137 research outputs found
Does a transformation approach improve students' ability in constructing auxiliary lines for solving geometric problems? An intervention-based study with two Chinese classrooms
No full textWe conducted an intervention-based study in secondary classrooms to explore whether the use of geometric transformations can help improve students’ ability in constructing auxiliary lines to solve geometric proof problems, especially high-level cognitive problems. A pre- and post-test quasi-experimental design was employed. The participants were 130 eighth-grade students in two classes with a comparable background that were taught by the same teacher. A two-week intervention was implemented in the experimental class aiming to help students learn how to use geometric transformations to draw auxiliary lines in solving geometric problems. The data were collected from a teacher interview, video-recordings of the intervention, and pre- and post- tests. The results revealed that there was a positive impact of using geometric transformations on the experimental students’ ability in solving high-level cognitive problems by adding auxiliary lines, though the impact on the students’ ability in solving general geometric problems as measured using the overall average scores was not statistically significant. Recommendations for future research are provided at the end of the article
Unobserved Contributions and Political Influence: Evidence from the Death of Top Donors
No full textIt has long been observed that there is little money in U.S. politics compared to the stakes. But
what if contributions are not fully observable or non-monetary in nature and thus not easily
quantifiable?We study this question with a new data set on the top 1000 donors in U.S.
congressional races. Since top donors do not randomly support candidates, we propose an
identification strategy based on information about top donors' deaths and the observed variations
in candidates' performance after these events. The death of a top donor significantly decreases a
candidate's chances of being elected in the current and future election cycles. Moreover, it affects
the legislative activities of elected candidates. These effects do not depend on top donors'
monetary contributions to a candidate but on their prominence and their total contributions during
the election campaign
Flow of ionic liquids in nanoconfinement
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Previous issue date: 2021-07-14Embargo set by: Seth Robbins for item 121101
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Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemIonic liquids (ILs) are considered well suited alternatives for conventional electrolytes in next-generation electrochemical devices to grant enhanced stability, safer handling and improved performance. Key to ILs’ application as electrolytes are the structure and transport properties near the solid-liquid interface and in nanopores, as most electrochemical processes take place at the electrolyte-electrode interface and mesoporous electrode materials are often adopted to maximize specific area. Unlike dilute electrolyte, which is well characterized by the Debye–Hückel equation and electrical double layer (EDL) model, the understanding of ILs (and concentrated electrolytes in general) near the solid-liquid interface and under confinement is still primitive and sometimes self-conflicting, especially in regards of the unequilibrated processes. The dissertation summarizes my attempts to elucidate on ionic liquids (ILs)’ interfacial structures, the kinetics in the formation of such structures, the flow properties and relaxation kinetics, through nanomechanical measurements. Experimental evidence is contributed to answering to three key questions pivoted around the theme: 1) how do ions arrange themselves within in the last tens of nm from a charged solid-IL interface; 2) how do ILs flow or relax in confined space only a few times the dimension of ions; and 3) how will water affect the flow of nanoconfined ILs.
Specifically, the interfacial region between IL and a charged surface is investigated with surface forces apparatus (SFA) using the classic mica sensors. The nanostructures of and the interactions within the interfacial region are revealed by the surface force profile as a function of separation between the two opposing mica surfaces. Time-dependent measurements revealed an ultra-slow kinetics in the formation of the structure, which is concerted with a transition in the bulk nanostructure studied with X-ray. Rheological properties of the nanoconfined ILs are measured by either squeezing out the ILs as the opposing mica surfaces approach each in the normal direction, or laterally oscillating one of the mica surfaces to create shear motions. Finally, water is introduced through gas phase by modulating the relative humidity in the sealed chamber to probe its influence.
