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Sample records for paradoxically enhance gpvi-induced

  1. Paradoxes

    ERIC Educational Resources Information Center

    Partis, M.

    1972-01-01

    Examples of logical paradoxes, including the square root of two paradox, Achilles and the tortoise paradox, author paradox, Russell paradox, bibliomaniac paradox, and Berry paradox, are presented; some are resolved. (DT)

  2. Instability-Enhanced Collisional Effects and Langmuir's Paradox

    SciTech Connect

    Baalrud, S. D.; Callen, J. D.; Hegna, C. C.

    2009-06-19

    Anomalously fast equilibration of the electron distribution function to a Maxwellian in gas-discharge plasmas with low temperature and pressure, i.e., Langmuir's paradox, may be explained by electron scattering via an instability-enhanced collective response and hence fluctuations arising from convective ion-acoustic instabilities near the discharge boundaries.

  3. Moral enhancement, gnosticism, and some philosophical paradoxes.

    PubMed

    Barilan, Y M

    2015-01-01

    This article examines the concept of moral enhancement from two different perspectives. The first is a bottom-up approach, which aims at identifying fundamental moral traits and subcapacities as targets for enhancement. The second perspective, a top-down approach, is holistic and in line with virtue ethics. Both perspectives lead to the observation that alterations of material and social conditions are the most reliable means to improve prosocial behavior overall. Moral enhancement as a preventive measure invokes Gnostic narratives on the allegedly fallen status of human nature, its search for salvation, and the dependence of the laity on heteronomous salvific interventions. The allure of the preventive kind of enhancement is attributable to its religious hues. Owing to the absence of clarity regarding moral enhancement and of metrics to evaluate its progress, humanity is at risk of prioritizing unclear and unsubstantiated measures of preventive diminishment at the expense of celebrating human capacities and joys. PMID:25473860

  4. Ethanol enhances neurosteroidogenesis in hippocampal pyramidal neurons by paradoxical NMDA receptor activation.

    PubMed

    Tokuda, Kazuhiro; Izumi, Yukitoshi; Zorumski, Charles F

    2011-07-01

    Using an antibody against 5α-reduced neurosteroids, predominantly allopregnanolone, we found that immunostaining in the CA1 region of rat hippocampal slices was confined to pyramidal neurons. This neurosteroid staining was increased following 15 min administration of 60 mm but not 20 mm ethanol, and the enhancement was blocked by finasteride and dutasteride, selective inhibitors of 5α-reductase, a key enzyme required for allopregnanolone synthesis. Consistent with a prior report indicating that N-methyl-D-aspartate (NMDA) receptor (NMDAR) activation can promote steroid production, we observed that D-2-amino-5-phosphonovalerate (APV), a competitive NMDAR antagonist, blocked the effects of 60 mm ethanol on staining. We previously reported that 60 mm ethanol inhibits the induction of long-term potentiation (LTP), a cellular model for memory formation, in the CA1 region. In the present study, LTP inhibition by 60 mm ethanol was also overcome by both the 5α-reductase inhibitors and by APV. Furthermore, the effects of ethanol on neurosteroid production and LTP were mimicked by a low concentration of NMDA (1 μm), and the ability of NMDA to inhibit LTP and to enhance neurosteroid staining was reversed by finasteride and dutasteride, as well as by APV. These results indicate that ethanol paradoxically enhances GABAergic neurosteroid production by activation of unblocked NMDARs and that acute LTP inhibition by ethanol represents a form of NMDAR-mediated metaplasticity. PMID:21734282

  5. Importance of contrast-enhanced fluid-attenuated inversion recovery imaging to detect paradoxical expansion of tuberculoma.

    PubMed

    Kim, Hee-Jin

    2014-07-01

    Tuberculosis is a significant public health problem that continues to be a major cause of morbidity and mortality worldwide. Tuberculous meningoencephalitis (TM) is the most common extrapulmonary lesion in tuberculosis. A 41-year-old female was thought to have TM. Tests to confirm the TM diagnosis were initially negative, including tuberculosis PCR and adenosine deaminase level in serum and cerebrospinal fluid (CSF). Anti-tuberculous medication and intravenous steroids were administered to her on the basis of brain imaging and lactate dehydrogenase electrophoresis in CSF, suggestive of the diagnosis of TM. Her neurological problems improved rapidly following treatment. Serologic and CSF markers were positive in PCR and culture after 60 days. Radiological findings are often nonspecific and TM is difficult to diagnose without an increased index of suspicion. The detection of paradoxical expansion of tuberculoma is very important in the maintenance of medication. Magnetic resonance imaging was used to detect paradoxical expansion of the tuberculoma using various methods, such as contrast-enhanced fluid-attenuated inversion recovery (CE-FLAIR) imaging. CE-FLAIR imaging conspicuously showed paradoxical expansion of the tuberculoma. If patients present with clear meningitis, without any identified pathogen, there is a need to constantly and scrupulously check for TM, including with the use of CE-FLAIR brain imaging. PMID:24794323

  6. Paradox: increased blood perfusion to the face enhances protection against frostbite while it lowers wind chill equivalent temperatures.

    PubMed

    Shitzer, Avraham

    2007-05-01

    A model of facial heat exchange in cold and windy environments is presented. The tissue is depicted as a hollow cylinder and the model includes heat conduction and heat transport by blood circulation from the warmer core. A steady-state solution facilitating the estimation of wind chill equivalent temperature (WCET) as a function of the effective wind velocity, air temperature and blood perfusion rate was obtained. The results quantify and demonstrate the elevation of skin temperatures caused by increased flow of warmer blood from the inner core to the face. Elevated facial temperatures, while enhancing protection against frostbite and other cold-related injuries, also increase heat loss to the colder environment. Paradoxically, such elevated facial temperatures cause WCETs, as estimated by the prevailing definition, to attain lower rather than higher values, indicating, in fact, increased risk of frostbite. The results of this study should be useful in understanding and quantifying the effects of blood perfusion in protection against cold-related injuries. They should also be considered in the re-evaluation and re-formulation of the concept of wind chill, which has been a useful cold weather indicator for decades. PMID:17333290

  7. Paradox: increased blood perfusion to the face enhances protection against frostbite while it lowers wind chill equivalent temperatures

    NASA Astrophysics Data System (ADS)

    Shitzer, Avraham

    2007-05-01

    A model of facial heat exchange in cold and windy environments is presented. The tissue is depicted as a hollow cylinder and the model includes heat conduction and heat transport by blood circulation from the warmer core. A steady-state solution facilitating the estimation of wind chill equivalent temperature (WCET) as a function of the effective wind velocity, air temperature and blood perfusion rate was obtained. The results quantify and demonstrate the elevation of skin temperatures caused by increased flow of warmer blood from the inner core to the face. Elevated facial temperatures, while enhancing protection against frostbite and other cold-related injuries, also increase heat loss to the colder environment. Paradoxically, such elevated facial temperatures cause WCETs, as estimated by the prevailing definition, to attain lower rather than higher values, indicating, in fact, increased risk of frostbite. The results of this study should be useful in understanding and quantifying the effects of blood perfusion in protection against cold-related injuries. They should also be considered in the re-evaluation and re-formulation of the concept of wind chill, which has been a useful cold weather indicator for decades.

  8. Paradoxical effects of testing: retrieval enhances both accurate recall and suggestibility in eyewitnesses.

    PubMed

    Chan, Jason C K; Langley, Moses M

    2011-01-01

    Although retrieval practice typically enhances memory retention, it can also impair subsequent eyewitness memory accuracy (Chan, Thomas, & Bulevich, 2009). Specifically, participants who had taken an initial test about a witnessed event were more likely than nontested participants to recall subsequently encountered misinformation—an effect we called retrieval-enhanced suggestibility (RES). Here, we sought to test the generality of RES and to further elucidate its underlying mechanisms. To that end, we tested a dual mechanism account, which suggests that RES occurs because initial testing (a) enhances learning of the later misinformation by reducing proactive interference and (b) causes the reactivated memory trace to be more susceptible to later interference (i.e., a reconsolidation account). Three major findings emerged. First, RES was found after a 1-week delay, where a robust testing benefit occurred for event details that were not contradicted by later misinformation. Second, blockage of reconsolidation was unnecessary for RES to occur. Third, initial testing enhanced learning of the misinformation even when proactive interference played a minimal role. PMID:20919785

  9. Paradoxical Effects of Testing: Retrieval Enhances Both Accurate Recall and Suggestibility in Eyewitnesses

    ERIC Educational Resources Information Center

    Chan, Jason C. K.; Langley, Moses M.

    2011-01-01

    Although retrieval practice typically enhances memory retention, it can also impair subsequent eyewitness memory accuracy (Chan, Thomas, & Bulevich, 2009). Specifically, participants who had taken an initial test about a witnessed event were more likely than nontested participants to recall subsequently encountered misinformation--an effect we…

  10. Paradoxical reversal learning enhancement by stress or prefrontal cortical damage: rescue with BDNF

    PubMed Central

    Graybeal, Carolyn; Feyder, Michael; Schulman, Emily; Saksida, Lisa M.; Bussey, Timothy J.; Brigman, Jonathan L.; Holmes, Andrew

    2012-01-01

    Stress often has deleterious effects on cognition. We show that moderate stress enhanced late reversal learning in a mouse touchscreen-based choice task. Ventromedial prefrontal cortex (vmPFC) lesions mimicked the effects of stress, while orbitofrontal (OFC) and dorsolateral striatal (DLS) lesions impaired reversal. Stress-facilitation of reversal was prevented by BDNF infusion into the vmPFC. These findings suggest a mechanism in which stress-induced vmPFC dysfunction disinhibits learning by alternate (e.g., striatal) systems. PMID:22057192

  11. Peripheral Attentional Targets under Covert Attention Lead to Paradoxically Enhanced Alpha Desynchronization in Neurofibromatosis Type 1

    PubMed Central

    Silva, Gilberto; Ribeiro, Maria J.; Costa, Gabriel N.; Violante, Inês; Ramos, Fabiana; Saraiva, Jorge; Castelo-Branco, Miguel

    2016-01-01

    The limited capacity of the human brain to process the full extent of visual information reaching the visual cortex requires the recruitment of mechanisms of information selection through attention. Neurofibromatosis type-1 (NF1) is a neurodevelopmental disease often exhibiting attentional deficits and learning disabilities, and is considered to model similar impairments common in other neurodevelopmental disorders such as autism. In a previous study, we found that patients with NF1 are more prone to miss targets under overt attention conditions. This finding was interpreted as a result of increased occipito-parietal alpha oscillations. In the present study, we used electroencephalography (EEG) to study alpha power modulations and the performance of patients with NF1 in a covert attention task. Covert attention was required in order to perceive changes (target offset) of a peripherally presented stimulus. Interestingly, alpha oscillations were found to undergo greater desynchronization under this task in the NF1 group compared with control subjects. A similar pattern of desynchronization was found for beta frequencies while no changes in gamma oscillations could be identified. These results are consistent with the notion that different attentional states and task demands generate different patterns of abnormal modulation of alpha oscillatory processes in NF1. Under covert attention conditions and while target offset was reported with relatively high accuracy (over 90% correct responses), excessive desynchronization was found. These findings suggest an abnormal modulation of oscillatory activity and attentional processes in NF1. Given the known role of alpha in modulating attention, we suggest that alpha patterns can show both abnormal increases and decreases that are task and performance dependent, in a way that enhanced alpha desynchronization may reflect a compensatory mechanism to keep performance at normal levels. These results suggest that dysregulation of

  12. A direct thrombin inhibitor suppresses protein C activation and factor Va degradation in human plasma: Possible mechanisms of paradoxical enhancement of thrombin generation.

    PubMed

    Kamisato, Chikako; Furugohri, Taketoshi; Morishima, Yoshiyuki

    2016-05-01

    We have demonstrated that antithrombin (AT)-independent thrombin inhibitors paradoxically increase thrombin generation (TG) in human plasma in a thrombomodulin (TM)- and protein C (PC)-dependent manner. We determined the effects of AT-independent thrombin inhibitors on the negative-feedback system, activation of PC and production and degradation of factor Va (FVa), as possible mechanisms underlying the paradoxical enhancement of TG. TG in human plasma containing 10nM TM was assayed by means of the calibrated automated thrombography. As an index of PC activation, plasma concentration of activated PC-PC inhibitor complex (aPC-PCI) was measured. The amounts of FVa heavy chain and its degradation product (FVa(307-506)) were examined by western blotting. AT-independent thrombin inhibitors, melagatran and dabigatran (both at 25-600nM) and 3-30μg/ml active site-blocked thrombin (IIai), increased peak levels of TG. Melagatran, dabigatran and IIai significantly decreased plasma concentration of aPC-PCI complex at 25nM or more, 75nM or more, and 10 and 30μg/ml, respectively. Melagatran (300nM) significantly increased FVa and decreased FVa(307-506). In contrast, a direct factor Xa inhibitor edoxaban preferentially inhibited thrombin generation (≥25nM), and higher concentrations were required to inhibit PC activation (≥150nM) and FVa degradation (300nM). The present study suggests that the inhibitions of protein C activation and subsequent degradation of FVa and increase in FVa by antithrombin-independent thrombin inhibitors may contribute to the paradoxical TG enhancement, and edoxaban may inhibit PC activation and FVa degradation as a result of TG suppression. PMID:26974491

  13. Space Curvature and the "Heavy Banana 'Paradox.'"

    ERIC Educational Resources Information Center

    Gruber, Ronald P.; And Others

    1991-01-01

    Two ways to visually enhance the concept of space curvature are described. Viewing space curvature as a meterstick contraction and the heavy banana "paradox" are discussed. The meterstick contraction is mathematically explained. (KR)

  14. Paradoxical Enhancement of the Power Factor of Polycrystalline Silicon as a Result of the Formation of Nanovoids

    NASA Astrophysics Data System (ADS)

    Lorenzi, B.; Narducci, D.; Tonini, R.; Frabboni, S.; Gazzadi, G. C.; Ottaviani, G.; Neophytou, N.; Zianni, X.

    2014-10-01

    Hole-containing silicon has been regarded as a viable candidate thermoelectric material because of its low thermal conductivity. However, because voids are efficient scattering centers not just for phonons but also for charge carriers, achievable power factors (PFs) are normally too low for its most common form, i.e. porous silicon, to be of practical interest. In this communication we report that high PFs can, indeed, be achieved with nanoporous structures obtained from highly doped silicon. High PFs, up to a huge 22 mW K-2 m-1 (more than six times higher than values for the bulk material), were observed for heavily boron-doped nanocrystalline silicon films in which nanovoids (NVs) were generated by He+ ion implantation. In contrast with single-crystalline silicon in which He+ implantation leads to large voids, in polycrystalline films implantation followed by annealing at 1000°C results in homogeneous distribution of NVs with final diameters of approximately 2 nm and densities of the order of 1019 cm-3 with average spacing of 10 nm. Study of its morphology revealed silicon nanograins 50 nm in diameter coated with 5-nm precipitates of SiB x . We recently reported that PFs up to 15 mW K-2 m-1 could be achieved for silicon-boron nanocomposites (without NVs) because of a simultaneous increase of electrical conductivity and Seebeck coefficient. In that case, the high Seebeck coefficient was achieved as a result of potential barriers on the grain boundaries, and high electrical conductivity was achieved as a result of extremely high levels of doping. The additional increase in the PF observed in the presence of NVs (which also include SiB x precipitates) might have several possible explanations; these are currently under investigation. Experimental results are reported which might clarify the reason for this paradoxical effect of NVs on silicon PF.

  15. Aharonov-bohm paradox.

    NASA Technical Reports Server (NTRS)

    Trammel, G. T.

    1964-01-01

    Aharonov-bohm paradox involving charge particle interaction with stationary current distribution showing that vector potential term in canonical momenta expression represents electromagnetic field momentum

  16. The Integration Paradox

    PubMed Central

    Verkuyten, Maykel

    2016-01-01

    The integration paradox refers to the phenomenon of the more highly educated and structurally integrated immigrants turning away from the host society, rather than becoming more oriented toward it. This article provides an overview of the empirical evidence documenting this paradox in the Netherlands. In addition, the theoretical arguments and the available findings about the social psychological processes involved in this paradox are considered. The existing evidence for the integration paradox and what might explain it form the basis for making suggestion for future theoretical work and empirical research, and for discussing possible policy implications. PMID:27152028

  17. Paradoxes in dermatology

    PubMed Central

    Adya, Keshavmurthy A.; Inamadar, Arun C.; Palit, Aparna

    2013-01-01

    Many paradoxical phenomena related to clinical, immunological, and therapeutic dermatology have been described. While some of them can be explained logically, the cause for others can only be speculated. Whenever encountered in clinical practice, background knowledge of such paradoxes may be useful to the clinician. PMID:23741675

  18. Quantum Quasi-Paradoxes and Quantum Sorites Paradoxes

    NASA Astrophysics Data System (ADS)

    Smarandache, Florentin

    2009-03-01

    There can be generated many paradoxes or quasi-paradoxes that may occur from the combination of quantum and non-quantum worlds in physics. Even the passage from the micro-cosmos to the macro-cosmos, and reciprocally, can generate unsolved questions or counter-intuitive ideas. We define a quasi-paradox as a statement which has a prima facie self-contradictory support or an explicit contradiction, but which is not completely proven as a paradox. We present herein four elementary quantum quasi-paradoxes and their corresponding quantum Sorites paradoxes, which form a class of quantum quasi-paradoxes.

  19. Paradoxical response to levalbuterol.

    PubMed

    Broski, Sarah E; Amundson, Dennis E

    2008-04-01

    Asthma is a common condition that can substantially affect patients' quality of life. Although several drugs, most commonly beta-adrenergic agonists, alleviate symptoms of asthma, they may cause paradoxical bronchospasm or paradoxical bronchoconstriction. Levalbuterol hydrochloride-a pure form of the (R)-stereoisomer in racemic albuterol-eliminates the adrenergic properties that can cause such adverse effects. However, we report a case of paradoxical bronchoconstriction in a 36-year-old man who was recently diagnosed as having new-onset asthma and was treated with levalbuterol. PMID:18443029

  20. Counsellor Education: A Paradox

    ERIC Educational Resources Information Center

    Davis, William L.; Marks, Stephen E.

    1972-01-01

    This article examines the nature and impact of paradoxical situations in counsellor education. The counsellor educator and trainee are the focus for defining and then examining these dilemmas. (Author)

  1. Thermal Expansion "Paradox."

    ERIC Educational Resources Information Center

    Fakhruddin, Hasan

    1993-01-01

    Describes a paradox in the equation for thermal expansion. If the calculations for heating a rod and subsequently cooling a rod are determined, the new length of the cool rod is shorter than expected. (PR)

  2. Length Paradox in Relativity

    ERIC Educational Resources Information Center

    Martins, Roberto de A.

    1978-01-01

    Describes a thought experiment using a general analysis approach with Lorentz transformations to show that the apparent self-contradictions of special relativity concerning the length-paradox are really non-existant. (GA)

  3. Paradoxes of geoelectrics

    NASA Astrophysics Data System (ADS)

    Savin, M. G.

    2016-03-01

    The problem of energy paradoxes revealed in geoelectrics are discussed. The experimental facts illustrating the anomalous energy characteristics of the magnetotelluric (MT) field are presented. An attempt is made to interpret these anomalies from the standpoint of directional analysis. Two three-layer models corresponding to the situation | Q| > 1 and widetilde {{S_z}} < 0 are found by the numerical modeling. The possibility of accounting for the observed paradoxes within the resonance model "heterogeneous plane wave—layered medium" is discussed.

  4. The core paradox.

    NASA Technical Reports Server (NTRS)

    Kennedy, G. C.; Higgins, G. H.

    1973-01-01

    Rebuttal of suggestions from various critics attempting to provide an escape from the seeming paradox originated by Higgins and Kennedy's (1971) proposed possibility that the liquid in the outer core was thermally stably stratified and that this stratification might prove a powerful inhibitor to circulation of the outer core fluid of the kind postulated for the generation of the earth's magnetic field. These suggestions are examined and shown to provide no reasonable escape from the core paradox.

  5. The quercetin paradox

    SciTech Connect

    Boots, Agnes W. . E-mail: a.boots@farmaco.unimaas.nl; Li, Hui; Schins, Roel P.F.; Duffin, Rodger; Heemskerk, Johan W.M.; Bast, Aalt; Haenen, Guido R.M.M.

    2007-07-01

    Free radical scavenging antioxidants, such as quercetin, are chemically converted into oxidation products when they protect against free radicals. The main oxidation product of quercetin, however, displays a high reactivity towards thiols, which can lead to the loss of protein function. The quercetin paradox is that in the process of offering protection, quercetin is converted into a potential toxic product. In the present study, this paradox is evaluated using rat lung epithelial (RLE) cells. It was found that quercetin efficiently protects against H{sub 2}O{sub 2}-induced DNA damage in RLE cells, but this damage is swapped for a reduction in GSH level, an increase in LDH leakage as well as an increase of the cytosolic free calcium concentration. To our knowledge, this is the first study that indicates that the quercetin paradox, i.e. the exchange of damage caused by quercetin and its metabolites, also occurs in living lung cells. Following depletion of GSH in the cells by BSO pre-treatment, this quercetin paradox becomes more pronounced, confirming that the formation of thiol reactive quercetin metabolites is involved in the quercetin paradox. The quercetin paradox in living cells implies that the anti-oxidant directs oxidative damage selectively to thiol arylation. Apparently, the potential toxicity of metabolites formed during the actual antioxidant activity of free radical scavengers should be considered in antioxidant supplementation.

  6. Paradoxical Manifestation is Common in HIV-negative Tuberculous Meningitis.

    PubMed

    Tai, Mei-Ling Sharon; Nor, Hazman Mohd; Kadir, Khairul Azmi Abdul; Viswanathan, Shanthi; Rahmat, Kartini; Zain, Norzaini Rose Mohd; Ong, Kuo Ghee; Rafia, Mohd Hanip; Tan, Chong Tin

    2016-01-01

    Paradoxical manifestation is worsening of pre-existing tuberculous lesion or appearance of new lesions in patients whose condition initially improved with antituberculous treatment. Our hypothesis was that paradoxical manifestation in non-HIV tuberculous meningitis (TBM) patients was underestimated and this could contribute to patients' prognosis. This was the first systemic study of paradoxical manifestation in HIV-negative TBM patients. Between 2009 and 2014, TBM patients were studied prospectively in 2 hospitals. Clinical features, cerebrospinal fluid, and radiological findings were monitored. Paradoxical manifestation was divided into definite (4 weeks or more) and probable (between 14 and 27 d) after commencement of antituberculous treatment. Forty-one non-HIV TBM patients were recruited. Definite paradoxical manifestation occurred in 23/41 (56%) of the patients. Time to onset of paradoxical manifestation was between 28 days and 9 months, and majority was between 28 and 50 days. Neuroimaging manifestation in the brain (22/41 patients, 54%) and clinical manifestation (22/41 patients, 54%) were most commonly seen, followed by cerebrospinal fluid manifestation (7/41 patients, 17%). Neuroimaging changes most commonly seen were worsening of leptomeningeal enhancement, new infarcts, new tuberculomas, and enlargement of tuberculoma. Initial Computed Tomography Angiography/magnetic resonance angiography brain showed vasculitis in 14 patients, with 2 (12.5%) showing paradoxical vasculitis during follow-up. Recurrence of the paradoxical manifestation was seen in 7/23 (30%) of the patients. More than half (14/23, 61%) of the patients improved, 6 (26%) patients died, and 3 (13%) patients had persistent neurological deficit. Paradoxical manifestation was very common in non-HIV TBM patients. Neuroimaging paradoxical manifestation of 2-4 weeks may not be paradoxical manifestation but could be delayed treatment response. PMID:26735523

  7. Paradoxical Manifestation is Common in HIV-negative Tuberculous Meningitis

    PubMed Central

    Tai, Mei-Ling Sharon; Nor, Hazman Mohd; Kadir, Khairul Azmi Abdul; Viswanathan, Shanthi; Rahmat, Kartini; Zain, Norzaini Rose Mohd; Ong, Kuo Ghee; Rafia, Mohd Hanip; Tan, Chong Tin

    2016-01-01

    Abstract Paradoxical manifestation is worsening of pre-existing tuberculous lesion or appearance of new lesions in patients whose condition initially improved with antituberculous treatment. Our hypothesis was that paradoxical manifestation in non-HIV tuberculous meningitis (TBM) patients was underestimated and this could contribute to patients’ prognosis. This was the first systemic study of paradoxical manifestation in HIV-negative TBM patients. Between 2009 and 2014, TBM patients were studied prospectively in 2 hospitals. Clinical features, cerebrospinal fluid, and radiological findings were monitored. Paradoxical manifestation was divided into definite (4 weeks or more) and probable (between 14 and 27 d) after commencement of antituberculous treatment. Forty-one non-HIV TBM patients were recruited. Definite paradoxical manifestation occurred in 23/41 (56%) of the patients. Time to onset of paradoxical manifestation was between 28 days and 9 months, and majority was between 28 and 50 days. Neuroimaging manifestation in the brain (22/41 patients, 54%) and clinical manifestation (22/41 patients, 54%) were most commonly seen, followed by cerebrospinal fluid manifestation (7/41 patients, 17%). Neuroimaging changes most commonly seen were worsening of leptomeningeal enhancement, new infarcts, new tuberculomas, and enlargement of tuberculoma. Initial Computed Tomography Angiography/magnetic resonance angiography brain showed vasculitis in 14 patients, with 2 (12.5%) showing paradoxical vasculitis during follow-up. Recurrence of the paradoxical manifestation was seen in 7/23 (30%) of the patients. More than half (14/23, 61%) of the patients improved, 6 (26%) patients died, and 3 (13%) patients had persistent neurological deficit. Paradoxical manifestation was very common in non-HIV TBM patients. Neuroimaging paradoxical manifestation of 2-4 weeks may not be paradoxical manifestation but could be delayed treatment response. PMID:26735523

  8. Some irreverent thoughts on paradox.

    PubMed

    Dell, P F

    1981-03-01

    There is currently great interest in the use of paradox in psychotherapy. Unfortunately, there is also considerable confusion and misunderstanding of paradox, owing, in part, to the lack of a comprehensive theory that explains the role of paradox in human problems. This paper does not address itself to such theory but explores some cultural and epistemological components of therapists' misperceptions and misattributions of "paradox." PMID:7215523

  9. Paradoxical Interventions in Counseling Psychology.

    ERIC Educational Resources Information Center

    Dowd, E. Thomas; Milne, Christopher R.

    1986-01-01

    Discusses the use of paradoxical interventions in counseling psychology and surveys the research literature to date. After a description of the historical background of paradoxical interventions, current schools of therapy using paradox are presented. Discusses theoretical and definitional underpinnings, with particular attention paid to the…

  10. Adventures in Paradox

    ERIC Educational Resources Information Center

    Lynch, Pip; Moore, Kevin

    2004-01-01

    The popularity of adventure recreation and adventure education has arisen, in part, from an assumption that adventure experiences are radically different from those of everyday life in modern societies. A paradox previously pointed out is that those seeking adventurous experiences often make use of technical and technological prosthetics, thus…

  11. The Hydrostatic Paradox.

    ERIC Educational Resources Information Center

    Wilson, Alpha E.

    1995-01-01

    Presents an example demonstrating the quantitative resolution of the hydrostatic paradox which is the realization that the force due to fluid pressure on the bottom of a vessel can be considerably greater or considerably less than the weight of the fluid in the vessel. (JRH)

  12. A Hydrostatic Paradox Revisited

    ERIC Educational Resources Information Center

    Ganci, Salvatore

    2012-01-01

    This paper revisits a well-known hydrostatic paradox, observed when turning upside down a glass partially filled with water and covered with a sheet of light material. The phenomenon is studied in its most general form by including the mass of the cover. A historical survey of this experiment shows that a common misunderstanding of the phenomenon…

  13. Behind the Mpemba paradox.

    PubMed

    Sun, Chang Qing

    2015-01-01

    Mpemba paradox results from hydrogen-bond anomalous relaxation. Heating stretches the O:H nonbond and shortens the H-O bond via Coulomb coupling; cooling reverses this process to emit heat at a rate depending on its initial storage. Skin ultra-low mass density raises the thermal diffusivity and favors outward heat flow from the liquid. PMID:27227000

  14. A Magnetic Paradox

    NASA Astrophysics Data System (ADS)

    Arndt, Ebe

    2006-11-01

    Two recent articles1,2 in this journal described how an air core solenoid connected to an ac power source may restore the magnetization of a bar magnet with an alternating magnetic field (see Figs. 1 and 2). Although we are quite accustomed to using a constant magnetic field in an air core solenoid to remagnetize a ferromagnet, it is puzzling that we can also use an alternating magnetic field to realign the magnetic domains of a ferromagnet. To make the puzzle even more intriguing, the very same setup may be used to degauss a TV screen; that is, the alternating magnetic field of an air core solenoid can also "scramble" the magnetic domains of a ferromagnet! Although the latter phenomenon intuitively makes more sense, we are still left with a confusing paradox: How can an alternating magnetic field align the magnetic domains in one ferromagnet and scramble the magnetic domains in another? Paradoxes like these are ideal for student investigations because they create a natural interest. In fact, since the two articles mentioned above were unable to explain the magnetic paradox, my students and I were intrigued enough to investigate the phenomenon and then try to understand it theoretically. This paper describes how we used the paradoxical phenomenon for a student investigation into nonlinear systems. In order to be successful, students should be familiar with calculus, preferably at the level of an advanced-placement class.

