192 research outputs found
On tuning a reactive silencer by varying the position of an internal membrane
A mode-matching method is used to investigate the performance of a two-dimensional, modified reactive silencer. The modification takes the form of a membrane which is attached to the internal walls of the expansion chamber parallel to the axis of the inlet/outlet ducts. The height of the membrane above the level of the inlet/outlet ducts can be varied and, by this means, the device is tuned. It is shown that the stopband produced by the silencer can be broadened and/or shifted depending upon the height to which the membrane is raised. Attention is focused on the efficiency of the device at low-frequencies - the regime where dissipative silencers are usually least effective. The potential use of the device as a component in a hybrid silencer for heating ventilation and air-conditioning (HVAC) ducting systems is discussed
Pharmacologic inhibition of reactive gliosis blocks TNF-α-mediated neuronal apoptosis.
Reactive gliosis is an early pathological feature common to most neurodegenerative diseases, yet its regulation and impact remain poorly understood. Normally astrocytes maintain a critical homeostatic balance. After stress or injury they undergo rapid parainflammatory activation, characterized by hypertrophy, and increased polymerization of type III intermediate filaments (IFs), particularly glial fibrillary acidic protein and vimentin. However, the consequences of IF dynamics in the adult CNS remains unclear, and no pharmacologic tools have been available to target this mechanism in vivo. The mammalian retina is an accessible model to study the regulation of astrocyte stress responses, and their influence on retinal neuronal homeostasis. In particular, our work and others have implicated p38 mitogen-activated protein kinase (MAPK) signaling as a key regulator of glutamate recycling, antioxidant activity and cytokine secretion by astrocytes and related Müller glia, with potent influences on neighboring neurons. Here we report experiments with the small molecule inhibitor, withaferin A (WFA), to specifically block type III IF dynamics in vivo. WFA was administered in a model of metabolic retinal injury induced by kainic acid, and in combination with a recent model of debridement-induced astrocyte reactivity. We show that WFA specifically targets IFs and reduces astrocyte and Müller glial reactivity in vivo. Inhibition of glial IF polymerization blocked p38 MAPK-dependent secretion of TNF-α, resulting in markedly reduced neuronal apoptosis. To our knowledge this is the first study to demonstrate that pharmacologic inhibition of IF dynamics in reactive glia protects neurons in vivo
Rancangan Kontroler Perangkat Keras EH1 Milano dengan Modul Wireless Electronics
Teknologi dalam dunia robot medis perkembangannya sangat pesat sekali, salah satunya adalah EH1 Milano yang dimiliki oleh salah satu laboratotium yang ada di kampus ITS Surabaya. Modul lengan robot EH1 Milano sebelumnya telah di riset oleh mahasiswa teknik elektro. Kekurangan dari riset tersebut, sistem perangkat keras masih terlalu rumit karena interface antara robot dan user masih menggunakan kabel. Sistem yang dirancang menggunakan modul Wireless Electronics untuk mengatasi masalah pengkabelan dan modul yang digunakan adalah modul Bluetooth model HC dengan jarak jangkauan sampai dengan 50 meter dan waktu pairing rata-rata 8 detik. Sensor flex dengan karakteristik sensor yang linier, dengan error percentage terkecil sebesar 0,58% sedangkan terbesar 15,13% terhadap garis linier dapat menggantikan sensor yang sebelumnya digunakan. Untuk penelitian berikutnya dapat ditambahkan EMG sebagai pembanding impuls dari sensor flex dengan sinyal electromyogram dari tiap-tiap jari
Enhancing Human-Robot Collaboration Transportation through Obstacle-Aware Vibrotactile Feedback
Transporting large and heavy objects can benefit from Human-Robot
Collaboration (HRC), increasing the contribution of robots to our daily tasks
and reducing the risk of injuries to the human operator. This approach usually
posits the human collaborator as the leader, while the robot has the follower
role. Hence, it is essential for the leader to be aware of the environmental
situation. However, when transporting a large object, the operator's
situational awareness can be compromised as the object may occlude different
parts of the environment. This paper proposes a novel haptic-based
environmental awareness module for a collaborative transportation framework
that informs the human operator about surrounding obstacles. The robot uses two
LIDARs to detect the obstacles in the surroundings. The warning module alerts
the operator through a haptic belt with four vibrotactile devices that provide
feedback about the location and proximity of the obstacles. By enhancing the
operator's awareness of the surroundings, the proposed module improves the
safety of the human-robot team in co-carrying scenarios by preventing
collisions. Experiments with two non-expert subjects in two different
situations are conducted. The results show that the human partner can
successfully lead the co-transportation system in an unknown environment with
hidden obstacles thanks to the haptic feedback.Comment: 6 pages, 5 figures, for associated video, see this
https://youtu.be/UABeGPIIrH
Pembahasan Defence Cooperation Agreement Indonesia –Singapuraoleh DPR dan Pemerintah Indonesia dan Implikasinya Bagi Teori Birokratik Politik
This paper aims to examine the extent to which the internal dicsusion of the Defence and Cooperation Agreement between Indonesia and Singapore consistent with the bureaucratic politics theory. Using the null hypotesis and process tracing methods, this paper tests the bureaucratic politic theory, which was first introduced in the foreign policy studies by Graham Allison and Philip Zelikiow. Specifically, this paper asks the following questions: Who are the foreign policy makers in Indonesia with regards to the faith of DCA? What are their stances toward the future of DCA? How does each decision makers advance their own opinion on this matter? What influence their stance? Does the final outcome reflect each actor\u27s initial preference over the outcome? Based on the paper\u27s content and other authors\u27 observation, this paper argues that the internal discussion regarding the future of DCA is not entirely consistent with the argument made by Allison and Zelikow in bureuacratic politics theory
