote the growth and metastasis of cancer cells. Overexpression of PP2Ac, or the dominant‐negative forms of IKK or IκB, attenuated the acceleration on cancer cell growth and metastasis by TAMs. CXCL1 and COL6A1 could be downstream of NF‐κB/PP2Ac pathway. Elevated CXCL1 facilitated angiogenesis, whereas upregulated COL6A1 promoted cancer cell proliferation and migration.
Thermoplastic polyurethane (TPU) is a melt‐processing polymer with a high elasticity, high tensile strength, low‐temperature resistance, wear‐resistance, and corrosion resistance ability. TPU can be ...used in the automotive industry, electronics, medical supplies, coatings, and sports equipment. Introduction of self‐healing performance has made a considerable contribution to the service life and recyclability of TPU. The present article analyzes recent progress in self‐healing supramolecular TPUs. In particular, the importance of self‐healing mechanisms governed by covalent bonds and non‐covalent interactions in polymer design that allows for balancing mechanical performance and repairability is summarized. The critical issues and challenges associated with self‐healing supramolecular TPUs are also discussed.
Self‐healing thermoplastic polyurethanes have attracted considerable attention due to their recyclability and huge implications for the reduction of environmental burden. In this short overview, self‐healing mechanisms are summarized and the critical issues and challenges are discussed.
Cancerous microvesicles (MVs), which are heterogeneous membrane-bound nanovesicles shed from the surfaces of cancer cells into the extracellular environment, have been widely recognized as promising ...“biofingerprints” for various cancers. High-performance identification of cancerous MVs plays a vital role in the early diagnosis of cancer, yet it is still technically challenging. Herein, we report a gold nanoparticle (AuNP)-decorated, dual-aptamer modified reduced graphene oxide (RGO) field-effect transistor (AAP-GFET) nanosensor for the label-free, specific, and sensitive quantification of HepG2 cell-derived MVs (HepG2-MVs). After GFET chips were fabricated, AuNPs were then decorated on the RGO surface. For specific capture and detection of HepG2-MVs, both sulfhydrylated HepG2 cell specific TLS11a aptamer (AptTLS11a) and epithelial cell adhesion molecule aptamer (AptEpCAM) were immobilized on the AuNP surface through an Au–S bond. This developed nanosensor delivered a broad linear dynamic range from 6 × 105 to 6 × 109 particles/mL and achieved a high sensitivity of 84 particles/μL for HepG2-MVs detection. Moreover, this AAP-GFET platform was able to distinguish HepG2-MVs from other liver cancer-related serum proteins (such as AFP and CEA) and MVs derived from human normal cells and other cancer cells of lung, pancreas, and prostate, suggesting its excellent method specificity. Compared with those modified with a single type of aptamer alone (AptTLS11a or AptEpCAM), such an AAP-GFET nanosensor showed greatly enhanced signals, suggesting that the dual-aptamer-based bio–nano interface was uniquely designed and could realize more sensitive quantification of HepG2-MVs. Using this platform to detect HepG2-MVs in clinical blood samples, we found that there were significant differences between healthy controls and hepatocellular carcinoma (HCC) patients, indicating its great potential in early HCC diagnosis.
Treatment strategies targeting tumor-associated macrophages (TAMs) have been proposed in cancer areas. The functional alterations of macrophages in the microenvironment during the tumorigenesis of ...human epithelial cancer remain poorly understood. Here, we explored phenotypic alteration of macrophages during the development of oral squamous cell carcinoma (OSCC).
Conditioned media (CM) and exosome supernatants were harvested from normal oral epithelium, oral leukoplakia cells and OSCC cells. We measured phenotypic alteration of macrophages using flow cytometry, luminex assays, and quantitative real-time PCR assay. Intracellular signaling pathway analysis, mass spectrometry proteomics, western blotting, enzyme-linked immunosorbent assay, immunohistochemical staining, and bioinformatics analysis were performed to uncover the underlying mechanisms.
THP-1-derived and PBMCs derived macrophages exhibited an M1-like phenotype but not M2-like phenotype, when treated with CM from OSCC cells but not with the CM from normal epithelium or leukoplakia cells. Further investigations revealed that macrophages were activated by taking up exosomes released from OSCC cells through p38, Akt, and SAPK/JNK signaling at the early phase. We further provided evidences that THBS1 derived from OSCC exosomes participated in the polarization of macrophages to an M1-like phenotype. Reciprocally, CM from exosomes induced M1-like TAMs and significantly promoted migration of OSCC cells.
We proposed a novel paracrine loop between cancer cells and macrophages based on exosomes from OSCC. Therefore, target management of M1-like TAMs polarized by exosomes shows great potential as a therapeutic target for the control of cancerous migration in OSCC.
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