  15. Paramagnetism Paradoxes: Projectable Demonstrations

    ERIC Educational Resources Information Center

    Sauls, Frederick C.; Vitz, Ed

    2008-01-01

    Drops of oil in Mn(SO[subscript 4])(aq) and drops of the solution in oil show opposite effects when brought near a rare earth magnet. Oxygen, nitrogen, and air bubbles atop water show expected attraction, repulsion, and null behavior, respectively. Air bubbles atop aqueous Mn(SO[subscript 4]) show paradoxical behavior because the magnet's…

  16. The lanolin paradox.

    PubMed

    Wolf, R

    1996-01-01

    Several puzzling aspects of the use of lanolin are discussed as "lanolin paradoxes', in analogy with the 'paraben paradoxes'. Lanolin in topical therapeutic agents sensitizes a high proportion of patients, whereas the same lanolin is 'safe' in cosmetics so widely used by millions of individuals. Patients with an allergic contact dermatitis to lanolin in a medication applied to a stasis ulcer can nevertheless use lanolin-containing cosmetics and not experience a reaction. Lanolin-sensitive individuals often show false-negative patch test reactions to unaltered lanolin. Patch testing with 30% wool wax alcohols used in the standard patch test tray cannot be considered a reliable method for detecting and confirming lanolin allergies. There are too many false-positive and false-negative results using the standard patch test tray. PMID:8726630

  17. The Information Paradox

    NASA Astrophysics Data System (ADS)

    Amati, D.

    The incompatibility between gravity and quantum coherence represented by black holes should be solved by a consistent quantum theory that contains gravity as superstring theory. Despite many encouraging results in that sense, I question here the general feeling of a na"ive resolution of the paradox. And indicate non-trivial physical possibilities towards its solution that are suggested by string theory and may be further investigated in its context.

  18. The Bohr paradox

    NASA Astrophysics Data System (ADS)

    Crease, Robert P.

    2008-05-01

    In his book Niels Bohr's Times, the physicist Abraham Pais captures a paradox in his subject's legacy by quoting three conflicting assessments. Pais cites Max Born, of the first generation of quantum physics, and Werner Heisenberg, of the second, as saying that Bohr had a greater influence on physics and physicists than any other scientist. Yet Pais also reports a distinguished younger colleague asking with puzzlement and scepticism "What did Bohr really do?".

  19. Comment on the extinct paradox

    NASA Technical Reports Server (NTRS)

    Levine, D. M.

    1983-01-01

    The extinction paradox is a contradiction between geometrical optics results which predict that at high frequencies the scattering cross section of an object should equal its geometrical cross section and rigorous scattering theory which shows that at high frequencies the scattering cross section approaches twice the geometrical cross section of the object. Confusion about the reason for this paradox persists today even though the nature of the paradox was correctly identified many years ago by Brillouin. The resolution of the paradox is restated and illustrated with an example, and then the implications to the interpretation of scattering cross sections are identified.

  20. The paradox of Schrodinger's cat

    NASA Astrophysics Data System (ADS)

    Villars, C. N.

    1986-07-01

    Erwin Schrodinger first described the thought-experiment which has since become known as 'the paradox of Schrodinger's cat' 51 years ago. In recent years, popular accounts of quantum mechanics have tended to adopt one or other of the philosophically most extreme solutions to this paradox, i.e. the consciousness hypothesis or the many worlds interpretation. The author attempts to redress the balance by describing what he takes to be the orthodox solution to the paradox which explains the paradox, without recourse to such counterintuitive notions as a cat simultaneously dead and alive or a universe continually splitting into multiple worlds, as being due to a misapplication of the quantum formalism.

  1. Paradoxical Vocal Fold Movement (PVFM)

    MedlinePlus

    ... Careers Certification Publications Events Advocacy Continuing Education Practice Management Research Home / Information for the Public / Speech, Language and Swallowing / Disorders and Diseases Paradoxical Vocal Fold ...

  2. Zermelo, Boltzmann, and the recurrence paradox

    NASA Astrophysics Data System (ADS)

    Steckline, Vincent S.

    1983-10-01

    The papers exchanged by Ludwig Boltzmann and Ernst Zermelo concerning the recurrence paradox are summarized. The historical context of the paradox, Zermelo's proof of the paradox, his opinions of its consequences, Boltzmann's reply, and the ensuing discussion are described.

  3. The paradox of enrichment in phytoplankton by induced competitive interactions.

    PubMed

    Tubay, Jerrold M; Ito, Hiromu; Uehara, Takashi; Kakishima, Satoshi; Morita, Satoru; Togashi, Tatsuya; Tainaka, Kei-ichi; Niraula, Mohan P; Casareto, Beatriz E; Suzuki, Yoshimi; Yoshimura, Jin

    2013-01-01

    The biodiversity loss of phytoplankton with eutrophication has been reported in many aquatic ecosystems, e.g., water pollution and red tides. This phenomenon seems similar, but different from the paradox of enrichment via trophic interactions, e.g., predator-prey systems. We here propose the paradox of enrichment by induced competitive interactions using multiple contact process (a lattice Lotka-Volterra competition model). Simulation results demonstrate how eutrophication invokes more competitions in a competitive ecosystem resulting in the loss of phytoplankton diversity in ecological time. The paradox is enhanced under local interactions, indicating that the limited dispersal of phytoplankton reduces interspecific competition greatly. Thus, the paradox of enrichment appears when eutrophication destroys an ecosystem either by elevated interspecific competition within a trophic level and/or destabilization by trophic interactions. Unless eutrophication due to human activities is ceased, the world's aquatic ecosystems will be at risk. PMID:24089056

  4. The Easterlin paradox revisited.

    PubMed

    Frank, Robert H

    2012-12-01

    The traditional view that well-being depends on both absolute and relative income was challenged in a 1974 paper by Richard Easterlin (Does economic growth improve the human lot? In P. David and M. Reder (Eds.), Nations and households in economic growth: Essays in honor of Moses Abramovitz (pp. 89-125), New York: Academic Press). He noted that although individual well-being is strongly positively associated with income within any country at a given point in time, the average level of measured well-being for a country changes little over time, even in the face of substantial growth in average incomes. For decades, social scientists have struggled to explain this "Easterlin Paradox." In a 2008 paper, Betsey Stephenson and Justin Wolfers (Economic growth and subjective well-being: Reassessing the Easterlin Paradox, Brookings Papers on Economic Activity, Vol. 39, pp. 1-87) argued that the Easterlin Paradox was a statistical illusion. Using richer data sets that facilitate more precise estimates of the various links between income and well-being, they assert that average well-being in a country does, in fact, rise as average income rises over time, and that rich countries are happier than slightly poorer ones. They also suggest that the link between income and well-being may run through absolute income alone-that is, that individual well-being may be completely independent of relative income. In this article, I argue that there have always been good reasons to believe that well-being is positively linked to absolute income. I also argue, however, that there is no reason to believe that individual well-being is independent of relative income. PMID:23088778

  5. Confronting Twin Paradox Acceleration

    NASA Astrophysics Data System (ADS)

    Murphy, Thomas W.

    2016-05-01

    The resolution to the classic twin paradox in special relativity rests on the asymmetry of acceleration. Yet most students are not exposed to a satisfactory analysis of what exactly happens during the acceleration phase that results in the nonaccelerated observer's more rapid aging. The simple treatment presented here offers both graphical and quantitative solutions to the problem, leading to the correct result that the acceleration-induced age gap is 2Lβ years when the one-way distance L is expressed in light-years and velocity β ≡v/c .

  6. From Paradox to Reality

    NASA Astrophysics Data System (ADS)

    Rohrlich, Fritz

    1989-08-01

    Preface; Part I. At the Roof of the Endeavor: 1. Human limitations; 2. Theory and the role of mathematics; 3. Scientific objectivity; 4. The aim of scientific theory; Part II. The World of Relativity: 5. Space and time: from absolute to relative; 6. Imposed consistency: special relativity; 7. Gravitation as geometry: general relativity; 8. Revolutions without revolutions; Part III. The Quantum World: 9. The limits of the classical world; 10. Concepts of the quantum world; 11. From apparent paradox to a new reality; 12. The present state of the art; Epilogue; Notes; Glossary of technical terms; Name index; Subject index.

  7. The Floating Ball Paradox

    NASA Astrophysics Data System (ADS)

    Wente, Henry C.

    2008-11-01

    In capillary theory there are two kinds of surface tension. There is the surface tension at the interface between two immiscible fluids. Thomas Young [9] also allowed for there to be a surface tension associated with a liquid-solid interface. He proceeded to use a balance of forces argument to derive the well-known contact angle condition along a liquid-liquid-solid intersection. The validity of this argument has recently been called into question by R. Finn [6]. A floating ball experiment discussed in that paper leads to an apparent paradox. We address this issue.

  8. The Teacher's Paradox

    NASA Astrophysics Data System (ADS)

    Lilyquist, J. Gary

    1998-06-01

    New findings suggest that the way in which schools conduct their business is blocking our educational system from improving at a rate required to meet society's needs. A ground theory developed by exploring six organizational dimensions: external and internal environment cultures, leadership, strategy, structure, and results, verified the existence of the teacher's paradox. Implications suggest educational reformers must rethink approaches to school improvement by work within cultural boundaries. The forth coming book, "Are schools really like this?" presents "The Balance Alignment Model and Theory" to improve our schools using system thinking.

  9. The Paradox in Institutional Renewal.

    ERIC Educational Resources Information Center

    Cameron, Kim

    The renewal of institutions and maintenance of excellence in the uncertain future are discussed, based on research with 335 four-year universities and colleges. In examining the function of paradox in adaptation and renewal, it was found that individuals who can simultaneously focus on opposites, or paradoxes, are tolerant and flexible.…

  10. Mathematical background of Parrondo's paradox

    NASA Astrophysics Data System (ADS)

    Behrends, Ehrhard

    2004-05-01

    Parrondo's paradox states that there are losing gambling games which, when being combined stochastically or in a suitable deterministic way, give rise to winning games. Here we investigate the probabilistic background. We show how the properties of the equilibrium distributions of the Markov chains under consideration give rise to the paradoxical behavior, and we provide methods how to find the best a priori strategies.

  11. Barn and Pole Paradox: Revisited

    ERIC Educational Resources Information Center

    Cacioppo, Robert; Gangopadhyaya, Asim

    2012-01-01

    Paradoxes have played great instructive roles in many cultures. They provide an excellent paradigm for teaching concepts that require deep reflection. In this article, the authors present two different paradoxes related to the length contraction in special relativity and explain their resolution. They hope that these two Gedanken experiments and…

  12. The lunar apatite paradox.

    PubMed

    Boyce, J W; Tomlinson, S M; McCubbin, F M; Greenwood, J P; Treiman, A H

    2014-04-25

    Recent discoveries of water-rich lunar apatite are more consistent with the hydrous magmas of Earth than the otherwise volatile-depleted rocks of the Moon. Paradoxically, this requires H-rich minerals to form in rocks that are otherwise nearly anhydrous. We modeled existing data from the literature, finding that nominally anhydrous minerals do not sufficiently fractionate H from F and Cl to generate H-rich apatite. Hydrous apatites are explained as the products of apatite-induced low magmatic fluorine, which increases the H/F ratio in melt and apatite. Mare basalts may contain hydrogen-rich apatite, but lunar magmas were most likely poor in hydrogen, in agreement with the volatile depletion that is both observed in lunar rocks and required for canonical giant-impact models of the formation of the Moon. PMID:24652938

  13. Resveratrol: French Paradox Revisited

    PubMed Central

    Catalgol, Betul; Batirel, Saime; Taga, Yavuz; Ozer, Nesrin Kartal

    2012-01-01

    Resveratrol is a polyphenol that plays a potentially important role in many disorders and has been studied in different diseases. The research on this chemical started through the “French paradox,” which describes improved cardiovascular outcomes despite a high-fat diet in French people. Since then, resveratrol has been broadly studied and shown to have antioxidant, anti-inflammatory, anti-proliferative, and anti-angiogenic effects, with those on oxidative stress possibly being most important and underlying some of the others, but many signaling pathways are among the molecular targets of resveratrol. In concert they may be beneficial in many disorders, particularly in diseases where oxidative stress plays an important role. The main focus of this review will be the pathways affected by resveratrol. Based on these mechanistic considerations, the involvement of resveratrol especially in cardiovascular diseases, cancer, neurodegenerative diseases, and possibly in longevity will be is addressed. PMID:22822401

  14. Paradoxes of neutrino oscillations

    SciTech Connect

    Akhmedov, E. Kh.; Smirnov, A. Yu.

    2009-08-15

    Despite the theory of neutrino oscillations being rather old, some of its basic issues are still being debated in the literature. We discuss a number of such issues, including the relevance of the 'same energy' and 'same momentum' assumptions, the role of quantum-mechanical uncertainty relations in neutrino oscillations, the dependence of the coherence and localization conditions that ensure the observability of neutrino oscillations on neutrino energy and momentum uncertainties, the question of (in)dependence of the oscillation probabilities on the neutrino production and detection processes, and the applicability limits of the stationary-source approximation. We also develop a novel approach to calculation of the oscillation probability in the wave-packet approach, based on the summation/integration conventions different from the standard one, which allows a new insight into the 'same energy' vs. 'same momentum' problem. We also discuss a number of apparently paradoxical features of the theory of neutrino oscillations.

  15. Reconsideration of the Paradox of Inquiry

    ERIC Educational Resources Information Center

    Sato, Kunimasa

    2014-01-01

    It is well known that the Meno presents the argument called "the paradox of inquiry." This paper has two purposes. First, I analyze the paradox of inquiry and reformulate the argument as the "renewed paradox of inquiry." Second, I clarify that the problem of inquiry posed by this paradox concerns the necessary conditions for a…

  16. Enhancing Visitors' Interest in Science--A Possibility or a Paradox? A Study of What Scientific Content Staff Members Focus on when Planning a New Exhibition

    ERIC Educational Resources Information Center

    Davidsson, Eva

    2009-01-01

    Within the enterprise of science and technology centres there exists explicit aims and ambitions to enhance visitors' interest in and knowledge about science. Meanwhile, several researchers question the choice of the scientific content in exhibitions when arguing that a too unproblematic view of science commonly is presented. But how do staff…

  17. Unveiling the Mobile Learning Paradox.

    PubMed

    Mather, Carey; Cummings, Elizabeth

    2015-01-01

    A mobile learning paradox exists in Australian healthcare settings. Although it is increasingly acknowledged that timely, easy, and convenient access to health information using mobile learning technologies can enhance care and improve patient outcomes, currently there is an inability for nurses to access information at the point of care. Rapid growth in the use of mobile technology has created challenges for learning and teaching in the workplace. Easy access to educational resources via mobile devices challenges traditional strategies of knowledge and skill acquisition. Redesign of learning and teaching in the undergraduate curriculum and the development of policies to support the use of mobile learning at point of care is overdue. This study explored mobile learning opportunities used by clinical supervisors in tertiary and community-based facilities in two Australian States. Individual, organisation and systems level governance were sub-themes of professionalism that emerged as the main theme and impacts on learning and teaching in situ in healthcare environments. It is imperative healthcare work redesign includes learning and teaching that supports professional identity formation of students during work integrated learning. PMID:26262539

  18. Paradoxical activation of MEK/ERK signaling induced by B-Raf inhibition enhances DR5 expression and DR5 activation-induced apoptosis in Ras-mutant cancer cells

    PubMed Central

    Oh, You-Take; Deng, Jiusheng; Yue, Ping; Sun, Shi-Yong

    2016-01-01

    B-Raf inhibitors have been used for the treatment of some B-Raf–mutated cancers. They effectively inhibit B-Raf/MEK/ERK signaling in cancers harboring mutant B-Raf, but paradoxically activates MEK/ERK in Ras-mutated cancers. Death receptor 5 (DR5), a cell surface pro-apoptotic protein, triggers apoptosis upon ligation with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) or aggregation. This study focused on determining the effects of B-Raf inhibition on DR5 expression and DR5 activation-induced apoptosis in Ras-mutant cancer cells. Using chemical and genetic approaches, we have demonstrated that the B-Raf inhibitor PLX4032 induces DR5 upregulation exclusively in Ras-mutant cancer cells; this effect is dependent on Ras/c-Raf/MEK/ERK signaling activation. PLX4032 induces DR5 expression at transcriptional levels, largely due to enhancing CHOP/Elk1-mediated DR5 transcription. Pre-exposure of Ras-mutated cancer cells to PLX4032 sensitizes them to TRAIL-induced apoptosis; this is also a c-Raf/MEK/ERK-dependent event. Collectively, our findings highlight a previously undiscovered effect of B-Raf inhibition on the induction of DR5 expression and the enhancement of DR5 activation-induced apoptosis in Ras-mutant cancer cells and hence may suggest a novel therapeutic strategy against Ras-mutated cancer cells by driving their death due to DR5-dependent apoptosis through B-Raf inhibition. PMID:27222248

  19. Paradoxical activation of MEK/ERK signaling induced by B-Raf inhibition enhances DR5 expression and DR5 activation-induced apoptosis in Ras-mutant cancer cells.

    PubMed

    Oh, You-Take; Deng, Jiusheng; Yue, Ping; Sun, Shi-Yong

    2016-01-01

    B-Raf inhibitors have been used for the treatment of some B-Raf-mutated cancers. They effectively inhibit B-Raf/MEK/ERK signaling in cancers harboring mutant B-Raf, but paradoxically activates MEK/ERK in Ras-mutated cancers. Death receptor 5 (DR5), a cell surface pro-apoptotic protein, triggers apoptosis upon ligation with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) or aggregation. This study focused on determining the effects of B-Raf inhibition on DR5 expression and DR5 activation-induced apoptosis in Ras-mutant cancer cells. Using chemical and genetic approaches, we have demonstrated that the B-Raf inhibitor PLX4032 induces DR5 upregulation exclusively in Ras-mutant cancer cells; this effect is dependent on Ras/c-Raf/MEK/ERK signaling activation. PLX4032 induces DR5 expression at transcriptional levels, largely due to enhancing CHOP/Elk1-mediated DR5 transcription. Pre-exposure of Ras-mutated cancer cells to PLX4032 sensitizes them to TRAIL-induced apoptosis; this is also a c-Raf/MEK/ERK-dependent event. Collectively, our findings highlight a previously undiscovered effect of B-Raf inhibition on the induction of DR5 expression and the enhancement of DR5 activation-induced apoptosis in Ras-mutant cancer cells and hence may suggest a novel therapeutic strategy against Ras-mutated cancer cells by driving their death due to DR5-dependent apoptosis through B-Raf inhibition. PMID:27222248

  20. The Statistical Fermi Paradox

    NASA Astrophysics Data System (ADS)

    Maccone, C.

    In this paper is provided the statistical generalization of the Fermi paradox. The statistics of habitable planets may be based on a set of ten (and possibly more) astrobiological requirements first pointed out by Stephen H. Dole in his book Habitable planets for man (1964). The statistical generalization of the original and by now too simplistic Dole equation is provided by replacing a product of ten positive numbers by the product of ten positive random variables. This is denoted the SEH, an acronym standing for “Statistical Equation for Habitables”. The proof in this paper is based on the Central Limit Theorem (CLT) of Statistics, stating that the sum of any number of independent random variables, each of which may be ARBITRARILY distributed, approaches a Gaussian (i.e. normal) random variable (Lyapunov form of the CLT). It is then shown that: 1. The new random variable NHab, yielding the number of habitables (i.e. habitable planets) in the Galaxy, follows the log- normal distribution. By construction, the mean value of this log-normal distribution is the total number of habitable planets as given by the statistical Dole equation. 2. The ten (or more) astrobiological factors are now positive random variables. The probability distribution of each random variable may be arbitrary. The CLT in the so-called Lyapunov or Lindeberg forms (that both do not assume the factors to be identically distributed) allows for that. In other words, the CLT "translates" into the SEH by allowing an arbitrary probability distribution for each factor. This is both astrobiologically realistic and useful for any further investigations. 3. By applying the SEH it is shown that the (average) distance between any two nearby habitable planets in the Galaxy may be shown to be inversely proportional to the cubic root of NHab. This distance is denoted by new random variable D. The relevant probability density function is derived, which was named the "Maccone distribution" by Paul Davies in

  1. Enhancing Visitors' Interest in Science - A Possibility or A Paradox?. A Study of What Scientific Content Staff Members Focus on When Planning a New Exhibition

    NASA Astrophysics Data System (ADS)

    Davidsson, Eva

    2009-03-01

    Within the enterprise of science and technology centres there exists explicit aims and ambitions to enhance visitors’ interest in and knowledge about science. Meanwhile, several researchers question the choice of the scientific content in exhibitions when arguing that a too unproblematic view of science commonly is presented. But how do staff members consider what scientific content to include and how this content can be organised in exhibitions? The results from interviews of staff members, responsible for planning and creating new exhibitions, suggest that they consider the scientific content of their exhibitions to a high extent in terms of organizational matters. This means that the staff members tend to not consider discussions about what aspects of science to include or exclude. Further on, the results imply that the relation between science and society risk being implicit to the visitors, whereas the aspect of scientific processes tend to be overlooked when constructing new exhibitions. The staff members express an anxiety in displaying scientific uncertainties or different models of explanations when arguing that this risks confusing the visitors. However, these aspects of science are, in the field of science education, considered crucial in order to create curiosity and interest in science. Does this mean that science and technology centres, through their eagerness to enhance young visitors’ scientific literacy, risk contributing to their detachment from or unconcern for scientific issues?

  2. The Bicyclist's Paradox

    NASA Astrophysics Data System (ADS)

    Knight, Randy

    2008-05-01

    It's a situation every avid cyclist knows only too well. If you cycle up a hill and then back down with no net change in elevation, it seems as if your slower uphill speed and faster downhill speed should offset each other. But they don't. Your average speed is less than it would have been had you cycled the same distance on a level road. Similarly, cycling into a headwind for half your trip and returning home with a tailwind yields an average speed less than you would have achieved on a windless day. The faster part of the ride doesn't compensate for the slower part. It seems unjust. Most cyclists expect the uphill and downhill, or the headwind and tailwind, to more or less cancel and are surprised (and frustrated!) when they don't. The purpose of this paper is to resolve this paradox. Doing so involves some nice real-world applications of Newton's laws, numerical problem solving, and exercise physiology. There's a lot to learn from analyzing this problem, and it's readily accessible to introductory physics students.

  3. A relativistic trolley paradox

    NASA Astrophysics Data System (ADS)

    Matvejev, Vadim N.; Matvejev, Oleg V.; Grøn, Ø.

    2016-06-01

    We present an apparent paradox within the special theory of relativity, involving a trolley with relativistic velocity and its rolling wheels. Two solutions are given, both making clear the physical reality of the Lorentz contraction, and that the distance on the rails between each time a specific point on the rim touches the rail is not equal to 2 π R , where R is the radius of the wheel, but 2 π R / √{ 1 - R 2 Ω 2 / c 2 } , where Ω is the angular velocity of the wheels. In one solution, the wheel radius is constant as the velocity of the trolley increases, and in the other the wheels contract in the radial direction. We also explain two surprising facts. First that the shape of a rolling wheel is elliptical in spite of the fact that the upper part of the wheel moves faster than the lower part, and thus is more Lorentz contracted, and second that a Lorentz contracted wheel with relativistic velocity rolls out a larger distance between two successive touches of a point of the wheel on the rails than the length of a circle with the same radius as the wheels.

  4. THE PARADOX OF THE PLANKTON: COMMUNITY STRUCTURE PROMOTES BLOOMS

    EPA Science Inventory

    ABSTRACT: The 'paradox of the plankton' refers to commensalism as well as symbiosis, predation, and impacts of non equilibrium conditions between two planktonic

    competitors. In regards to commensalism, phytoplankton can release organic carbon that enhances growth of its ba...

  5. The fermi paradox is neither Fermi's nor a paradox.

    PubMed

    Gray, Robert H

    2015-03-01

    The so-called Fermi paradox claims that if technological life existed anywhere else, we would see evidence of its visits to Earth--and since we do not, such life does not exist, or some special explanation is needed. Enrico Fermi, however, never published anything on this topic. On the one occasion he is known to have mentioned it, he asked "Where is everybody?"--apparently suggesting that we do not see extraterrestrials on Earth because interstellar travel may not be feasible, but not suggesting that intelligent extraterrestrial life does not exist or suggesting its absence is paradoxical. The claim "they are not here; therefore they do not exist" was first published by Michael Hart, claiming that interstellar travel and colonization of the Galaxy would be inevitable if intelligent extraterrestrial life existed, and taking its absence here as proof that it does not exist anywhere. The Fermi paradox appears to originate in Hart's argument, not Fermi's question. Clarifying the origin of these ideas is important, because the Fermi paradox is seen by some as an authoritative objection to searching for evidence of extraterrestrial intelligence--cited in the U.S. Congress as a reason for killing NASA's SETI program on one occasion. But evidence indicates that it misrepresents Fermi's views, misappropriates his authority, deprives the actual authors of credit, and is not a valid paradox. PMID:25719510

  6. Is "healthy dying" a paradox? revisiting an early Kastenbaum challenge.

    PubMed

    Kellehear, Allan

    This article is a review of Robert Kastenbaum's 1979 essay entitled "Healthy dying: A paradoxical quest continues." It begins with a summary of the arguments and challenges in the original essay. This is followed by an evaluation of his original claims in the light of contemporary insights in modern public health history and empirical studies of near-death experiences and death bed visions. The recent development of health promotion in palliative care is described in relation to these developments and Kastenbaum's early question about the paradoxical quest for health while dying is again posed against this background. Given our modern understanding of "health" in current global health policy and debates, it is argued that "healthy dying" is no paradox. Instead, the pursuit of health at the end of life represents a realistic modern desire to compress morbidity, minimize unnecessary suffering, and enhance quality of life at this time. PMID:25351589

  7. A general circulation model study of the effects of faster rotation rate, enhanced CO2 concentration, and reduced solar forcing: Implications for the faint young sun paradox

    NASA Technical Reports Server (NTRS)

    Jenkins, Gregory S.

    1993-01-01

    Solar energy at the top of the atmosphere (solar constant), rotation rate, and carbon dioxide (CO2) may have varied significantly over Earth's history, especially during the earliest times. The sensitivity of a general circulation model to faster rotation, enhanced CO2 concentration, and reduced solar constant is presented. The control simulation of this study has a solar constant reduced by 10% the present amount, zero land fraction using a swamp ocean surface, CO2 concentrations of 330 ppmv, present-day rotation rate, and is integrated under mean diurnal and seasonal solar forcing. Four sensitivity test are performed under zero land fraction and reduced solar constant conditions by varying the earth's rotation rate atmospheric CO2 concentration and solar constant. The global mean sea surface temperatures (SSTs) compared to the control simulation: were 6.6 K to 12 K higher than the control's global mean temperature of 264.7 K. Sea ice is confined to higher latitudes in each experiment compared to the control, with ice-free areas equatorward of the subtropics. The warm SSTs are associated with a 20% reduction in clouds for the rotation rate experiments and higher CO2 concentrations in the other experiments. These results are in contrast to previous studies that have used energy balance and radiative convective models. Previous studies required a much larger atmospheric CO2 increase to prevent an ice-covered Earth. The results of the study, suggest that because of its possible feedback with clouds, the general circulation of the atmosphere should be taken into account in understanding the climate of early Earth. While higher CO2 concentrations are likely in view of the results, very large atmospheric CO2 concentrations may not be necessary to counterbalance the lower solar constant that existed early in Earth's history.

