681 research outputs found
Unlocking "lock-in" and path dependency: A review across disciplines and socio-environmental contexts
Introduced in the early 2000s, the concept of carbon “lock-in” has been widely adopted by think tanks, academics, and civil society trying to break away from the consequences of fossil-fuel induced carbon emissions and climate change. The concept has been instrumental to energy economic policy, energy transitions, and automobile transportation and urban mobility. It has parallels with “path dependency” across sectors, including water governance, fisheries, farmer tenure, and debt. Yet its use has also fallen short in applying it to nontechnical settings beyond infrastructure. In this review article, we argue that the “lock-in” concept is relevant to a much broader range of multi-scalar socio-environmental challenges to development. We expand lock-in to consider granular issues that tend to slip out of macro-level technological and institutional path dependencies, without falling into the ‘naturalizing trap’ in systems thinking. Broadening and re-engaging the concept of lock-in strengthens our analytical ability to address a range of structurally uneven environmental and societal lock-ins. © 2022 The Author(s
Rotating saddle trap as Foucault's pendulum
One of the many surprising results found in the mechanics of rotating systems
is the stabilization of a particle in a rapidly rotating planar saddle
potential. Besides the counterintuitive stabilization, an unexpected
precessional motion is observed. In this note we show that this precession is
due to a Coriolis-like force caused by the rotation of the potential. To our
knowledge this is the first example where such force arises in an inertial
reference frame. We also propose an idea of a simple mechanical demonstration
of this effect.Comment: 13 pages, 9 figure
A general framework for nonholonomic mechanics: Nonholonomic Systems on Lie affgebroids
This paper presents a geometric description of Lagrangian and Hamiltonian
systems on Lie affgebroids subject to affine nonholonomic constraints. We
define the notion of nonholonomically constrained system, and characterize
regularity conditions that guarantee that the dynamics of the system can be
obtained as a suitable projection of the unconstrained dynamics. It is shown
that one can define an almost aff-Poisson bracket on the constraint AV-bundle,
which plays a prominent role in the description of nonholonomic dynamics.
Moreover, these developments give a general description of nonholonomic systems
and the unified treatment permits to study nonholonomic systems after or before
reduction in the same framework. Also, it is not necessary to distinguish
between linear or affine constraints and the methods are valid for explicitly
time-dependent systems.Comment: 50 page
Retinal Ganglion Cells Can Rapidly Change Polarity from Off to On
Retinal ganglion cells are commonly classified as On-center or Off-center depending on whether they are excited predominantly by brightening or dimming within the receptive field. Here we report that many ganglion cells in the salamander retina can switch from one response type to the other, depending on stimulus events far from the receptive field. Specifically, a shift of the peripheral image—as produced by a rapid eye movement—causes a brief transition in visual sensitivity from Off-type to On-type for approximately 100 ms. We show that these ganglion cells receive inputs from both On and Off bipolar cells, and the Off inputs are normally dominant. The peripheral shift strongly modulates the strength of these two inputs in opposite directions, facilitating the On pathway and suppressing the Off pathway. Furthermore, we identify certain wide-field amacrine cells that contribute to this modulation. Depolarizing such an amacrine cell affects nearby ganglion cells in the same way as the peripheral image shift, facilitating the On inputs and suppressing the Off inputs. This study illustrates how inhibitory interneurons can rapidly gate the flow of information within a circuit, dramatically altering the behavior of the principal neurons in the course of a computation
Analysis of Transient Processes in a Radiophysical Flow System
Transient processes in a third-order radiophysical flow system are studied
and a map of the transient process duration versus initial conditions is
constructed and analyzed. The results are compared to the arrangement of
submanifolds of the stable and unstable cycles in the Poincare section of the
system studied.Comment: 3 pages, 2 figure
Wernicke encephalopathy after sleeve gastrectomy
