295 research outputs found
Discrete breathers in a two-dimensional Fermi-Pasta-Ulam lattice
Using asymptotic methods, we investigate whether discrete
breathers are supported by a two-dimensional Fermi-Pasta-Ulam lattice. A scalar (one-component) two-dimensional
Fermi-Pasta-Ulam lattice is shown to model the charge stored
within an electrical transmission lattice. A third-order multiple-scale analysis in the semi-discrete limit fails, since at this order, the lattice equations reduce to the (2+1)-dimensional cubic nonlinear Schrödinger (NLS) equation which does not support stable soliton solutions for the breather envelope. We therefore extend
the analysis to higher order and find a generalised
-dimensional NLS equation which incorporates higher order dispersive and nonlinear terms as perturbations. We find an ellipticity criterion for the wave numbers of the carrier wave. Numerical simulations suggest that both stationary and moving breathers are supported by the system. Calculations of the energy show the expected threshold behaviour whereby the energy of breathers does {\em not} go to zero with the amplitude; we find
that the energy threshold is maximised by stationary breathers, and becomes arbitrarily small as the boundary of the domain of ellipticity is approached
Asymptotic analysis of combined breather-kink modes in a Fermi-Pasta-Ulam chain
We find approximations to travelling breather solutions of the
one-dimensional Fermi-Pasta-Ulam (FPU) lattice. Both bright
breather and dark breather solutions are found. We find that the
existence of localised (bright) solutions depends upon the
coefficients of cubic and quartic terms of the potential energy,
generalising an earlier inequality derived by James [CR Acad Sci
Paris 332, 581, (2001)]. We use the method of multiple scales to
reduce the equations of motion for the lattice to a nonlinear
Schr{\"o}dinger equation at leading order and hence construct an
asymptotic form for the breather. We show that in the absence of
a cubic potential energy term, the lattice supports combined
breathing-kink waveforms. The amplitude of breathing-kinks can be
arbitrarily small, as opposed to traditional monotone kinks, which
have a nonzero minimum amplitude in such systems. We also present
numerical simulations of the lattice, verifying the shape and
velocity of the travelling waveforms, and confirming the
long-lived nature of all such modes
THE IMPACT OF MOTIVATIONAL FACTORS ON ORGANIZATIONAL LEARNING: A STUDY ON EDUCATION SECTOR OF PAKISTAN
The main purpose of this study is to investigate the motivational factors that affect the organizational learning in the education sector of Pakistan. Self-administrated questionnaire with 5 point Likert scale is used for primary data collection and research journals and articles are used for secondary data collection. The sample size of the study is consisted of hundred academic employees of different educational institutes of Lahore. SPSS is used for measuring the relationships between variables and interpretations of their relationship. Organizational learning mainly depends upon peer cooperation motivational factor. As the peer cooperation increases in an organization, it leads the organization towards learning. Peer cooperation has a strong effect on organizational learning as a motivational factor in the education sector. A high level of peer cooperation in any organization helps in enhancing its learning. Furthermore, according to data analysis all other motivational factors used in this study i.e. working condition, recognition and reward has very small or no effect on learning of any organization. So, we can conclude that, among four different motivational factors i.e. peer cooperation, working condition, recognition and rewards, only peer cooperation has a strong relationship with organizational learning as compared to other factors
Asymptotic analysis of combined breather-kink modes in a Fermi-Pasta-Ulam chain
We find approximations to travelling breather solutions of the
one-dimensional Fermi-Pasta-Ulam (FPU) lattice. Both bright
breather and dark breather solutions are found. We find that the
existence of localised (bright) solutions depends upon the
coefficients of cubic and quartic terms of the potential energy,
generalising an earlier inequality derived by James [CR Acad Sci
Paris 332, 581, (2001)]. We use the method of multiple scales to
reduce the equations of motion for the lattice to a nonlinear
Schr{\"o}dinger equation at leading order and hence construct an
asymptotic form for the breather. We show that in the absence of
a cubic potential energy term, the lattice supports combined
breathing-kink waveforms. The amplitude of breathing-kinks can be
arbitrarily small, as opposed to traditional monotone kinks, which
have a nonzero minimum amplitude in such systems. We also present
numerical simulations of the lattice, verifying the shape and
velocity of the travelling waveforms, and confirming the