  8. The helium paradoxes.

    PubMed

    Anderson, D L

    1998-04-28

    The ratio 3He/4He (R) plays a central role in models of mantle evolution that propose an undegassed lower mantle, rich in the primordial isotope 3He. A large primordial volatile-rich reservoir, a feature of recent models, is inconsistent with high-temperature accretion and with estimates of crustal and bulk Earth chemistry. High R can alternatively reflect high integrated 3He/(U+Th) ratios or low 4He abundances, as expected in refractory portions of the upper mantle. I show that high R materials are gas-poor and are deficient in radiogenic 4He compared with midocean ridge basalts. The seemingly primitive (i.e., high R) signatures in "hotspot" magmas may be secondary, derived from CO2-rich gases, or residual peridotite, a result of differential partitioning of U and He into magmas. A shallow and low 3He source explains the spatial variability and the temporal trends of R in ocean islands and is consistent with a volatile-poor planet. A shallow origin for the "primitive" He signature in ocean island basalts, such as at Loihi, reconciles the paradoxical juxtaposition of crustal, seawater, and atmospheric signatures with inferred "primitive" characteristics. High 238U/204Pb components in ocean island basalts are generally attributed to recycled altered oceanic crust. The low 238U/3He component may be in the associated depleted refractory mantle. High 3He/4He ratios are due to low 4He, not excess 3He, and do not imply or require a deep or primordial or undegassed reservoir. 40Ar in the atmosphere also argues against such models. PMID:9560186

  9. The helium paradoxes

    PubMed Central

    Anderson, Don L.

    1998-01-01

    The ratio 3He/4He (R) plays a central role in models of mantle evolution that propose an undegassed lower mantle, rich in the primordial isotope 3He. A large primordial volatile-rich reservoir, a feature of recent models, is inconsistent with high-temperature accretion and with estimates of crustal and bulk Earth chemistry. High R can alternatively reflect high integrated 3He/(U+Th) ratios or low 4He abundances, as expected in refractory portions of the upper mantle. I show that high R materials are gas-poor and are deficient in radiogenic 4He compared with midocean ridge basalts. The seemingly primitive (i.e., high R) signatures in “hotspot” magmas may be secondary, derived from CO2-rich gases, or residual peridotite, a result of differential partitioning of U and He into magmas. A shallow and low 3He source explains the spatial variability and the temporal trends of R in ocean islands and is consistent with a volatile-poor planet. A shallow origin for the “primitive” He signature in ocean island basalts, such as at Loihi, reconciles the paradoxical juxtaposition of crustal, seawater, and atmospheric signatures with inferred “primitive” characteristics. High 238U/204Pb components in ocean island basalts are generally attributed to recycled altered oceanic crust. The low 238U/3He component may be in the associated depleted refractory mantle. High 3He/4He ratios are due to low 4He, not excess 3He, and do not imply or require a deep or primordial or undegassed reservoir. 40Ar in the atmosphere also argues against such models. PMID:9560186

  10. Biochemical pharmacology of paradoxical sleep

    PubMed Central

    Gaillard, J. -M.

    1983-01-01

    1 The role of noradrenergic cells in the regulation of paradoxical sleep is still controversial, and experimental data have given rise to contradictory interpretations. 2 Early investigations focused primarily on chemical neurotransmissions. However, the process of information transmission between cells involves many other factors, and the cell surface is an important site for transduction of messages into modifications of the activity of postsynaptic cells. 3 α-adrenoceptors are believed to play an important role in the control of wakefulness and paradoxical sleep. Experimental evidence suggests that physiological modulation of receptor sensitivity, possibly by specific neuro-modulators, may be a key mechanism in synaptic transmission. 4 In the investigation of the mechanisms involved in paradoxical sleep regulation, lesions of the locus coeruleus have given equivocal results. Collateral inhibition, probably mediated by α2-adrenoceptors, appears to be a powerful mechanism. The exact temporal relationship between noradrenergic cell activation and paradoxical sleep production is not established, but 5-HT appears to be involved. Differences between paradoxical sleep and waking may be related to a physiological modulation of α2-adrenoceptor sensitivity. PMID:6140943

  11. The Experiential Paradoxes of Pain.

    PubMed

    Leder, Drew

    2016-10-01

    Pain is far more than an aversive sensation. Chronic pain, in particular, involves the sufferer in a complex experience filled with ambiguity and paradox. The tensions thereby established, the unknowns, pressures, and oscillations, form a significant part of the painfulness of pain. This paper uses a phenomenological method to examine nine such paradoxes. For example, pain can be both immediate sensation and mediated by complex interpretations. It is a certainty for the experiencer, yet highly uncertain in character. It pulls one to the present but also projects one outward to a feared or desired future. Chronic pain can seem located in the body and/or mind; interior to the self, or an alien other; confined to a particular point and/or radiating everywhere. Such fundamental paradoxes, existential and epistemological, can challenge those living with long-term pain. PMID:27476188

  12. An Acid Hydrocarbon: A Chemical Paradox

    ERIC Educational Resources Information Center

    Burke, Jeffrey T.

    2004-01-01

    The chemical paradox of cyclopentadiene, a hydrocarbon, producing bubbles like a Bronsted acid is observed. The explanation that it is the comparative thermodynamic constancy of the fragrant cyclopentadienyl anion, which produces the powerful effect, resolves the paradox.

  13. Paradoxical effects of antioxidants on cancer.

    PubMed

    Mendelsohn, Andrew R; Larrick, James W

    2014-06-01

    Antioxidants have had a checkered history concerning their reported ability to prevent or treat cancer. Early studies that showed ascorbate had benefit in cancer were followed by more definitive studies that demonstrated no benefit. Recent work suggests that biological context may be key to predicting whether antioxidants impede or even promote tumorigenesis. In a recent report, the antioxidants N-acetylcysteine and vitamin E accelerated tumorigenesis of lung cancer in mice. antioxidants decrease reactive oxygen species (ROS) levels, which paradoxically increase the proliferation rate of lung cancer cells, resulting in greater tumor burdens and reduced survival. Increased proliferation rates result from decreased expression of the genomic watchdog protein p53. In mice lacking p53, neither anti-oxidant affects tumor growth. But antioxidants can be used to kill cancer, at least in rodents. High concentrations of the "antioxidant" ascorbate, achievable only by injection in vivo, result in the production of ascorbate radicals and hydrogen peroxide in the extracellular fluid that kills cancer cells, but not normal cells. In preliminary human trials, ascorbate reduced the toxicity of chemotherapy, but showed no statistical benefit on disease progression. Vitamin C is beneficial when it acts as an oxidant. These studies are consistent with others that suggest that even tumor suppressor genes, such as Nrf2, which stimulate innate cellular stress protection pathways that reduce ROS, can promote cancer progression. Nrf2 is required for the cancer preventive effects of compounds such as sulforaphane, but Nrf2 can help maintain an aggressive tumor phenotype by stimulating proliferation and offering protection from chemotherapy. Context determines whether a specific gene is a tumor enhancer or a suppressor. Such paradoxical behavior creates difficult problems for the development of conventional therapeutics to fight cancer. Personal genomic analysis may provide the means to

  14. The boundary paradox in the Bithorax complex.

    PubMed

    Kyrchanova, Olga; Mogila, Vladic; Wolle, Daniel; Magbanua, Jose Paolo; White, Robert; Georgiev, Pavel; Schedl, Paul

    2015-11-01

    The parasegment-specific expression of the three Drosophila Bithorax complex homeotic genes is orchestrated by nine functionally autonomous regulatory domains. Functional autonomy depends upon special elements called boundaries or insulators that are located between each domain. The boundaries ensure the independent activity of each domain by blocking adventitious interactions with initiators, enhancers and silencers in the neighboring domains. However, this blocking activity poses a regulatory paradox--the Bithorax boundaries are also able to insulate promoters from regulatory interactions with enhancers and silencers and six of the nine Bithorax regulatory domains are separated from their target genes by at least one boundary element. Here we consider several mechanisms that have been suggested for how the Bithorax regulatory domains are able to bypass intervening boundary elements and direct the appropriate parasegment-specific temporal and spatial expression of their target gene. PMID:26215349

  15. Mechanical Paradox: The Uphill Roller

    ERIC Educational Resources Information Center

    Cortes, Emilio; Cortes-Poza, D.

    2011-01-01

    We analyse in detail the dynamics of a mechanical system which is a rigid body with the geometry of a double cone. This double cone is apparently able to spontaneously roll uphill along inclined rails. The experiment has been known for some centuries, and because of its peculiar behaviour, it has been named "mechanical paradox". Although this…

  16. The Paradox of Painful Art

    ERIC Educational Resources Information Center

    Smuts, Aaron

    2007-01-01

    Many of the most popular genres of narrative art are designed to elicit negative emotions: emotions that are experienced as painful or involving some degree of pain, which people generally avoid in their daily lives. Traditionally, the question of why people seek out such experiences of painful art has been presented as the paradox of tragedy, and…

  17. Teaching Quantum Physics without Paradoxes

    ERIC Educational Resources Information Center

    Hobson, Art

    2007-01-01

    Although the resolution to the wave-particle paradox has been known for 80 years, it is seldom presented. Briefly, the resolution is that material particles and photons are the quanta of extended spatially continuous but energetically quantized fields. But because the resolution resides in quantum field theory and is not usually spelled out in…

  18. Gene networks and liar paradoxes

    PubMed Central

    Isalan, Mark

    2009-01-01

    Network motifs are small patterns of connections, found over-represented in gene regulatory networks. An example is the negative feedback loop (e.g. factor A represses itself). This opposes its own state so that when ‘on’ it tends towards ‘off’ – and vice versa. Here, we argue that such self-opposition, if considered dimensionlessly, is analogous to the liar paradox: ‘This statement is false’. When ‘true’ it implies ‘false’ – and vice versa. Such logical constructs have provided philosophical consternation for over 2000 years. Extending the analogy, other network topologies give strikingly varying outputs over different dimensions. For example, the motif ‘A activates B and A. B inhibits A’ can give switches or oscillators with time only, or can lead to Turing-type patterns with both space and time (spots, stripes or waves). It is argued here that the dimensionless form reduces to a variant of ‘The following statement is true. The preceding statement is false’. Thus, merely having a static topological description of a gene network can lead to a liar paradox. Network diagrams are only snapshots of dynamic biological processes and apparent paradoxes can reveal important biological mechanisms that are far from paradoxical when considered explicitly in time and space. PMID:19722183

  19. CCC and the Fermi paradox

    NASA Astrophysics Data System (ADS)

    Gurzadyan, V. G.; Penrose, R.

    2016-01-01

    Within the scheme of conformal cyclic cosmology (CCC), information can be transmitted from aeon to aeon. Accordingly, the "Fermi paradox" and the SETI programme --of communication by remote civilizations-- may be examined from a novel perspective: such information could, in principle, be encoded in the cosmic microwave background. The current empirical status of CCC is also discussed.

  20. Gene networks and liar paradoxes.

    PubMed

    Isalan, Mark

    2009-10-01

    Network motifs are small patterns of connections, found over-represented in gene regulatory networks. An example is the negative feedback loop (e.g. factor A represses itself). This opposes its own state so that when 'on' it tends towards 'off' - and vice versa. Here, we argue that such self-opposition, if considered dimensionlessly, is analogous to the liar paradox: 'This statement is false'. When 'true' it implies 'false' - and vice versa. Such logical constructs have provided philosophical consternation for over 2000 years. Extending the analogy, other network topologies give strikingly varying outputs over different dimensions. For example, the motif 'A activates B and A. B inhibits A' can give switches or oscillators with time only, or can lead to Turing-type patterns with both space and time (spots, stripes or waves). It is argued here that the dimensionless form reduces to a variant of 'The following statement is true. The preceding statement is false'. Thus, merely having a static topological description of a gene network can lead to a liar paradox. Network diagrams are only snapshots of dynamic biological processes and apparent paradoxes can reveal important biological mechanisms that are far from paradoxical when considered explicitly in time and space. PMID:19722183

  1. Paradoxical Results and Item Bundles

    ERIC Educational Resources Information Center

    Hooker, Giles; Finkelman, Matthew

    2010-01-01

    Hooker, Finkelman, and Schwartzman ("Psychometrika," 2009, in press) defined a paradoxical result as the attainment of a higher test score by changing answers from correct to incorrect and demonstrated that such results are unavoidable for maximum likelihood estimates in multidimensional item response theory. The potential for these results to…

  2. Cell size and cancer: a new solution to Peto's paradox?

    PubMed Central

    Maciak, Sebastian; Michalak, Pawel

    2015-01-01

    Cancer, one of the leading health concerns for humans, is by no means a human-unique malady. Accumulating evidence shows that cancer kills domestic and wild animals at a similar rate to humans and can even pose a conservation threat to certain species. Assuming that each physiologically active and proliferating cell is at risk of malignant transformation, any evolutionary increase in the number of cells (and thus body mass) will lead to a higher cancer frequency, all else being equal. However, available data fail to support the prediction that bigger animals are affected by cancer more than smaller ones. The unexpected lack of correlation between body size (and life span) and cancer risk across taxa was dubbed Peto's paradox. In this perspective, several plausible explanations of Peto's paradox are presented, with the emphasis on a largely underappreciated relation of cell size to both metabolism and cell division rates across species, which we believe are key factors underlying the paradox. We conclude that larger organisms have bigger and slowly dividing cells with lower energy turnover, all significantly reducing the risk of cancer initiation. Solving Peto's paradox will enhance our understanding the evolution of cancer and may provide new implications for cancer prevention and treatment. PMID:25667599

  3. Mechanical paradox: the uphill roller

    NASA Astrophysics Data System (ADS)

    Cortés, Emilio; Cortés-Poza, D.

    2011-11-01

    We analyse in detail the dynamics of a mechanical system which is a rigid body with the geometry of a double cone. This double cone is apparently able to spontaneously roll uphill along inclined rails. The experiment has been known for some centuries, and because of its peculiar behaviour, it has been named 'mechanical paradox'. Although this instrument is well known today, we have not found in the literature a dynamical study like the one we are presenting. A deeper analysis of this mechanical object will allow us to go further than explaining the apparent paradox in the system; it will show interesting features of the dynamics that are not evident or intuitive. In this work, we follow a complete study of the geometry, the kinematic variables and the Lagrangian dynamics of the problem for any set of the angular parameters and initial values, and obtain as a result a full description of the dynamic variables of this mechanical device. In addition to studying the dynamics of the system with the angles that yield the typical paradoxical behaviour, we study carefully what we call the constant potential geometry regime, where the centre of mass maintains its height, and found in this particular case some features of the dynamics which are not common in rolling objects. We believe that this work can offer the student good material to review some fundamental concepts of analytical mechanics.

  4. The paradoxes ofMTBE.

    PubMed

    Davis, J M; Farland, W H

    2001-06-01

    A widely used gasoline additive, methyl tertiary butyl ether (MTBE), has been controversial, in part because of concerns about potential inhalation health effects and more recently because of added concerns about water contamination. Although many of the issues related to MTBE have not been fully resolved, several apparent paradoxes can be discerned, including the fact that something intended to improve air quality is now seen as a threat to water quality. Among the lessons that can be derived from the MTBE experience is the value of a comprehensive understanding of the potential risk-benefit tradeoffs of different fuels and fuel additives. PMID:11353129

  5. The MedDRA paradox.

    PubMed

    Merrill, Gary H

    2008-01-01

    MedDRA (the Medical Dictionary for Regulatory Activities Terminology) is a controlled vocabulary widely used as a medical coding scheme. However, MedDRA's characterization of its structural hierarchy exhibits some confusing and paradoxical features. The goal of this paper is to examine these features, determine whether there is a coherent view of the MedDRA hierarchy that emerges, and explore what lessons are to be learned from this for using MedDRA and similar terminologies in a broad medical informatics context that includes relations among multiple disparate terminologies, thesauri, and ontologies. PMID:18998828

  6. Paradoxic vocal fold movement disorder.

    PubMed

    Matrka, Laura

    2014-02-01

    Paradoxical Vocal Fold Movement Disorder (PVFMD) is a cause of dyspnea that can mimic or occur alongside asthma or other pulmonary disease. Treatment with Laryngeal Control Therapy is very effective once the entity is properly diagnosed and contributing comorbidities are managed appropriately. In understanding the etiology of PVFMD, focus has broadened beyond psychiatric factors alone to include the spectrum of laryngeal irritants (laryngopharyngeal reflux, allergic and sinus disease, sicca, and possibly obstructive sleep apnea). The following is a discussion of the history, terminology, epidemiology, diagnosis, comorbid conditions, and treatment of this entity. PMID:24286687

  7. Bioterrorism and the Fermi Paradox

    NASA Astrophysics Data System (ADS)

    Cooper, Joshua

    2013-04-01

    We proffer a contemporary solution to the so-called Fermi Paradox, which is concerned with conflict between Copernicanism and the apparent paucity of evidence for intelligent alien civilizations. In particular, we argue that every community of organisms that reaches its space-faring age will (1) almost immediately use its rocket-building computers to reverse-engineer its genetic chemistry and (2) self-destruct when some individual uses said technology to design an omnicidal pathogen. We discuss some of the possible approaches to prevention with regard to Homo sapiens' vulnerability to bioterrorism, particularly on a short-term basis.

  8. How river rocks round: resolving the shape-size paradox.

    PubMed

    Domokos, Gabor; Jerolmack, Douglas J; Sipos, Andras Á; Török, Akos

    2014-01-01

    River-bed sediments display two universal downstream trends: fining, in which particle size decreases; and rounding, where pebble shapes evolve toward ellipsoids. Rounding is known to result from transport-induced abrasion; however many researchers argue that the contribution of abrasion to downstream fining is negligible. This presents a paradox: downstream shape change indicates substantial abrasion, while size change apparently rules it out. Here we use laboratory experiments and numerical modeling to show quantitatively that pebble abrasion is a curvature-driven flow problem. As a consequence, abrasion occurs in two well-separated phases: first, pebble edges rapidly round without any change in axis dimensions until the shape becomes entirely convex; and second, axis dimensions are then slowly reduced while the particle remains convex. Explicit study of pebble shape evolution helps resolve the shape-size paradox by reconciling discrepancies between laboratory and field studies, and enhances our ability to decipher the transport history of a river rock. PMID:24533132

  9. How River Rocks Round: Resolving the Shape-Size Paradox

    PubMed Central

    Domokos, Gabor; Jerolmack, Douglas J.; Sipos, Andras Á.; Török, Ákos

    2014-01-01

    River-bed sediments display two universal downstream trends: fining, in which particle size decreases; and rounding, where pebble shapes evolve toward ellipsoids. Rounding is known to result from transport-induced abrasion; however many researchers argue that the contribution of abrasion to downstream fining is negligible. This presents a paradox: downstream shape change indicates substantial abrasion, while size change apparently rules it out. Here we use laboratory experiments and numerical modeling to show quantitatively that pebble abrasion is a curvature-driven flow problem. As a consequence, abrasion occurs in two well-separated phases: first, pebble edges rapidly round without any change in axis dimensions until the shape becomes entirely convex; and second, axis dimensions are then slowly reduced while the particle remains convex. Explicit study of pebble shape evolution helps resolve the shape-size paradox by reconciling discrepancies between laboratory and field studies, and enhances our ability to decipher the transport history of a river rock. PMID:24533132

  10. Increased Oil Production and Reserves Utilizing Secondary/Terriary Recovery Techniques on Small Reservoirs in the Paradox Basin, Utah

    SciTech Connect

    David E. Eby; Thomas C. Chidsey, Jr.

    1998-04-08

    The primary objective of this project is to enhance domestic petroleum production by demonstration and technology transfer of an advanced oil recovery technology in the Paradox basin, southeastern Utah. If this project can demonstrate technical and economic feasibility, the technique can be applied to about 100 additional small fields in the Paradox basin alone, and result in increased recovery of 150 to 200 million barrels of oil. This project is designed to characterize five shallow-shelf carbonate reservoirs in the Pennsylvanian (Desmoinesian) Paradox Formation and choose the best candidate for a pilot demonstration project for either a waterflood or carbon dioxide-(CO -) 2 flood project. The field demonstration, monitoring of field performance, and associated validation activities will take place in the Paradox basin within the Navajo Nation. Two activities continued this quarter as part of the geological and reservoir characterization of productive carbonate buildups in the Paradox basin: (1) diagenetic characterization of project field reservoirs, and (2) technology transfer.

  11. Virtue Acquisition: The Paradox of Striving

    ERIC Educational Resources Information Center

    Snow, Nancy

    2016-01-01

    Aristotelian-inspired accounts of virtue acquisition stress guided practice and habituated action to develop virtue. This emphasis on action can lead to the "paradox of striving". The paradox occurs when we try too hard to act well and thereby spoil our efforts. I identify four forms of striving--forcing, impulsivity, overthinking, and…

  12. Yule-Simpson's Paradox in Research

    ERIC Educational Resources Information Center

    Goltz, Heather Honore; Smith, Matthew Lee

    2010-01-01

    Yule (1903) and Simpson (1951) described a statistical paradox that occurs when data is aggregated. In such situations, aggregated data may reveal a trend that directly contrasts those of sub-groups trends. In fact, the aggregate data trends may even be opposite in direction of sub-group trends. To reveal Yule-Simpson's paradox (YSP)-type…

  13. Differential Effectiveness of Theoretical Accounts for Paradox.

    ERIC Educational Resources Information Center

    Forsyth, Nancy M.; Strong, Stanley R.

    Paradoxical techniques in counseling consist of directing clients to practice the symptom which is causing them psychological distress. Both impression management theory and reactance theory have been advanced to explain the efficacy of such techniques. To examine the effectiveness of paradoxical techniques according to impression management and…

  14. New Paradoxes of Risky Decision Making

    ERIC Educational Resources Information Center

    Birnbaum, Michael H.

    2008-01-01

    During the last 25 years, prospect theory and its successor, cumulative prospect theory, replaced expected utility as the dominant descriptive theories of risky decision making. Although these models account for the original Allais paradoxes, 11 new paradoxes show where prospect theories lead to self-contradiction or systematic false predictions.…

  15. Three paradoxes of habitat conservation plans.

    PubMed

    Wilhere, George F

    2009-12-01

    Habitat conservation plans (HCPs) are enabled under section 10(a) of the Endangered Species Act. The substantial increase since 1994 in the number of HCPs has motivated numerous critiques of nearly every aspect of HCPs. These critiques have overlooked several paradoxes that expose fundamental shortcomings of section 10(a) or its implementation. I refer to them as: the Trainwreck Paradox, the Jeopardy Paradox, and the Maximum Mitigation Paradox. The Trainwreck Paradox states that HCPs are needed to avert the listing of species as threatened or endangered, but federal listings are needed to motivate landowners to develop HCPs. The Jeopardy Paradox stems from the vague language of section 10(a) which allows an HCP to reduce the likelihood of a species' survival and recovery but establishes no objective limit on the magnitude of reduction. The Maximum Mitigation Paradox argues that if a landowner provides maximum mitigation at the onset of an HCP, then there will be no financial resources for adaptive management in the future, but if resources are reserved for adaptive management, then the landowner is not mitigating to the maximum extent practicable as required by section 10(a). The purpose of this article is to explain these paradoxes of HCPs and discuss potential remedies. PMID:19902294

  16. Upwelling off Namibia: Approaches to Solving the Walvis Opal Paradox

    NASA Astrophysics Data System (ADS)

    Berger, W. H.; Paul, A.; Wefer, G.

    2002-12-01

    Upwelling off Namibia was enhanced during glacial time in the coastal ocean off southwestern Africa, as documented in a number of productivity proxies. However, the deposition of diatoms and other siliceous plankton remains was diminished. This discrepancy is known as the "Walvis Opal Paradox." Understanding this paradox is fundamental to the understanding of glacial-interglacial productivity fluctuations. Several conceptual approaches to solving this paradox have been offered. We consider two of these: (1) The suggestion that the thermocline was impoverished in silicate during glacial time, and (2) the suggestion that the change in topography that results from a drop in sea level has important implications for the rate of deposition of diatoms on the upper slope. The first approach focuses on changes in circulation and changes in overall nutrient supply. The second emphasizes regional factors affecting the position of upwelling centers and the role of recycling and redeposition of siliceous materials. Simple models incorporating the relevant processes are presented, models that can suggest observations allowing a choice between these alternatives.

  17. Paradoxical ratcheting in cornstarch suspensions

    NASA Astrophysics Data System (ADS)

    Shinbrot, Troy; Siu, Theo; Rutala, Matthew

    2014-11-01

    Cornstarch suspensions are well known to exhibit strong shear thickening, and we show as a result that they must - and do - climb vertically vibrating rods and plates. This occurs because when the rod moves upward, it shears the suspension against gravity, and so the fluid stiffens, but when the rod moves downward, the suspension moves with gravity, and so the fluid is more compliant. This causes the fluid to be dragged up by the upstroke more than it is dragged down by the downstroke, effectively ratcheting the fluid up the rod every cycle. We show experimentally and computationally that this effect is paradoxically caused by gravity - and so goes away when gravity is removed - and we show that the suspension can be made to balance on the uphill side of an inclined rod in an analog of the inverted ``Kapitza pendulum,'' closely related to the recent report by Ramachandran & Nosonovsky, Soft Matter 10, 4633 (2014).

  18. Paradoxical Behavior of Granger Causality

    NASA Astrophysics Data System (ADS)

    Witt, Annette; Battaglia, Demian; Gail, Alexander

    2013-03-01

    Granger causality is a standard tool for the description of directed interaction of network components and is popular in many scientific fields including econometrics, neuroscience and climate science. For time series that can be modeled as bivariate auto-regressive processes we analytically derive an expression for spectrally decomposed Granger Causality (SDGC) and show that this quantity depends only on two out of four groups of model parameters. Then we present examples of such processes whose SDGC expose paradoxical behavior in the sense that causality is high for frequency ranges with low spectral power. For avoiding misinterpretations of Granger causality analysis we propose to complement it by partial spectral analysis. Our findings are illustrated by an example from brain electrophysiology. Finally, we draw implications for the conventional definition of Granger causality. Bernstein Center for Computational Neuroscience Goettingen

  19. Investigations on the Aridity Paradox

    NASA Astrophysics Data System (ADS)

    Donohue, R. J.; Roderick, M. L.

    2014-12-01

    How global aridity might change in the immediate future is an important question. Several recent analyses have concluded that aridity will, in general, increase over land primarily because of increasing vapour pressure deficit. Taken at face value that result is difficult to understand because a warmer world is also anticipated to be a moister world. For example, at the global scale, climate model projections are for increasing rainfall and runoff. In this presentation we investigate this seeming paradox. We find that the previous analyses have not accounted for the biological impacts of elevated CO2 and when that is incorporated, the climate model projections are for a modest reduction in meteorological and hydrologic aridity and for larger reductions in biological aridity.

  20. Resolving thermoelectric "paradox" in superconductors.

    PubMed

    Shelly, Connor D; Matrozova, Ekaterina A; Petrashov, Victor T

    2016-02-01

    For almost a century, thermoelectricity in superconductors has been one of the most intriguing topics in physics. During its early stages in the 1920s, the mere existence of thermoelectric effects in superconductors was questioned. In 1944, it was demonstrated that the effects may occur in inhomogeneous superconductors. Theoretical breakthrough followed in the 1970s, when the generation of a measurable thermoelectric magnetic flux in superconducting loops was predicted; however, a major crisis developed when experiments showed puzzling discrepancies with the theory. Moreover, different experiments were inconsistent with each other. This led to a stalemate in bringing theory and experiment into agreement. With this work, we resolve this stalemate, thus solving this long-standing "paradox," and open prospects for exploration of novel thermoelectric phenomena predicted recently. PMID:26933688

  1. Bosonic analog of the Klein paradox

    SciTech Connect

    Wagner, R. E.; Ware, M. R.; Su, Q.; Grobe, R.

    2010-02-15

    The standard Klein paradox describes how an incoming electron scatters off a supercritical electrostatic barrier that is so strong that it can generate electron-positron pairs. This fermionic system has been widely discussed in textbooks to illustrate some of the discrepancies between quantum mechanical and quantum field theoretical descriptions for the pair creation process. We compare the fermionic dynamics with that of the corresponding bosonic system. We point out that the direct counterpart of the Pauli exclusion principle (the central mechanism to resolve the fermionic Klein paradox) is stimulated emission, which leads to the resolution of the analogous bosonic paradox.

  2. Gray's paradox: A fluid mechanical perspective

    NASA Astrophysics Data System (ADS)

    Bale, Rahul; Hao, Max; Bhalla, Amneet Pal Singh; Patel, Namrata; Patankar, Neelesh A.

    2014-07-01

    Nearly eighty years ago, Gray reported that the drag power experienced by a dolphin was larger than the estimated muscle power - this is termed as Gray's paradox. We provide a fluid mechanical perspective of this paradox. The viewpoint that swimmers necessarily spend muscle energy to overcome drag in the direction of swimming needs revision. For example, in undulatory swimming most of the muscle energy is directly expended to generate lateral undulations of the body, and the drag power is balanced not by the muscle power but by the thrust power. Depending on drag model utilized, the drag power may be greater than muscle power without being paradoxical.

