68,387 research outputs found
A role-based perspective on leadership as a network of relationships.
The research described in this article seeks to address the question of the extent to which a role-based perspective can provide insight into the distributed and networked form of leadership
Caloric vestibular stimulation reduces pain and somatoparaphrenia in a severe chronic central post-stroke pain patient: a case study
Central post-stroke pain is a neuropathic syndrome characterized by intolerable contralesional pain and, in rare cases, somatic delusions. To date, there is limited evidence for the effective treatments of this disease. Here we used caloric vestibular stimulation to reduce pain and somatoparaphrenia in a 57-year-old woman suffering from central post-stroke pain. Resting-state functional magnetic resonance imaging was used to assess the neurological effects of this treatment. Following vestibular stimulation we observed impressive improvements in motor skills, pain, and somatic delusions. In the functional connectivity study before the vestibular stimulation, we observed differences in the patient's left thalamus functional connectivity, with respect to the thalamus connectivity of a control group (N = 20), in the bilateral cingulate cortex and left insula. After the caloric stimulation, the left thalamus functional connectivity with these regions, which are known to be involved in the cortical response to pain, disappeared as in the control group. The beneficial use of vestibular stimulation in the reduction of pain and somatic delusion in a CPSP patient is now documented by behavioral and imaging data. This evidence can be applied to theoretical models of pain and body delusions
Performance Spillovers and Social Network in the Workplace: Evidence from Rural and Urban Weavers in a Chinese Textile Firm
We provide some of the first rigorous evidence on performance spillovers and social network in the workplace. The data we use are rather extraordinary – weekly data for rejection rates (proportion of defective output) for all weavers in a firm during a 12 months (April 2003-March 2004) period, more than 10,000 observations. Our fixed effect estimates first point to significant spillovers of performance from high-ability weavers to low-ability weavers. On the other hand, we find no evidence for performance spillovers from low-ability to high-ability weavers. The findings are consistent with the knowledge sharing hypothesis that low-ability workers learn from high-ability workers but not vice versa. Second, by exploiting the well-documented fact that an exogenously-formed sharp divide between urban workers and rural migrant workers exists in firms in Chinese cities, we find that performance spillovers/knowledge sharing take place only within the confines of social network. Specifically rural low-ability weavers are found to improve their performance as their high-ability teammates (who are also rural migrants) improve their performance while they do not benefit from performance improvement of their high-ability teammates who are urban residents. Such heterogeneous performance interdependence of workers within the same team suggests that our evidence for performance spillovers is less likely to be a result of team specific demand shocks that generate spurious performance interdependence of all team members.knowledge sharing, performance spillovers, social network
Security Through Amnesia: A Software-Based Solution to the Cold Boot Attack on Disk Encryption
Disk encryption has become an important security measure for a multitude of
clients, including governments, corporations, activists, security-conscious
professionals, and privacy-conscious individuals. Unfortunately, recent
research has discovered an effective side channel attack against any disk
mounted by a running machine\cite{princetonattack}. This attack, known as the
cold boot attack, is effective against any mounted volume using
state-of-the-art disk encryption, is relatively simple to perform for an
attacker with even rudimentary technical knowledge and training, and is
applicable to exactly the scenario against which disk encryption is primarily
supposed to defend: an adversary with physical access. To our knowledge, no
effective software-based countermeasure to this attack supporting multiple
encryption keys has yet been articulated in the literature. Moreover, since no
proposed solution has been implemented in publicly available software, all
general-purpose machines using disk encryption remain vulnerable. We present
Loop-Amnesia, a kernel-based disk encryption mechanism implementing a novel
technique to eliminate vulnerability to the cold boot attack. We offer
theoretical justification of Loop-Amnesia's invulnerability to the attack,
verify that our implementation is not vulnerable in practice, and present
measurements showing our impact on I/O accesses to the encrypted disk is
limited to a slowdown of approximately 2x. Loop-Amnesia is written for x86-64,
but our technique is applicable to other register-based architectures. We base
our work on loop-AES, a state-of-the-art open source disk encryption package
for Linux.Comment: 13 pages, 4 figure
Functional Electrical Stimulation mediated by Iterative Learning Control and 3D robotics reduces motor impairment in chronic stroke
Background: Novel stroke rehabilitation techniques that employ electrical stimulation (ES) and robotic technologies are effective in reducing upper limb impairments. ES is most effective when it is applied to support the patients’ voluntary effort; however, current systems fail to fully exploit this connection. This study builds on previous work using advanced ES controllers, and aims to investigate the feasibility of Stimulation Assistance through Iterative Learning (SAIL), a novel upper limb stroke rehabilitation system which utilises robotic support, ES, and voluntary effort. Methods: Five hemiparetic, chronic stroke participants with impaired upper limb function attended 18, 1 hour intervention sessions. Participants completed virtual reality tracking tasks whereby they moved their impaired arm to follow a slowly moving sphere along a specified trajectory. To do this, the participants’ arm was supported by a robot. ES, mediated by advanced iterative learning control (ILC) algorithms, was applied to the triceps and anterior deltoid muscles. Each movement was repeated 6 times and ILC adjusted the amount of stimulation applied on each trial to improve accuracy and maximise voluntary effort. Participants completed clinical assessments (Fugl-Meyer, Action Research Arm Test) at baseline and post-intervention, as well as unassisted tracking tasks at the beginning and end of each intervention session. Data were analysed using t-tests and linear regression. Results: From baseline to post-intervention, Fugl-Meyer scores improved, assisted and unassisted tracking performance improved, and the amount of ES required to assist tracking reduced. Conclusions: The concept of minimising support from ES using ILC algorithms was demonstrated. The positive results are promising with respect to reducing upper limb impairments following stroke, however, a larger study is required to confirm this
Middleware-based Database Replication: The Gaps between Theory and Practice
The need for high availability and performance in data management systems has
been fueling a long running interest in database replication from both academia
and industry. However, academic groups often attack replication problems in
isolation, overlooking the need for completeness in their solutions, while
commercial teams take a holistic approach that often misses opportunities for
fundamental innovation. This has created over time a gap between academic
research and industrial practice.
This paper aims to characterize the gap along three axes: performance,
availability, and administration. We build on our own experience developing and
deploying replication systems in commercial and academic settings, as well as
on a large body of prior related work. We sift through representative examples
from the last decade of open-source, academic, and commercial database
replication systems and combine this material with case studies from real
systems deployed at Fortune 500 customers. We propose two agendas, one for
academic research and one for industrial R&D, which we believe can bridge the
gap within 5-10 years. This way, we hope to both motivate and help researchers
in making the theory and practice of middleware-based database replication more
relevant to each other.Comment: 14 pages. Appears in Proc. ACM SIGMOD International Conference on
Management of Data, Vancouver, Canada, June 200
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