It is discovered that the long-ranged repulsive surface force across a range of a few tens of nanometers could be due to the presence of multi-ionic structures intrinsic to each IL, while the step-like features at below 10 nm region suggest the presence of multiple layers immediately on the solid surface. Such layers, upon adequate normal force, are squeezed out sequentially with increasing force thresholds. The squeeze-out processes are modelled with Reynold’s law of lubrication to extract the effective viscosity for each layer, which is found to increase by orders of magnitude in the next resolvable layer compared to the previous one. The effective viscosity obtained from squeeze-out is further studied by taking into account the influence of multiple parameters including the long-ranged screening length, the bulk viscosity and the degree of confinement. Further study through oscillatory shear motion asserted on the confined ILs deconvolutes the viscous and elastic moduli of the ILs in each layer. Through modeling the storage and loss moduli with Einstein Stokes law and the effective shear viscosity as a function of shear rate by Eyring’s theory, the collective motion of ions under confinement is unveiled and discussed regarding to the chemical structures of the ions. The compressibility of the ions is found to be the key. When water is introduced, the interfacial structures, the effective viscosity, and the moduli are clearly altered, despite its low abundance. The intrusion of water into the nanoconfined ILs is investigated separately in static measurements. The dissertation extends the scope of IL nanorheology to address the application of IL as a lubricant and comments on the link between the nanorheology and nanotribology of ILs, and the influence of water.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2023-08-01The student, Mengwei Han, accepted the attached license on 2021-07-12 at 10:29.The student, Mengwei Han, submitted this Dissertation for approval on 2021-07-12 at 20:46.This Dissertation was approved for publication on 2021-07-14 at 09:31.DSpace SAF Submission Ingestion Package generated from Vireo submission #16861 on 2022-01-12 at 12:54:31Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemU of I Onl
Essays on Political Economy and Public Policy
No full text255 pagesThis dissertation consists of three chapters that study political economy and public policy. Chapter 1 develops an innovative method to measure the "unmeasurable" local industrial policies. Chapter 2 examines the impact of state taxes and subsidies on retail establishments. Chapter 3 explores how peace and reunification events affect petty corruption. The first chapter, "Local Policies and Firm Location: Measuring the 'Unmeasurable'," explores how local governments in China compete to attract businesses and examines the role of local leaders' promotion motives in intensifying such competition. Local governments compete by offering city-wide policies, such as lowering tax rates, giving subsidies, providing financial support, or loosening environmental regulations. The difference between what is practiced and what is legally mandated is non-negligible, and many of these policies remain unobservable due to limited data accessibility. To address this issue, I introduce a novel method to quantify the net effect of various policies proposed by local governments. This net effect, referred to as the policy index, is identified using data from all manufacturing plant locations along with a spatial border design. When applying this method to Jiangsu, a province in China with 13 competitive cities, all ranked in the top 100 by GDP over the past decade, I find that geographically proximate cities tend to adopt similar industrial policies, and contrary to popular belief, coastal cities are not necessarily more pro-business. I then incorporate the estimated policy index into a promotion competition framework to understand how policies are determined in equilibrium and how competition, in turn, affects the business landscape. Counterfactual simulations demonstrate that firms are distributed more evenly across space, with only 23% of them choosing a different location if leaders' incentives were the same across all cities. The second chapter, "A Tax-Shaped Retail Landscape," co-authored with Feng Chi, Limin Fang, and Nathan Yang, investigates the impact that seemingly uniform tax policies have on shaping the retail landscape. Using comprehensive data about all retail establishments in the conterminous United States from 1990 to 2014, we first show that while retail establishments are more likely to open in markets with favorable state tax policies, it is primarily the largest chains that are contributing towards this effect on entry. Motivated by these empirical realities, we analyze an entry model where firms are subject to taxes to demonstrate that tax effects on retailer entry can potentially amplify market dominance, such that retailers with preexisting size-based advantages are disproportionately more responsive to the tax policies. Furthermore, we show that revenue-maximizing tax levels that the government could set have the potential to exacerbate the dominance of strong firms. Finally, we provide calibrated model analysis based on data about home improvement retail chain entry. This calibration exercise illustrates the economic magnitude associated with asymmetric retail entry responses to tax policy. The third chapter, "Peace and Petty Corruption: Evidence from Trucking in Côte d'Ivoire," co-authored with Jeremy Foltz and Souleymane Soumahoro, examines how peace and reunification affect petty corruption. We explore a sequence of exogenous peace events following the arrest of the incumbent president of Côte d'Ivoire in April 2011, which lessened the tension caused by armed conflicts in the north (rebel area) and made the political management similar to the south (non-rebel area). A unique dataset on extortion payments by truck drivers allows us to observe more than 1,000 truck journeys and 26,000 stops over two years in corridors going from Côte d'Ivoire to Mali and Burkina Faso. Specifically, we use a difference-in-differences strategy to compare bribe behaviors at checkpoints in Côte d'Ivoire with those in Mali and Burkina Faso before and after the peace events. We find a large and significant "peace dividend": bribe values and bribe efforts decreased by 67% and 75%, respectively. We demonstrate with a simple theoretical model and our empirical estimates that the larger reduction in corrupt behavior in the rebel zone relative to the non-rebel zone can be explained by a composition effect—i.e., a shift of the checker’s identity from a rebel to a civil servant—and a market structure effect—i.e., a change in the bureaucracy structure within each checkpoint from a monopoly (only rebels) to competition (customs, police, gendarmerie, and others).2026-06-1
7 Lessons towards Effective Economics PhD Research
No full textThis Guide is intended to offer early-career economists, especially PhD students, insights from leading
researchers on how to take the “best steps” at each key stage of a research project. It is based on a series
of lectures held at the University of Barcelona (UB) School of Economics under the BESTEPS project.