  3. Gray's paradox: A fluid mechanical perspective

    PubMed Central

    Bale, Rahul; Hao, Max; Bhalla, Amneet Pal Singh; Patel, Namrata; Patankar, Neelesh A.

    2014-01-01

    Nearly eighty years ago, Gray reported that the drag power experienced by a dolphin was larger than the estimated muscle power – this is termed as Gray's paradox. We provide a fluid mechanical perspective of this paradox. The viewpoint that swimmers necessarily spend muscle energy to overcome drag in the direction of swimming needs revision. For example, in undulatory swimming most of the muscle energy is directly expended to generate lateral undulations of the body, and the drag power is balanced not by the muscle power but by the thrust power. Depending on drag model utilized, the drag power may be greater than muscle power without being paradoxical. PMID:25082341

  4. The autophagic paradox in cancer therapy.

    PubMed

    Wu, W K K; Coffelt, S B; Cho, C H; Wang, X J; Lee, C W; Chan, F K L; Yu, J; Sung, J J Y

    2012-02-23

    Autophagy, hallmarked by the formation of double-membrane bound organelles known as autophagosomes, is a lysosome-dependent pathway for protein degradation. The role of autophagy in carcinogenesis is context dependent. As a tumor-suppressing mechanism in early-stage carcinogenesis, autophagy inhibits inflammation and promotes genomic stability. Moreover, disruption of autophagy-related genes accelerates tumorigenesis in animals. However, autophagy may also act as a pro-survival mechanism to protect cancer cells from various forms of cellular stress. In cancer therapy, adaptive autophagy in cancer cells sustains tumor growth and survival in face of the toxicity of cancer therapy. To this end, inhibition of autophagy may sensitize cancer cells to chemotherapeutic agents and ionizing radiation. Nevertheless, in certain circumstances, autophagy mediates the therapeutic effects of some anticancer agents. Data from recent studies are beginning to unveil the apparently paradoxical nature of autophagy as a cell-fate decision machinery. Taken together, modulation of autophagy is a novel approach for enhancing the efficacy of existing cancer therapy, but its Janus-faced nature may complicate the clinical development of autophagy modulators as anticancer therapeutics. PMID:21765470

  5. The Obesity Paradox in Cancer: a Review.

    PubMed

    Lennon, Hannah; Sperrin, Matthew; Badrick, Ellena; Renehan, Andrew G

    2016-09-01

    There is a common perception that excess adiposity, commonly approximated by body mass index (BMI), is associated with reduced cancer survival. A number of studies have emerged challenging this by demonstrating that overweight and early obese states are associated with improved survival. This finding is termed the "obesity paradox" and is well recognized in the cardio-metabolic literature but less so in oncology. Here, we summarize the epidemiological findings related to the obesity paradox in cancer. Our review highlights that many observations of the obesity paradox in cancer reflect methodological mechanisms including the crudeness of BMI as an obesity measure, confounding, detection bias, reverse causality, and a specific form of the selection bias, known as collider bias. It is imperative for the oncologist to interpret the observation of the obesity paradox against the above methodological framework and avoid the misinterpretation that being obese might be "good" or "protective" for cancer patients. PMID:27475805

  6. The Lindley paradox in optical interferometry

    NASA Astrophysics Data System (ADS)

    Mauri, Camillo; Paris, Matteo G. A.

    2016-02-01

    The so-called Lindley paradox is a counterintuitive statistical effect where the Bayesian and frequentist approaches to hypothesis testing give radically different answers, depending on the choice of the prior distribution. In this paper we address the occurrence of the Lindley paradox in optical interferometry and discuss its implications for high-precision measurements. In particular, we focus on phase estimation by Mach-Zehnder interferometers and show how to mitigate the conflict between the two approaches by using suitable priors.

  7. Barrier paradox in the Klein zone

    SciTech Connect

    De Leo, Stefano; Rotelli, Pietro P.

    2006-04-15

    We study the solutions for a one-dimensional electrostatic potential in the Dirac equation when the incoming wave packet exhibits the Klein paradox (pair production). With a barrier potential we demonstrate the existence of multiple reflections (and transmissions). The antiparticle solutions which are necessarily localized within the barrier region create new pairs with each reflection at the potential walls. Consequently we encounter a new 'paradox' for the barrier because successive outgoing wave amplitudes grow geometrically.

  8. Simple games to illustrate Parrondo's paradox

    NASA Astrophysics Data System (ADS)

    Martin, Hal; von Baeyer, Hans Christian

    2004-05-01

    Parrondo's paradox is the proposition that two losing strategies can, by alternating randomly, produce a winner. R. D. Astumian has recently created a simple board game to illustrate this counterintuitive phenomenon. We prove that the inherent symmetry of Astumian's game prevents it from achieving its purpose, and suggest amended versions that do. We also display the additional paradoxical effect of two slow, losing games combining into a fast, winning one.

  9. Paradoxical response to anti-tubercular treatment

    PubMed Central

    Zaki, Syed Ahmed; Shenoy, Prithi

    2011-01-01

    We report a 5-year-old boy who developed optic neuritis as a paradoxical reaction to anti-tuberculous therapy. Steroids were re-started in the patient with gradual recovery of his vision. The case emphasizes the importance of recognizing paradoxical reactions in patients on anti-tuberculous therapy. Prompt recognition and treatment of such reactions will reduce the associated morbidity. PMID:21572663

  10. Experimental Implementations of Quantum Paradoxes

    NASA Astrophysics Data System (ADS)

    Briggs, G. A. D.

    Remarkable progress is being made in experiments that highlight the distinctive predictions of quantum mechanics. The Leggett-Garg inequality was devised to test for macrorealism (Leggett and Garg in Phys. Rev. Lett. 54:857-860, 1985). Various experiments have been performed, including one with non-invasive measurements in the kind of way that was originally envisaged, using spins in phosphorous impurities in silicon (Knee et al. in Nat. Commun. 3:606, 2012). This has led to fresh understanding of what kind of realism is excluded by the result. The quantum three-box paradox (Aharonov and Vaidman in J. Phys. A, Math. Gen. 24:2315-2328, 1991) provides a further test, which can be re-expressed in terms of the Leggett-Garg inequality. This has been experimentally implemented with projective measurements using an NV- centre in diamond, yielding results 7.8 standard deviations beyond a classical bound (George et al. in Proc. Natl. Acad. Sci. USA 110:3777-3781, 2013). [Editor's note: for a video of the talk given by Prof. Briggs at the Aharonov-80 conference in 2012 at Chapman University, see http://quantum.chapman.edu/talk-18.

  11. Phosphorus and Water Quality Paradox

    NASA Astrophysics Data System (ADS)

    Pant, H. K.

    2008-12-01

    Paradoxically, phosphorus (P) is one of the major nutrients for higher agricultural production, as well as it causes eutrophication/algal blooms in aquatic and semi-aquatic systems. Phosphorus loadings from agricultural/urban runoffs into lakes and rivers are becoming a global concern for the protection of water quality. Artificial wetlands are considered as a low cost alternative for treating wastewater including removal of P from sources such as agricultural and urban runoffs. However, the selection of the construction site may well determine the effectiveness of these wetlands. Studies show that P transformations in sediments/ soils are crucial for P sequestration in a wetland rather than the amounts of native P. Using 31Phosphorus Nuclear Magnetic Resonance Spectroscopy (31P NMR), previously unreported an active organic P form, phosphoarginine, was identified, and the study indicates that abandonment of P impacted sites may not solve the P loading problem to the water bodies as the organic P compounds would not be as stable as they were thought, thus, can play a detrimental role in eutrophication of water bodies, after all.

  12. Personal Interaction with Researchers or Detached Synthesis of the Evidence: Modelling the Health Policy Paradox

    ERIC Educational Resources Information Center

    Hanney, Steve

    2004-01-01

    Personal interaction between health policy makers and researchers is widely seen as the key to enhancing research use, but there are also increasing demands that policies be based on syntheses of the available evidence. A potential paradox arises in that whilst interaction may result in greater use of the evidence it might also lead to a partial…

  13. Paradoxes, puzzles and passing time.

    PubMed

    Rankin-Box, D

    1999-12-01

    Whilst technology and our understanding about the world has improved, I suspect that in many ways, the hopes, fears, worries, joy and love we feel are not so different from that of our ancestors of 500 or 700 years ago, though the social circumstances may have altered. We have beliefs and dreams and daily routines in our lives and many people hang onto age old superstitions without really knowing their origins, e.g. crossing our fingers for luck, touching wood, throwing salt over a shoulder or reading about star signs. The night sky also looks different to 1000 years ago. When we look up at the stars we see an image of the past in the present: the light we see set off from its origin long before the advent of antibiotics, the Russian Revolution or the first man on the moon. As we move forwards, the benefits of modern medicine and improvements in social and environmental issues (compared to just 100 years ago) have, paradoxically, provided us with a quality of life that allows us to live longer and gain a greater insight into the world around us. There is an opportunity to reflect and wonder at the healers of the early middle ages and of the way in which we wish medicine to develop. When reflecting about the past 1000 years, patterns begin to emerge of times past, epochs of healing and revolutions in the way we perceive myriad aspects of health and healing. I am sure there are ways of combining ancient ways with modern thinking, of blending art and science, of balancing logic and rationality with love, fun, humour and empathy. Of building on experience, so that caring is spiritually therapeutic, freeing our patients and ourselves as we move into the future and the new millennium. PMID:10887877

  14. Clouds and the Faint Young Sun Paradox

    NASA Astrophysics Data System (ADS)

    Goldblatt, C.; Zahnle, K. J.

    2011-03-01

    We investigate the role which clouds could play in resolving the Faint Young Sun Paradox (FYSP). Lower solar luminosity in the past means that less energy was absorbed on Earth (a forcing of -50 W m-2 during the late Archean), but geological evidence points to the Earth having been at least as warm as it is today, with only very occasional glaciations. We perform radiative calculations on a single global mean atmospheric column. We select a nominal set of three layered, randomly overlapping clouds, which are both consistent with observed cloud climatologies and reproduced the observed global mean energy budget of Earth. By varying the fraction, thickness, height and particle size of these clouds we conduct a wide exploration of how changed clouds could affect climate, thus constraining how clouds could contribute to resolving the FYSP. Low clouds reflect sunlight but have little greenhouse effect. Removing them entirely gives a forcing of +25 W m-2 whilst more modest reduction in their efficacy gives a forcing of +10 to +15 W m-2. For high clouds, the greenhouse effect dominates. It is possible to generate +50 W m-2 forcing from enhancing these, but this requires making them 3.5 times thicker and 14 K colder than the standard high cloud in our nominal set and expanding their coverage to 100% of the sky. Such changes are not credible. More plausible changes would generate no more than +15 W m-2 forcing. Thus neither fewer low clouds nor more high clouds can provide enough forcing to resolve the FYSP. Decreased surface albedo can contribute no more than +5 W m-2 forcing. Some models which have been applied to the FYSP do not include clouds at all. These overestimate the forcing due to increased CO2 by 20 to 25% when pCO2 is 0.01 to 0.1 bar.

  15. Universal Braess paradox in open quantum dots.

    PubMed

    Barbosa, A L R; Bazeia, D; Ramos, J G G S

    2014-10-01

    We present analytical and numerical results that demonstrate the presence of the Braess paradox in chaotic quantum dots. The paradox that we identify, originally perceived in classical networks, shows that the addition of more capacity to the network can suppress the current flow in the universal regime. We investigate the weak localization term, showing that it presents the paradox encoded in a saturation minimum of the conductance, under the presence of hyperflow in the external leads. In addition, we demonstrate that the weak localization suffers a transition signal depending on the overcapacity lead and presents an echo on the magnetic crossover before going to zero due to the full time-reversal symmetry breaking. We also show that the quantum interference contribution can dominate the Ohm term in the presence of constrictions and that the corresponding Fano factor engenders an anomalous behavior. PMID:25375575

  16. Universal Braess paradox in open quantum dots

    NASA Astrophysics Data System (ADS)

    Barbosa, A. L. R.; Bazeia, D.; Ramos, J. G. G. S.

    2014-10-01

    We present analytical and numerical results that demonstrate the presence of the Braess paradox in chaotic quantum dots. The paradox that we identify, originally perceived in classical networks, shows that the addition of more capacity to the network can suppress the current flow in the universal regime. We investigate the weak localization term, showing that it presents the paradox encoded in a saturation minimum of the conductance, under the presence of hyperflow in the external leads. In addition, we demonstrate that the weak localization suffers a transition signal depending on the overcapacity lead and presents an echo on the magnetic crossover before going to zero due to the full time-reversal symmetry breaking. We also show that the quantum interference contribution can dominate the Ohm term in the presence of constrictions and that the corresponding Fano factor engenders an anomalous behavior.

  17. Information-driven societies and Fermi's paradox

    NASA Astrophysics Data System (ADS)

    Lampton, Michael

    2013-10-01

    Fermi's paradox is founded on the idea that one or more Galactic extraterrestrial civilizations (ETCs) existed long ago and sustained exploration for millions of years, but in spite of their advanced knowledge, they could not find a way to explore the Galaxy other than with fleets of starships or self replicating probes. Here, I question this second assumption: if advanced technology generally allows long-distance remote sensing, and if ETCs were motivated by gaining information rather than conquest or commerce, then such voyages would be unnecessary, thereby resolving Fermi's paradox.

  18. Congenital Malformations Leading to Paradoxical Embolism.

    PubMed

    Bruckheimer, Elchanan

    2016-05-01

    The absolute separation of the right and left circulations and the filtration of blood by the pulmonary circulation are essential to prevent the passage of thrombotic material from the venous system into the systemic arterial circulation. Any breach of the intracardiac septae or circumvention of the pulmonary capillary network may cause a paradoxical embolus. The most common causes are atrial septal defects and pulmonary arteriovenous malformations. This article discusses unusual connections and pathways related to congenital malformations. Although anticoagulation is necessary to prevent paradoxical emboli, the hematologic disturbances and the most appropriate therapy in these patients warrant further investigation. PMID:27150173

  19. Another paradox involving the second law of thermodynamics

    SciTech Connect

    Sheehan, D.P.

    1996-01-01

    Recently a paradox has been posed that appears to challenge the second law of thermodynamics in a plasma blackbody environment [D. P. Sheehan, Phys. Plasmas {bold 2}, 1893 (1995)]. In this paper another, related paradox is posed in an unmagnetized Q plasma. Laboratory experiments simulating some necessary conditions for the paradoxical system corroborate theoretical predictions and fail to resolve the paradox in favor of the second law. {copyright} {ital 1996 American Institute of Physics.}

  20. The paradox prescription: leading the medical group of the future.

    PubMed

    Blair, J D; Payne, G T

    2000-01-01

    Leaders of health care organizations must constantly deal with paradox in and around their organizations. The paradox profile is a modeling technique for examining how organizations prioritize their dealings with the eight competing issues from which the four paradoxes are derived. This article demonstrates the leadership challenges that exist when a paradox is present and how these tensions differ when the integrative status of the medical group--as either part of an integrated system or not--is considered. PMID:10710728

  1. Evaluating paradox walnut rootstocks for resistance to Armillaria root disease

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The most common Juglans regia (English walnut) rootstock in California is Paradox, a hybrid between J. hindsii (Northern California black walnut) and J. regia. Unfortuntely, Paradox rootstock is highly susceptible to Armillaria root disease. The relative resistance of new clonal, Paradox rootstock...

  2. Paradox Lost: Toward a Robust Test of the Chinese Learner

    ERIC Educational Resources Information Center

    Morrison, Keith

    2006-01-01

    This article suggests that attempts to date to unravel the paradox of the Chinese learner are incomplete and inadequately modeled, and that the complexities of the paradox have not yet been fittingly operationalized or alternative explanations of research data investigated. It contends that attempts either to state or to unravel the paradox are…

  3. The Policy Maker's Anguish: Regulating Personal Data Behavior Between Paradoxes and Dilemmas

    NASA Astrophysics Data System (ADS)

    Compañó, Ramón; Lusoli, Wainer

    Regulators in Europe and elsewhere are paying great attention to identity, privacy and trust in online and converging environments. Appropriate regulation of identity in a ubiquitous information environment is seen as one of the major drivers of the future Internet economy. Regulation of personal identity data has come to the fore including mapping conducted on digital personhood by the OECD; work on human rights and profiling by the Council of Europe andmajor studies by the European Commission with regard to self-regulation in the privacy market, electronic identity technical interoperability and enhanced safety for young people. These domains overlap onto an increasingly complex model of regulation of individuals' identity management, online and offline. This chapter argues that policy makers struggle to deal with issues concerning electronic identity, due to the apparently irrational and unpredictable behavior of users when engaging in online interactions involving identity management. Building on empirical survey evidence from four EU countries, we examine the first aspect in detail - citizens' management of identity in a digital environment. We build on data from a large scale (n = 5,265) online survey of attitudes to electronic identity among young Europeans (France, Germany, Spain, UK) conducted in August 2008. The survey asked questions about perceptions and acceptance of risks, general motivations, attitudes and behaviors concerning electronic identity. Four behavioral paradoxes are identified in the analysis: a privacy paradox (to date well known), but also a control paradox, a responsibility paradox and an awareness paradox. The chapter then examines the paradoxes in relation of three main policy dilemmas framing the debate on digital identity. The paper concludes by arguing for an expanded identity debate spanning policy circles and the engineering community.

  4. Twin Paradox in de Sitter Spacetime

    ERIC Educational Resources Information Center

    Boblest, Sebastian; Muller, Thomas; Wunner, Gunter

    2011-01-01

    The "twin paradox" of special relativity offers the possibility of making interstellar flights within a lifetime. For very long journeys with velocities close to the speed of light, however, we have to take into account the expansion of the universe. Inspired by the work of Rindler on hyperbolic motion in curved spacetime, we study the worldline…

  5. A resolution of the paradox of enrichment.

    PubMed

    Mougi, Akihiko; Nishimura, Kinya

    2007-09-01

    Theoretical studies have shown a paradoxical destabilizing response of predator-prey ecosystems to enrichment, but there is the gap between the intuitive view of nature and this theoretical prediction. We studied a minimal predator-prey system (a two predator-two prey system) in which the paradox of enrichment pattern can vanish; the destabilization with enrichment is reversed, leading to stabilization (a decrease in the amplitude of oscillation of population densities). For resolution of the paradox, two conditions must be met: (1) the same prey species must be preferred as a dietary item by both predator species, creating the potential for high exploitative competition between the predator species, and (2), while both predators are assumed to select their diet in accordance with optimal diet utilization theory, one predator must be a specialist and the other a generalist. In this system, the presence of a less profitable prey species can cause the increase in population oscillation amplitudes associated with increasing enrichment to be suppressed via the optimal diet utilization of the generalist predator. The resulting stabilization is explained by the mitigating effect of the less profitable prey showing better population growth with increasing enrichment on the destabilization underlying the specialist predator and prey relation, thus resolving the paradox of enrichment. PMID:17543997

  6. The Paradox of Being a Woman Teacher.

    ERIC Educational Resources Information Center

    Tamboukou, Maria

    2000-01-01

    Examines discourses that interweave women's position in education today, theorizing education as a nexus of created paradoxical spaces, where the female self attempts to surpass closed boundaries, questioning the dichotomy of the feminized private and/or masculine public. Considers the importance of time restrictions upon women's lives. Discusses…

  7. Bell's Paradox under Different Capital Market Regimes.

    ERIC Educational Resources Information Center

    Kang, Johan Moonwon

    1993-01-01

    In 1984 "Economics of Education Review" paper, E. Bell indicates that, when capital markets are imperfect in a certain sense, demand for education may not always be directly related with present net value of education. This study shows Bell's paradox is possible under the alternative definitions of capital market imperfections and specifies…

  8. An alternative resolution to the Mansuripur paradox

    NASA Astrophysics Data System (ADS)

    Redfern, Francis

    2016-04-01

    In 2013 an article published online by the journal Science declared that the paradox proposed by Masud Mansuripur was resolved. This paradox concerns a point charge-Amperian magnetic dipole system as seen in a frame of reference where they are at rest and one in which they are moving. In the latter frame an electric dipole appears on the magnetic dipole. A torque is then exerted upon the electric dipole by the point charge, a torque that is not observed in the at-rest frame. Mansuripur points out this violates the relativity principle and suggests the Lorentz force responsible for the torque be replaced by the Einstein-Laub force. The resolution of the paradox reported by Science, based on numerous papers in the physics literature, preserves the Lorentz force but depends on the concept of hidden momentum. Here I propose a different resolution based on the overlooked fact that the charge-magnetic dipole system contains linear and angular electromagnetic field momentum. The time rate of change of the field angular-momentum in the frame through which the system is moving cancels that due to the charge-electric dipole interaction. From this point of view hidden momentum is not needed in the resolution of the paradox.

  9. Negotiating Social Change: The Paradox of Youth.

    ERIC Educational Resources Information Center

    Wyn, Johanna; White, Rob

    2000-01-01

    Explores paradoxical elements in the relationship between youth and society, arguing that researchers must consider both the distinctive circumstances of the post-1970 generation and the new approaches they are developing to make a life. Argues that questions about how social structures and social divisions affect young people's life patterns must…

  10. Consistent resolution of some relativistic quantum paradoxes

    SciTech Connect

    Griffiths, Robert B.

    2002-12-01

    A relativistic version of the (consistent or decoherent) histories approach to quantum theory is developed on the basis of earlier work by Hartle, and used to discuss relativistic forms of the paradoxes of spherical wave packet collapse, Bohm's formulation of the Einstein-Podolsky-Rosen paradox, and Hardy's paradox. It is argued that wave function collapse is not needed for introducing probabilities into relativistic quantum mechanics, and in any case should never be thought of as a physical process. Alternative approaches to stochastic time dependence can be used to construct a physical picture of the measurement process that is less misleading than collapse models. In particular, one can employ a coarse-grained but fully quantum-mechanical description in which particles move along trajectories, with behavior under Lorentz transformations the same as in classical relativistic physics, and detectors are triggered by particles reaching them along such trajectories. States entangled between spacelike separate regions are also legitimate quantum descriptions, and can be consistently handled by the formalism presented here. The paradoxes in question arise because of using modes of reasoning which, while correct for classical physics, are inconsistent with the mathematical structure of quantum theory, and are resolved (or tamed) by using a proper quantum analysis. In particular, there is no need to invoke, nor any evidence for, mysterious long-range superluminal influences, and thus no incompatibility, at least from this source, between relativity theory and quantum mechanics.

  11. ID in Higher Education: A Paradox.

    ERIC Educational Resources Information Center

    Terrell, William R.; Shrock, Sharon A.

    This chapter examines, within the higher education context, the difficulties which instructional developers often encounter in gaining cooperation to achieve their goals. It is argued that instructional development in the university involves a paradox in that a great deal of money is provided for the improvement of instruction, but an environment…

  12. A Developmental Perspective on the Imperfective Paradox

    ERIC Educational Resources Information Center

    Kazanina, Nina; Phillips, Colin

    2007-01-01

    Imperfective or progressive verb morphology makes it possible to use the name of a whole event to refer to an activity that is clearly not a complete instance of that event, leading to what is known as the Imperfective Paradox. For example, a sentence like "John was building a house" does not entail that a house ever got built. The Imperfective…

  13. The Free Rider and Voter Paradox "Games."

    ERIC Educational Resources Information Center

    Sulock, Joseph M.

    1990-01-01

    Presents several time-effective classroom games that can be used to help students discover the consequences of two important concepts in public finance: the free rider problem and the voting paradox. Maintains that these games encourage student involvement and stimulate class discussion. (DB)

  14. Jack London: The Paradox of Individualism.

    ERIC Educational Resources Information Center

    Deane, Paul

    1968-01-01

    Because of their interest in naturalism and socialism, critics often overlook the major intellectual conflict in Jack London's work: the paradox of individualism. London regards society as affecting the individual in two ways: it either promotes individuality or it demands a conformity that undermines individualism. When society fails Buck in "The…

  15. The Paradox of the Excluded Child

    ERIC Educational Resources Information Center

    Haynes, Bruce

    2005-01-01

    A paradox seems to exist where a child, of compulsory schooling age, is excluded from a school. The practice of exclusion has evolved over the almost two centuries of compulsory schooling. Abolition of corporal punishment in Western Australia and elsewhere has tended to focus attention on exclusion and the grounds justifying such action by school…

  16. Toward a Theory of Coaching Paradox

    ERIC Educational Resources Information Center

    Barnson, Steven C.

    2014-01-01

    Multiple tensions exist as part of the coaching process. How a coach responds to these tensions is a fundamental determinant of an athlete or team's fate. In today's highly competitive, socially demanding, and ever-changing sports environment, and as the expectations on coaches become more complex, the paradox becomes a critical lens to…

  17. Sustainable Development: Paradoxes, Misunderstandings and Learning Organizations

    ERIC Educational Resources Information Center

    Ramirez, Gabriel A.

    2012-01-01

    Purpose: Sustainability is, in itself, the idea of a harmonic answer to the dual nature of the most pressing problem for global society. Most of the problems dealing with sustainability concern its dual and contradictory nature. That paradoxical reality is in no way a unique feature of sustainability; its universal pervasiveness is demonstrated by…

  18. The vista paradox: Framing or contrast?

    PubMed

    Daum, S Oliver; Both, Bernhard S; Bertamini, Marco; Hecht, Heiko

    2015-12-01

    The vista paradox is the illusion in which an object seen through a window appears to shrink in apparent size (and appears farther away) as the observer approaches the window. Paradoxically, the distal object appears smaller as its visual angle increases. We investigated the effect in four experiments varying object size, distance, point of fixation, and texture of the frame and of the object. In the first experiment, we tried to confirm the illusion and to test the robustness of the phenomenon. In the second experiment, we manipulated where subjects fixated (on the frame or on the object) as well as the texture of the object and the frame. Fixation was essential for the illusion: fixating the frame led to an apparent shrinking of the object, whereas fixation on the object did not. Texture of the frame intensified the apparent shrinking of the object. In a third experiment, we separated the point of fixation from the frame in a between-subjects design. Finally, in Experiment 4, we showed that the paradox does not require a frame, but it requires a fixation on a location different from the object. That is, the window or frame is dispensable for the vista paradox, but fixation is critical. PMID:26280259

  19. The Paradox of National Language Movements.

    ERIC Educational Resources Information Center

    Eckert, Penelope

    1983-01-01

    The paradox inherent in a situation in which the need for political unification requires submersion of authentic local or subregional differences is illustrated by the case of Occitania (southern France), where a community is culturally and linguistically removed from the center of a movement intending to represent it. (MSE)

  20. Paradox lost. The latah problem revisited.

    PubMed

    Kenny, M G

    1983-03-01

    This paper examines the validity of Dr. R. C. Simons' resolution (Simons, R. C. The resolution of the latah paradox. J. Nerv. Ment. Dis., 168: 195-206, 1980) of the so-called latah paradox. Latah, a Malay condition precipitated by sudden fright and involving compulsive obscenity and mimesis, was found to be closely related to local cultural values; yet a paradox seems to arise from the fact that analogous conditions are reported from unrelated cultures. Simons accounts for this by proposing that latah and its kindred states are based on the universal human startle reflex and that latah is merely a culture-specific exploitation of a neurophysiological potential shared by humans and other animals. It is here argued that the evidence does not support such a view and that latah-like conditions are best considered in terms of their local meaning within their societies of origin; ethnographic material from Siberia is examined as a case in point. It is concluded that the "latah paradox" is illusory and that biomedical approaches to the question have seriously misread the nature of the phenomenon and potentially distort clinical practice in relation to it. PMID:6827254

  1. Secure Communication in the Twin Paradox

    NASA Astrophysics Data System (ADS)

    Garcia-Escartin, Juan Carlos; Chamorro-Posada, Pedro

    2015-11-01

    The amount of information that can be transmitted through a noisy channel is affected by relativistic effects. Under the presence of a fixed noise at the receiver, there appears an asymmetry between "slowly aging" and "fast aging" observers which can be used to have private information transmission. We discuss some models for users inside gravitational wells and in the twin paradox scenario.

  2. Art's Pedagogical Paradox

    ERIC Educational Resources Information Center

    Kalin, Nadine M.

