Surveillance in Hogwarts: Dumbledore's balancing act between managerialism and anarchism

This article considers the fictional depiction of surveillance in Harry Potter, and compares the two different models of school leadership represented by Dolores Umbridge and Albus Dumbledore. The Harry Potter books put forward a vision of school leadership that affirms the necessity of surveillance. The optimal degree of surveillance means a fine balance between managerialism and anarchism. Neither a panoptic gaze of discipline and management which aims to control the minutest details of a person’s action, nor the absence of surveillance is desirable. Hogwarts is a surveillance school, and the difference between the two principals, both of whom insist on the maintenance of a hierarchical power structure, lies in the extent to which surveillance is in operation. Whereas Umbridge represents the failure of extreme managerialism which only results in fierce resistance, Dumbledore is portrayed as the desirable model of a temperate leader who, through reducing management and developing trust, succeeds in cultivating in students a version of discipline that is not based on external behaviour but on internal values

Van der Waerden's Theorem and Avoidability in Words

Pirillo and Varricchio, and independently, Halbeisen and Hungerbuhler considered the following problem, open since 1994: Does there exist an infinite word w over a finite subset of Z such that w contains no two consecutive blocks of the same length and sum? We consider some variations on this problem in the light of van der Waerden's theorem on arithmetic progressions.Comment: Co-author added; new result

Tracking Chinese CPI inflation in real time

With recovery from the global financial crisis in 2009 and 2010, inflation emerged as a major concern for many central banks in emerging Asia. We use data observed at mixed frequencies to estimate the movement of Chinese headline inflation within the framework of a state-space model, and then take the estimated indicator to nowcast Chinese CPI inflation. The importance of forward-looking and high-frequency variables in tracking inflation dynamics is highlighted and the policy implications discussed.nowcasting; CPI inflation cycle; mixed-frequency modelling; dynamic factor model; China

The Carnegie-Irvine Galaxy Survey. V. Statistical study of bars and buckled bars

Simulations have shown that bars are subject to a vertical buckling instability that transforms thin bars into boxy or peanut-shaped structures, but the physical conditions necessary for buckling to occur are not fully understood. We use the large sample of local disk galaxies in the Carnegie-Irvine Galaxy Survey to examine the incidence of bars and buckled bars across the Hubble sequence. Depending on the disk inclination angle ($i$), a buckled bar reveals itself as either a boxy/peanut-shaped bulge (at high $i$) or as a barlens structure (at low $i$). We visually identify bars, boxy/peanut-shaped bulges, and barlenses, and examine the dependence of bar and buckled bar fractions on host galaxy properties, including Hubble type, stellar mass, color, and gas mass fraction. We find that the barred and unbarred disks show similar distributions in these physical parameters. The bar fraction is higher (70\%--80\%) in late-type disks with low stellar mass ($M_{*} < 10^{10.5}\, M_{\odot}$) and high gas mass ratio. In contrast, the buckled bar fraction increases to 80\% toward massive and early-type disks ($M_{*} > 10^{10.5}\, M_{\odot}$), and decreases with higher gas mass ratio. These results suggest that bars are more difficult to grow in massive disks that are dynamically hotter than low-mass disks. However, once a bar forms, it can easily buckle in the massive disks, where a deeper potential can sustain the vertical resonant orbits. We also find a probable buckling bar candidate (ESO 506$-$G004) that could provide further clues to understand the timescale of the buckling process.Comment: 9 pages, 7 figures, 2 tables. Accepted for publication in The Astrophysical Journa

What drives urban consumption in mainland China? The role of property price dynamics

This paper adds to the literature on wealth effects on consumption by disentangling house price effects on consumption for mainland China. In a stochastic modelling framework, the riskiness, rate of increase and persistence of house price movements have different implications for the consumption/housing ratio. We exploit the geographical variation in property prices by using a quarterly city-level panel dataset for the period 1998Q1 – 2009Q4 and rely on a panel error correction model. Overall, the results suggest a significant long run impact of property prices on consumption. They also broadly confirm the predictions from the theoretical model.consumption; house prices; China; panel data

Satellite Alignment: I. Distribution of Substructures and Their Dependence On Assembly History From N-Body Simulations

Observations have shown that the spatial distribution of satellite galaxies is not random, but aligned with the major axes of central galaxies. This alignment is dependent on galaxy properties, such that red satellites are more strongly aligned than blue satellites. Theoretical work done to interpret this phenomena has found that it is due to the non-spherical nature of dark matter halos. However, most studies over-predict the alignment signal under the assumption that the central galaxy shape follows the shape of the host halo. It is also not clear whether the color dependence of alignment is due to an assembly bias or an evolution effect. In this paper we study these problems using a cosmological N-body simulation. Subhalos are used to trace the positions of satellite galaxies. It is found that the shape of dark matter halos are mis-aligned at different radii. If the central galaxy shares the same shape as the inner host halo, then the alignment effect is weaker and agrees with observational data. However, it predicts almost no dependence of alignment on the color of satellite galaxies, though the late accreted subhalos show stronger alignment with the outer layer of the host halo than their early accreted counterparts. We find that this is due to the limitation of pure N-body simulations that satellites galaxies without associated subhalos ('orphan galaxies') are not resolved. These orphan (mostly red) satellites often reside in the inner region of host halos and should follow the shape of the host halo in the inner region.Comment: 12 pages, 11 figures, Published on Ap

Optimisation Of Milling Parameter And Annealing Condition For Machining Polyetheretherketones (PEEK) Biomaterials Implant

Polyetheretherketones (PEEK) which has been widely used in many applications is now commercialized as implant components because of its biodegradability and non-allergic reactions compared to the metal implants. Generally, implants are fabricated by extrusion and injection molding for a larger scale. However, often for prototype designs or patient specific implant designs, it is not economically viable to manufacture by an injection molding. Under such circumstances, it is common to employ a machining process on the PEEK materials to form the components. However, milling parameters are the factors that have to be considered in the machining process to reduce the defects to the minimum and increase its durability. Apart from milling parameters, annealing also plays important roles in reducing residual stress and improving surface finishes. Thus, this research aims to develop exact milling parameters prior to the annealing process for machining PEEK material in order to enhance the machining performance and productivity. To achieve the objective, both statistical and experimental techniques were employed for the methodology. Response surface methods (RSM) were used to get the mathematical models and ANOVA analysis while milling parameters (feed rate, depth of cut and cutting speed) were used in order to get the machining performance on surface roughness, machining force, dimensional accuracy and material removal rate. Through experiments, the optimised parameters have improved the machining performance and qualities prior to the annaeling. The conclusions provide a theoretical basis for the annealing technique where the increased of the percentage crystalline, it helps improving the properties and the materials structure which leads to improve the machinability of the materials. Milling parameters (feed rate, depth of cut and cutting speed) are important factors in machining process and significantly affect the machining performances. To obtain 0.87μm surface finish, unannealed PEEK with 25.3 percentages crystalline will be using cutting speed 150.8 mm/min, feed rate of 0.035mm/tooth and 2mm depth of cut. PEEK annealed with 200°C increase crystalline to 30.3 percentages using high cutting speed (150.8 mm/min), low feed rate (0.033mm/tooth) and low depth of cut (2mm) can produce 0.4μm surface finish. PEEK annealed with 250°C has 30.9 percentages crystalline and 0.39μm surface finish can be obtained by using high cutting speed (150.8 mm/min), low feed rate (0.034mm/tooth) and low depth of cut (2mm). Therefore, milling machining is recommended to be further used in fabricating PEEK biomedical implants