Robot-Assisted Navigation for Visually Impaired through Adaptive Impedance and Path Planning
This paper presents a framework to navigate visually impaired people through
unfamiliar environments by means of a mobile manipulator. The Human-Robot
system consists of three key components: a mobile base, a robotic arm, and the
human subject who gets guided by the robotic arm via physically coupling their
hand with the cobot's end-effector. These components, receiving a goal from the
user, traverse a collision-free set of waypoints in a coordinated manner, while
avoiding static and dynamic obstacles through an obstacle avoidance unit and a
novel human guidance planner. With this aim, we also present a legs tracking
algorithm that utilizes 2D LiDAR sensors integrated into the mobile base to
monitor the human pose. Additionally, we introduce an adaptive pulling planner
responsible for guiding the individual back to the intended path if they veer
off course. This is achieved by establishing a target arm end-effector position
and dynamically adjusting the impedance parameters in real-time through a
impedance tuning unit. To validate the framework we present a set of
experiments both in laboratory settings with 12 healthy blindfolded subjects
and a proof-of-concept demonstration in a real-world scenario.Comment: 7 pages, 7 figures, submitted to IEEE International Conference on
Robotics and Automation, for associated video, see
https://youtu.be/B94n3QjdnJ
Analysis of Resistance to Antimicrobials and Presence of Virulence/Stress Response Genes in Campylobacter Isolates from Patients with Severe Diarrhoea
Campylobacter infections are a major cause of diarrhoea world-wide and two of the antimicrobials
used for their control (erythromycin and ciprofloxacin) have been losing efficacy in
recent years. In a sample of 174 genotyped isolates from the stools of patients with severe
diarrhoea in Qatar, collected between 2005 and 2012, 63.2%showed resistance to ciprofloxacin,
8.6% to erythromycin, 0.57%to chloramphenicol and all were sensitive to gentamycin.
While 33.9%of isolates were sensitive to all four antimicrobials, 59.8% were
resistant to at least one, 6.3% were resistant to two and none showed resistance to three
antimicrobials. There was no host sex- or age-dependence among isolates resistant to ciprofloxacin
and erythromycin and no significant variation was found with the region of origin
of the patients. All isolates were screened for the presence of 3 virulence factors (ciaB,
cadF and cdtB) and two stress-response factors (htrB and clpP), all of which were present
in more than 50% of the isolates. Host sex-, age- and region of origin-dependent variations
in prevalence were found for some of these factors. Data analysis for the combination of virulence
factors and their effect on antimicrobial resistance indicated that the prevalence of
resistance to both erythromycin and ciprofloxacin was higher in isolates harbouring ciaB but
not clpP. Prevalence of resistance to ciprofloxacin was similar in clpP positive and negative
isolates also possessing htrB, while for htrB-negative isolates prevalence was higher in the
absence of clpP. These results are discussed and their implications are highlighted.National Priority Research Program grant number NPRP4-1283-3-327 from the Qatar National Research Fund, Hamad Medical Corporation grant #13334/1
Functionally Heterogenous Macrophage Subsets in the Pathogenesis of Giant Cell Arteritis:Novel Targets for Disease Monitoring and Treatment
Giant cell arteritis (GCA) is a granulomatous large-vessel vasculitis that affects adults above 50 years of age. In GCA, circulating monocytes are recruited to the inflamed arteries. With cues from the vascular microenvironment, they differentiate into macrophages and play important roles in the pathogenesis of GCA via pro-inflammatory cytokine production and vascular remodeling. However, a deeper understanding of macrophage heterogeneity in GCA pathogenesis is needed to assist the development of novel diagnostic tools and targeted therapies. Here, we review the current knowledge on macrophage heterogeneity and diverse functions of macrophage subsets in the pathogenesis of GCA. We next discuss the possibility to exploit their heterogeneity as a source of novel biomarkers and as targets for nuclear imaging. Finally, we discuss novel macrophage-targeted therapies and future directions for targeting these cells in GCA
Apparatus to investigate the insulation impedance and accelerated life-testing of neural interfaces
OBJECTIVE: Neural interfaces and other implantable micro-devices that use polymer-encapsulated integrated circuits will only be allowed in medical devices when their lifetimes can be estimated from experimental data. An apparatus has been developed and tested that allows hundreds of insulation samples (interdigitated combs) to be aged under accelerated conditions of high temperature and voltage stress. Occasionally, aging is interrupted while the sample's impedance is measured; the impedance spectrogram shows degradation as it progresses before failure. Approach. The design was based on practical considerations which are reviewed. A Solartron Modulab provides the frequency response analyser and the femtoammeter. The apparatus can accommodate batches of samples at several temperatures and with different aging voltage waveforms. It is important to understand features of the spectra that are not due to comb-comb leakage; these have been observed and investigated using SPICE. Main results. The design is described in detail and tests show that it is capable of making measurements over long periods, at least up to 67°C. Despite the size of the apparatus, background capacitance is about 1 pF and comb-comb capacitances of about 30 pF can be measured down to 10 mHz. an impedance of about 100GΩ. An important discovery was the advantage of grounding the bathing solution, mainly because it raises the measurement ceiling. Observation and SPICE simulation show that leakage from the substrate to the bathing solution can give phase lags >90°, in contrast to comb-comb leakage which reduces phase lag to <90°. Significance. We think that the value of this paper is that it will facilitate research into the endurance of small implanted devices because, given a description of proven apparatus, researchers can start building their own apparatus relatively quickly and with confidence.
- …