    2014-01-01

    This article contributes to conversations concerning art education futures through engaging alternative relations between art, education, and democracy that mobilize education as art projects associated with the "pedagogical turn" as sites of liminality and paradox. An analysis of the art project, Pedagogical Factory, is used to outline…

  3. Challenges and Paradoxes of Human Factors in Health Technology Design

    PubMed Central

    2016-01-01

    Usability testing allows human factors professionals to identify and mitigate issues with the design and use of medical technology. The test results, however, can be paradoxical and therefore be misinterpreted, limiting their usefulness. The paradoxical findings can lead to products that are not aligned with the needs and constraints of their users. We herein report on our observations of the paradox of expertise, the paradox of preference versus performance, and the paradox of choice. Each paradox explored is in the perspective of the design of medical technology, the issues that need to be considered in the interpretation of the test results, as well as suggestions on how to avoid the pitfalls in the design of medical technology. Because these paradoxes can influence product design at various stages of product development, it is important to be aware of the effects to interpret the findings properly. PMID:27025862

  4. Challenges and Paradoxes of Human Factors in Health Technology Design.

    PubMed

    Morita, Plinio P; Cafazzo, Joseph A

    2016-01-01

    Usability testing allows human factors professionals to identify and mitigate issues with the design and use of medical technology. The test results, however, can be paradoxical and therefore be misinterpreted, limiting their usefulness. The paradoxical findings can lead to products that are not aligned with the needs and constraints of their users. We herein report on our observations of the paradox of expertise, the paradox of preference versus performance, and the paradox of choice. Each paradox explored is in the perspective of the design of medical technology, the issues that need to be considered in the interpretation of the test results, as well as suggestions on how to avoid the pitfalls in the design of medical technology. Because these paradoxes can influence product design at various stages of product development, it is important to be aware of the effects to interpret the findings properly. PMID:27025862

  5. A Resolution of the Paradox of Enrichment

    NASA Astrophysics Data System (ADS)

    Feng, Z. C.; Li, Y. Charles

    2015-06-01

    The paradox of enrichment was observed by Rosenzweig [1971] in a class of predator-prey models. Two of the parameters in the models are crucial for the paradox. These two parameters are the prey's carrying capacity and prey's half-saturation for predation. Intuitively, increasing the carrying capacity due to enrichment of the prey's environment should lead to a more stable predator-prey system. Analytically, it turns out that increasing the carrying capacity always leads to an unstable predator-prey system that is susceptible to extinction from environmental random perturbations. This is the so-called paradox of enrichment. Our resolution here rests upon a closer investigation on a dimensionless number H formed from the carrying capacity and the prey's half-saturation. By recasting the models into dimensionless forms, the models are in fact governed by a few dimensionless numbers including H. The effects of the two parameters: carrying capacity and half-saturation are incorporated into the number H. In fact, increasing the carrying capacity is equivalent (i.e. has the same effect on H) to decreasing the half-saturation which implies more aggressive predation. Since there is no paradox between more aggressive predation and instability of the predator-prey system, the paradox of enrichment is resolved. The so-called instability of the predator-prey system is characterized by the existence of a stable limit cycle in the phase plane, which gets closer and closer to the predator axis and prey axis. Due to random environmental perturbations, this can lead to extinction. We also further explore spatially dependent models for which the phase space is infinite-dimensional. The spatially independent limit cycle which is generated by a Hopf bifurcation from an unstable steady state, is linearly stable in the infinite-dimensional phase space. Numerical simulations indicate that the basin of attraction of the limit cycle is riddled. This shows that spatial perturbations can

  6. Mercury Toxicity on Sodium Pump and Organoseleniums Intervention: A Paradox

    PubMed Central

    Kade, Ige Joseph

    2012-01-01

    Mercury is an environmental poison, and the damage to living system is generally severe. The severity of mercury poisoning is consequent from the fact that it targets the thiol-containing enzymes, irreversibly oxidizing their critical thiol groups, consequently leading to an inactivation of the enzyme. The Na+/K+-ATPase is a sulfhydryl protein that is sensitive to Hg2+ assault. On the other hand, organoseleniums are a class of pharmacologically promising compounds with potent antioxidant effects. While Hg2+ oxidizes sulfhydryl groups of Na+/K+-ATPase under in vitro and in vivo conditions, the organoselenium compounds inhibit Na+/K+-ATPase in vitro but enhance its activities under in vivo conditions with concomitant increase in the level of endogenous thiols. Paradoxically, it appears that these two thiol oxidants can be used to counteract one another under in vivo conditions, and this hypothesis serves as the basis for this paper. PMID:22927724

  7. The happiness–income paradox revisited

    PubMed Central

    Easterlin, Richard A.; McVey, Laura Angelescu; Switek, Malgorzata; Sawangfa, Onnicha; Zweig, Jacqueline Smith

    2010-01-01

    The striking thing about the happiness–income paradox is that over the long-term —usually a period of 10 y or more—happiness does not increase as a country's income rises. Heretofore the evidence for this was limited to developed countries. This article presents evidence that the long term nil relationship between happiness and income holds also for a number of developing countries, the eastern European countries transitioning from socialism to capitalism, and an even wider sample of developed countries than previously studied. It also finds that in the short-term in all three groups of countries, happiness and income go together, i.e., happiness tends to fall in economic contractions and rise in expansions. Recent critiques of the paradox, claiming the time series relationship between happiness and income is positive, are the result either of a statistical artifact or a confusion of the short-term relationship with the long-term one. PMID:21149705

  8. A history of the Allais paradox.

    PubMed

    Heukelom, Floris

    2015-03-01

    This article documents the history of the Allais paradox, and shows that underneath the many discussions of the various protagonists lay different, irreconcilable epistemological positions. Savage, like his mentor von Neumann and similar to economist Friedman, worked from an epistemology of generalized characterizations. Allais, on the other hand, like economists Samuelson and Baumol, started from an epistemology of exact descriptions in which every axiom was an empirical claim that could be refuted directly by observations. As a result, the two sides failed to find a common ground. Only a few decades later was the now so-called Allais paradox rediscovered as an important precursor when a new behavioural economic subdiscipline started to adopt the epistemology of exact descriptions and its accompanying falsifications of rational choice theory. PMID:25833801

  9. The South Ray Crater age paradox

    NASA Technical Reports Server (NTRS)

    Mckay, D. S.; Heiken, G. H.

    1973-01-01

    Relative exposure ages based on agglutinate content are calculated for 26 Apollo 16 surface and core samples. These ages increase from the northern part of the traverse to the southern part and are in general agreement with cosmogenic gas ages and particle track ages. An apparent paradox exists in which presumed ray soil from South Ray Crater is much older than the age of South Ray Crater itself as determined by a variety of methods. The most likely explanation for the paradox is that the presumed South Ray Crater soil is not ejecta from South Ray Crater but is pre-existing regolith upon which blocks and fragments from South Ray Crater are scattered.

  10. Optimal GHZ Paradox for Three Qubits.

    PubMed

    Ren, Changliang; Su, Hong-Yi; Xu, Zhen-Peng; Wu, Chunfeng; Chen, Jing-Ling

    2015-01-01

    Quatum nonlocality as a valuable resource is of vital importance in quantum information processing. The characterization of the resource has been extensively investigated mainly for pure states, while relatively less is know for mixed states. Here we prove the existence of the optimal GHZ paradox by using a novel and simple method to extract an optimal state that can saturate the tradeoff relation between quantum nonlocality and the state purity. In this paradox, the logical inequality which is formulated by the GHZ-typed event probabilities can be violated maximally by the optimal state for any fixed amount of purity (or mixedness). Moreover, the optimal state can be described as a standard GHZ state suffering flipped color noise. The maximal amount of noise that the optimal state can resist is 50%. We suggest our result to be a step toward deeper understanding of the role played by the AVN proof of quantum nonlocality as a useful physical resource. PMID:26272658

  11. Optimal GHZ Paradox for Three Qubits

    PubMed Central

    Ren, Changliang; Su, Hong-Yi; Xu, Zhen-Peng; Wu, Chunfeng; Chen, Jing-Ling

    2015-01-01

    Quatum nonlocality as a valuable resource is of vital importance in quantum information processing. The characterization of the resource has been extensively investigated mainly for pure states, while relatively less is know for mixed states. Here we prove the existence of the optimal GHZ paradox by using a novel and simple method to extract an optimal state that can saturate the tradeoff relation between quantum nonlocality and the state purity. In this paradox, the logical inequality which is formulated by the GHZ-typed event probabilities can be violated maximally by the optimal state for any fixed amount of purity (or mixedness). Moreover, the optimal state can be described as a standard GHZ state suffering flipped color noise. The maximal amount of noise that the optimal state can resist is 50%. We suggest our result to be a step toward deeper understanding of the role played by the AVN proof of quantum nonlocality as a useful physical resource. PMID:26272658

  12. Optimal GHZ Paradox for Three Qubits

    NASA Astrophysics Data System (ADS)

    Ren, Changliang; Su, Hong-Yi; Xu, Zhen-Peng; Wu, Chunfeng; Chen, Jing-Ling

    2015-08-01

    Quatum nonlocality as a valuable resource is of vital importance in quantum information processing. The characterization of the resource has been extensively investigated mainly for pure states, while relatively less is know for mixed states. Here we prove the existence of the optimal GHZ paradox by using a novel and simple method to extract an optimal state that can saturate the tradeoff relation between quantum nonlocality and the state purity. In this paradox, the logical inequality which is formulated by the GHZ-typed event probabilities can be violated maximally by the optimal state for any fixed amount of purity (or mixedness). Moreover, the optimal state can be described as a standard GHZ state suffering flipped color noise. The maximal amount of noise that the optimal state can resist is 50%. We suggest our result to be a step toward deeper understanding of the role played by the AVN proof of quantum nonlocality as a useful physical resource.

  13. Adaptationism Fails to Resolve Fermi's Paradox

    NASA Astrophysics Data System (ADS)

    Cirkovic, M. M.; Dragicevic, I.; Beric-Bjedov, T.

    2005-06-01

    One of the most interesting problems in the nascent discipline of astrobiology is more than half-century old Fermi's paradox: why, considering extraordinary young age of Earth and the Solar System in the Galactic context, don't we perceive much older intelligent communities or signposts of their activity? In spite of a vigorous research activity in recent years, especially bolstered by successes of astrobiology in finding extrasolar planets and extremophiles, this problem (also known as the "Great Silence" or "astrosociological" paradox) remains as open as ever. In a previous paper, we have discussed a particular evolutionary solution suggested by Karl Schroeder based on the currently dominant evolutionary doctrine of adaptationism. Here, we extend that discussion with emphasis on the problems such a solution is bound to face, and conclude that it is ultimately quite unlikely.

  14. "Permanence" - An Adaptationist Solution to Fermi's Paradox?

    NASA Astrophysics Data System (ADS)

    Cirkovic, Milan M.

    A new solution of Fermi's paradox sketched by SF writer Karl Schroeder in his 2002. novel Permanence is investigated. It is argued that this solution is tightly connected with adaptationism - a widely discussed working hypothesis in evolutionary biology. Schroeder's hypothesis has important ramifications for astrobiology, SETI projects, and future studies. Its weaknesses should be explored without succumbing to the emotional reactions often accompanying adaptationist explanations.

  15. Obesity paradox in patients on maintenance dialysis.

    PubMed

    Kalantar-Zadeh, Kamyar; Kopple, Joel D

    2006-01-01

    Overweight (body mass index [BMI]=25-30 kg/m2) and obesity (BMI>30 kg/m2) have become mass phenomena with a pronounced upward trend in prevalence in most countries throughout the world and are associated with increased cardiovascular risk and poor survival. In patients with chronic kidney disease (CKD) undergoing maintenance hemodialysis an 'obesity paradox' has been consistently reported, i.e., a high BMI is incrementally associated with better survival. While this 'reverse epidemiology' of obesity is relatively consistent in maintenance hemodialysis patients, studies in peritoneal dialysis patients have yielded mixed results. A similar obesity paradox has been described in patients with chronic heart failure as well as in 20 million members of other distinct medically 'at risk' populations in the USA. Possible causes of the reverse epidemiology of obesity include: (1) time-discrepancies between the competing risks for the adverse events that are associated with overnutrition and undernutrition; (2) sequestration of uremic toxins in adipose tissue; (3) selection of a gene pool favorable to longer survival in dialysis patients during the course of CKD progression, which eliminates over 95% of the CKD population before they commence maintenance dialysis therapy; (4) a more stable hemodynamic status; (5) alterations in circulating cytokines; (6) unique neurohormonal constellations; (7) endotoxin-lipoprotein interactions; and (8) reverse causation. Examining the causes and consequences of the obesity paradox in dialysis patients can improve our understanding of similar paradoxes observed both for other conventional risk factors in chronic dialysis patients, such as blood pressure and serum cholesterol, and in other populations, such as patients with heart failure, cancer or AIDS or geriatric populations. PMID:16929133

  16. Enjoying Sad Music: Paradox or Parallel Processes?

    PubMed

    Schubert, Emery

    2016-01-01

    Enjoyment of negative emotions in music is seen by many as a paradox. This article argues that the paradox exists because it is difficult to view the process that generates enjoyment as being part of the same system that also generates the subjective negative feeling. Compensation theories explain the paradox as the compensation of a negative emotion by the concomitant presence of one or more positive emotions. But compensation brings us no closer to explaining the paradox because it does not explain how experiencing sadness itself is enjoyed. The solution proposed is that an emotion is determined by three critical processes-labeled motivational action tendency (MAT), subjective feeling (SF) and Appraisal. For many emotions the MAT and SF processes are coupled in valence. For example, happiness has positive MAT and positive SF, annoyance has negative MAT and negative SF. However, it is argued that in an aesthetic context, such as listening to music, emotion processes can become decoupled. The decoupling is controlled by the Appraisal process, which can assess if the context of the sadness is real-life (where coupling occurs) or aesthetic (where decoupling can occur). In an aesthetic context sadness retains its negative SF but the aversive, negative MAT is inhibited, leaving sadness to still be experienced as a negative valanced emotion, while contributing to the overall positive MAT. Individual differences, mood and previous experiences mediate the degree to which the aversive aspects of MAT are inhibited according to this Parallel Processing Hypothesis (PPH). The reason for hesitancy in considering or testing PPH, as well as the preponderance of research on sadness at the exclusion of other negative emotions, are discussed. PMID:27445752

  17. Enjoying Sad Music: Paradox or Parallel Processes?

    PubMed Central

    Schubert, Emery

    2016-01-01

    Enjoyment of negative emotions in music is seen by many as a paradox. This article argues that the paradox exists because it is difficult to view the process that generates enjoyment as being part of the same system that also generates the subjective negative feeling. Compensation theories explain the paradox as the compensation of a negative emotion by the concomitant presence of one or more positive emotions. But compensation brings us no closer to explaining the paradox because it does not explain how experiencing sadness itself is enjoyed. The solution proposed is that an emotion is determined by three critical processes—labeled motivational action tendency (MAT), subjective feeling (SF) and Appraisal. For many emotions the MAT and SF processes are coupled in valence. For example, happiness has positive MAT and positive SF, annoyance has negative MAT and negative SF. However, it is argued that in an aesthetic context, such as listening to music, emotion processes can become decoupled. The decoupling is controlled by the Appraisal process, which can assess if the context of the sadness is real-life (where coupling occurs) or aesthetic (where decoupling can occur). In an aesthetic context sadness retains its negative SF but the aversive, negative MAT is inhibited, leaving sadness to still be experienced as a negative valanced emotion, while contributing to the overall positive MAT. Individual differences, mood and previous experiences mediate the degree to which the aversive aspects of MAT are inhibited according to this Parallel Processing Hypothesis (PPH). The reason for hesitancy in considering or testing PPH, as well as the preponderance of research on sadness at the exclusion of other negative emotions, are discussed. PMID:27445752

  18. Quantum structure in economics: The Ellsberg paradox

    NASA Astrophysics Data System (ADS)

    Aerts, Diederik; Sozzo, Sandro

    2012-03-01

    The expected utility hypothesis and Savage's Sure-Thing Principle are violated in real life decisions, as shown by the Allais and Ellsberg paradoxes. The popular explanation in terms of ambiguity aversion is not completely accepted. As a consequence, uncertainty is still problematical in economics. To overcome these difficulties a distinction between risk and ambiguity has been introduced which depends on the existence of a Kolmogorovian probabilistic structure modeling these uncertainties. On the other hand, evidence of everyday life suggests that context plays a fundamental role in human decisions under uncertainty. Moreover, it is well known from physics that any probabilistic structure modeling contextual interactions between entities structurally needs a non-Kolmogorovian framework admitting a quantum-like representation. For this reason, we have recently introduced a notion of contextual risk to mathematically capture situations in which ambiguity occurs. We prove in this paper that the contextual risk approach can be applied to the Ellsberg paradox, and elaborate a sphere model within our hidden measurement formalism which reveals that it is the overall conceptual landscape that is responsible of the disagreement between actual human decisions and the predictions of expected utility theory, which generates the paradox. This result points to the presence of a quantum conceptual layer in human thought which is superposed to the usually assumed classical logical layer, and conceptually supports the thesis of several authors suggesting the presence of quantum structure in economics and decision theory.

  19. Solving the hard problem of Bertrand's paradox

    SciTech Connect

    Aerts, Diederik; Sassoli de Bianchi, Massimiliano

    2014-08-15

    Bertrand's paradox is a famous problem of probability theory, pointing to a possible inconsistency in Laplace's principle of insufficient reason. In this article, we show that Bertrand's paradox contains two different problems: an “easy” problem and a “hard” problem. The easy problem can be solved by formulating Bertrand's question in sufficiently precise terms, so allowing for a non-ambiguous modelization of the entity subjected to the randomization. We then show that once the easy problem is settled, also the hard problem becomes solvable, provided Laplace's principle of insufficient reason is applied not to the outcomes of the experiment, but to the different possible “ways of selecting” an interaction between the entity under investigation and that producing the randomization. This consists in evaluating a huge average over all possible “ways of selecting” an interaction, which we call a universal average. Following a strategy similar to that used in the definition of the Wiener measure, we calculate such universal average and therefore solve the hard problem of Bertrand's paradox. The link between Bertrand's problem of probability theory and the measurement problem of quantum mechanics is also briefly discussed.

  20. A Probabilistic Analysis of the Fermi Paradox

    NASA Astrophysics Data System (ADS)

    Solomonides, Evan; Terzian, Yervant

    2016-06-01

    The Fermi paradox uses an appeal to the mediocrity principle to make it seem counterintuitive that humanity has not been contacted by extraterrestrial intelligence. A numerical, statistical analysis was conducted to determine whether this apparent loneliness is, in fact, unexpected. An inequality was derived to relate the frequency of life arising and developing technology on a suitable planet in the galaxy; the average length of time since the first broadcast of such a civilization; and a constant term. An analysis of the sphere reached thus far by human communication was also conducted, considering our local neighborhood and planets of particular interest. These analyses both conclude that the Fermi paradox is not, in fact, unexpected. By the mediocrity principle and numerical modeling, it is actually unlikely that the Earth would have been reached by extraterrestrial communication at this point. We predict that under 1% of the galaxy has been reached at all thus far, and we do not anticipate to be reached until approximately 50% of stars/planets have been reached. We offer a prediction that we should not expect this until at least 1,500 years in the future. Thus the Fermi paradox is not a shocking observation- or lack thereof- and humanity may very well be contacted within our species’ lifespan (we can begin to expect to be contacted 1,500 years in the future).

  1. Obesity and poverty paradox in developed countries.

    PubMed

    Żukiewicz-Sobczak, Wioletta; Wróblewska, Paula; Zwoliński, Jacek; Chmielewska-Badora, Jolanta; Adamczuk, Piotr; Krasowska, Ewelina; Zagórski, Jerzy; Oniszczuk, Anna; Piątek, Jacek; Silny, Wojciech

    2014-01-01

    Obesity is a civilization disease and the proportion of people suffering from it continues to grow, especially in the developed countries. Number of obese people in Europe has increased threefold over the last 20 years. The paradox of obesity and poverty relationship is observed especially in the developed and developing countries. In developing countries, along with economic development and income growth, the number of people with overweight and obesity is increasing. This paradox has a relationship with both the easy availability and low cost of highly processed foods containing 'empty calories' and no nutritional value. To date, this paradox has been described in the United States and the United Kingdom, although many European countries are also experiencing high percentages of obese people. Among the reasons for the growing obesity in the population of poor people are: higher unemployment, lower education level, and irregular meals. Another cause of obesity is low physical activity, which among the poor is associated with a lack of money for sports equipment. Due to the large rate of deaths caused by diseases directly linked to obesity, the governments of many countries implement prevention programmes of overweight and obesity. These programmes are based primarily on educating the public about a healthy lifestyle based on healthy eating, daily physical activity and avoiding alcohol and cigarettes. PMID:25292135

  2. Fermi's Paradox - The Last Challenge For Copernicanism?

    NASA Astrophysics Data System (ADS)

    Cirkovic, M. M.

    2009-06-01

    We review Fermi's paradox (or the "Great Silence" problem), not only arguably the oldest and crucial problem for the Search for ExtraTerrestrial Intelligence (SETI), but also a conundrum of profound scientific, philosophical and cultural importance. By a simple analysis of observation selection effects, the correct resolution of Fermi's paradox is certain to tell us something about the future of humanity. Already more than three quarters of century old puzzle -- and a quarter of century since the last major review paper in the field by G. David Brin -- has generated many ingenious discussions and hypotheses. We analyze the often tacit methodological assumptions built in various answers to this puzzle and attempt a new classification of the numerous solutions proposed in an already huge literature on the subject. Finally, we consider the ramifications of various classes of hypotheses for the practical SETI projects. Somewhat paradoxically, it seems that the class of (neo)catastrophic hypotheses gives, on the balance, the strongest justification to optimism regarding our current and near-future SETI efforts.

  3. Paradoxical Herniation following Decompressive Craniectomy in the Subacute Setting

    PubMed Central

    Espinosa, Jose

    2016-01-01

    Decompressive craniectomy is reserved for extreme cases of intracranial hypertension. An uncommon complication known as paradoxical herniation has been documented within weeks to months following surgery. Here we present a unique case within days of surgery. Since standard medical treatment for intracranial hypertension will exacerbate paradoxical herniation, any abrupt neurological changes following decompressive craniectomy should be carefully investigated. Immediate treatment for paradoxical herniation is placement of the patient in the supine position with adequate hydration. Cranioplasty is the ultimate treatment option. PMID:27446619

  4. Paradoxical Herniation following Decompressive Craniectomy in the Subacute Setting.

    PubMed

    Michael, Alex P; Espinosa, Jose

    2016-01-01

    Decompressive craniectomy is reserved for extreme cases of intracranial hypertension. An uncommon complication known as paradoxical herniation has been documented within weeks to months following surgery. Here we present a unique case within days of surgery. Since standard medical treatment for intracranial hypertension will exacerbate paradoxical herniation, any abrupt neurological changes following decompressive craniectomy should be carefully investigated. Immediate treatment for paradoxical herniation is placement of the patient in the supine position with adequate hydration. Cranioplasty is the ultimate treatment option. PMID:27446619

  5. Towards a Resolution of the New Core Paradox

    NASA Astrophysics Data System (ADS)

    Driscoll, P. E.; Davies, C. J.

    2015-12-01

    Paleomagnetic observations that indicate a geodynamo as old as 4.2 Gyr are at odds with the "new core paradox", which claims insufficient energy to drive the ancient geodynamo prior to inner core nucleation. Recent upward revisions to the thermal conductivity of iron in the core strain the energy budget by increasing the conductive heat flow that must be overcome in order to drive thermal convection and maintain an ancient geodynamo. We address this paradox by computing thermal-magnetic evolutions of the Earth using a 1-D model with parameterizations for heat sources and sinks in the mantle and core. This model includes a number of important new features that have not been previous coupled in a single model. New features in the mantle model include enhanced mantle heat loss to due extrusive volcanism, crust formation and insolation, and latent heating due to magma ocean solidification. New features in the core model include realistic iron conductivities, time-dependent partitioning of light elements (O, S, and Si) between solid and liquid and their effect on the liquidus depression and gravitational energy release. Core evolutions derived from an energy model are compared to an energy-entropy model, which accounts for ohmic dissipation. We identify the conditions necessary to avoid shut-down of the geodynamo prior to inner core nucleation and to maintain a strong magnetic field over the last 4.2 Gyr. Using a dipole field scaling law derived from numerical dynamo models we compare the predicted paleo-dipole intensity to the paleointensity record and speculate on possible observational evidence for the inner core nucleation event.

  6. Increased Oil Production and Reserves Utilizing Secondary/Tertiary Recovery Techniques on Small Reservoirs in the Paradox Basin, Utah

    SciTech Connect

    Chidsey Jr., Thomas C.

    2003-02-06

    The primary objective of this project was to enhance domestic petroleum production by field demonstration and technology transfer of an advanced-oil-recovery technology in the Paradox Basin, southeastern Utah. If this project can demonstrate technical and economic feasibility, the technique can be applied to approximately 100 additional small fields in the Paradox Basin alone, and result in increased recovery of 150 to 200 million barrels (23,850,000-31,800,000 m3) of oil. This project was designed to characterize five shallow-shelf carbonate reservoirs in the Pennsylvanian (Desmoinesian) Paradox Formation and choose the best candidate for a pilot demonstration project for either a waterflood or carbon-dioxide-(CO2-) miscible flood project. The field demonstration, monitoring of field performance, and associated validation activities will take place within the Navajo Nation, San Juan County, Utah.

  7. Increased Oil Production and Reserves Utilizing Secondary/Tertiary Recovery Techniques on Small Reservoirs in the Paradox Basin, Utah

    SciTech Connect

    Jr., Chidsey, Thomas C.; Allison, M. Lee

    1999-11-02

    The primary objective of this project is to enhance domestic petroleum production by field demonstration and technology transfer of an advanced- oil-recovery technology in the Paradox basin, southeastern Utah. If this project can demonstrate technical and economic feasibility, the technique can be applied to approximately 100 additional small fields in the Paradox basin alone, and result in increased recovery of 150 to 200 million barrels (23,850,000-31,800,000 m3) of oil. This project is designed to characterize five shallow-shelf carbonate reservoirs in the Pennsylvanian (Desmoinesian) Paradox Formation and choose the best candidate for a pilot demonstration project for either a waterflood or carbon-dioxide-(CO2-) miscible flood project. The field demonstration, monitoring of field performance, and associated validation activities will take place within the Navajo Nation, San Juan County, Utah.

  8. Learning through Paradox: A Pedagogical Strategy for Exploring Contradictions and Complexity.

    ERIC Educational Resources Information Center

    Lewis, Marianne W.; Dehler, Gordon E.

    2000-01-01

    Paradox is composed of contradictions or polarities, provoking responses of anxiety or defensiveness. It can stimulate creative thinking. Strategies for learning through paradox include constructing complexity from simplicity, discovering inner paradoxes, and learning to read complexity. (SK)

  9. Effect of Paradoxical and Non-Paradoxical Self-Disclosure on Counselor Social Influence.

    ERIC Educational Resources Information Center

    Perrin, Deborah K.; Dowd, E. Thomas

    The purpose of this study was to examine the effects of counselor self-disclosure and paradoxical and nonparadoxical homework directives on subjects' reactions to the homework directive and on perceived counselor social influence. It was hypothesized that counselor self-disclosure would reduce potentially negative perceptions of paradoxical…

  10. Vitamin paradox in obesity: Deficiency or excess?

    PubMed

    Zhou, Shi-Sheng; Li, Da; Chen, Na-Na; Zhou, Yiming

    2015-08-25

    Since synthetic vitamins were used to fortify food and as supplements in the late 1930s, vitamin intake has significantly increased. This has been accompanied by an increased prevalence of obesity, a condition associated with diabetes, hypertension, cardiovascular disease, asthma and cancer. Paradoxically, obesity is often associated with low levels of fasting serum vitamins, such as folate and vitamin D. Recent studies on folic acid fortification have revealed another paradoxical phenomenon: obesity exhibits low fasting serum but high erythrocyte folate concentrations, with high levels of serum folate oxidation products. High erythrocyte folate status is known to reflect long-term excess folic acid intake, while increased folate oxidation products suggest an increased folate degradation because obesity shows an increased activity of cytochrome P450 2E1, a monooxygenase enzyme that can use folic acid as a substrate. There is also evidence that obesity increases niacin degradation, manifested by increased activity/expression of niacin-degrading enzymes and high levels of niacin metabolites. Moreover, obesity most commonly occurs in those with a low excretory reserve capacity (e.g., due to low birth weight/preterm birth) and/or a low sweat gland activity (black race and physical inactivity). These lines of evidence raise the possibility that low fasting serum vitamin status in obesity may be a compensatory response to chronic excess vitamin intake, rather than vitamin deficiency, and that obesity could be one of the manifestations of chronic vitamin poisoning. In this article, we discuss vitamin paradox in obesity from the perspective of vitamin homeostasis. PMID:26322161

  11. The paradox of strategic environmental assessment

    SciTech Connect

    Bidstrup, Morten Hansen, Anne Merrild

    2014-07-01

    Strategic Environmental Assessment (SEA) is a tool that can facilitate sustainable development and improve decision-making by introducing environmental concern early in planning processes. However, various international studies conclude that current planning practice is not taking full advantage of the tool, and we therefore define the paradox of SEA as the methodological ambiguity of non-strategic SEA. This article explores causality through at three-step case study on aggregates extraction planning in Denmark, which consists of a document analysis; a questionnaire survey and follow-up communication with key planners. Though the environmental reports on one hand largely lack strategic considerations, practitioners express an inherent will for strategy and reveal that their SEAs in fact have been an integrated part of the planning process. Institutional context is found to be the most significant barrier for a strategy and this suggests that non-strategic planning setups can prove more important than non-strategic planning in SEA practice. Planners may try to execute strategy within the confinements of SEA-restricted planning contexts; however, such efforts can be overlooked if evaluated by a narrow criterion for strategy formation. Consequently, the paradox may also spark from challenged documentation. These findings contribute to the common understanding of SEA quality; however, further research is needed on how to communicate and influence the strategic options which arguably remain inside non-strategic planning realities. - Highlights: • International studies conclude that SEAs are not strategic. = The paradox of SEA. • Even on the highest managerial level, some contexts do not leave room for strategy. • Non-strategic SEA can derive from challenged documentation. • Descriptive and emergent strategy formation can, in practice, be deemed non-strategic.