long-lived nature of all such modes
AN UNUSUAL MASS OF THE CHEST WALL IN A 7 YEARS OLD CHILD: AN ASKIN'S TUMOUR
Askin’s tumour is a primitive neuroectodermal tumour developing from the soft tissues of the chest wall. It is commonly misdiagnosed due to features similar to other round blue cell tumours. The approach for its diagnosis and treatment is complex and requires a multidisciplinary team. The recommended treatment is chemotherapy and surgical excision mainly. The prognosis is dependent on many factors. We managed a child of Askin’s tumour using modalities such as neoadjuvant chemotherapy and surgical excision and found a good response.Key words: Chest wall mass, Askin’s tumour, Ewing sarcom
Strategic design of culture for digital transformation
Industrial organizations need to take a cultural leap in order to integrate social systems with rapidly evolving digital technologies. Subsequently, aspiration for digital transformation enabled by organizational culture is ubiquitous; however, guidance in the literature on how to refresh the culture in pursuit of digital transformation strategy is underdeveloped. We conducted a diagnostic multi-case study on the organization culture in three globally renowned industrial organizations undergoing digital transformation strategy implementation. Through thematic analysis of qualitative data, we identified cultural artefacts, values in action, and assumptions that industrial organizations should refresh to enable digital transformation. It was found that forerunner industrial organizations’ approach to culture is strategically proactive and thoughtful. Furthermore, their leaders employed culture as a social control system for digital technology adoption. The research findings are summarized as an exploratory framework for the strategic design of culture for the purpose, governance, ecosystem, and organization of sociotechnical systems.© 2024 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).fi=vertaisarvioitu|en=peerReviewed
Structural challenges to adopt digital transformation in industrial organizations : A multiple case study
Digital Transformation requires significant changes in industrial organization’s setting to remain relevant in this fast-paced environment. This calls for modifications in their organizational structures. The existing organizational structures of industrial organizations are mechanistic, while, digital transformation needs organic and flexible organizational structure. Therefore, the main aim of this study is to identify the main challenges that industrial organizations face in the process of modifying their mechanistic structures into organic structures. To explore these challenges, we conducted multiple case study from three global industrial organizations. We interviewed 41 middle to high-level management personnel. The results of this study highlight six main challenges that industrial organizations need to cope for structural modifications. These challenges are structural rigidity, traditional hierarchy, silos, problems with resource allocations, organizational size and old-fashioned-leadership.© 2022. Published by AHFE Open Access. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).fi=vertaisarvioitu|en=peerReviewed
Discrete Breathers in One- and Two-Dimensional Lattices
Discrete breathers are time-periodic and spatially localised exact
solutions in translationally invariant nonlinear lattices. They
are generic solutions, since only moderate conditions are required
for their existence. Closed analytic forms for breather solutions
are generally not known. We use asymptotic methods to determine
both the properties and the approximate form of discrete breather
solutions in various lattices.
We find the conditions for which the one-dimensional FPU chain
admits breather solutions, generalising a known result for
stationary breathers to include moving breathers. These
conditions are verified by numerical simulations. We show that the
FPU chain with quartic interaction potential supports long-lived
waveforms which are combinations of a breather and a kink. The
amplitude of classical monotone kinks is shown to have a nonzero
minimum, whereas the amplitude of breathing-kinks can be
arbitrarily small.
We consider a two-dimensional FPU lattice with square rotational
symmetry. An analysis to third-order in the wave amplitude is
inadequate, since this leads to a partial differential equation
which does not admit stable soliton solutions for the breather
envelope. We overcome this by extending the analysis to
higher-order, obtaining a modified partial differential equation
which includes known stabilising terms. From this, we determine
regions of parameter space where breather solutions are expected.
Our analytic results are supported by extensive numerical
simulations, which suggest that the two-dimensional square FPU
lattice supports long-lived stationary and moving breather modes.
