Summary
We consider the weighted bootstrap approximation to the distribution of a class of M-estimators for the parameters of the generalized autoregressive conditional heteroscedastic model. We ...prove that the bootstrap distribution, given the data, is a consistent estimate in probability of the distribution of the M-estimator, which is asymptotically normal. We propose an algorithm for the computation of M-estimates which at the same time is useful for computing bootstrap replicates from the given data. Our simulation study indicates superior coverage rates for various weighted bootstrap schemes compared with the rates based on the normal approximation and existing bootstrap methods for the generalized autoregressive conditional heteroscedastic model, such as percentile $t$-subsampling schemes. Since some familiar bootstrap schemes are special cases of the weighted bootstrap, this paper thus provides a unified theory and algorithm for bootstrapping in generalized autoregressive conditional heteroscedastic models.
Abstract
Study of quantum magnetism in rare earth orthovanadates (RVO
4
, R = rare earth) is a topic which is currently being investigated by the condensed matter physicists. In this work, through ...both experimental and theoretical tools, we report the presence of field induced magnetic phase, attributed to fifth order susceptibility, in TbVO
4
, at low temperatures. The structural transition reported around 31 K, results in the formation of pseudospin—
$${\raise0.7ex\hbox{$1$} \!\mathord{\left/ {\vphantom {1 2}}\right.\kern-0pt} \!\lower0.7ex\hbox{$2$}}$$
1
/
2
doublet ground state separated by an energy
δ
. Temperature dependent heat capacity indicates toward an increment in
δ
, on application of magnetic fields. Above 10 kOe, the Zeeman energy associated with magnetic anisotropy strengthens, resulting in an enhanced splitting of the pseudo-doublet ground state. This increased splitting stabilizes the magnetic phase associated with higher order moments. These observations are further supported by our theoretical model to evaluate
δ
, as a function of applied field. Our study provides a platform to study the possible presence of higher order moments in other Jahn–Teller systems.
In the race towards economic growth, increased pollutant emissions have spurred the rise in global surface temperatures, intensifying the process of climate change. While the existing literature on ...the economic impact of climate-related variables has looked at outcomes such as growth, income, fiscal response, and poverty, the effect of temperature shocks on inflation has largely been neglected. This paper is an attempt to fill this lacuna. Indeed, we analyze the dynamic impact of temperature shocks on inflation, a key policy variable of most central banks. We use a panel-VAR method with fixed-effects and a sample of developed and developing countries over the period 1961–2014. Our results suggest that temperature shocks lead to inflationary pressures. Worryingly, and for developing countries in particular, we find that these effects persist several years after the initial shock. Our finding remained unaltered by various robustness checks. We show that these effects pose a threat to monetary policy making. We argue that central banks should pay more attention to temperature shocks.
The oral microbiome-organisms residing in the oral cavity and their collective genome-are critical components of health and disease. The fungal component of the oral microbiota has not been ...characterized. In this study, we used a novel multitag pyrosequencing approach to characterize fungi present in the oral cavity of 20 healthy individuals, using the pan-fungal internal transcribed spacer (ITS) primers. Our results revealed the "basal" oral mycobiome profile of the enrolled individuals, and showed that across all the samples studied, the oral cavity contained 74 culturable and 11 non-culturable fungal genera. Among these genera, 39 were present in only one person, 16 genera were present in two participants, and 5 genera were present in three people, while 15 genera (including non-culturable organisms) were present in >/=4 (20%) participants. Candida species were the most frequent (isolated from 75% of participants), followed by Cladosporium (65%), Aureobasidium, Saccharomycetales (50% for both), Aspergillus (35%), Fusarium (30%), and Cryptococcus (20%). Four of these predominant genera are known to be pathogenic in humans. The low-abundance genera may represent environmental fungi present in the oral cavity and could simply be spores inhaled from the air or material ingested with food. Among the culturable genera, 61 were represented by one species each, while 13 genera comprised between 2 and 6 different species; the total number of species identified were 101. The number of species in the oral cavity of each individual ranged between 9 and 23. Principal component (PCO) analysis of the obtained data set followed by sample clustering and UniFrac analysis revealed that White males and Asian males clustered differently from each other, whereas both Asian and White females clustered together. This is the first study that identified the "basal mycobiome" of healthy individuals, and provides the basis for a detailed characterization of the oral mycobiome in health and disease.
•Ti2MnAl crystallizes with significant atomic disorder resulting in random mixing of constituent elements.•Atomic disorder plays an important role in determination of physical properties.•Ti2MnAl ...exhibits Pauli's paramagnetic behaviour.•Non-interacting superparamagnetic clusters emerge at low temperatures due to defects.•Disorder give rise to a negative temperature coefficient of resistivity.
