3,522 research outputs found
Exact results for the extreme Thouless effect in a model of network dynamics
If a system undergoing phase transitions exhibits some characteristics of
both first and second order, it is said to be of 'mixed order' or to display
the Thouless effect. Such a transition is present in a simple model of a
dynamic social network, in which extreme introverts/extroverts always
cut/add random links. In particular, simulations showed that , the average fraction of cross-links between the two groups
(which serves as an 'order parameter' here), jumps dramatically when crosses the 'critical point' , as in typical
first order transitions. Yet, at criticality, there is no phase co-existence,
but the fluctuations of are much larger than in typical second order
transitions. Indeed, it was conjectured that, in the thermodynamic limit, both
the jump and the fluctuations become maximal, so that the system is said to
display an 'extreme Thouless effect.' While earlier theories are partially
successful, we provide a mean-field like approach that accounts for all known
simulation data and validates the conjecture. Moreover, for the critical system
, an analytic expression for the mesa-like stationary
distribution, , shows that it is essentially flat in a range
, with . Numerical evaluations of
provides excellent agreement with simulation data for .
For large , we find ,
though this behavior begins to set in only for . For accessible
values of , we provide a transcendental equation for an approximate
which is better than 1% down to . We conjecture how this approach
might be used to attack other systems displaying an extreme Thouless effect.Comment: 6 pages, 4 figure
Mesoscale Convective Systems and Early Development of Tropical Cyclones
This chapter studies two Tropical cyclone (TC) cases, Typhoon Dan (1999) and Typhoon Ketsana (2003), and discusses their rates of formation and relationship with the mesoscale convective activities through examining the numerical simulations of the two cases. Many TCs generate from a single mesoscale convective System (MCS) or multiple MCSs; the physical processes under these two patterns are found to include dissipation of convection leading to new eruptions of deep convection located near the edge of the dissipating convection core, ingestion of nearby convection, merging of multiple MCSs into one MCS, and merging of deep convection within the MCS associated with the aggregation of vorticity in early development stage of TCs. How these activities lead to the formation of Typhoon Ketsana has been diagnosed. The diabatic heating associated with these convective activities also help to form the TC warm core. The relationship between the rate of TC formation and early development and convection energy consumption is discussed
Dimensions of Event Quality Associated with High School Football Games: Scale Development
The current study was the first attempt to develop a scale that measures high school football event quality that could lead to sport consumption. With continued improvement of the scale, the EQS-HSF has great potential to be a valuable marketing tool to examine sport consumption behavior associated with high school football games
Identifying Key Market Demand Factors Associated with High School Basketball Tournaments
High school sports are popular in the United States and the associated state championships are often publicized, well-attended special events providing an economic impact on host communities. Understanding attendees, particularly those variables affecting market demand for high-profile interscholastic sporting events, would help athletic directors and state associations improve marketing efforts. Through an abridged adoption of the Theory of Reason Action, this study was conducted to develop a consumer profile of high school tournament spectators by understanding their sociodemographic characteristics and market demand variables. Based on a review of literature, we identified four market demand factors to influence attendance (Event Attractiveness, Economic Consideration, Local Attractiveness, and Venue Accessibility) and studied high school regional basketball tournament attendees (N = 647). The factors were tested in a confirmatory factor analysis and t-tests and general linear model found three of the factors influenced attendance, while one influenced economic spending
Unveiling multi-scale laser dynamics through time-stretch and time-lens spectroscopies