We find no restriction upon the direction in which breathers can
travel through the lattice. Asymptotic estimates for the breather
energy confirm that there is a minimum threshold energy which must
be exceeded for breathers to exist in the two-dimensional lattice.
We find similar results for a two-dimensional FPU lattice with
hexagonal rotational symmetry
Upregulation of Transglutaminase andε(γ-Glutamyl)-Lysine in the Fisher-Lewis Rat Model of Chronic Allograft Nephropathy
Background. Tissue transglutaminase (TG2), a cross-linking enzyme, modulates deposition of extracellular matrix protein in renal fibrosis. This study aimed to examine TG2 and its cross-link product ε(γ-glutamyl)-lysine in the Fisher-Lewis rat renal transplantation (RTx) model of chronic allograft nephropathy (CAN). Materials and Methods. Left renal grafts from male Fisher and Lewis were transplanted into Lewis rats, generating allografts and isografts, respectively. Blood pressure, renal function, and proteinuria were monitored for up to 52 weeks. At termination, CAN was assessed in the renal tissue by light and electron microscopy, TG2 and ε(γ-glutamyl)-lysine by immunofluorescence, and the urinary ε(γ-glutamyl)-lysine by high performance liquid chromatography.
Results. Compared to the isograft, the allografts were hypertensive, proteinuric, and uraemic and developed CAN. Extracellular TG2 (glomerulus: 64.55 + 17.61 versus 2.11 + 0.17, P<0.001; interstitium: 13.72 + 1.62 versus 3.19 + 0.44, P<0.001), ε(γ-glutamyl)-lysine (glomerulus: 21.74 + 2.71 versus 1.98 + 0.37, P<0.01; interstitium: 37.96 + 17.06 versus 0.42 + 0.11, P<0.05), TG2 enzyme activity (1.09 + 0.13 versus 0.41 + 0.03 nmol/h/mg protein, P<0.05), TG2 mRNA (20-fold rise), and urinary ε(γ-glutamyl)-lysine (534.2 + 198.4 nmol/24 h versus 57.2 + 4.1 nmol/24 h,P<0.05) levels were significantly elevated in the allografts and showed a positive linear correlation with tubulointerstitial fibrosis. Conclusion. CAN was associated with upregulation of renal TG2 pathway, which has a potential for pharmacological intervention. The elevated urinary ε(γ-glutamyl)-lysine, measured for the first time in RTx, is a potential biomarker of CA
Role of Endoscopic Third Ventriculostomy in Congenital Obstructive Hydrocephalus
Object: To improve the care of Obstructive Hydrocephalic infants, from six months to twelve months and to evaluate the efficacy and complications of Endoscopic Third Ventriculostomy (ETV).
Materials and Methods: The study was conducted in the Department of Neurosurgery PGMI, Lahore General Hospital, Lahore from July 2007 to June 2008. Total numbers of patients were 30, which were divided into two equal groups. Group A (15 patients) underwent Endoscopic Third Ventriculostomy (ETV) and Ventriculo-peritoneal VP Shunt were done in Group B (15 patients). Cases were selected randomly.
Results: The mean age for Group A was 9 months and for Group B was 8 months Endoscopic Third Ventriculo-stomy (ETV) procedure found successful in older than 8 months of age while ventriculoperitoneal VP Shunt procedure found successful in all age groups. Before procedure mean head circumference for Group A was 50.86 cm and for Group B was 50.84 cm. After one year follow up mean head circumference in Endoscopic Third Ventriculostomy (ETV) Group was 50.18 cm and in VP Shunt Group was 47.38 cm. Primary success in Endoscopic Third Ventriculostomy (ETV) Group was 53.3% (8 out of 15), whereas in VP Shunt Group it was 66.7% (10 out of 15).
Conclusion: Although results are same in both groups but Endoscopic Third Ventriculostomy (ETV) Group remain shunt free. Endoscopic Third Ventriculostomy seems to be an effective alternative than VP Shunt in the management of Hydrocephalus in infants provided careful patient selection is done and surgeon is competent enough with Endoscopic Third Ventriculostomy technique
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