3,931 research outputs found
On the Statistical Origin of Topological Symmetries
We investigate a quantum system possessing a parasupersymmetry of order 2, an
orthosupersymmetry of order , a fractional supersymmetry of order , and
topological symmetries of type and . We obtain the
corresponding symmetry generators, explore their relationship, and show that
they may be expressed in terms of the creation and annihilation operators for
an ordinary boson and orthofermions of order . We give a realization of
parafermions of order~2 using orthofermions of arbitrary order , discuss a
parasupersymmetry between parafermions and parabosons of arbitrary
order, and show that every orthosupersymmetric system possesses topological
symmetries. We also reveal a correspondence between the orthosupersymmetry of
order and the fractional supersymmetry of order .Comment: 12 page
Topological Symmetries
We introduce the notion of a topological symmetry as a quantum mechanical
symmetry involving a certain topological invariant. We obtain the underlying
algebraic structure of the Z_2-graded uniform topological symmetries of type
(1,1) and (2,1). This leads to a novel derivation of the algebras of
supersymmetry and parasupersummetry.Comment: Plain LaTeX Ref: Mod. Phys. Lett. A 15, 175-184 (2000
A review of CAD/CAM use in dentistry (part II): Comparison of intraoral digital scanners used in restorative dentistry
Introduction: Intraoral imaging technology has become one of the most exciting new fields in
dentistry. Three-dimensional scanning of the oral cavity is used in many dental procedures such as
restorative dentistry and orthodontics. To date, a number of intraoral scanners have been
developed for restorative dentistry throughout the world, and many researchers and manufacturers
seek the design and development of new digital devices. Only some of these devices are currently
available on the market and some others are being clinically tested. All existing intraoral scanners
try to overcome the drawbacks of traditional impression processes. The aim of the present article is
to provide an extensive evaluation of intraoral scanners in restorative dentistry, with special
attention to their assessment principles, characteristics and performance.
Review report: This review article was prepared by scientific searching in electronic sources of
Pubmed and ISI Web of Science in connection with articles published in English until 2014, and
with these key words: intraoral scanners and digital impression.
Conclusion: Over the years there have been major advances in digital scanning systems, and a
variety of digital systems have been introduced that enable the dentist to select different intraoral
reconstruction methods in the extraoral environment. The ultimate goal of dentists is to provide
accurate and efficient dental restorations for the patient, while maintaining patient comfort during
the impression process. High-resolution dental optical scanners will enable the operator to provide
high-quality restorations. With digital impression techniques, the number of operators and material
variables will decrease, making restoration fabrication processes more predictable and easier
Virtual patient design : exploring what works and why : a grounded theory study
Objectives:
Virtual patients (VPs) are online representations of clinical cases used in medical education. Widely adopted, they are well placed to teach clinical reasoning skills. International technology standards mean VPs can be created, shared and repurposed between institutions. A systematic review has highlighted the lack of evidence to support which of the numerous VP designs may be effective, and why. We set out to research the influence of VP design on medical undergraduates.
Methods:
This is a grounded theory study into the influence of VP design on undergraduate medical students. Following a review of the literature and publicly available VP cases, we identified important design properties. We integrated them into two substantial VPs produced for this research. Using purposeful iterative sampling, 46 medical undergraduates were recruited to participate in six focus groups. Participants completed both VPs, an evaluation and a 1-hour focus group discussion. These were digitally recorded, transcribed and analysed using grounded theory, supported by computer-assisted analysis. Following open, axial and selective coding, we produced a theoretical model describing how students learn from VPs.
Results:
We identified a central core phenomenon designated ‘learning from the VP’. This had four categories: VP Construction; External Preconditions; Student–VP Interaction, and Consequences. From these, we constructed a three-layer model describing the interactions of students with VPs. The inner layer consists of the student's cognitive and behavioural preconditions prior to sitting a case. The middle layer considers the VP as an ‘encoded object’, an e-learning artefact and as a ‘constructed activity’, with associated pedagogic and organisational elements. The outer layer describes cognitive and behavioural change.
Conclusions:
This is the first grounded theory study to explore VP design. This original research has produced a model which enhances understanding of how and why the delivery and design of VPs influence learning. The model may be of practical use to authors, institutions and researchers
Non-Simplified SUSY: Stau-Coannihilation at LHC and ILC
If new phenomena beyond the Standard Model will be discovered at the LHC, the
properties of the new particles could be determined with data from the
High-Luminosity LHC and from a future linear collider like the ILC. We discuss
the possible interplay between measurements at the two accelerators in a
concrete example, namely a full SUSY model which features a small stau_1-LSP
mass difference. Various channels have been studied using the Snowmass 2013
combined LHC detector implementation in the Delphes simulation package, as well
as simulations of the ILD detector concept from the Technical Design Report. We
investigate both the LHC and ILC capabilities for discovery, separation and
identification of various parts of the spectrum. While some parts would be
discovered at the LHC, there is substantial room for further discoveries at the
ILC. We finally highlight examples where the precise knowledge about the lower
part of the mass spectrum which could be acquired at the ILC would enable a
more in-depth analysis of the LHC data with respect to the heavier states.Comment: 42 pages, 18 figures, 12 table
Solving inverse problems of unknown contaminant source in groundwater-river integrated systems using a surrogate transport model based optimization
The paper presents a new approach to identify the unknown characteristics (release history and location) of contaminant sources in groundwater, starting from a few concentration observations at monitoring points. An inverse method that combines the forward model and an optimization algorithm is presented. To speed up the computation, the transfer function theory is applied to create a surrogate transport forward model. The performance of the developed approach is evaluated on two case studies (literature and a new one) under different scenarios and measurement error conditions. The literature case study regards a heterogeneous confined aquifer, while the proposed case study was never investigated before, it involves an aquifer-river integrated flow and transport system. In this case, the groundwater contaminant originated from a damaged tank, migrates to a river through the aquifer. The approach, starting from few concentration observations monitored at a downstream river cross-section, accurately estimates the release history at a groundwater contaminant source, even in presence of noise on observations. Moreover, the results show that the methodology is very fast, and can solve the inverse problem in much less computation time in comparison with other existing approaches
Perception about family physicians: results of a survey of patients visiting specialist clinics for treatment
Objective: To study the perceptions about Family Medicine among patients visiting Specialist Physicians for treatment. Methods: A questionnaire based survey was conducted at the Specialist Clinic, Aga Khan University Hospital, Karachi, Pakistan, in June 2004. Trained volunteers administered the questionnaire among patients visiting Specialist Physicians for treatment. Confidentiality was ensured to all patients and written informed consent was taken as part of the ethical requirements for the conduct of the study. SPSS computer software and Microsoft Excel were used for data management. Results: A total of 100 patients visiting the Specialist Clinic were interviewed, of which fifty four (54%) were women and forty six (46%) were men. The mean age was 36.3 years. Twenty four (24%) respondents had graduate education. Being well-mannered, being familiar with a family\u27s medical history and possessing the abilities to conduct proper checkups were quoted as main characteristics of Family Physicians by thirty eight (38%), seventeen (17%) and twenty five (25%) respondents respectively. If they had a chest pain, fifty six (56%), forty three (43%) and one (1%) respondents would consult a Family Physician, Cardiologist and Chest Specialist, respectively. Conclusion: We have documented perceptions regarding family medicine among patient\u27s visiting Specialist Physicians for treatment. It is recommended that programs highlighting role and functions of family medicine should be started for the publi
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