Spectro-temporal studies on the nonlinear physics of complex laser dynamics are essential in approaching its ultimate performance as well as understanding interdisciplinary problems. Unfortunately, it has long been limited by the insufficient spectro-temporal resolving power of conventional temporal and spectral analyzers, particularly when an indefinite optical signal ensemble contains polychromatic mixtures of continuous-wave (CW) and short pulse. In this work, we propose a real-time optical spectro-temporal analyzer (ROSTA) with three synchronized processing channels (i.e., multi-core) for single-shot studies on laser dynamics. It simultaneously provides temporal resolutions of ~70 ps in the time domain and 10’s ns (or 10’s MHz frame rate) in the spectral domain, as well as a high spectral resolution for multiscale optical inputs, i.e., ranging from CW to fs pulses. Its non-trivial record length of up to 6.4 ms enables continuous observations of non-repetitive optical events over an extensive time period ― equivalent to a propagation distance of ~1900 km. To showcase its practical applications, ROSTA is applied to visualize the onset of passive mode-locking of a fiber laser, and interesting phenomena, i.e., evolution from quasi-CW noise burst to strong shock, transition from fluctuation to mode-locking, and coexistence of CW and mode-locked pulses, have been spectro-temporally observed in a single-shot manner for the first time. It is anticipated that ROSTA will be a powerful technology for spectro-temporal optical diagnosis in different areas involving polychromatic transients
Metformin-mediated increase in DICER1 regulates microRNA expression and cellular senescence
Metformin, an oral hypoglycemic agent, has been used for
decades to treat type 2 diabetes mellitus. Recent studies indicate
that mice treated with metformin live longer and have fewer
manifestations of age-related chronic disease. However, the
molecular mechanisms underlying this phenotype are unknown.
Here, we show that metformin treatment increases the levels of
the microRNA-processing protein DICER1 in mice and in humans
with diabetes mellitus. Our results indicate that metformin
upregulates DICER1 through a post-transcriptional mechanism
involving the RNA-binding protein AUF1. Treatment with metformin
altered the subcellular localization of AUF1, disrupting its
interaction with DICER1 mRNA and rendering DICER1 mRNA
stable, allowing DICER1 to accumulate. Consistent with the role
of DICER1 in the biogenesis of microRNAs, we found differential
patterns of microRNA expression in mice treated with metformin
or caloric restriction, two proven life-extending interventions.
Interestingly, several microRNAs previously associated with
senescence and aging, including miR-20a, miR-34a, miR-130a,
miR-106b, miR-125, and let-7c, were found elevated. In agreement
with these findings, treatment with metformin decreased
cellular senescence in several senescence models in a DICER1-
dependent manner. Metformin lowered p16 and p21 protein
levels and the abundance of inflammatory cytokines and oncogenes
that are hallmarks of the senescence-associated secretory
phenotype (SASP). These data lead us to hypothesize that
changes in DICER1 levels may be important for organismal aging
and to propose that interventions that upregulate DICER1
expression (e.g., metformin) may offer new pharmacotherapeutic
approaches for age-related disease
Examining the Impact of Provenance-Enabled Media on Trust and Accuracy Perceptions
In recent years, industry leaders and researchers have proposed to use
technical provenance standards to address visual misinformation spread through
digitally altered media. By adding immutable and secure provenance information
such as authorship and edit date to media metadata, social media users could
potentially better assess the validity of the media they encounter. However, it
is unclear how end users would respond to provenance information, or how to
best design provenance indicators to be understandable to laypeople. We
conducted an online experiment with 595 participants from the US and UK to
investigate how provenance information altered users' accuracy perceptions and
trust in visual content shared on social media. We found that provenance
information often lowered trust and caused users to doubt deceptive media,
particularly when it revealed that the media was composited. We additionally
tested conditions where the provenance information itself was shown to be
incomplete or invalid, and found that these states have a significant impact on
participants' accuracy perceptions and trust in media, leading them, in some
cases, to disbelieve honest media. Our findings show that provenance, although
enlightening, is still not a concept well-understood by users, who confuse
media credibility with the orthogonal (albeit related) concept of provenance
credibility. We discuss how design choices may contribute to provenance
(mis)understanding, and conclude with implications for usable provenance
systems, including clearer interfaces and user education.Comment: Accepted to CSCW 202
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