2,323 research outputs found
A proof of the Ryser-Brualdi-Stein conjecture for large even
A Latin square of order is an by grid filled using symbols so
that each symbol appears exactly once in each row and column. A transversal in
a Latin square is a collection of cells which share no symbol, row or column.
The Ryser-Brualdi-Stein conjecture, with origins from 1967, states that every
Latin square of order contains a transversal with cells, and a
transversal with cells if is odd. Keevash, Pokrovskiy, Sudakov and
Yepremyan recently improved the long-standing best known bounds towards this
conjecture by showing that every Latin square of order has a transversal
with cells. Here, we show, for sufficiently large ,
that every Latin square of order has a transversal with cells.
We also apply our methods to show that, for sufficiently large , every
Steiner triple system of order has a matching containing at least
edges. This improves a recent result of Keevash, Pokrovskiy, Sudakov and
Yepremyan, who found such matchings with edges, and
proves a conjecture of Brouwer from 1981 for large .Comment: 71 pages, 13 figure
Nanomaterial fate and bioavailability in freshwater environments
Given the widespread use of silver nanomaterials (AgNM), their accidental or intentional
release into the environment is inevitable. AgNM release into riverine systems is a daily
occurrence, and following their release, they will undoubtedly interact with naturally
occurring organic and inorganic particulates and sediment interfaces. At this point, AgNM's
long-term threat to freshwater ecosystems is unclear. We must develop our understanding
of AgNM fate, toxicity, and bioavailability using testing approaches that systematically
investigate AgNM environmental interaction within single-factor and multifactor systems.
This body of research aimed to comprehensively examine selected AgNM particles that
were tracked within parallel fate scenarios and toxicity and bioavailability studies. Results
showed contrasting behavior between the two tested AgNM. Findings also demonstrated
that low shear flow is a significant factor influencing the flocculation and settling rates of
AgNM, which differentially regulated the persistence and residence time of aqueous phase
AgNM within simulated riverine systems. Experiments with low shear flow showed a
significant increase in AgNM water column removal and modulated the physicochemistry
differentially compared to quiescent systems. The findings on the influence of bed
sediment interactions with waterborne AgNM demonstrated that they are a vital process
that increases the transfer and exchange of AgNM from the water column to the bed.
Toxicity studies showed how abiotic factors could modulate toxicity differentially between
aquatic species and how inorganic and organic matter can increase and decrease AgNM
toxicity. Exposure studies contrasting singular and multifactor exposures with and without
low shear flow demonstrated that they modulate the exposure of AgNM significantly
differently. In conclusion, the proof-of-concept flume designs for testing the environmental
fate and exposure of AgNM showed promise and that, with further refinement, could be
further incorporated into the life-cycle testing framework of ENMs, to produce accurate
semi-empirical coefficients for environmental models for the assessment of hazard
A general approach to transversal versions of Dirac-type theorems
Given a collection of hypergraphs with the same
vertex set, an -edge graph is a transversal if
there is a bijection such that for
each . How large does the minimum degree of each need to be so
that necessarily contains a copy of that is a transversal?
Each in the collection could be the same hypergraph, hence the minimum
degree of each needs to be large enough to ensure that .
Since its general introduction by Joos and Kim [Bull. Lond. Math. Soc., 2020,
52(3):498-504], a growing body of work has shown that in many cases this lower
bound is tight. In this paper, we give a unified approach to this problem by
providing a widely applicable sufficient condition for this lower bound to be
asymptotically tight. This is general enough to recover many previous results
in the area and obtain novel transversal variants of several classical
Dirac-type results for (powers of) Hamilton cycles. For example, we derive that
any collection of graphs on an -vertex set, each with minimum degree at
least , contains a transversal copy of the -th power of a
Hamilton cycle. This can be viewed as a rainbow version of the P\'osa-Seymour
conjecture.Comment: 21 pages, 4 figures; final version as accepted for publication in the
Bulletin of the London Mathematical Societ
Food - Media - Senses: Interdisciplinary Approaches
Food is more than just nutrition. Its preparation, presentation and consumption is a multifold communicative practice which includes the meal's design and its whole field of experience. How is food represented in cookbooks, product packaging or in paintings? How is dining semantically charged? How is the sensuality of eating treated in different cultural contexts? In order to acknowledge the material and media-related aspects of eating as a cultural praxis, experts from media studies, art history, literary studies, philosophy, experimental psychology, anthropology, food studies, cultural studies and design studies share their specific approaches
Behavior quantification as the missing link between fields: Tools for digital psychiatry and their role in the future of neurobiology
The great behavioral heterogeneity observed between individuals with the same
psychiatric disorder and even within one individual over time complicates both
clinical practice and biomedical research. However, modern technologies are an
exciting opportunity to improve behavioral characterization. Existing
psychiatry methods that are qualitative or unscalable, such as patient surveys
or clinical interviews, can now be collected at a greater capacity and analyzed
to produce new quantitative measures. Furthermore, recent capabilities for
continuous collection of passive sensor streams, such as phone GPS or
smartwatch accelerometer, open avenues of novel questioning that were
previously entirely unrealistic. Their temporally dense nature enables a
cohesive study of real-time neural and behavioral signals.