Search for novel spintronic materials in family of Heusler alloys has attained significant interest in recent years. In this context, Ti2MnAl is interesting as it is predicted to host spin gapless semiconducting state and compensated ferrimagnetic ordering. Here we report a detailed experimental investigation of Ti2MnAl. Our studies reveal that Ti2MnAl crystallizes in cubic structure with strong atomic disorder along with Pauli paramagnetic behaviour. The influence of disorder manifests in form of non-interacting superparamagnetic clusters at low temperatures and negative temperature co-efficient of resistivity. The carrier concentration obtained from Hall resistivity rules out the possibility of spin gapless semiconducting state. Our studies indicate that atomic disorder plays an important role in determination of physical properties of Ti2MnAl.
The efficiency of
Bacillus subtilis DM-04 and
Pseudomonas aeruginosa M and NM strains isolated from a petroleum contaminated soil sample from North-East India was compared for the biodegradation of ...crude petroleum-oil hydrocarbons in soil and shake flask study. These bacterial strains could utilize crude petroleum-oil hydrocarbons as sole source of carbon and energy. Bioaugmentation of TPH contaminated microcosm with
P. aeruginosa M and NM consortia and
B. subtilis strain showed a significant reduction of TPH levels in treated soil as compared to control soil at the end of experiment (120
d).
P. aeruginosa strains were more efficient than
B. subtilis strain in reducing the TPH content from the medium. The plate count technique indicated expressive growth and biosurfactant production by exogenously seeded bacteria in crude petroleum-oil rich soil. The results showed that
B. subtilis DM-04 and
P. aeruginosa M and NM strains could be effective for in situ bioremediation.
Abstract
Exploration of low temperature phase transitions associated with quantum critical point is one of the most mystifying fields of research which is under intensive focus in recent times. In ...this work, through comprehensive experimental evidences, we report the possibility of achieving quantum criticality in the neighborhood of a magnetic field-tuned tricritical point separating paramagnetic, antiferromagnetic and metamagnetic phases in a magnetic insulator, DyVO
4
. Magnetic susceptibility and heat capacity indicate to the presence of a long-range second order antiferromagnetic transition at
T
N
~ 3.2 K. Field variation of Magnetic susceptibility and heat capacity, along with differential magnetic susceptibility and DC field dependent AC susceptibility gives evidence of the modification of the antiferromagnetic structure below the tricritical point; implying the presence of a field-induced first order metamagnetic transition which persists down to 1.8 K. Further, the magnetic field dependence of the thermodynamic quantity − d
M
/d
T
, which is related to magnetic Gruneisen parameter, approaches a minimum, followed by a crossover near 5 kOe to a maximum; along with a hyperbolic divergence in temperature response of d
M
/d
T
in the critical field regime. Temperature response of heat capacity at 5 kOe also shows a deviation from the conventional behavior. Entropic topography phase diagram allows tracking of the variation of the entropy, which indicates towards the emergence of the peak at quantum critical point into a V-shaped region at high temperatures. Our studies yield an inimitable phase diagram describing a tricritical point at which the second-order antiferromagnetic phase line terminates followed by a first order line of metamagnetic transition, as the temperature is lowered, leading to metamagnetic quantum critical end point.
Snakebite is a neglected medical emergency causing fatalities and long-term disabilities throughout the world, especially in tropical countries. The effectiveness of therapy against snakebite is ...reliant on the unambiguous identification of bitten species of snake followed by immediate administration of venom-specific monovalent antivenom. However, this is a challenging task and therefore, over the several years scientists are constantly trying to address this issue by developing species-specific snake venom diagnostic kits as an alternative to classical methods of snake identification in clinics. Recently quite a few modern tools and techniques have been deployed for the development of simple, inexpensive, rapid, specific, and sensitive snake venom detection kits. However, despite these efforts a lone snakebite diagnostic kit is available until now which is a severe concern for efficacious snakebite therapy. In this article, we have reviewed the key issues pertaining to the rapid diagnosis of snake envenomation, tools and techniques developed and/or invented particularly over the past 40 years for the detection of snakebite as well as quantity of venom in the body fluids and/or tissues of victims. To overcome the practical constraints against the successful commercialization of these diagnostic kits, much more intensive studies for their improvement in terms of efficacy, affordability, storage stability, and usability, in addition to standardization of techniques for use in clinics are required to fulfil the objectives of the user-friendliness and commercial viability of snakebite diagnostic kits particularly in the rural and underdeveloped areas of tropical countries showing the maximum incidence of snakebite.
Display omitted
•Concerns involved in developing effective snake venom diagnostic kit underlined.•Developments in snake venom detection assays till most recent are summarized.•The pros and cons of the lone diagnostic kit available are discussed.•Practical hurdles in commercialization of diagnostic kits in rural areas are summarized.
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