Each lecture is self-contained and can be read independently. Taken together, the seven lectures aim to
offer a practical and comprehensive guide to conducting research effectively during the PhD. This version
collects the first three lectures by Antonio Cabrales, Libertad González, and Joan Llull
Nephrotoma virgata
No full text<i>Nephrotoma virgata</i> (Coquillett, 1898) (Figs 61–71) <p> <i>Pachyrhina virgata</i> Coquillett, 1898: 306 (original description); Alexander, 1914: 163 (additional illustration).</p> <p> <i>Nephrotoma virgata</i> (Coquillett): Masaki, 1933: 368 (transfer); Alexander, 1953: 149 (redescription); Liu <i>et al</i>., 2009: 43 (redescription); Savchenko, 1973: 51 (redescription and additional illustration).</p> <p> <i>Nephrotoma decrepita</i> Alexander, 1935a: 140 (original description); Alexander, 1953: 149 (synonymy).</p> <p> <i>Limnophila japonica</i> Esaki, 1950: 1532 (original description); Alexander, 1953: 149 (synonymy).</p> <p>Redescription. Hypopygium with tergite ninth and sternite ninth fused at basal one third (Fig. 61). Tergite ninth with posterior margin transverse, lateral corners in right angle; posterior margin produced into paired lobes which separated by a deep oval notch, lobes directed inward, densely covered with black teeth, mesal portion of lobe extended inward, forming a V-shaped notch; tergite ninth possessing paired posterior extensions directed outward, gradually narrowed to an acute apex, base and mesal regions of posterior extension with several teeth; surface of tergite ninth with lateral regions sparsely equipped with long setae (Figs 61–62). Sternite ninth split laterally, deeply concaved at posterior border, a spiculose projection arising from middle and pointed ventrad. Sternite eighth shallowly emarginated at posterior margin, densely covered with long setae at posterior margin and ventral surface, medially with a sclerotized spoon-shaped projection, directed cephalad, S-shaped in lateral view (Figs 61, 63–64). Outer gonostylus lanceolate, widest region near middle (Fig. 65). Inner gonostylus with apical beak massive, strongly produced; basal beak curved and hooked; posterolateral part forming a serrated blade, upper margin of which equipped with more than a dozen of spinules; dorsal crest narrow, rounded, produced behind; dorsal region of inner gonostylus with many long setae, directed basad; apical region of inner gonostylus having an elongated lacuna, widened at basal half (Fig. 66). Aedeagal guide with gonapophyses small, appearing as transparent and obtused slice (Figs 67–68). Semen pump with ejaculatory apodeme divided by a deeply V-shaped notch into two lobes, each lobe obtuse and enlarged apically (Fig. 69). Posterior immovable apodeme shorter than ejaculatory apodeme, curved dorsally, acute at apex in lateral view (Figs 70–71). Anterior immovable apodeme enlarged and rounded in dorsal view (Figs 70–71). Aedeagus very long, more than three times longer than abdomen, extended to second abdominal segment, and then turned to eighth abdominal segment after two bends (Fig. 61).</p> <p>Material examined. 1♂, China, Anhui, Yaoluoping Natinal Natural Reserve, 17.IX.2021, leg. Qiulei Men.</p> <p>Distribution. China (Hebei, Anhui, Zhejiang, Hubei, Sichuan), Russia, North Korea, South Korea, Japan.</p> <p> Remarks. The species is similar to <i>N. subpallida</i> Alexander, 1925 based on the structure of posterior extension of tergite ninth, but differs from the latter by the sternite ninth with a spoon-shaped lobe (absent in <i>N. subpallida</i>), and the inner gonostylus with narrow dorsal crest (with broad and strongly protruded dorsal crest in <i>N. subpallida</i>).</p> <p> <b>Funding</b> This study was supported by the National Natural Science Foundation of China (31300551), the Scientific Research Foundation of the Higher Education Institutions of Anhui Province (KJ2021A0646) and the Anhui Outstanding Young Talent Support Program (gxbjZD2020073).