To develop comprehensive neurobiological models of psychiatric disease, it
will be critical to first develop strong methods for behavioral quantification.
There is huge potential in what can theoretically be captured by current
technologies, but this in itself presents a large computational challenge --
one that will necessitate new data processing tools, new machine learning
techniques, and ultimately a shift in how interdisciplinary work is conducted.
In my thesis, I detail research projects that take different perspectives on
digital psychiatry, subsequently tying ideas together with a concluding
discussion on the future of the field. I also provide software infrastructure
where relevant, with extensive documentation.
Major contributions include scientific arguments and proof of concept results
for daily free-form audio journals as an underappreciated psychiatry research
datatype, as well as novel stability theorems and pilot empirical success for a
proposed multi-area recurrent neural network architecture.Comment: PhD thesis cop
Studying effects of light pollution and aquacultural light regimes using the teleost model medaka (Oryzias latipes)
Light is the main cue in synchronizing daily circadian rhythm in most animals, in addition to synchronizing the perception of the year for some species. Due to the steady increase of light pollution around the world, and especially near water bodies, this study aims to investigate the effects of different light regimes. Those regimes include light pollution and the continuous light regime used in aquaculture, mainly to increase growth and delay sexual maturation, is also studied.
Firstly, light pollution levels were measured in Oslo’s main river, and the harbor area. I found that urban light pollution is severe in some places and can reach relatively deep as I detected it at 5 meters depth in the fjord. These results suggest that aquatic animals may be exposed to light pollution in the Oslo area and thus the effects should be studied.
I then investigated in a laboratory setup the effect of light pollution on the teleost model Japanese medaka (Oryzias latipes). In addition to the continuous light regime was also studied. I found several effects of the altered light regimes. The reproductive cycle was found to be desynchronized for both light regimes. The fish’s behavior was also found to be altered. Additionally, fish development was found to be affected with promoted growth and altered brain and heart morphology. The artificial light regimes were also found to affect neurochemistry and the gene expression of one pituitary gene. A clear noradrenergic response was found, with the control fish having higher noradrenergic activity. Fish exposed to light pollution had a higher serotonergic brain activity. The pituitary gonadotropin lhb was found to be decreased in the continuous light regime.
All together these results demonstrate that light pollution and continuous light clearly affect the fish, having welfare implications for aquaculture production, and suggesting that light pollution indeed affects wild fish
The mad manifesto
The “mad manifesto” project is a multidisciplinary mediated investigation into the circumstances by which mad (mentally ill, neurodivergent) or disabled (disclosed, undisclosed) students faced far more precarious circumstances with inadequate support models while attending North American universities during the pandemic teaching era (2020-2023).
Using a combination of “emergency remote teaching” archival materials such as national student datasets, universal design for learning (UDL) training models, digital classroom teaching experiments, university budgetary releases, educational technology coursewares, and lived experience expertise, this dissertation carefully retells the story of “accessibility” as it transpired in disabling classroom containers trapped within intentionally underprepared crisis superstructures. Using rhetorical models derived from critical disability studies, mad studies, social work practice, and health humanities, it then suggests radically collaborative UDL teaching practices that may better pre-empt the dynamic needs of dis/abled students whose needs remain direly underserviced.
The manifesto leaves the reader with discrete calls to action that foster more critical performances of intersectionally inclusive UDL classrooms for North American mad students, which it calls “mad-positive” facilitation techniques:
1. Seek to untie the bond that regards the digital divide and access as synonyms.
2. UDL practice requires an environment shift that prioritizes change potential.
3. Advocate against the usage of UDL as a for-all keystone of accessibility.
4. Refuse or reduce the use of technologies whose primary mandate is dataveillance.
5. Remind students and allies that university space is a non-neutral affective container.
6. Operationalize the tracking of student suicides on your home campus.
7. Seek out physical & affectual ways that your campus is harming social capital potential.
8. Revise policies and practices that are ability-adjacent imaginings of access.
9. Eliminate sanist and neuroscientific languaging from how you speak about students.
10. Vigilantly interrogate how “normal” and “belong” are socially constructed.
11. Treat lived experience expertise as a gift, not a resource to mine and to spend.
12. Create non-psychiatric routes of receiving accommodation requests in your classroom.
13. Seek out uncomfortable stories of mad exclusion and consider carceral logic’s role in it.
14. Center madness in inclusive methodologies designed to explicitly resist carceral logics.
15. Create counteraffectual classrooms that anticipate and interrupt kairotic spatial power.
16. Strive to refuse comfort and immediate intelligibility as mandatory classroom presences.
17. Create pathways that empower cozy space understandings of classroom practice.
18. Vector students wherever possible as dynamic ability constellations in assessment
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