  12. On radar time and the twin ``paradox''

    NASA Astrophysics Data System (ADS)

    Dolby, Carl E.; Gull, Stephen F.

    2001-12-01

    In this paper we apply the concept of radar time (popularized by Bondi in his work on k calculus) to the well-known relativistic twin "paradox." Radar time is used to define hypersurfaces of simultaneity for a class of traveling twins, from the "immediate turn-around" case, through the "gradual turn-around" case, to the "uniformly accelerating" case. We show that this definition of simultaneity is independent of choice of coordinates, and assigns a unique time to any event (with which the traveling twin can send and receive signals), resolving some common misconceptions.

  13. Nuclear proliferation and the stability-instability paradox. Master`s thesis

    SciTech Connect

    Barretta, M.A.

    1995-06-01

    This thesis tests the theory that nuclear proliferation might enhance strategic stability by making the use of military force between possessors of nuclear weapons unlikely. It discusses the existing literature on deterrence and nonproliferation, emphasizing the stability-instability paradox. The stability-instability paradox offers an alternative to the optimism of deterrence logic, which views nuclear weapons as a beneficial and stabilizing force, and the pessimism of nonproliferation, which foresees dire consequences in the spread of nuclear weapons. The paradox is a synthesis of deterrence and nonproliferation logic because it allows for the coexistence of nuclear peace and lower levels of conventional war. Three cases of nuclear rivalry are examined. They are the United States and the Soviet Union, the Soviet Union and the People`s Republic of China, and India and Pakistan. These cases provide evidence that challenges the Waltzian argument that nuclear weapons enhance international stability by forbidding violent response to confrontations between nuclear-armed states. Nuclear powers that have employable conventional forces at their disposal, a territorial interest at stake, and exist in a condition of nuclear stalemate can, and do, engage in conventional warfare.

  14. Boxfish swimming paradox resolved: forces by the flow of water around the body promote manoeuvrability

    PubMed Central

    Van Wassenbergh, S.; van Manen, K.; Marcroft, T. A.; Alfaro, M. E.; Stamhuis, E. J.

    2015-01-01

    The shape of the carapace protecting the body of boxfishes has been attributed an important hydrodynamic role in drag reduction and in providing automatic, flow-direction realignment and is therefore used in bioinspired design of cars. However, tight swimming-course stabilization is paradoxical given the frequent, high-performance manoeuvring that boxfishes display in their spatially complex, coral reef territories. Here, by performing flow-tank measurements of hydrodynamic drag and yaw moments together with computational fluid dynamics simulations, we reverse several assumptions about the hydrodynamic role of the boxfish carapace. Firstly, despite serving as a model system in aerodynamic design, drag-reduction performance was relatively low compared with more generalized fish morphologies. Secondly, the current theory of course stabilization owing to flow over the boxfish carapace was rejected, as destabilizing moments were found consistently. This solves the boxfish swimming paradox: destabilizing moments enhance manoeuvrability, which is in accordance with the ecological demands for efficient turning and tilting. PMID:25505133

  15. Boxfish swimming paradox resolved: forces by the flow of water around the body promote manoeuvrability.

    PubMed

    Van Wassenbergh, S; van Manen, K; Marcroft, T A; Alfaro, M E; Stamhuis, E J

    2015-02-01

    The shape of the carapace protecting the body of boxfishes has been attributed an important hydrodynamic role in drag reduction and in providing automatic, flow-direction realignment and is therefore used in bioinspired design of cars. However, tight swimming-course stabilization is paradoxical given the frequent, high-performance manoeuvring that boxfishes display in their spatially complex, coral reef territories. Here, by performing flow-tank measurements of hydrodynamic drag and yaw moments together with computational fluid dynamics simulations, we reverse several assumptions about the hydrodynamic role of the boxfish carapace. Firstly, despite serving as a model system in aerodynamic design, drag-reduction performance was relatively low compared with more generalized fish morphologies. Secondly, the current theory of course stabilization owing to flow over the boxfish carapace was rejected, as destabilizing moments were found consistently. This solves the boxfish swimming paradox: destabilizing moments enhance manoeuvrability, which is in accordance with the ecological demands for efficient turning and tilting. PMID:25505133

  16. Induced Seismicity of the Paradox Valley Brine Injection

    NASA Astrophysics Data System (ADS)

    Bachmann, C. E.; Foxall, W.; Daley, T. M.

    2013-12-01

    for such a long time. We aim to get more insight of long-term processes so it can be applied to the study of Carbon Capture and Sequestration (CCS), where large volumes of carbon are injected into the underground for long-term storage. A first step is to understand the frequency magnitude distributions (FMD) of the ongoing seismicity at Paradox Valley better. We divide the events into sub-clusters and examine them individually. We find that the b-Values of the Gutenberg-Richter relationship change substantially within the different clusters from values of 0.7 to 1.2. Comparing the b-Values from this study with earlier studies of induced seismicity in from an Enhanced Geothermal System in Basel, Switzerland, we find that while the values are smaller, the overall pattern is surprisingly similar. We find the largest b-Values closest to the injection well and early on during the injections. Unlike in Basel, we can't compare co-injection and post-injection seismicity, as the injection is still ongoing. However, there are biannual 20-day shutdowns of the injection since 1999, which were implemented to reduce the risk of large magnitude events. We investigate the different behavior of the seismicity during this shut-in compared to the seismicity during the active injection.

  17. The Use of Paradoxical Intention: Self-Management through Laughter.

    ERIC Educational Resources Information Center

    Lamb, C. Sue

    1980-01-01

    Paradoxical intention helps clients separate themselves from their neurotic symptoms. The client is instructed to exaggerate the symptom and finds, paradoxically, the symptom occurs less. In provocative exaggeration symptoms are described so as to evoke laughter at the very symptom that causes anxiety. (Author)

  18. The "Paradox of Interdisciplinarity" in Australian Research Governance

    ERIC Educational Resources Information Center

    Woelert, Peter; Millar, Victoria

    2013-01-01

    This paper identifies what can be called the "paradox of interdisciplinarity" (Weingart 2000) in Australian higher education research governance and explores some of its constitutive dimensions. In the Australian context, the paradox of interdisciplinarity primarily concerns the proliferation of a programmatic discourse of…

  19. Killing Mosquitoes and Keeping Practice: Teacher Education as Sustaining Paradox

    ERIC Educational Resources Information Center

    Keiser, David Lee

    2013-01-01

    The moral and ethical charge of teaching and teacher education includes sustaining equanimity and paradox, and maintaining poise amongst contradicting policies and interests. This paper draws upon the wisdom of the Tao Te Ching to address some paradoxes in education and teacher preparation. Specifically, the article looks at four chapters of the…

  20. Bolzano's Approach to the Paradoxes of Infinity: Implications for Teaching

    ERIC Educational Resources Information Center

    Waldegg, Guillermina

    2005-01-01

    In this paper we analyze excerpts of "Paradoxes of the Infinite", the posthumous work of Bernard Bolzano (1781-1848), in order to show that Georg Cantor's (1845-1918) approach to the problem of defining actual mathematical infinity is not the most natural. In fact, Bolzano's approach to the paradoxes of infinity is more intuitive, while remaining…

  1. Paradox and Double Binds in Adventure-Based Education.

    ERIC Educational Resources Information Center

    Bacon, Stephen Barcia

    Paradox and therapeutic double bind techniques are used to overcome resistance in students with a history of success avoidance. Predictions of failure, restraining comments, and the use of paradox in the midst of an activity are defended theoretically by presenting historical roots and a rationale of effectiveness. A skill-building approach…

  2. Paradoxical bronchospasm: a potentially life threatening adverse effect of albuterol.

    PubMed

    Raghunathan, Kalpana; Nagajothi, Nagapradeep

    2006-03-01

    We report a case of paradoxical bronchospasm to both levalbuterol and albuterol. While the exact mechanism for this known adverse effect of albuterol is not known, awareness of this adverse effect can be life saving to the patient. To our knowledge, this is the first reported case of paradoxical bronchospasm to levalbuterol inhalation solution. PMID:16553105

  3. A Simple Explanation of the Classic Hydrostatic Paradox

    ERIC Educational Resources Information Center

    Kontomaris, Stylianos-Vasileios; Malamou, Anna

    2016-01-01

    An interesting problem in fluid mechanics, with significant educational importance, is the classic hydrostatic paradox. The hydrostatic paradox states the fact that in different shaped containers, with the same base area, which are filled with a liquid of the same height, the applied force by the liquid on the base of each container is exactly the…

  4. Feynman's Relativistic Electrodynamics Paradox and the Aharonov-Bohm Effect

    NASA Astrophysics Data System (ADS)

    Caprez, Adam; Batelaan, Herman

    2009-03-01

    An analysis is done of a relativistic paradox posed in the Feynman Lectures of Physics involving two interacting charges. The physical system presented is compared with similar systems that also lead to relativistic paradoxes. The momentum conservation problem for these systems is presented. The relation between the presented analysis and the ongoing debates on momentum conservation in the Aharonov-Bohm problem is discussed.

  5. THE EVAPORATION PARADOX: AN ENHANCED HYDROLOGIC CYCLE? (R824995)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  6. Linear stability and the Braess paradox in coupled-oscillator networks and electric power grids

    NASA Astrophysics Data System (ADS)

    Coletta, Tommaso; Jacquod, Philippe

    2016-03-01

    We investigate the influence that adding a new coupling has on the linear stability of the synchronous state in coupled-oscillator networks. Using a simple model, we show that, depending on its location, the new coupling can lead to enhanced or reduced stability. We extend these results to electric power grids where a new line can lead to four different scenarios corresponding to enhanced or reduced grid stability as well as increased or decreased power flows. Our analysis shows that the Braess paradox may occur in any complex coupled system, where the synchronous state may be weakened and sometimes even destroyed by additional couplings.

  7. The Hispanic paradox in cardiovascular disease and total mortality.

    PubMed

    Medina-Inojosa, Jose; Jean, Nathalie; Cortes-Bergoderi, Mery; Lopez-Jimenez, Francisco

    2014-01-01

    Health statistics and epidemiologic studies have shown that Hispanics live longer than Non Hispanic Whites, despite a high prevalence of cardiovascular disease (CVD) risk factors and an average low socioeconomic status, both strong predictors of CVD and mortality. This phenomenon has been dubbed "The Hispanic paradox" and has been demonstrated in old and contemporary cohorts. To date, no factor has been identified that could explain this phenomenon, but socio demographic factors, dietary intake and genetic predisposition have been proposed as possible explanations for the Hispanic paradox. As with the French paradox, where French were found to have a lower rate of coronary heart disease (CHD), helped to identify the role of the Mediterranean diet and wine consumption in the prevention of CHD, the Hispanic paradox could help identify protective factors against CHD. This article describes the current evidence supporting the existence of the Hispanic paradox and provides a brief review on the possible explanations. PMID:25246267

  8. Resolution of a paradox in classical electrodynamics

    SciTech Connect

    Pinto, Fabrizio

    2006-05-15

    It is an early result of electrostatics in curved space that the gravitational mass of a charge distribution changes by an amount equal to U{sub es}/c{sup 2}, where U{sub es} is the internal electrostatic potential energy and c is the speed of light, if the system is supported at rest by external forces. This fact, independently rediscovered in recent years in the case of a simple dipole, confirms a very reasonable expectation grounded in the mass-energy equivalency equation. However, it is an unsolved paradox of classical electrodynamics that the renormalized mass of an accelerated dipole calculated from the self-forces due to the distortion of the Coulomb field differs in general from that expected from the energy correction, U{sub es}/c{sup 2}, unless the acceleration is transversal to the orientation of the dipole. Here we show that this apparent paradox disappears for any dipole orientation if the self-force is evaluated by means of Whittaker's exact solution for the field of the single charge in a homogeneous gravitational field described in the Rindler metric. The discussion is supported by computer algebra results, diagrams of the electric fields distorted by gravitation, and a brief analysis of the prospects for realistic experimentation. The gravitational correction to dipole-dipole interactions is also discussed.

  9. Birthday Paradox for Multi-Collisions

    NASA Astrophysics Data System (ADS)

    Suzuki, Kazuhiro; Tonien, Dongvu; Kurosawa, Kaoru; Toyota, Koji

    In this paper, we study multi-collision probability. For a hash function H:D→R with |R|=n, it has been believed that we can find an s-collision by hashing Q=n(s-1)/s times. We first show that this probability is at most 1/s! for any s, which is very small for large s. (for example, s=n(s-1)/s) Thus the above folklore is wrong for large s. We next show that if s is small, so that we can assume Q-s≈Q, then this probability is at least 1/s!-1/2(s!)2, which is very high for small s (for example, s is a constant). Thus the above folklore is true for small s. Moreover, we show that by hashing (s!)1/s×Q+s-1(≤n) times, an s-collision is found with probability approximately 0.5 for any n and s such that (s!/n)1/s≈0. Note that if s=2, it coincides with the usual birthday paradox. Hence it is a generalization of the birthday paradox to multi-collisions.

  10. Magma chamber paradox: decompression upon replenishment

    NASA Astrophysics Data System (ADS)

    Papale, Paolo; Longo, Antonella; Montagna, Chiara Paola

    2013-04-01

    The invasion of active magma chambers by fresh magma of deeper provenance is invariably assumed to cause chamber pressurization. Pressure increase thus stands as an intuitive consequence of magma chamber replenishment. However, new numerical simulations demonstrate that pressure evolution is highly non-linear, and that decompression dominates when large density contrasts exist between injected and resident magmas. This apparent paradox originates from the compressible nature of volatile-rich magma and the dynamics of convection associated with injections of buoyant magma. While decompression can dominate in a shallow chamber, pressure increase develops in the connected deep regions of magma provenance. These results contradict classical views adopted to interpret observations at active as well as fossil magma chambers, and demonstrate that a simple reliance on intuition is insufficient: what may be perceived as a paradox - magma chamber decompression upon replenishment - is instead likely, and rooted in the complex physics that governs the multiphase, multi-component dynamics of magma transport in geometrically composite, spatially extended magmatic systems.

  11. The von Neumann Triple Point Paradox

    NASA Astrophysics Data System (ADS)

    Sanders, Richard; Tesdall, Allen M.

    We describe the problem of weak shock reflection off a wedge and discuss the triple point paradox that arises. When the shock is sufficiently weak and the wedge is thin, Mach reflection appears to be observed but is impossible according to what von Neumann originally showed in 1943. We summarize some recent numerical results for weak shock reflection problems for the unsteady transonic small disturbance equations, the nonlinear wave system, and the Euler equations. Rather than finding a standard but mathematically inadmissible Mach reflection with a shock triple point, the solutions contain a complex structure: there is a sequence of triple points and supersonic patches in a tiny region behind the leading triple point, with an expansion fan originating at each triple point. The sequence of patches may be infinite, and we refer to this structure as Guderley Mach reflection. The presence of the expansion fans at the triple points resolves the paradox. We describe some recent experimental evidence which is consistent with these numerical findings.

  12. Perspectives on the quantum Zeno paradox

    NASA Astrophysics Data System (ADS)

    Itano, Wayne M.

    2009-11-01

    As of October 2006, there were approximately 535 citations to the seminal 1977 paper of Misra and Sudarshan that pointed out the quantum Zeno paradox (more often called the quantum Zeno effect). In simple terms, the quantum Zeno effect refers to a slowing down of the evolution of a quantum state in the limit that the state is observed continuously. There has been much disagreement as to how the quantum Zeno effect should be defined and as to whether it is really a paradox, requiring new physics, or merely a consequence of "ordinary" quantum mechanics. The experiment of Itano, Heinzen, Bollinger, and Wineland, published in 1990, has been cited around 347 times and seems to be the one most often called a demonstration of the quantum Zeno effect. Given that there is disagreement as to what the quantum Zeno effect is, there naturally is disagreement as to whether that experiment demonstrated the quantum Zeno effect. Some differing perspectives regarding the quantum Zeno effect and what would constitute an experimental demonstration are discussed.

  13. Paradoxical muscle movement in human standing

    PubMed Central

    Loram, Ian D; Maganaris, Constantinos N; Lakie, Martin

    2004-01-01

    In human standing, gravity causes forward toppling about the ankle joint which is prevented by activity in the soleus and gastrocnemius muscles. It has long been assumed that when people sway forwards the calf muscles are stretched and conversely that they shorten with backward sway. Consequently, for many years, two explanations for standing stabilization have flourished. First, tonic muscle activity itself may generate adequate intrinsic ankle stiffness. Second, if intrinsic ankle stiffness is inadequate, the resistance to stretch of the calf muscles may be augmented by stretch reflexes or by central control. These explanations require that the passive tissue (Achilles' tendon, foot) transmitting the calf muscle tension is stiff. However, our recent measurements have indicated that this passive tissue is not stiff during standing. Accordingly, we predicted a counterintuitive mode of control where the muscles and body must, on average, move in opposite directions (paradoxical movements). Here we use dynamic ultrasound imaging in vivo with novel automated tracking of muscle length to test our hypothesis. We show that soleus and gastrocnemius do indeed move paradoxically, shortening when the body sways forward and lengthening when the body returns. This confirms that intrinsic ankle stiffness is too low to stabilize human standing. Moreover, it shows that the increase in active tension is associated with muscle shortening. This pattern cannot be produced by muscle stretch reflexes and can only arise from the anticipatory neural control of muscle length that is necessary for balance. PMID:15047776

  14. Simpson's paradox in psychological science: a practical guide

    PubMed Central

    Kievit, Rogier A.; Frankenhuis, Willem E.; Waldorp, Lourens J.; Borsboom, Denny

    2013-01-01

    The direction of an association at the population-level may be reversed within the subgroups comprising that population—a striking observation called Simpson's paradox. When facing this pattern, psychologists often view it as anomalous. Here, we argue that Simpson's paradox is more common than conventionally thought, and typically results in incorrect interpretations—potentially with harmful consequences. We support this claim by reviewing results from cognitive neuroscience, behavior genetics, clinical psychology, personality psychology, educational psychology, intelligence research, and simulation studies. We show that Simpson's paradox is most likely to occur when inferences are drawn across different levels of explanation (e.g., from populations to subgroups, or subgroups to individuals). We propose a set of statistical markers indicative of the paradox, and offer psychometric solutions for dealing with the paradox when encountered—including a toolbox in R for detecting Simpson's paradox. We show that explicit modeling of situations in which the paradox might occur not only prevents incorrect interpretations of data, but also results in a deeper understanding of what data tell us about the world. PMID:23964259

  15. Simpson's paradox in psychological science: a practical guide.

    PubMed

    Kievit, Rogier A; Frankenhuis, Willem E; Waldorp, Lourens J; Borsboom, Denny

    2013-01-01

    The direction of an association at the population-level may be reversed within the subgroups comprising that population-a striking observation called Simpson's paradox. When facing this pattern, psychologists often view it as anomalous. Here, we argue that Simpson's paradox is more common than conventionally thought, and typically results in incorrect interpretations-potentially with harmful consequences. We support this claim by reviewing results from cognitive neuroscience, behavior genetics, clinical psychology, personality psychology, educational psychology, intelligence research, and simulation studies. We show that Simpson's paradox is most likely to occur when inferences are drawn across different levels of explanation (e.g., from populations to subgroups, or subgroups to individuals). We propose a set of statistical markers indicative of the paradox, and offer psychometric solutions for dealing with the paradox when encountered-including a toolbox in R for detecting Simpson's paradox. We show that explicit modeling of situations in which the paradox might occur not only prevents incorrect interpretations of data, but also results in a deeper understanding of what data tell us about the world. PMID:23964259

  16. The paradox of evil/homosexuality.

    PubMed

    Woo, Juhyun

    2015-01-01

    In this article, I analyze "personal experience stories around the homosexual" that entered into the parliamentary debates on the Sexual Offences Act in Britain in the 1950s and 1960s and shaped understandings of sexual citizenship in particular ways. Specific attention is paid to the effects of political storytelling involved in the making of British sexual citizens. I explore how the paradoxical figure of the evil homosexual emerges and how politicians, in telling stories of the evil homosexuality, police the border that can effectively separate sexual outsiders from sexual citizens. I conclude with an analysis of these stories, and how their telling is closely linked to the postwar social welfare thinking in Britain. PMID:25264568

  17. Cannabinoid Hyperemesis Syndrome: A Paradoxical Cannabis Effect.

    PubMed

    Figueroa-Rivera, Ivonne Marie; Estremera-Marcial, Rodolfo; Sierra-Mercado, Marielly; Gutiérrez-Núñez, José; Toro, Doris H

    2015-01-01

    Despite well-established antiemetic properties of marijuana, there has been increasing evidence of a paradoxical effect in the gastrointestinal tract and central nervous system, given rise to a new and underrecognized clinical entity called the Cannabinoid Hyperemesis Syndrome. Reported cases in the medical literature have established a series of patients exhibiting a classical triad of symptoms: cyclic vomiting, chronic marijuana use, and compulsive bathing. We present a case of a 29-year-old man whose clinical presentation strongly correlates with cannabinoid hyperemesis syndrome. Despite a diagnosis of exclusion, this syndrome should be considered plausible in the setting of a patient with recurrent intractable vomiting and a strong history of cannabis use as presented in this case. PMID:26266060

  18. Principles, problems, and paradoxes of cosmogony

    NASA Astrophysics Data System (ADS)

    Treder, H.-J.

    The historical development of scientific theories of cosmogony since Newton and Kant is traced, with emphases on the inherent problems and paradoxes and on the evolution of the solar system. The basic conflict between the Newtonian concept of ahistorical physical processes in reversible time and the thermodynamic principle of irreversible entropy increase is seen as only partially resolved by the modern view that microscale events are reversible while macroscale events are not. It is shown that the theory of an adiabatic isentropic expansion of the universe cannot yet explain the genesis of galaxies of 10 billion stars. Kant's cosmogony of the solar system by condensation from a gas cloud is considered qualitatively valid; quantitative corrections, especially for the planets and their satellites, are discussed and related to the hypotheses of La Place. The observations of Barnard's star by van de Kamp, indicating the existence of Jupiter-like planets in almost circular orbits around it, are considered.

  19. Job engagement's paradoxical role in nurse burnout.

    PubMed

    Vinje, Hege F; Mittelmark, Maurice B

    2007-06-01

    Interviews were undertaken with 11 community health nurses and qualitative analysis sought to illuminate the ways in which job engagement was connected to their health and functioning. High job engagement followed from the nurses' deep feeling of calling to the nursing profession and contributed to a strong sense of duty and strict self-demand regarding one's own and other's levels of performance. In nine cases, perceived failures to live up to their own performance demands contributed to the nurses' near-burnout. This triggered extensive introspection and reflection, leading to positive coping and avoidance of burnout. The nurses coped by using their well-honed skills in introspection and reflection, which they had practiced habitually all their careers, to help them determine which personal and professional changes were required to maintain job engagement and satisfaction. Paradoxically, job engagement can not only promote thriving on the job, but also contribute to negative processes leading to poor functioning. PMID:17470184

  20. An epigenetic resolution of the lek paradox.

    PubMed

    Bonilla, Melvin M; Zeh, Jeanne A; Zeh, David W

    2016-04-01

    Female choice for traits signaling male genetic quality is expected to erode heritable variation in fitness, undermining the benefits of choice. Known as the lek paradox, this contradiction has motivated extensive population genetic theory, yet remains unresolved. Recent modeling by Bonduriansky and Day concludes that costly female preference is best maintained when male condition is determined by environmentally induced factors transmitted across single generations. Here, we reformulate their model in explicitly epigenetic terms, and review evidence that environmentally induced paternal effects are mediated through epigenetic changes in sperm. Noncoding RNA expression, DNA methylation and histone modifications are highly sensitive to diet, stress, toxicants and stochastic events. Epigenetic variation renews each generation and cannot be exhausted by selection. By choosing well-endowed males that produce gametes in epigenetically good states, females can increase their fitness directly through increased fertilization success or indirectly through epigenetic effects on the fitness of offspring and potentially subsequent generations. Also watch the video abstract. PMID:26928130

  1. Zeno's paradox in decision-making.

    PubMed

    Yearsley, James M; Pothos, Emmanuel M

    2016-04-13

    Classical probability theory has been influential in modelling decision processes, despite empirical findings that have been persistently paradoxical from classical perspectives. For such findings, some researchers have been successfully pursuing decision models based on quantum theory (QT). One unique feature of QT is the collapse postulate, which entails that measurements (or in decision-making, judgements) reset the state to be consistent with the measured outcome. If there is quantum structure in cognition, then there has to be evidence for the collapse postulate. A striking, a prioriprediction, is that opinion change will be slowed down (under idealized conditions frozen) by continuous judgements. In physics, this is the quantum Zeno effect. We demonstrate a quantum Zeno effect in decision-making in humans and so provide evidence that advocates the use of quantum principles in decision theory, at least in some cases. PMID:27053743

  2. The St. Petersburg paradox: An experimental solution

    NASA Astrophysics Data System (ADS)

    Da Silva, Sergio; Matsushita, Raul

    2016-03-01

    The St. Petersburg paradox refers to a gamble of infinite expected value, where people are likely to spend only a small entrance fee for it. There is a huge volume of literature that mostly concentrates on the psychophysics of the game; experiments are scant. Here, rather than focusing on the psychophysics, we offer an experimental, "physical" solution as if robots played the game. After examining the time series formed by one billion plays, we: confirm that there is no characteristic scale for this game; explicitly formulate the implied power law; and identify the type of α-stable distribution associated with the game. We find an α = 1 and, thus, the underlying distribution of the game is a Cauchy flight, as hinted by Paul Samuelson.

  3. Water conservation--whole effluent toxicity paradox.

    PubMed

    Fort, Douglas J; Meyers, Jeffrey D; Page, Michael W; Hercyk, Neta L

    2013-06-01

    Total dissolved solids (TDS) management in water has become an increasingly important topic as competition for water supply sources and the intensity of use both increase. Regulatory failure of National Pollutant Discharge Elimination System (NPDES) whole effluent toxicity (WET) tests is one of several potential factors in managing TDS concentrations in effluent. Consequently, WET tests have become a de facto concentration standard that sets the limit for the intensity of water use and the amount of water conservation feasibly obtained for a facility. Conflicting regulations dealing with the application of mixing zones and antidegradation policies can prevent water conservation and actually result in the unintended consequence of causing more water use. The impact of TDS on NPDES-required WET tests, conflicting regulations dealing with the application of mixing zones that are counter-productive to water conservation, alternative practices currently being used, and other means of rectifying this paradox are discussed. PMID:23833811

  4. The information paradox: Conflicts and resolutions

    NASA Astrophysics Data System (ADS)

    Mathur, Samir D.

    2012-11-01

    Many relativists have been long convinced that black hole evaporation leads to information loss or remnants. String theorists have however not been too worried about the issue, largely due to a belief that the Hawking argument for information loss is flawed in its details. A recently derived inequality shows that the Hawking argument for black holes with horizon can in fact be made rigorous. What happens instead is that in string theory black hole microstates have no horizons. Thus the evolution of radiation quanta with E ~ kT is modified by order unity at the horizon, and we resolve the information paradox. We discuss how it is still possible for E >> kT objects to see an approximate black hole like geometry. We also note some possible implications of this physics for the early Universe.

  5. EPR paradox, quantum nonlocality and physical reality

    NASA Astrophysics Data System (ADS)

    Kupczynski, M.