The article describes the case of a patient with Wernicke encephalopathy, which developed 3 months after the sleeve gastrectomy. An MRI of the brain was performed to verify the diagnosis, which revealed a symmetrical non-uniform increase in the MR signal on T2-WI and Tirm from the medial part of the thalamus, mastoid bodies and gray matter around the aqueduct of Sylvius. Thiamine infusion was promptly initiated as therapy. During treatment, acute neurological symptoms almost regressed, the patient was discharged in a satisfactory condition with preservation of vertical nystagmus under the supervision of specialists at the place of residence. Wernicke–Korsakoff syndrome more often occurs as a complication of alcoholism and arising from thiamine deficiency. However, the fact that this condition also occurs under the influence of other etiopathogenetic factors is often ignored by clinicians. In the management of patients after bariatric interventions, this condition is much more common in malabsorptive operations. However, a combination of certain factors can be described in patients after restrictive types of bariatric surgeries
Anthropometric characteristics of patients suffering from chronic cystitis
Introduction. With a depressingly high prevalence of chronic cystitis (it is believed that half of women suffer from acute cystitis at least once in their lives), there is still no clarity on this disease. We were unable to find any studies on the anthropometric characteristics of patients with chronic cystitis either in the domestic or in the English literature.Objective. To assess the anthropometric characteristics of patients with chronic recurrent cystitis.Material & methods. A prospective multicenter cohort study included 91 patients with symptoms of acute cystitis. All underwent anthropometric measurements, analyzed complaints, studied anamnesis morbi et vitae, performed a study on a gynecological chair; urine was sent for general analysis and bacteriological examination for nonspecific microflora with the determination of the sensitivity of the isolated pathogen to antimicrobial drugs. The patients answered questions about the Russian version of the Acute Cystitis Symptom Score (ACSS). A urethra and cervical canal smear was studied using the polymerase chain reaction method to identify the causative agents of sexually transmitted infections. The diagnosis was considered confirmed in the presence of leukocyturia, bacteriuria, and the sum of symptoms on the ACSS scale was 6 or more.Results. The duration of chronic recurrent cystitis was averaged at 7.1 ± 4.2 years. The age of the patients ranged from 18 to 49 years, averaging 28.9 ± 3.9 years. The height ranged from 150 cm to 178 cm, on average 165.9 ± 7.1 cm. The average weight was within the normal range: 64.2 ± 6.1 kg. However, the spread in the cohort by body weight was two-fold: from 42 to 86 kg. Overweight was found in five (5.5%) patients; two patients (2.2%), on the contrary, had a body weight deficit. When analyzing anthropometric indicators, along with the obvious ones (direct dependence of the duration of the disease on the age of the patient; direct dependence of the quality of life on the severity of symptoms), other statistically significant correlations were established: a positive relationship between age and weight, weight and duration of the disease.Conclusion. The analysis showed that overweight women respond to treatment worse, they have a longer history of cystitis. Neither typical symptoms nor ACSS score correlated with any of the anthropometric measures
Unlocking "lock-in" and path dependency : a review across disciplines and socio-environmental contexts
Introduced in the early 2000s, the concept of carbon "lock-in" has been widely adopted by think tanks, academics, and civil society trying to break away from the consequences of fossil-fuel induced carbon emissions and climate change. The concept has been instrumental to energy economic policy, energy transitions, and automobile transportation and urban mobility. It has parallels with "path dependency" across sectors, including water governance, fisheries, farmer tenure, and debt. Yet its use has also fallen short in applying it to nontechnical settings beyond infrastructure. In this review article, we argue that the "lock-in" concept is relevant to a much broader range of multi-scalar socio-environmental challenges to development. We expand lock-in to consider granular issues that tend to slip out of macro-level technological and institutional path dependencies, without falling into the 'naturalizing trap' in systems thinking. Broadening and re-engaging the concept of lock-in strengthens our analytical ability to address a range of structurally uneven environmental and societal lock-ins
Capillary condensation in disordered porous materials: hysteresis versus equilibrium behavior
We study the interplay between hysteresis and equilibrium behavior in
capillary condensation of fluids in mesoporous disordered materials via a
mean-field density functional theory of a disordered lattice-gas model. The
approach reproduces all major features observed experimentally. We show that
the simple van der Waals picture of metastability fails due to the appearance
of a complex free-energy landscape with a large number of metastable states. In
particular, hysteresis can occur both with and without an underlying
equilibrium transition, thermodynamic consistency is not satisfied along the
hysteresis loop, and out-of-equilibrium phase transitions are possible.Comment: 4 pages, 4 figure
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