A single trapped ion in a finite range trap

This paper presents a method to describe dynamics of an ion confined in a realistic finite range trap. We model this realistic potential with a solvable one and we obtain dynamical variables (raising and lowering operators) of this potential. We consider coherent interaction of this confined ion in a finite range trap and we show that its center-of-mass motion steady state is a special kind of nonlinear coherent states. Physical properties of this state and their dependence on the finite range of potential are studied

A Note on Using the Nonparametric Levene Test When Population Means Are Unequal

This computer simulation study evaluates the robustness of the nonparametric Levene test of equal variances (Nordstokke & Zumbo, 2010) when sampling from populations with unequal (and unknown) means. Testing for population mean differences when population variances are unknown and possibly unequal is often referred to as the Behrens-Fisher problem when the populations are normally distributed, and the generalized Behrens-Fisher problem when the populations are non-normal. The nonparametric Levene test was developed to overcome reductions in power of the original Levene test of equal variances in the case of the generalized Behrens-Fisher problem. We use a Monte Carlo computer simulation to demonstrate that sampling from populations with unequal and unknown means can lead to incorrect (either inflated or decreased) Type I error rates of the nonparametric Levene test. Centering samples using either sample means or medians does not correct the Type I error rates. This note is intended to make applied researchers aware of this problem when testing for the equality of population variances with the NPL test and in general. Accessed 1,444 times on https://pareonline.net from September 17, 2018 to December 31, 2019. For downloads from January 1, 2020 forward, please click on the PlumX Metrics link to the right

The operating characteristics of the nonparametric Levene test for equal variances with assessment and evaluation data

Many assessment and evaluation studies use statistical hypothesis tests, such as the independent samples t test or analysis of variance, to test the equality of two or more means for gender, age groups, cultures or language group comparisons. In addition, some, but far fewer, studies compare variability across these same groups or research conditions. Tests of the equality of variances can therefore be used on their own for this purpose but they are most often used alongside other methods to support assumptions made about variances. This is often done so that variances can be pooled across groups to yield an estimate of variance that is used in the standard error of the statistic in question. The purposes of this paper are twofold. The first purpose is to describe a new nonparametric Levene test for equal variances that can be used with widely available statistical software such as SPSS or SAS, and the second purpose is to investigate this test’s operating characteristics, Type I error and statistical power, with real assessment and evaluation data. To date, the operating characteristics of the nonparametric Levene test have been studied with mathematical distributions in computer experiments and, although that information is valuable, this study will be an important next step in documenting both the level of non-normality (skewness and kurtosis) of real assessment and evaluation data, and how this new statistical test operates in these conditions. Accessed 15,120 times on https://pareonline.net from February 26, 2011 to December 31, 2019. For downloads from January 1, 2020 forward, please click on the PlumX Metrics link to the right

Constrained Monte Carlo Method and Calculation of the Temperature Dependence of Magnetic Anisotropy

We introduce a constrained Monte Carlo method which allows us to traverse the phase space of a classical spin system while fixing the magnetization direction. Subsequently we show the method's capability to model the temperature dependence of magnetic anisotropy, and for bulk uniaxial and cubic anisotropies we recover the low-temperature Callen-Callen power laws in M. We also calculate the temperature scaling of the 2-ion anisotropy in L10 FePt, and recover the experimentally observed M^2.1 scaling. The method is newly applied to evaluate the temperature dependent effective anisotropy in the presence of the N'eel surface anisotropy in thin films with different easy axis configurations. In systems having different surface and bulk easy axes, we show the capability to model the temperature-induced reorientation transition. The intrinsic surface anisotropy is found to follow a linear temperature behavior in a large range of temperatures

Fast electron transport patterns in intense laser-irradiated solids diagnosed by modeling measured multi-MeV proton beams

The measured spatial-intensity distribution of the beam of protons accelerated from the rear side of a solid target irradiated by an intense (>10 Wcm) laser pulse provides a diagnostic of the two-dimensional fast electron density profile at the target rear surface and thus the fast electron beam transport pattern within the target. An analytical model is developed, accounting for rear-surface fast electron sheath dynamics, ionization and projection of the resulting beam of protons. The sensitivity of the spatial-intensity distribution of the proton beam to the fast electron density distribution is investigated. An annular fast electron beam transport pattern with filamentary structure is inferred for the case of a thick diamond target irradiated at a peak laser intensity of 6 × 10 Wcm

'Being in Being': Contesting the Ontopolitics of Indigeneity Today

This article critiques the shift towards valorizing indigeneity in western thought and contemporary practice. This shift in approach to indigenous ways of knowing and being, historically derided under conditions of colonialism, is a reflection of the ‘ontological turn’ in anthropology. Rather than indigenous peoples simply having an inferior or different understanding of the world to a modernist one, the ‘ontological turn’ suggests their importance is that they constitute different worlds, and that they ‘world’ in a performatively different way. The radical promise is that a different world already exists in potentia and that access to this alternative world is a question of ontology - of being differently: being in being rather than thinking, acting and ‘worlding’ as if we were transcendent or ‘possessive’ subjects. We argue that ontopolitical arguments for the superiority of indigenous ways of being should not be seen as radical or emancipatory resistances to modernist or colonial epistemological and ontological legacies but instead as a new form of neoliberal governmentality, cynically manipulating critical, postcolonial and ecological sensibilities for its own ends. Rather than ‘provincialising’ dominant western hegemonic practices, discourses of ‘indigeneity’ are functioning to extend them, instituting new forms of governing through calls for adaptation and resilience

Photoluminescence lineshape of ZnO

The merger of the absorption coefficient dispersion, retrieved from transmission by the modified Urbach rule introduced by Ullrich and Bouchenaki [Jpn. J. Appl. Phys. 30, L1285, 1991], with the extended Roosbroeck-Shockley relation reveals that the optical absorption in ZnO distinctively determines the photoluminescence lineshape. Additionally, the ab initio principles employed enable the accurate determination of the carrier lifetime without further specific probing techniques

Control over imidazoquinoline immune stimulation by pH-degradable poly(norbornene) nanogels

The reactivation of the innate immune system by toll-like receptor (TLR) agonists holds promise for anticancer immunotherapy. Severe side effects caused by unspecific and systemic activation of the immune system upon intravenous injection prevent the use of small-molecule TLR agonists for such purposes. However, a covalent attachment of small-molecule imidazoquinoline (IMDQ) TLR7/8 agonists to pH-degradable polymeric nanogels could be shown to drastically reduce the systemic inflammation but retain the activity to tumoral tissues and their draining lymph nodes. Here, we introduce the synthesis of poly(norbornene)-based, acid-degradable nanogels for the covalent ligation of IMDQs. While the intact nanogels trigger sufficient TLR7/8 receptor stimulation, their degraded version of soluble, IMDQ-conjugated poly(norbornene) chains hardly activates TLR7/8. This renders their clinical safety profile, as degradation products are obtained, which would not only circumvent nanoparticle accumulation in the body but also provide nonactive, polymer-bound IMDQ species. Their immunologically silent behavior guarantees both spatial and temporal control over immune activity and, thus, holds promise for improved clinical applications