    2016-03-01

    Eighty years ago Einstein, Podolsky and Rosen demonstrated that instantaneous reduction of wave function, believed to describe completely a pair of entangled physical systems, led to EPR paradox. The paradox disappears in statistical interpretation of quantum mechanics (QM) according to which a wave function describes only an ensemble of identically prepared physical systems. QM predicts strong correlations between outcomes of measurements performed on different members of EPR pairs in far-away locations. Searching for an intuitive explanation of these correlations John Bell analysed so called local realistic hidden variable models and proved that correlations consistent with these models satisfy Bell inequalities which are violated by some predictions of QM and by experimental data. Several different local models were constructed and inequalities proven. Some eminent physicists concluded that Nature is definitely nonlocal and that it is acting according to a law of nonlocal randomness. According to these law perfectly random, but strongly correlated events, can be produced at the same time in far away locations and a local and causal explanation of their occurrence cannot be given. We strongly disagree with this conclusion and we prove the contrary by analysing in detail some influential finite sample proofs of Bell and CHSH inequalities and so called Quantum Randi Challenges. We also show how one can win so called Bell's game without violating locality of Nature. Nonlocal randomness is inconsistent with local quantum field theory, with standard model in elementary particle physics and with causal laws and adaptive dynamics prevailing in the surrounding us world. The experimental violation of Bell-type inequalities does not prove the nonlocality of Nature but it only confirms a contextual character of quantum observables and gives a strong argument against counterfactual definiteness and against a point of view according to which experimental outcomes are produced

  6. Avoiding Braess' Paradox Through Collective Intelligence

    NASA Technical Reports Server (NTRS)

    Wolpert , David H.; Tumer, Kagan

    1999-01-01

    In an Ideal Shortest Path Algorithm (ISPA), at each moment each router in a network sends all of its traffic down the path that will incur the lowest cost to that traffic. In the limit of an infinitesimally small amount of traffic for a particular router, its routing that traffic via an ISPA is optimal, as far as cost incurred by that traffic is concerned. We demonstrate though that in many cases, due to the side-effects of one router's actions on another routers performance, having routers use ISPA's is suboptimal as far as global aggregate cost is concerned, even when only used to route infinitesimally small amounts of traffic. As a particular example of this we present an instance of Braess' paradox for ISPA'S, in which adding new links to a network decreases overall throughput. We also demonstrate that load-balancing, in which the routing decisions are made to optimize the global cost incurred by all traffic currently being routed, is suboptimal as far as global cost averaged across time is concerned. This is also due to "side-effects", in this case of current routing decision on future traffic. The theory of COllective INtelligence (COIN) is concerned precisely with the issue of avoiding such deleterious side-effects. We present key concepts from that theory and use them to derive an idealized algorithm whose performance is better than that of the ISPA, even in the infinitesimal limit. We present experiments verifying this, and also showing that a machine-learning-based version of this COIN algorithm in which costs are only imprecisely estimated (a version potentially applicable in the real world) also outperforms the ISPA, despite having access to less information than does the ISPA. In particular, this COIN algorithm avoids Braess' paradox.

  7. Paradoxical proepileptic response to NMDA receptor blockade linked to cortical interneuron defect in stargazer mice.

    PubMed

    Maheshwari, Atul; Nahm, Walter K; Noebels, Jeffrey L

    2013-01-01

    Paradoxical seizure exacerbation by anti-epileptic medication is a well-known clinical phenomenon in epilepsy, but the cellular mechanisms remain unclear. One possibility is enhanced network disinhibition by unintended suppression of inhibitory interneurons. We investigated this hypothesis in the stargazer mouse model of absence epilepsy, which bears a mutation in stargazin, an AMPA receptor trafficking protein. If AMPA signaling onto inhibitory GABAergic neurons is impaired, their activation by glutamate depends critically upon NMDA receptors. Indeed, we find that stargazer seizures are exacerbated by NMDA receptor blockade with CPP (3-[(R)-2-carboxypiperazin-4-yl]-prop-2-enyl-1-phosphonic acid) and MK-801, whereas other genetic absence epilepsy models are sensitive to these antagonists. To determine how an AMPA receptor trafficking defect could lead to paradoxical network activation, we analyzed stargazin and AMPA receptor localization and found that stargazin is detected exclusively in parvalbumin-positive (PV (+)) fast-spiking interneurons in somatosensory cortex, where it is co-expressed with the AMPA receptor subunit GluA4. PV (+) cortical interneurons in stargazer show a near twofold decrease in the dendrite:soma GluA4 expression ratio compared to wild-type (WT) littermates. We explored the functional consequence of this trafficking defect on network excitability in neocortical slices. Both NMDA receptor antagonists suppressed 0 Mg (2) (+)-induced network discharges in WT but augmented bursting in stargazer cortex. Interneurons mediate this paradoxical response, since the difference between genotypes was masked by GABA receptor blockade. Our findings provide a cellular locus for AMPA receptor-dependent signaling defects in stargazer cortex and define an interneuron-dependent mechanism for paradoxical seizure exacerbation in absence epilepsy. PMID:24065886

  8. Linear optics implementation of weak values in Hardy's paradox

    SciTech Connect

    Ahnert, S.E.; Payne, M.C.

    2004-10-01

    We propose an experimental setup for the implementation of weak measurements in the context of the gedanken experiment known as Hardy's paradox. As Aharonov et al. [Y. Aharonov, A. Botero, S. Popescu, B. Reznik, and J. Tollaksen, Phys. Lett. A301, 130 (2002)] showed, these weak values form a language with which the paradox can be resolved. Our analysis shows that this language is indeed consistent and experimentally testable. It also reveals exactly how a combination of weak values can give rise to an apparently paradoxical result.

  9. A simple explanation of the classic hydrostatic paradox

    NASA Astrophysics Data System (ADS)

    Kontomaris, Stylianos-Vasileios; Malamou, Anna

    2016-07-01

    An interesting problem in fluid mechanics, with significant educational importance, is the classic hydrostatic paradox. The hydrostatic paradox states the fact that in different shaped containers, with the same base area, which are filled with a liquid of the same height, the applied force by the liquid on the base of each container is exactly the same. However, if the shape of the container is different, the amount of the liquid (and as a consequence the weight) can greatly vary. In this paper, a simple explanation of the hydrostatic paradox, specifically designed and implemented for educational purposes regarding secondary education, is provided.

  10. The relativistic velocity composition paradox and the Thomas rotation

    NASA Astrophysics Data System (ADS)

    Ungar, Abraham A.

    1989-11-01

    The relativistic velocity composition paradox of Mocanu and its resolution are presented. The paradox, which rests on the bizarre and counterintuitive non-communtativity of the relativistic velocity composition operation, when applied to noncollinear admissible velocities, led Mocanu to claim that there are “some difficulties within the framework of relativistic electrodynamics.” The paradox is resolved in this article by means of the Thomas rotation, shedding light on the role played by composite velocities in special relativity, as opposed to the role they play in Galilean relativity.

  11. The food-insecurity obesity paradox: A resource scarcity hypothesis.

    PubMed

    Dhurandhar, Emily J

    2016-08-01

    Food insecurity is paradoxically associated with obesity in the United States. Current hypotheses to explain this phenomenon are descriptive regarding the low food security population's dietary and physical activity habits, but are not mechanistic. Herein it is proposed that a resource scarcity hypothesis may explain this paradox, such that fattening is a physiologically regulated response to threatened food supply that occurs specifically in low social status individuals. Evidence that this may be occurring, the implications for addressing the food insecurity-obesity paradox, and future areas of research, are reviewed and discussed. PMID:27126969

  12. Towards a Nonviolent Alternative for the Black Hole Information Paradox

    NASA Astrophysics Data System (ADS)

    Shi, Yinbo

    In the semiclassical approximation, quantum field theory suggests that black holes eventually evaporate in a manner largely independent of their internal structure. Doing so, however, leads to a violation of unitarity of quantum mechanics, rendering the system inconsistent. One possible resolution is soft violations of locality in the near horizon region. The first consistency check is whether such a proposal can actually get the information out. Using quantum information techniques, a large class of evolutions into paired states is ruled out. More generally, information transfer can be characterized by the mutual information of a specially prepared state. Minimizing this quantity saturates a subadditivity inequality, leading to "subspace transfer"; maximizing it generically leads to an enhanced particle flux. Using the tools of effective field theory, one can then try to model the nonlocality as arising from an effective source localized near the horizon. To get information out at the right rate, this source must have a characteristic size. The horizon is altered, but nonviolent. This model also naturally accommodates black hole mining, avoiding a potential flaw. Having passed important consistency checks, nonviolent nonlocality is a viable solution to the information paradox.

  13. Intimate partner violence against women and the Nordic paradox.

    PubMed

    Gracia, Enrique; Merlo, Juan

    2016-05-01

    Nordic countries are the most gender equal countries in the world, but at the same time they have disproportionally high prevalence rates of intimate partner violence (IPV) against women. High prevalence of IPV against women, and high levels of gender equality would appear contradictory, but these apparently opposite statements appear to be true in Nordic countries, producing what could be called the 'Nordic paradox'. Despite this paradox being one of the most puzzling issues in the field, this is a research question rarely asked, and one that remains unanswered. This paper explores a number of theoretical and methodological issues that may help to understand this paradox. Efforts to understand the Nordic paradox may provide an avenue to guide new research on IPV and to respond to this major public health problem in a more effective way. PMID:27058634

  14. Maximal Parrondo's Paradox for Classical and Quantum Markov Chains

    NASA Astrophysics Data System (ADS)

    Grünbaum, F. Alberto; Pejic, Michael

    2016-02-01

    Parrondo's paradox refers to the situation where two, multi-round games with a fixed winning criteria, both with probability greater than one-half for one player to win, are combined. Using a possibly biased coin to determine the rule to employ for each round, paradoxically, the previously losing player now wins the combined game with probability greater than one-half. In this paper, we will analyze classical observed, classical hidden, and quantum versions of a game that displays this paradox. The game we have utilized is simpler than games for which this behavior has been previously noted in the classical and quantum cases. We will show that in certain situations the paradox can occur to a greater degree in the quantum version than is possible in the classical versions.

  15. Patent foramen ovale and paradoxical embolization: a historical perspective.

    PubMed Central

    Lippmann, H.; Rafferty, T.

    1993-01-01

    The use of transesophageal echocardiography for intraoperative management of critically ill patients allows for routine evaluation of foramen ovale patency. The high prevalence of preoperatively unrecognized flow-patency of this structure has led investigators to emphasize the potential for paradoxical embolization in any patient undergoing anesthesia. This perspective led us to research earliest documentation of paradoxical embolization through a patent foramen ovale as a historical issue with present day relevance. This report examines the 1877 text of Julius Cohnheim in which he described a fatal case of paradoxical embolization to the middle meningeal artery. The 1880 manuscript of Moritz Litten documenting paradoxical embolization to the lower extremity is also presented. Both translations, to our knowledge, represent the first such representations of both the original 1877 edition of Cohnheim's work and Litten's journal article. Images FIG. 1 FIG. 2 FIG. 3 FIG. 4 PMID:8256459

  16. One-Piece Faraday Generator: A Paradoxical Experiment from 1851

    ERIC Educational Resources Information Center

    Crooks, M. J.; And Others

    1978-01-01

    Describes an experiment based on Faraday's one-piece generator, where the rotating disk is replaced by a cylindrical permanent magnet. Explains the apparent paradox that an observer in an inertial frame could measure his absolute velocity. (GA)

  17. Increased Oil Production and Reserves Utilizing Secondary/Tertiary Recovery Techniques on Small Reservoirs in the Paradox Basin, Utah

    SciTech Connect

    Allison, M. Lee; Chidsey, Jr., Thomas

    1999-11-03

    The primary objective of this project is to enhance domestic petroleum production by demonstration and technology transfer of an advanced oil recovery technology in the Paradox basin, southeastern Utah. If this project can demonstrate technical and economic feasibility, the technique can be applied to about 100 additional small fields in the Paradox basin alone, and result in increased recovery of 150 to 200 million bbl of oil. This project is designed to characterize five shallow-shelf carbonate reservoirs in the Pennsylvanian (Desmoinesian) Paradox Formation and choose the best candidate for a pilot demonstration project for either a waterflood or carbon dioxide-(CO-) flood 2 project. The field demonstration, monitoring of field performance, and associated validation activities will take place in the Paradox basin within the Navajo Nation. The results of this project will be transferred to industry and other researchers through a petroleum extension service, creation of digital databases for distribution, technical workshops and seminars, field trips, technical presentations at national and regional professional meetings, and publication in newsletters and various technical or trade journals.

  18. Increased Oil Production and Reserves Utilizing Secondary/Tertiary Recovery Techniques on Small Reservoirs in the Paradox Basin, Utah.

    SciTech Connect

    Chidsey, T.C. Jr.; Lorenz, D.M.; Culham, W.E.

    1997-10-15

    The primary objective of this project is to enhance domestic petroleum production by demonstration and technology transfer of an advanced oil recovery technology in the Paradox basin, southeastern Utah. If this project can demonstrate technical and economic feasibility, the technique can be applied to approximately 100 additional small fields in the Paradox basin alone, and result in increased recovery of 150 to 200 million barrels of oil. This project is designed to characterize five shallow-shelf carbonate reservoirs in the Pennsylvanian (Desmoinesian) Paradox Formation and choose the best candidate for a pilot demonstration project for either a waterflood or carbon dioxide- (CO{sub 2}-) flood project. The field demonstration, monitoring of field performance, and associated validation activities will take place in the Paradox basin within the Navajo Nation. The results of this project will be transferred to industry and other researchers through a petroleum extension service, creation of digital databases for distribution, technical workshops and seminars, field trips, technical presentations at national and regional professional meetings, and publication in newsletters and various technical or trade journals.

  19. Unitary solution to a quantum gravity information paradox

    SciTech Connect

    Ralph, T. C.

    2007-07-15

    We consider a toy model of the interaction of a qubit with an exotic space-time containing a timelike curve. Consistency seems to require that the global evolution of the qubit be nonunitary. Given that quantum mechanics is globally unitary, this then is an example of a quantum gravity information paradox. However, we show that a careful analysis of the problem in the Heisenberg picture reveals an underlying unitarity, thus resolving the paradox.

  20. Paradoxical Cerebral Fat Embolism in Revision Hip Surgery

    PubMed Central

    Piuzzi, Nicolás S.; Zanotti, Gerardo; Comba, Fernando M.; Buttaro, Martin A.; Piccaluga, Francisco

    2014-01-01

    The incidence of clinical fat embolism syndrome (FES) is low (<1%) whilst fat embolism (FE) of marrow fat appears to occur more often (Mellor and Soni (2001)). Paradoxical brain FE may occur in patients undergoing hip orthopedic surgery who have an undocumented patent foramen ovale (PFO). We report a case of an eighty-year-old male patient, who underwent a scheduled revision hip surgery suffering a paradoxical cerebral FE. PMID:25184065

  1. Brownian motion and gambling: from ratchets to paradoxical games

    NASA Astrophysics Data System (ADS)

    Parrondo, J. M. R.; Dinís, Luis

    2004-02-01

    Two losing gambling games, when alternated in a periodic or random fashion, can produce a winning game. This paradox has been inspired by certain physical systems capable of rectifying fluctuations: the so-called Brownian ratchets. In this paper we review this paradox, from Brownian ratchets to the most recent studies on collective games, providing some intuitive explanations of the unexpected phenomena that we will find along the way.

  2. A photochemical answer to the 'xenon paradox'

    NASA Astrophysics Data System (ADS)

    Hébrard; Marty, B.

    2012-12-01

    Xenon is depleted by one order of magnitude relative to other volatile elements when normalized to the chondritic composition. Furthermore, atmospheric xenon is far more enriched in the heavy isotopes relatively to chondritic and solar compositions (3-4%.amu-1) than atmospheric krypton (< 1%.amu-1). This discrepancy, known as the 'xenon paradox', has led to sophisticated models of atmospheric evolution coupled with mantle geodynamics (Pepin, 1991; Tolstikhin and Marty, 1998) and cometary contributions (Dauphas, 2003; Owen et al., 1992) that could explain terrestrial noble gas patterns under ad hoc conditions during the building stages of the Earth, no more than ~200 Ma following the beginning of solar system formation. Yet, xenon having an isotopic composition intermediate between the atmospheric and the chondritic ones has been recently documented in Archean (≤3 Ga-old) sedimentary rocks (Pujol et al., 2011), suggesting that isotopic fractionation of Xe occurred over a much longer period of time than previously thought, during the Hadean and the Archean eons. In that case, assuming a Rayleigh type isotope evolution for atmospheric Xe requires an enrichment fractionation factor of 1.3% in heavy isotopes for Xe remaining in the atmosphere. This is clearly within the range of values observed in laboratory experiments aimed at trapping and fractionating Xe isotopes in solids, which is only effective upon ionization (Marrocchi et al., 2011; Kuga et al., 2012). We report here a possibility for explaining the 'xenon paradox' through interaction of the Hadean/Archean atmosphere with EUV light from the young Sun. By using a new photochemical model, we have found out that atmospheric Xe depletion and enrichment in heavy Xe isotopes could be achieved by EUV photoionization deep enough in the atmosphere to allow the preferential implantation of the heavier Xe isotopes in organic aerosols, the formation of which is itself triggered by UV photochemistry. Most of the ionized

  3. Is the faint young Sun paradox solved?

    NASA Astrophysics Data System (ADS)

    Wolf, E. T.; Toon, O. B.

    2013-12-01

    How did the early Earth remain warm despite weak solar luminosity? The faint young Sun paradox has stubbornly resisted a self-consistent solution since it was first introduced by Sagan and Mullen [1] over four decades ago. However, recent revisions to expected paleo-ocean temperatures [2, 3] along with new results from three-dimensional climate models [4] may allow this long standing problem to be finally put to rest. Here we use a modified version of the Community Atmosphere Model version 3 from the National Center for Atmospheric Research to study early climate. We find that resolving the faint young Sun paradox becomes less problematic when viewing a full representation of the climate system. For the late Archean climate (80% solar constant), relatively modest amounts of CO2 (≤0.02 bar) and CH4 (0.001 bar) yield surface temperatures equal to the present day with no other alterations to climate. Cooler climates with large ice caps but with temperate tropical regions can be supported with considerably smaller greenhouse gas burdens. The incorporation of systematic climate system elements expected for the Archean such as fewer cloud condensation nuclei (CCN) [5], reduced land albedos [5], and an increased atmospheric inventory of N2 [6], can provide a combined 10 to 20 K of additional surface warming given reasonable assumptions. With the inclusion of 0.001 bar of CH4, 2 PAL of N2, reduced land albedos, and reduced CCN, present day mean surface temperatures can be maintained for the earliest Archean (75% solar constant) with only ~0.01 bar of CO2. However, lower requirements for atmospheric CO2 may imply that photochemical hazes were frequent during the Archean. [1] Sagan, C., & Mullen, G. Science 177, 52 (1972) [2] Hren, M.T., Tice, M.M., & Chamberlin, C.P. Nature 462, 205 (2009) [3] Blake. R.E., Chang, S.J., & Lepland, A. Nature 464, 1029 (2010) [4] Wolf, E.T., & Toon, O.B. Astrobiology 13(7), 1 (2013) [5] Rosing, M.T., Bird, D.K., Sleep, N.H., & Bjerrum, C

  4. The paradox of enrichment in metaecosystems.

    PubMed

    Gounand, Isabelle; Mouquet, Nicolas; Canard, Elsa; Guichard, Frédéric; Hauzy, Céline; Gravel, Dominique

    2014-12-01

    The paradox of enrichment has been studied almost exclusively within communities or metacommunities, without explicit nutrient dynamics. Yet local recycling of materials from enriched ecosystems may affect the stability of connected ecosystems. Here we study the effect of nutrient, detritus, producer, and consumer spatial flows-combined with changes in regional enrichment-on the stability of a metaecosystem model. We considered both spatially homogeneous and heterogeneous enrichment. We found that nutrient and detritus spatial flows are destabilizing, whereas producer or consumer spatial flows are either neutral or stabilizing. We noticed that detritus spatial flows have only a weak impact on stability. Our study reveals that heterogeneity no longer stabilizes well-connected systems when accounting for explicit representation of nutrient dynamics. We also found that intermediate consumer diffusion could lead to multiple equilibria in strongly enriched metaecosystems. Stability can emerge from a top-down control allowing the storage of materials into inorganic form, a mechanism never documented before. In conclusion, local enrichment can be stabilized if spatial flows are strong enough to efficiently redistribute the local excess of enrichment to unfertile ecosystems. However, high regional enrichment can be dampened only by intermediate consumer diffusion rates. PMID:25438175

  5. Resolving the paradox of suboptimal choice.

    PubMed

    Zentall, Thomas R

    2016-01-01

    When humans engage in commercial (totally probabilistic) gambling they are making suboptimal choices because the return is generally less than the investment. This review (a) examines the literature on pigeon suboptimal choice, (b) describes the conditions under which it occurs, (c) identifies the mechanisms that appear to be responsible for the effect, and (d) suggests that similar processes may be able to account for analogous suboptimal choice when humans engage in commercial gambling. Pigeons show suboptimal choice when they choose between 1 alternative that 20% of the time provides them with a signal that they will always get fed or 80% of the time with a signal that they will not get fed (overall 20% reinforcement) and a second alternative that 100% of the time provides them with a signal that they will get fed 50% of the time (overall 50% reinforcement). The pigeons' strong preference for the suboptimal choice was investigated in a series of experiments that found the preference for the suboptimal alternative was determined by the value of the signal that predicted reinforcement, rather its frequency and that the frequency of the signal that predicted nonreinforcement had little effect on the suboptimal choice. Paradoxically, this account makes the prediction that pigeons will be indifferent between an alternative that 50% of the time provides a fully predictive stimulus for reinforcement and an alternative that 100% of the time provides a fully predictive stimulus for reinforcement. The similarities and differences of this suboptimal choice task to human gambling are discussed. PMID:26640967

  6. Paradoxical sleep as a programming system.

    PubMed

    Jouvet, M

    1998-01-01

    The concept of 'psychological individuation' i.e 'intraspecific variability' is essential for evolution as stated by Mayr (1958). It has been recently revived by the study of Bouchard (1990) in homozygous twins separated at birth and reared in different environments. These twins still retain identical psychological idiosyncratic reactions. Even if their brains are almost identical at birth, it is most likely that the different epigenetic stimuli from the external world have differently altered many cerebral synaptic circuitry due to the plasticity of the brain. Therefore, in order to maintain an identical psychological profile, there should be a mechanism which would reinforce the genetic programmation of the central nervous system either in reinforcing or erasing special genetic circuitry which would be stimulated during previous and/or subsequent waking periods. In ectothermic vertebrates, in immature mammals or sometimes in mature birds, this programming can be effectuated by neurogenesis. After neurogenesis has stopped in mammals, paradoxical sleep would be well suited for reinforcing the genetic programming during sleep. The patterns of portogeniculo-occipital (PGO) activity (which depend upon genetic factors) would be responsible for this function, together with the theta activity of the hippocampus (read out of previous waking events) and fast cortical EEG. This programming would activate all the brain including the pyramidal motor system while movements would be suppressed by the system controlling muscle atonia. PMID:9682187

  7. A paradoxical teratogenic mechanism for retinoic acid.

    PubMed

    Lee, Leo M Y; Leung, Chun-Yin; Tang, Walfred W C; Choi, Heung-Ling; Leung, Yun-Chung; McCaffery, Peter J; Wang, Chi-Chiu; Woolf, Adrian S; Shum, Alisa S W

    2012-08-21

    Retinoic acid, an active metabolite of vitamin A, plays essential signaling roles in mammalian embryogenesis. Nevertheless, it has long been recognized that overexposure to vitamin A or retinoic acid causes widespread teratogenesis in rodents as well as humans. Although it has a short half-life, exposure to high levels of retinoic acid can disrupt development of yet-to-be formed organs, including the metanephros, the embryonic organ which normally differentiates into the mature kidney. Paradoxically, it is known that either an excess or a deficiency of retinoic acid results in similar malformations in some organs, including the mammalian kidney. Accordingly, we hypothesized that excess retinoic acid is teratogenic by inducing a longer lasting, local retinoic acid deficiency. This idea was tested in an established in vivo mouse model in which exposure to excess retinoic acid well before metanephric rudiments exist leads to failure of kidney formation several days later. Results showed that teratogen exposure was followed by decreased levels of Raldh transcripts encoding retinoic acid-synthesizing enzymes and increased levels of Cyp26a1 and Cyp26b1 mRNAs encoding enzymes that catabolize retinoic acid. Concomitantly, there was significant reduction in retinoic acid levels in whole embryos and kidney rudiments. Restoration of retinoic acid levels by maternal supplementation with low doses of retinoic acid following the teratogenic insult rescued metanephric kidney development and abrogated several extrarenal developmental defects. This previously undescribed and unsuspected mechanism provides insight into the molecular pathway of retinoic acid-induced teratogenesis. PMID:22869719

  8. Variational Principles, Occam Razor and Simplicity Paradox

    NASA Astrophysics Data System (ADS)

    Berezin, Alexander A.

    2004-05-01

    Variational minimum principles (VMP) refer to energy (statics, Thomson and Earnshaw theorems in electrostatics), action (Maupertuis, Euler, Lagrange, Hamilton), light (Fermat), quantum paths (Feynman), etc. Historically, VMP appeal to some economy in nature, similarly to Occam Razor Parsimony (ORP) principle. Version of ORP are "best world" (Leibniz), Panglossianism (Voltaire), and "most interesting world" (Dyson). Conceptually, VMP exemplify curious fact that infinite set is often simpler than its subsets (e.g., set of all integers is simpler than set of primes). Algorithmically very simple number 0.1234567... (Champernowne constant) contains Library of Babel of "all books" (Borges) and codes (infinitely many times) everything countably possible. Likewise, full Megaverse (Everett, Deutsch, Guth, Linde) is simpler than our specific ("Big Bang") universe. Dynamically, VMP imply memory effects akin to hysteresis. Similar ideas are "water memory" (Benveniste, Josephson) and isotopic biology (Berezin). Paradoxically, while ORP calls for economy (simplicity), unfolding of ORP in VMP seemingly works in the opposite direction allowing for complexity emergence (e.g., symmetry breaking in Jahn-Teller effect). Metaphysical extrapolation of this complimentarity may lead to "it-from-bit" (Wheeler) reflection of why there is something rather than nothing.

  9. Conscious processing and the process goal paradox.

    PubMed

    Mullen, Richard; Hardy, Lew

    2010-06-01

    The three experiments reported here examined the process goal paradox, which has emerged from the literature on goal setting and conscious processing. We predicted that skilled but anxious performers who adopted a global movement focus using holistic process goals would outperform those who used part-oriented process goals. In line with the conscious processing hypothesis, we also predicted that performers using part process goals would experience performance impairment in test compared with baseline conditions. In all three experiments, participants performed motor tasks in baseline and test conditions. Cognitive state anxiety increased in all of the test conditions. The results confirmed our first prediction; however, we failed to find unequivocal evidence to support our second prediction. The consistent pattern of the results lends support to the suggestion that, for skilled athletes who perform under competitive pressure, using a holistic process goal that focuses attention on global aspects of a motor skill is a more effective attentional focus strategy than using a part process goal. PMID:20587818

  10. Mad about Physics: Braintwisters, Paradoxes, and Curiosities

    NASA Astrophysics Data System (ADS)

    Jargodzki, Christopher; Potter, Franklin

    2000-11-01

    Why is there eight times more ice in Antarctica than in the Arctic? Why can you warm your hands by blowing gently, and cool your hands by blowing hard? Why would a pitcher scuff a baseball?Which weighs more-a pound of feathers or a pound of iron? Let science experts Christopher Jargodzki and Franklin Potter guide you through the curiosities of physics and you'll find the answers to these and hundreds of other quirky conundrums. You'll discover why sounds carry well over water (especially in the summer), how a mouse can be levitated in a magnetic field, why backspin is so important when shooting a basketball, and whether women are indeed as strong as men. With nearly 400 questions and answers on everything from race cars to jumping fleas to vanishing elephants, Mad about Physics presents a comprehensive collection of braintwisters and paradoxes that will challenge and entertain even the brainiest of science lovers. Whether you're a physicist by trade or just want to give your brain a power workout, this collection of intriguing and unusual physics challenges will send you on a highly entertaining ride that reveals the relevance of physics in our everyday lives.

