7,775 research outputs found
Understanding the Higher-Order Approach to Consciousness
Critics have often misunderstood the higher-order theory (HOT) of consciousness. Here we clarify its position on several issues, and distinguish it from other views such as the global The higher-order theory (HOT) of consciousness has often been misunderstood by critics. Here we clarify its position on several issues, and distinguish it from other views such as the global workspace theory (GWT) and early sensory models (e.g. first-order local recurrency theories). For example, HOT has been criticized for over-intellectualizing consciousness. We show that while higher-order states are cognitively assembled, the requirements are actually considerably less than often presumed. In this sense HOT may be viewed as an intermediate position between GWT and early sensory views. Also, we clarify that most proponents of HOT do not stipulate consciousness as equivalent to metacognition or confidence. Further, compared to other existing theories, HOT can arguably account better for complex everyday experiences, such as of emotions and episodic memories. This makes HOT particularly useful as a framework for conceptualizing pathological mental states
On Intelligent Mitigation of Process Starvation In Multilevel Feedback Queue Scheduling
CPU time-share process schedulers for computer operating systems have existed since Corbato published his paper on the Compatible Time Sharing System in 1962 [8]. With this new type of scheduler came the need to effectively divide CPU time between N processes, where N could be 2 or more processes. Modern time-sharing process schedulers which have been developed in the decades since have been designed to favor shorter, interactive processes over long-running processes, especially when incoming demand for CPU time exceeds supply and process starvation is inevitable. These schedulers, including Linux CFS, FreeBSD Ule, and the Solaris Fair Share Scheduler, are all effective at favoring interactive processes under starvation conditions.
Sometimes it’s not desirable that long-running processes be sacrificed altogether, but none of these schedulers have safeguards under starvation conditions. This thesis revisits and extends the research conducted in [13], in which it was demonstrated that starvation of long-running processes could be safely and effectively mitigated without adversely affecting the performance of shorter, interactive processes.
The questions this thesis will answer are: Can MLFQ-NS, proposed in [13], be compared to other modern process schedulers? Can MLFQ-NS be improved?
To answer the first question, a scheduler must be found which is similar enough to MFLQ for a direct comparison. This will require a survey of current schedulers. To answer the second question, the research conducted in [13] must be duplicated MLFQ-NS to ascertain the following: How much diverted time is actually used? Why does MLFQ-NS become ineffective past a certain system-load threshold, i.e. stop real- locating time to long-runnning processes?
In this research, the original work was duplicated in simulations to validate previous re- sults, and determine why MLFQ-NS became ineffective after incoming CPU time demand exceeds a threshold. Research was conducted in order to determine if starvation mitigation in MLFQ-NS could be compared to other process schedulers used in production, with the conclusion that recent emphasis on priority scheduling and heurstic interactivity determination makes such a comparison impossible. Research then continued with simulations in which MLFQ-NS was given different run- time arguments than original simulations. Investigations into those results led to an algorithmic modification to MLFQ-NS called MLFQ-IM and analysis of simulations of MLFQ-IM. Conclu- sions about the effectiveness of MLFQ-IM will be explored. Finally, ideas for future research are offered
Which Way Was I Going? Contextual Retrieval Supports the Disambiguation of Well Learned Overlapping Navigational Routes
Groundbreaking research in animals has demonstrated that the hippocampus contains neurons that distinguish betweenoverlapping navigational trajectories. These hippocampal neurons respond selectively to the context of specific episodes despite interference from overlapping memory representations. The present study used functional magnetic resonanceimaging in humans to examine the role of the hippocampus and related structures when participants need to retrievecontextual information to navigate well learned spatial sequences that share common elements. Participants were trained outside the scanner to navigate through 12 virtual mazes from a ground-level first-person perspective. Six of the 12 mazes shared overlapping components. Overlapping mazes began and ended at distinct locations, but converged in the middle to share some hallways with another maze. Non-overlapping mazes did not share any hallways with any other maze. Successful navigation through the overlapping hallways required the retrieval of contextual information relevant to thecurrent navigational episode. Results revealed greater activation during the successful navigation of the overlapping mazes compared with the non-overlapping mazes in regions typically associated with spatial and episodic memory, including thehippocampus, parahippocampal cortex, and orbitofrontal cortex. When combined with previous research, the current findings suggest that an anatomically integrated system including the hippocampus, parahippocampal cortex, and orbitofrontal cortexis critical for the contextually dependent retrieval of well learned overlapping navigational routes
Shear thickening in densely packed suspensions of spheres and rods confined to few layers
We investigate confined shear thickening suspensions for which the sample
thickness is comparable to the particle dimensions. Rheometry measurements are
presented for densely packed suspensions of spheres and rods with aspect ratios
6 and 9. By varying the suspension thickness in the direction of the shear
gradient at constant shear rate, we find pronounced oscillations in the stress.
These oscillations become stronger as the gap size is decreased, and the stress
is minimized when the sample thickness becomes commensurate with an integer
number of particle layers. Despite this confinement-induced effect, viscosity
curves show shear thickening that retains bulk behavior down to samples as thin
as two particle diameters for spheres, below which the suspension is jammed.