</p> <p> <b>Acknowledgements</b> We are grateful to Dr. Lin Lü (Northwest A & F University, Shaanxi, China), Dr. Guoxi Xue (Zhengzhou University of Light Industry, Henan, China) and Dr. Yixin Huang (Anhui Normal University, Anhui, China) for their help with collecting of specimen material. We express our sincere appreciation to Dr. Pjotr Oosterbroek (Naturalis, Leiden, the Netherlands) for his valuable web site, the Catalogue of the Craneflies of the World (http://ccw.naturalis.nl/index. php), which provides much valuable information about taxonomy, classification, general systematics and distribution. We also sincerely thank two anonymous reviewers who provided valuable comments and advices on the manuscript.</p>Published as part of <i>Men, Qiulei, Yu, Dong & Sun, Mengwei, 2023, Description of a new species in the genus Nephrotoma (Diptera: Tipuloidea: Tipulidae) from China, with redescriptions of hypopygiums of six species, pp. 249-263 in Zoological Systematics 48 (3)</i> on page 262, DOI: 10.11865/zs.2023304, <a href="http://zenodo.org/record/10941824">http://zenodo.org/record/10941824</a>
ARTISTIC UNIQUENESS OF M.A. BULGAKOV’S “A YOUNG DOCTOR’S NOTEBOOK”
No full textThe article thoroughly describes the artistic uniqueness of M.A. Bulgakov’s one of the earliest works - “A young doctor’s notebook”. These series were inspired by writer’s own experience working as a country doctor in Nikolskoe. Seven stories are united not only by the narrator’s personality, but also by the time and place of the action. The single storyline, which connects all the stories, is the fate of a young doctor in a collision with the harsh historical reality. Bulgakov filled his short stories with different strokes, which are fragments of the medical practice for recently graduated young doctor. These fragments were able to create the whole vision of life for the intellectual hero living in a small village during the Revolution. The mosaic, multifaceted composition of works are some of the early characteristics attributed to the author
An Automatic Sleep Stage Classification Approach Based on Multi-Spike Supervised Learning
No full textAn Epilepsy and Seizure Classification Approach Based on Multi-Spike Liquid State Machines
No full textA study on the functions of ubiquitin metabolic system related gene FBG2 in gastric cancer cell line
No full textAbstract Background FBG2 (F-BOX6) gene is an important member in ubiquitin metabolic system F-BOX family, and forms E3 complex with the other members in the family. But its role in gastric cancer is still not clear. In the present study, we intended to investigate the influence of FBG2 on the growth, proliferation, apoptosis, invasion and cell cycle of the gastric cancer line MKN45 and gastric cell line HFE145. Methods As a critical component of ubiquitin-protein ligase complex, FBG2 cDNA was subcloned into a constitutive vector PCDNA3.1 followed by transfection in MKN45 and HFE145 by using liposome. Then stable transfectants were selected and appraised. The apoptosis and cell cycles of these clones were analyzed by using flow cytometry. The growth and proliferation were analyzed by cell growth curves and colony-forming assay respectively. The invasion of these clones was tested by using cancer cell migration assay. The FBG2 stable expression clones(MKN-FBG2 and HFE-FBG2) and their control groups were detected and compared respectively. Results MKN-FBG2 grew faster than MKN45 and MKN-PC(MKN45 transfected with PCDNA3.1 vector). HFE-FBG2 grew faster than HFE145 and HFE-PC(HFE145 transfected with PCDNA3.1 vector). The cell counts of MKN-FBG2 in the forth, fifth, sixth and seventh days were significantly more than those of others (P Conclusion FBG2 can promote the growth and proliferation of gastric cancer cells and normal gastric cells. It can help tumor cell maintain malignant phenotype too. But it can have a negative influence on the apoptosis or the ability of invasion of gastric cancer cells.</p
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