  11. Senescence and cancer: An evolving inflammatory paradox.

    PubMed

    Ruhland, Megan K; Coussens, Lisa M; Stewart, Sheila A

    2016-01-01

    The senescent phenotype was first described in 1961 as a phenomenon characterized by the cessation of cellular division. After years of debate as to whether it represented a tissue culture artifact or an important biological process, it is now appreciated that senescence plays an important role in tumorigenesis. Further, senescence is integral to normal biological processes such as embryogenesis and the maintenance of tissue homeostasis. Now with defined roles in development, wound healing, tumor promotion and tumor suppression, it is not surprising that attention has turned to refining our understanding of the mechanisms behind, and consequences of, the induction of senescence. One emerging role for senescence lies in the ability of senescence to orchestrate an inflammatory response: factors secreted by senescent cells have been identified in multiple contexts to modulate various aspects of the immune response. As with many of the previously described roles for senescence, the type of inflammation established by the senescence phenotype is varied and dependent on context. In this review, we discuss the current state of the field with a focus on the paradoxical outcomes of the senescence-induced inflammatory responses in the context of cancer. A more complete understanding of senescence and an appreciation for its complexities will be important for eventual development of senescence-targeted therapies. PMID:26453912

  12. Paradoxical Vocal Cord Motion in Pediatric Patients.

    PubMed

    Palla, John; Friedman, Aaron D

    2016-05-01

    Paradoxical vocal cord motion (PVCM), also termed vocal cord dysfunction, is a poorly understood disorder of episodic dyspnea characterized by inappropriate vocal cord adduction during inspiration and potentially during expiration. It can coexist or be confused with asthma, so appropriate diagnosis is key to optimizing treatment success. Although many patients with PVCM may have underlying psychologic issues, there is emerging evidence to suggest that this entity is not psychogenic in every patient. Both laryngeal irritants and exercise have been identified as additional contributing factors in PVCM. Diagnosis of PVCM requires awake laryngoscopic confirmation. However, many patients do not exhibit signs of PVCM during this examination, despite provocation during testing. Therefore, clinical history remains key in determining which patients should proceed with behavioral therapy under the guidance of a speech pathologist. In addition, treatment may include limiting patient exposure to potential sources of laryngeal irritation. Refractory patients may benefit from psychologic assessment and treatment. [Pediatr Ann. 2016;45(5):e184-e188.]. PMID:27171808

  13. Paradox in South Asian summer monsoon circulation change: Lower tropospheric strengthening and upper tropospheric weakening

    NASA Astrophysics Data System (ADS)

    Ma, Jian; Yu, Jin-Yi

    2014-04-01

    In the literature, there exist contradictory conclusions on the South Asian summer monsoon (SASM) precipitation and circulation changes: whether the circulation change contributes positively by strengthening or negatively by weakening to the rainfall enhancement, on a background of moisture content increase. Based on Representative Concentration Pathway 4.5 simulations by 18 Coupled Model Intercomparison Project phase 5 models, this study explains these puzzles by illustrating that the SASM circulation changes oppositely between the lower and upper troposphere, with tipping point at 450 hPa. However, this indicates a new paradox, created by competing mechanisms. By analyzing the intermodel variability, we determine that the mean advection of stratification change mechanism weakens the upper tropospheric circulation, while the enhanced surface land-sea thermal contrast strengthens the lower level and surface winds. Our moisture budget analysis shows that the SASM precipitation enhancement (8% K-1) attributes to moisture increase (5% K-1) and lower tropospheric circulation strengthening (3% K-1).

  14. Genetic Susceptibility and Predictors of Paradoxical Reactions in Buruli Ulcer

    PubMed Central

    Johnson, Roch Christian; Phillips, Richard O.; van der Veer, Eveline; van Diemen, Cleo; van der Werf, Tjip S.; Stienstra, Ymkje

    2016-01-01

    Introduction Buruli ulcer (BU) is the third most frequent mycobacterial disease in immunocompetent persons after tuberculosis and leprosy. During the last decade, eight weeks of antimicrobial treatment has become the standard of care. This treatment may be accompanied by transient clinical deterioration, known as paradoxical reaction. We investigate the incidence and the risks factors associated with paradoxical reaction in BU. Methods The lesion size of participants was assessed by careful palpation and recorded by serial acetate sheet tracings. For every time point, surface area was compared with the previous assessment. All patients received antimicrobial treatment for 8 weeks. Serum concentration of 25-hydroxyvitamin D, the primary indicator of vitamin D status, was determined in duplex for blood samples at baseline by a radioimmunoassay. We genotyped four polymorphisms in the SLC11A1 gene, previously associated with susceptibility to BU. For testing the association of genetic variants with paradoxical responses, we used a binary logistic regression analysis with the occurrence of a paradoxical response as the dependent variable. Results Paradoxical reaction occurred in 22% of the patients; the reaction was significantly associated with trunk localization (p = .039 by Χ2), larger lesions (p = .021 by Χ2) and genetic factors. The polymorphisms 3’UTR TGTG ins/ins (OR 7.19, p < .001) had a higher risk for developing paradoxical reaction compared to ins/del or del/del polymorphisms. Conclusions Paradoxical reactions are common in BU. They are associated with trunk localization, larger lesions and polymorphisms in the SLC11A1 gene. PMID:27097163

  15. Quantum Bayesian networks with application to games displaying Parrondo's paradox

    NASA Astrophysics Data System (ADS)

    Pejic, Michael

    Bayesian networks and their accompanying graphical models are widely used for prediction and analysis across many disciplines. We will reformulate these in terms of linear maps. This reformulation will suggest a natural extension, which we will show is equivalent to standard textbook quantum mechanics. Therefore, this extension will be termed quantum. However, the term quantum should not be taken to imply this extension is necessarily only of utility in situations traditionally thought of as in the domain of quantum mechanics. In principle, it may be employed in any modelling situation, say forecasting the weather or the stock market---it is up to experiment to determine if this extension is useful in practice. Even restricting to the domain of quantum mechanics, with this new formulation the advantages of Bayesian networks can be maintained for models incorporating quantum and mixed classical-quantum behavior. The use of these will be illustrated by various basic examples. Parrondo's paradox refers to the situation where two, multi-round games with a fixed winning criteria, both with probability greater than one-half for one player to win, are combined. Using a possibly biased coin to determine the rule to employ for each round, paradoxically, the previously losing player now wins the combined game with probabilitygreater than one-half. Using the extended Bayesian networks, we will formulate and analyze classical observed, classical hidden, and quantum versions of a game that displays this paradox, finding bounds for the discrepancy from naive expectations for the occurrence of the paradox. A quantum paradox inspired by Parrondo's paradox will also be analyzed. We will prove a bound for the discrepancy from naive expectations for this paradox as well. Games involving quantum walks that achieve this bound will be presented.

  16. Increased oil production and reserves utilizing secondary/tertiary recovery techniques on small reservoirs in the Paradox basin, Utah. Quarterly report, October 1--December 31, 1996

    SciTech Connect

    Allison, M.L.

    1997-02-01

    The primary objective of this project is to enhance domestic petroleum production by demonstration and technology transfer of an advanced oil recovery technology in the Paradox basin, southeastern Utah. If this project can demonstrate technical and economic feasibility, the technique can be applied to approximately 100 additional small fields in the Paradox basin alone, and result in increased recovery of 150 to 200 million barrels of oil. This project is designed to characterize five shallow-shelf carbonate reservoirs in the Pennsylvanian (Desmoinesian) Paradox Formation and choose the best candidate for a pilot demonstration project for either a waterflood or carbon dioxide-(CO{sub 2}) flood project. The field demonstration, monitoring of field performance, and associated validation activities will take place in the Paradox basin within the Navajo Nation. The results of this project will be transferred to industry and other researchers through a petroleum extension service, creation of digital databases for distribution, technical workshops and seminars, field trips, technical presentations at national and regional professional meetings, and publication in newsletters and various technical or trade journals. Three activities continued this quarter as part of the geological and reservoir characterization of productive carbonate buidups in the Paradox basin: (1) interpretation of new seismic data in the Mule field area, (2) reservoir engineering analysis of the Anasazi field, and (3) technology transfer.

  17. Increased oil production and reserves utilizing secondary/tertiary recovery techniques on small reservoirs in the Paradox basin, Utah. Final technical progress report, October 1--December 31, 1995

    SciTech Connect

    Allison, M.L.

    1996-01-15

    The primary objective of this project is to enhance domestic petroleum production by demonstration and technology transfer of an advanced oil recovery technology in the Paradox basin, southeastern Utah. If this project can demonstrate technical and economic feasibility, the technique can be applied to approximately 100 additional small fields in the Paradox basin alone, and result in increased recovery of 150 to 200 million barrels of oil. This project is designed to characterize five shallow-shelf carbonate reservoirs in the Pennsylvanian (Desmoinesian) Paradox Formation and choose the best candidate for a pilot demonstration project for either a waterflood or carbon dioxide-(CO{sub 2}) flood project. The field demonstration, monitoring of field performance, and associated validation activities will take place in the Paradox basin within the Navajo Nation. The results of this project will be transferred to industry and other researchers through a petroleum extension service, creation of digital databases for distribution, technical workshops and seminars, field trips, technical presentations at national and regional professional meeting, and publication in newsletters and various technical or trade journals. Five activities continued this quarter as part of the geological and reservoir characterization of carbonate mound buildups in the Paradox basin: (1) regional facies evaluation, (2) evaluation of outcrop analogues, (3) field-scale geologic analysis, (4) reservoir analysis, and (5) technology transfer.

  18. Increased oil production and reserves utilizing secondary/tertiary recovery techniques on small reservoirs in the Paradox basin, Utah. Technical progress report, July 1--September 30, 1995

    SciTech Connect

    Allison, M.L.

    1995-12-01

    The primary objective of this project is to enhance domestic petroleum production by demonstration and technology transfer of an advanced oil recovery technology in the Paradox basin, southeastern Utah. If this project can demonstrate technical and economic feasibility, the technique can be applied to approximately 100 additional small fields in the Paradox basin alone, and result in increased recovery of 150 to 200 million barrels of oil. This project is designed to characterize five shallow-shelf carbonate reservoirs in the Pennsylvanian (Desmoinesian) Paradox Formation and choose the best candidate for a pilot demonstration project for either a waterflood or carbon dioxide-(CO{sub 2}-) flood project. The field demonstration, monitoring of field performance, and associated validation activities will take place in the Paradox basin within the Navajo Nation. The results of this project will be transferred to industry and other researchers through a petroleum extension service, creation of digital databases for distribution, technical workshops and seminars, field trips, technical presentations at national and regional professional meetings, and publication in newsletters and various technical or trade journals. Four activities continued this quarter as part of the geological and reservoir characterization of carbonate mound buildups in the Paradox basin: (1) field studies, (2) development well completion operations, (3) reservoir analysis and modeling, and (4) technology transfer. This paper reviews the status.

  19. Heterogeneous Shallow-Shelf Carbonate Buildups in the Paradox Basin, Utah and Colorado: Targets for Increased Oil Production and Reserves Using Horizontal Drilling Techniques

    SciTech Connect

    Chidsey, Jr., Thomas C.; Eby, David E.; Wray, Laural L.

    2001-11-26

    The project's primary objective was to enhance domestic petroleum production by demonstration and transfer of horizontal drilling technology in the Paradox Basin, Utah, Colorado, Arizona, and New Mexico. If this project can demonstrate technical and economic feasibility, then the technique can be applied to approximately 100 additional small fields in the Paradox Basin alone, and result in increased recovery of 25 to 50 million barrels (4-8 million m3) of oil. This project was designed to characterize several shallow-shelf carbonate reservoirs in the Pennsylvanian (Desmoinesian) Paradox Formation, choose the best candidate(s) for a pilot demonstration project to drill horizontally from existing vertical wells, monitor well performance(s), and report associated validation activities.

  20. Heterogeneous Shallow-Shelf Carbonate Buildups in the Paradox Basin, Utah and Colorado: Targets for Increased Oil Production and Reserves Using Horizontal Drilling Techniques

    SciTech Connect

    Chidsey, Thomas C. Jr.; Eby, David E.; Wray, Laura L.

    2001-04-19

    The primary objective of this project was to enhance domestic petroleum production by demonstration and transfer of horizontal drilling technology in the Paradox basin, Utah, Colorado, Arizona, and New Mexico. If this project can demonstrate technical and economic feasibility, then the technique can be applied to approximately 100 additional small fields in the Paradox basin alone, and result in increased recovery of 25 to 50 million barrels (40-80 million m3) of oil. This project was designed to characterize several shallow-shelf carbonate reservoirs in the Pennsylvania (Desmoinesian) Paradox Formation, choose the best candidate(s) for a pilot demonstration project to drill horizontally from existing vertical wells, monitor well performances, and report associated validation activities.

  1. Increased oil production and reserves utilizing secondary/tertiary recovery techniques on small reservoirs in the Paradox Basin, Utah, Class II

    SciTech Connect

    Chidsey, Thomas C.

    2000-07-28

    The primary objective of this project is to enhance domestic petroleum production by field demonstration and technology transfer of an advanced-oil-recovery technology in the Paradox basin, southeastern Utah. If this project can demonstrate technical and economic feasibility, the technique can be applied to approximately 100 additional small fields in the Paradox basin alone, and result in increased recovery of 150 to 200 million barrels (23,850,000-31,800,000 m{sup 3}) of oil. This project is designed to characterize five shallow-shelf carbonate reservoirs in the Pennsylvanian (Desmoinesian) Paradox Formation and choose the best candidate for a pilot demonstration project for either a waterflood or carbon-dioxide-miscible flood project. The field demonstration, monitoring of field performance, and associated validation activities will take place within the Navajo Nation, San Juan County, Utah.

  2. Paradoxical monocular stereopsis and perspective vergence

    NASA Technical Reports Server (NTRS)

    Enright, J. T.

    1989-01-01

    The question of how to most effectively convey depth in a picture is a multifaceted problem, both because of potential limitations of the chosen medium (stereopsis, image motion), and because effectiveness can be defined in various ways. Practical applications usually focus on information transfer, i.e., effective techniques for evoking recognition of implied depth relationships, but this issue depends on subjective judgements which are difficult to scale when stimuli are above threshold. Two new approaches to this question are proposed here which are based on alternative criteria for effectiveness. Paradoxical monocular stereopsis is a remarkably compelling impression of depth which is evoked during one-eyed viewing of only certain illustrations; it can be unequivocally recognized because the feeling of depth collapses when one shifts to binocular viewing. An exploration of the stimulus properties which are effective for this phenomenon may contribute useful answers for the more general perceptual problem. Positive vergence is an eye-movement response associated with changes of fixation point within a picture which implies depth; it also arises only during monocular viewing. The response is directionally appropriate (i.e., apparently nearer objects evoke convergence, and vice versa), but the magnitude of the response can be altered consistently by making relatively minor changes in the illustration. The cross-subject agreement in changes of response magnitude would permit systematic exploration to determine which stimulus configurations are most effective in evoking perspective vergence, with quantitative answers based upon this involuntary reflex. It may well be that most effective pictures in this context will embody features which would increase effectiveness of pictures in a more general sense.

  3. Bevacizumab and intraocular tumors: an intriguing paradox

    PubMed Central

    Ly, Long V.; Luyten, Gregorius P.M.; Versluis, Mieke; Grossniklaus, Hans E.; van der Velden, Pieter A.; Jager, Martine J.

    2012-01-01

    Purpose Bevacizumab, a humanized monoclonal antibody to vascular endothelial growth factor-A (VEGF-A), was originally developed as an anti-tumor treatment. In ocular oncology, it is being used to treat macular edema due to radiation retinopathy, but it may also be useful for the treatment of primary uveal melanoma (UM) or its metastases. We determined the effect of bevacizumab on the growth of B16F10 cells inside the eye and on B16F10 and UM cells cultured in vitro. Methods B16F10 melanoma cells were placed into the anterior chamber of the eye of C57Bl/6 mice and tumor growth was monitored after injection of different doses of bevacizumab or mock injection. In addition, the effect of bevacizumab on in vitro growth of B16F10 and human UM cells and on the expression of VEGF-A, GLUT-1, and HIF-1α was evaluated. Results Following intraocular injection of bevacizumab into murine B16 tumor-containing eyes, an acceleration of tumor growth was observed, with the occurrence of anterior chamber hemorrhages. Bevacizumab did not affect proliferation of B16F10 cells in vitro, while it inhibited UM cell proliferation. Expression analysis demonstrated that addition of bevacizumab under hypoxic conditions induced VEGF-A, GLUT-1 and HIF-1α in B16F10 cells as well as in UM cell lines and two of four primary UM tumor cultures. Conclusions In contrast with expectations, intraocular injection of bevacizumab stimulated B16F10 melanoma growth in murine eyes. In vitro exposure of B16 and human UM cells to bevacizumab led to paradoxical VEGF-A upregulation. The use of VEGF inhibitors for treatment of macular edema (due to radiation retinopathy) after irradiation of UM should be considered carefully, because of the possible adverse effects on residual UM cells. PMID:23077404

  4. Thermal Heterogeneity in the Solar Nebula: Paradox?

    NASA Astrophysics Data System (ADS)

    Boss, A. P.

    1995-09-01

    Chondritic meteorites contain components which have experienced widely varying degrees of thermal processing, yet eventually accumulated into the same planetesimal. The strong correlation of the depletion of volatile elements in the bulk compositions of CV3 carbonaceous chondrites with condensation temperature implies that either evaporation or incomplete condensation was responsible for volatile depletion [1]. The absence of any evidence for isotopic fraction of potassium in chondrites rules out evaporation of solids in a cool nebula, as nearly any conceivable evaporative process would have led to isotopic fractionation [2]. Survival of solids condensed during a relatively hot (about 1200 K) phase of nebular evolution seems to be required [1]. Flash heating to much higher temperatures (about 2000 K) is required to melt and thermally process chondrules [3]. Fluffy Type A calcium, aluminum-rich inclusions (CAIs) appear to have condensed from a hot (about 1400 K) nebular gas [4], while Type B CAIs seem to have been flash heated [5]. However, chondrules contain FeS, possibly implying that the ambient nebula temperature was less than 700 K during the flash heating event [3]. The retention of noble gases in presolar grains found in chondrite matrices similarly limits ambient temperatures to less than about 700 K at the time of their addition [6]. Regardless of the requirements of CAI and chondrule flash heating processes, we see that chondrites contain components that appear to have been formed when the ambient nebula temperature was about 700 K, 1200 K, and 1400 K -- hence the paradox. Two types of solutions to this thermal heterogeneity paradox are possible, namely spatial or temporal thermal variations. Provided that the midplane is hot enough [7,8,9], nebular temperatures spanning the range of 1400 K to 700 K (and considerably lower temperatures) could occur at increasing altitude at fixed orbital radius and at a given time. Considering that small dust grains may

  5. Radiological Follow-up of a Cerebral Tuberculoma with a Paradoxical Response Mimicking a Brain Tumor

    PubMed Central

    Kim, Jeong-Kwon; Lee, Kyung-Hwa; Kim, Seul-Kee

    2015-01-01

    We report a case of a paradoxical response of a tuberculoma in the brain mimicking a brain tumor. A 76-year-old woman presented with a 2 week history of headache, dysarthia, and orthopnea. Brain magnetic resonance images (MRI) revealed two rim-enhancing lesions on the pons and occipital lobe, and chest computed tomography showed randomly distributed miliary nodules. The tentative diagnosis was tuberculosis (TB) of the brain and lung. She complained of right hemiparesis and worsening general weakness after taking the anti-TB medication. On the monthly follow-up images, the enhanced lesions were enlarged with increased perfusion and choline/creatinine ratio, suggesting a high grade glioma. A surgical resection was completed to diagnose the occipital lesion, and the tuberculoma was pathologically confirmed by a positive TB-polymerase chain reaction. The anti-TB medication was continued for 13 months. A follow-up MRI showed decreased size of the brain lesions associated with perilesional edema, and the clinical symptoms had improved. Brain tuberculoma could be aggravated mimicking brain malignancy during administration of anti-TB medication. This paradoxical response can be effectively managed by continuing the anti-TB drugs. PMID:25932302

  6. Paradoxic effects of metformin on endothelial cells and angiogenesis.

    PubMed

    Dallaglio, Katiuscia; Bruno, Antonino; Cantelmo, Anna R; Esposito, Alessia I; Ruggiero, Luca; Orecchioni, Stefania; Calleri, Angelica; Bertolini, Francesco; Pfeffer, Ulrich; Noonan, Douglas M; Albini, Adriana

    2014-05-01

    The biguanide metformin is used in type 2 diabetes management and has gained significant attention as a potential cancer preventive agent. Angioprevention represents a mechanism of chemoprevention, yet conflicting data concerning the antiangiogenic action of metformin have emerged. Here, we clarify some of the contradictory effects of metformin on endothelial cells and angiogenesis, using in vitro and in vivo assays combined with transcriptomic and protein array approaches. Metformin inhibits formation of capillary-like networks by endothelial cells; this effect is partially dependent on the energy sensor adenosine-monophosphate-activated protein kinase (AMPK) as shown by small interfering RNA knockdown. Gene expression profiling of human umbilical vein endothelial cells revealed a paradoxical modulation of several angiogenesis-associated genes and proteins by metformin, with short-term induction of vascular endothelial growth factor (VEGF), cyclooxygenase 2 and CXC chemokine receptor 4 at the messenger RNA level and downregulation of ADAMTS1. Antibody array analysis shows an essentially opposite regulation of numerous angiogenesis-associated proteins in endothelial and breast cancer cells including interleukin-8, angiogenin and TIMP-1, as well as selective regulation of angiopioetin-1, -2, endoglin and others. Endothelial cell production of the cytochrome P450 member CYP1B1 is upregulated by tumor cell supernatants in an AMPK-dependent manner, metformin blocks this effect. Metformin inhibits VEGF-dependent activation of extracellular signal-regulated kinase 1/2, and the inhibition of AMPK activity abrogates this event. Metformin hinders angiogenesis in matrigel pellets in vivo, prevents the microvessel density increase observed in obese mice on a high-fat diet, downregulating the number of white adipose tissue endothelial precursor cells. Our data show that metformin has an antiangiogenic activity in vitro and in vivo associated with a contradictory short

  7. The archaeal molecular chaperone machine: peculiarities and paradoxes.

    PubMed Central

    Macario, A J; de Macario, E C

    1999-01-01

    A major finding within the field of archaea and molecular chaperones has been the demonstration that, while some species have the stress (heat-shock) gene hsp70(dnaK), others do not. This gene encodes Hsp70(DnaK), an essential molecular chaperone in bacteria and eukaryotes. Due to the physiological importance and the high degree of conservation of this protein, its absence in archaeal organisms has raised intriguing questions pertaining to the evolution of the chaperone machine as a whole and that of its components in particular, namely, Hsp70(DnaK), Hsp40(DnaJ), and GrpE. Another archaeal paradox is that the proteins coded by these genes are very similar to bacterial homologs, as if the genes had been received via lateral transfer from bacteria, whereas the upstream flanking regions have no bacterial markers, but instead have typical archaeal promoters, which are like those of eukaryotes. Furthermore, the chaperonin system in all archaea studied to the present, including those that possess a bacterial-like chaperone machine, is similar to that of the eukaryotic-cell cytosol. Thus, two chaperoning systems that are designed to interact with a compatible partner, e.g., the bacterial chaperone machine physiologically interacts with the bacterial but not with the eucaryal chaperonins, coexist in archaeal cells in spite of their apparent functional incompatibility. It is difficult to understand how these hybrid characteristics of the archaeal chaperoning system became established and work, if one bears in mind the classical ideas learned from studying bacteria and eukaryotes. No doubt, archaea are intriguing organisms that offer an opportunity to find novel molecules and mechanisms that will, most likely, enhance our understanding of the stress response and the protein folding and refolding processes in the three phylogenetic domains. PMID:10430558

  8. Where Was Everybody? Olaf Stapledon and the Fermi Paradox

    NASA Astrophysics Data System (ADS)

    Baxter, S.

    In 1948 Olaf Stapledon gave an address to the BIS in which he summarised his vision of mankind's cosmic future: `One can imagine some sort of cosmical community of worlds ...' One might ask, however, since the universe is vastly older than mankind, why races on other worlds have not already built such a community. This is a `Fermi Paradox' question. The Paradox is based on the observation that there has been time for extraterrestrial intelligence to arise and colonise the Galaxy many times over, yet we see no sign of such endeavours. In this paper Stapledon's novels are retrospectively analysed from the point of view of the Fermi Paradox. In Last and First Men (1930) humanity is forever isolated because life and mind are rare in the Galaxy, and interstellar distances are too large ever to be traversed. These are classic candidate Fermi `solutions'. The `solution' implicit in Star Maker (1937) might be criticised in that it posits that humanity lives at a special epoch, with the cosmically transforming development of interstellar travel occurring a `mere' ten billion years after mankind, in a universe supposedly ~200bn years old. Stapledon died in 1950, the year the Paradox was formulated, and was probably unaware of the Paradox. However to apply retrospectively Fermi thinking to Stapledon's cosmologies is to gain a new insight into the author's philosophy.

  9. RAF inhibitors that evade paradoxical MAPK pathway activation.

    PubMed

    Zhang, Chao; Spevak, Wayne; Zhang, Ying; Burton, Elizabeth A; Ma, Yan; Habets, Gaston; Zhang, Jiazhong; Lin, Jack; Ewing, Todd; Matusow, Bernice; Tsang, Garson; Marimuthu, Adhirai; Cho, Hanna; Wu, Guoxian; Wang, Weiru; Fong, Daniel; Nguyen, Hoa; Shi, Songyuan; Womack, Patrick; Nespi, Marika; Shellooe, Rafe; Carias, Heidi; Powell, Ben; Light, Emily; Sanftner, Laura; Walters, Jason; Tsai, James; West, Brian L; Visor, Gary; Rezaei, Hamid; Lin, Paul S; Nolop, Keith; Ibrahim, Prabha N; Hirth, Peter; Bollag, Gideon

    2015-10-22

    Oncogenic activation of BRAF fuels cancer growth by constitutively promoting RAS-independent mitogen-activated protein kinase (MAPK) pathway signalling. Accordingly, RAF inhibitors have brought substantially improved personalized treatment of metastatic melanoma. However, these targeted agents have also revealed an unexpected consequence: stimulated growth of certain cancers. Structurally diverse ATP-competitive RAF inhibitors can either inhibit or paradoxically activate the MAPK pathway, depending whether activation is by BRAF mutation or by an upstream event, such as RAS mutation or receptor tyrosine kinase activation. Here we have identified next-generation RAF inhibitors (dubbed 'paradox breakers') that suppress mutant BRAF cells without activating the MAPK pathway in cells bearing upstream activation. In cells that express the same HRAS mutation prevalent in squamous tumours from patients treated with RAF inhibitors, the first-generation RAF inhibitor vemurafenib stimulated in vitro and in vivo growth and induced expression of MAPK pathway response genes; by contrast the paradox breakers PLX7904 and PLX8394 had no effect. Paradox breakers also overcame several known mechanisms of resistance to first-generation RAF inhibitors. Dissociating MAPK pathway inhibition from paradoxical activation might yield both improved safety and more durable efficacy than first-generation RAF inhibitors, a concept currently undergoing human clinical evaluation with PLX8394. PMID:26466569

  10. Pennsylvanian carbonate buildups, Paradox basin: Increasing reserves in heterogeneous, shallow-shelf reservoirs

    USGS Publications Warehouse

    Montgomery, S.L.; Chidsey, T.C., Jr.; Eby, D.E.; Lorenz, D.M.; Culham, W.E.

    1999-01-01

    Productive carbonate buildups of Pennsylvanian age in the southern Paradox basin, Utah, contain up to 200 million bbl remaining oil potentially recoverable by enhanced recovery methods. These buildups comprise over 100 satellite fields to the giant Greater Aneth field, where secondary recovery operations thus far have been concentrated. Several types of satellite buildups exist and produce oil from the Desert Creek zone of the Paradox Formation. Many of the relevant fields have undergone early abandonment; wells in Desert Creek carbonate mounds commonly produce at very high initial rates (>1000 bbl/day) and then suffer precipitous declines. An important new study focused on the detailed characterization of five separate reservoirs has resulted in significant information relevant to their future redevelopment. Completed assessment of Anasazi field suggests that phylloid algal mounds, the major productive buildup type in this area, consist of ten separate lithotypes and can be described in terms of a two-level reservoir system with an underlying high-permeability mound-core interval overlain by a lower permeability but volumetrically larger supramound (mound capping) interval. Reservoir simulations and related performance predictions indicate that CO2 flooding of these reservoirs should have considerable success in recovering remaining oil reserves.Productive carbonate buildups of Pennsylvanian age in the southern Paradox basin, Utah, contain up to 200 million bbl remaining oil potentially recoverable by enhanced recovery methods. These buildups comprise over 100 satellite fields to the giant Greater Aneth field, where secondary recovery operations thus far have been concentrated. Several types of satellite buildups exist and produce oil from the Desert Creek zone of the Paradox Formation. Many of the relevant fields have undergone early abandonment; wells in Desert Creek carbonate mounds commonly produce at very high initial rates (>1000 bbl/day) and then suffer