Rods exhibit similar behavior commensurate with the particle width, but they
show additional effects when the thickness is reduced below about a particle
length as they are forced to align; the stress increases for decreasing gap
size at fixed shear rate while the shear thickening regime gradually
transitions to a Newtonian scaling regime. This weakening of shear thickening
as an ordered configuration is approached contrasts with the strengthening of
shear thickening when the packing fraction is increased in the disordered bulk
limit, despite the fact that both types of confinement eventually lead to
jamming.Comment: 21 pages, 14 figures. submitted to the Journal of Rheolog
Interview with Joseph Stiglitz: “The cost of keeping the Eurozone together probably exceeds the cost of breaking it up”
Can the euro be saved? In an interview with Artemis Photiadou and EUROPP’s editor Stuart Brown, Nobel Prize-winning economist and bestselling author Joseph Stiglitz discusses the structural problems at the heart of the Eurozone, why an amicable divorce may be preferable to maintaining the single currency, and how European leaders should respond to the UK’s vote to leave the EU
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Direct Laser Fabrication of a Gas Turbine Engine Component - Microstructure and Properties - Part I
This paper presents the development of a new technique for the production of abrasive
turbine blade tips by direct laser processing. This superalloy cermet component is an integral part
of the low pressure turbine sealing system in a demonstrator engine. Direct laser fabrication of
this component fiom a bed a loose powder results in significant cost savings and improved
performance over the currently employed production technique. The technology has been
demonstrated by fabricating a prototype lot of 100 blade tips, which will be subjected to an engine
test. This is the first instance of a direct fabrication method applied to the production of functional
engine hardware. This research was funded by the United States Air Force contract F33615-94-
C-2424 titled "Affordable Turbine Blade Tips".Mechanical Engineerin
Tempted to Text: College Students’ Mobile Phone Use During a Face-to-Face Interaction With a Close Friend
We examined whether emerging adults would engage in mobile phone use (MPU) when given the opportunity to socialize face-to-face with a close friend in a laboratory setting. Sixty-three U.S. college student friendship dyads rated their friendship quality in an online survey before coming into the laboratory together. When they arrived for their appointment, they were asked to wait together in a room for 5 min. A hidden camera recorded each dyad. Friends then separately rated the quality of the interaction. We coded time spent using mobile phone in seconds. A hierarchical regression conducted at the level of the dyad controlling for friendship quality and gender showed that more MPU was associated with lower quality interactions. We discuss findings in terms of the potential for MPU to interfere with the development of friendship intimacy
A Thermal Imaging Instrument with Uncooled Detectors
In this work, we performed an instrument concept study for sustainable thermal imaging over land with uncooled detectors. We evaluated two different uncooled detector technologies uncooled microbolometers and thermopiles. We have also evaluated materials for use in in a uncooled thermopile detector concept
Liver Transplantation to Provide Low-Density-Lipoprotein Receptors and Lower Plasma Cholesterol in a Child with Homozygous Familial Hypercholesterolemia
A six-year-old girl with severe hypercholesterolemia and atherosclerosis had two defective genes at the low-density-lipoprotein (LDL) receptor locus, as determined by biochemical studies of cultured fibroblasts. One gene, inherited from the mother, produced no LDL receptors; the other gene, inherited from the father, produced a receptor precursor that was not transported to the cell surface and was unable to bind LDL. The patient degraded intravenously administered 125I-LDL at an extremely low rate, indicating that her high plasma LDL-cholesterol level was caused by defective receptor-mediated removal of LDL from plasma. After transplantation of a liver and a heart from a normal donor, the patient's plasma LDL-cholesterol level declined by 81 per cent, from 988 to 184 mg per deciliter. The fractional catabolic rate for intravenously administered 125I-LDL, a measure of functional LDL receptors in vivo, increased by 2.5-fold. Thus, the transplanted liver, with its normal complement of LDL receptors, was able to remove LDL cholesterol from plasma at a nearly normal rate. We conclude that a genetically determined deficiency of LDL receptors can be largely reversed by liver transplantation. These data underscore the importance of hepatic LDL receptors in controlling the plasma level of LDL cholesterol in human beings. (N Engl J Med 1984; 311: 1658–64.). © 1984, Massachusetts Medical Society. All rights reserved
Novel secondary somatic mutations in Ewing's sarcoma and desmoplastic small round cell tumors.
BackgroundEwing's sarcoma (ES) and desmoplastic small round cell tumors (DSRCT) are small round blue cell tumors driven by an N-terminal containing EWS translocation. Very few somatic mutations have been reported in ES, and none have been identified in DSRCT. The aim of this study is to explore potential actionable mutations in ES and DSRCT.MethodologyTwenty eight patients with ES or DSRCT had tumor tissue available that could be analyzed by one of the following methods: 1) Next-generation exome sequencing platform; 2) Multiplex PCR/Mass Spectroscopy; 3) Polymerase chain reaction (PCR)-based single- gene mutation screening; 4) Sanger sequencing; 5) Morphoproteomics.Principal findingsNovel somatic mutations were identified in four out of 18 patients with advanced ES and two of 10 patients with advanced DSRCT (six out of 28 (21.4%));KRAS (n = 1), PTPRD (n = 1), GRB10 (n = 2), MET (n = 2) and PIK3CA (n = 1). One patient with both PTPRD and GRB10 mutations and one with a GRB10 mutation achieved a complete remission (CR) on an Insulin like growth factor 1 receptor (IGF1R) inhibitor based treatment. One patient, who achieved a partial remission (PR) with IGF1R inhibitor treatment, but later developed resistance, demonstrated a KRAS mutation in the post-treatment resistant tumor, but not in the pre-treatment tumor suggesting that the RAF/RAS/MEK pathway was activated with progression.ConclusionsWe have reported several different mutations in advanced ES and DSRCT that have direct implications for molecularly-directed targeted therapy. Our technology agnostic approach provides an initial mutational roadmap used in the path towards individualized combination therapy
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