First-Order Query Evaluation with Cardinality Conditions

We study an extension of first-order logic that allows to express cardinality conditions in a similar way as SQL's COUNT operator. The corresponding logic FOC(P) was introduced by Kuske and Schweikardt (LICS'17), who showed that query evaluation for this logic is fixed-parameter tractable on classes of structures (or databases) of bounded degree. In the present paper, we first show that the fixed-parameter tractability of FOC(P) cannot even be generalised to very simple classes of structures of unbounded degree such as unranked trees or strings with a linear order relation. Then we identify a fragment FOC1(P) of FOC(P) which is still sufficiently strong to express standard applications of SQL's COUNT operator. Our main result shows that query evaluation for FOC1(P) is fixed-parameter tractable with almost linear running time on nowhere dense classes of structures. As a corollary, we also obtain a fixed-parameter tractable algorithm for counting the number of tuples satisfying a query over nowhere dense classes of structures

On the Parameterized Intractability of Monadic Second-Order Logic

One of Courcelle's celebrated results states that if C is a class of graphs of bounded tree-width, then model-checking for monadic second order logic (MSO_2) is fixed-parameter tractable (fpt) on C by linear time parameterized algorithms, where the parameter is the tree-width plus the size of the formula. An immediate question is whether this is best possible or whether the result can be extended to classes of unbounded tree-width. In this paper we show that in terms of tree-width, the theorem cannot be extended much further. More specifically, we show that if C is a class of graphs which is closed under colourings and satisfies certain constructibility conditions and is such that the tree-width of C is not bounded by \log^{84} n then MSO_2-model checking is not fpt unless SAT can be solved in sub-exponential time. If the tree-width of C is not poly-logarithmically bounded, then MSO_2-model checking is not fpt unless all problems in the polynomial-time hierarchy can be solved in sub-exponential time

Intravitreal bevacizumab for the treatment of macular oedema secondary to branch retinal vein occlusion

Purpose: To evaluate the effect of intravitreal bevacizumab (Avastin) injections on visual acuity (VA) and foveal retinal thickness in patients with macular oedema secondary to branch retinal vein occlusion.Methods: A prospective, non-comparative, consecutive, interventional case series of 34 patients. Patients received repeated intravitreal injections of 1.25 mg bevacizumab. Main outcome measures were VA (Snellen charts and ETDRS) and retinal thickness (optical coherence tomography measurements) in a follow-up period of 6 months.Results: Patients presented at a mean age of 69 years (range 44--86). Mean duration of symptoms was 40 weeks (range 1--300). Mean (SD) VA at baseline was 0.79 (0.39) logMAR, improving to 0.51 (0.34) logMAR at 6 months (p = 0.009). Mean number of letters on the ETDRS chart at baseline was 45.3 (19.0), improving to 60.6 (19.9) at 6 months (p = 0.003). Mean (SD) retinal thickness at baseline was 474 (120) \textgreekmm, declining to 316 (41) \textgreekmm at 6 months.Conclusion: Intravitreal injection of 1.25 mg bevacizumb appears to be an effective treatment option for branch retinal vein occlusion

Size distribution prediction of nanoparticle agglomerates in a fluidized bed

Nanoparticles have acquired considerable attention from academia and industry due to their unique properties arising from the large surface area to volume ratio. A promising method to process these particles is fluidization. Furthermore, it is worth knowing that nanoparticles fluidize as clusters called agglomerates, formed by the relatively strong adhesion forces among the individual particles (1). These agglomerates are large, highly porous fractal structures; thus, easy to access but extremely fragile. During fluidization, agglomerates move, collide, break, reform, deform, and combine, which make them suitable for a wide range of applications. Nanopowders can fluidize with bubbles or uniformly, which show different dynamics that might affect the morphology of the fluidized agglomerates. In order to better understand the dynamic behaviour of the system, it is crucial to know the agglomerate size distribution within the fluidized bed. Therefore, we developed a model based on a simple force balance to predict the agglomerate size distribution, which enables the optimization of processing methods. Please click Additional Files below to see the full abstract

The heavy quark decomposition of the S-matrix and its relation to the pinch technique

We propose a decomposition of the S-matrix into individually gauge invariant sub-amplitudes, which are kinematically akin to propagators, vertices, boxes, etc. This decompsition is obtained by considering limits of the S-matrix when some or all of the external particles have masses larger than any other physical scale. We show at the one-loop level that the effective gluon self-energy so defined is physically equivalent to the corresponding gauge independent self-energy obtained in the framework of the pinch technique. The generalization of this procedure to arbitrary gluonic $n$-point functions is briefly discussed.Comment: 11 uuencoded pages, NYU-TH-94/10/0

Caffeine Supplementation Strategies Among Endurance Athletes

Caffeine is widely accepted as an endurance-performance enhancing supplement. Most scientific research studies use doses of 3–6 mg/kg of caffeine 60 min prior to exercise based on pharmacokinetics. It is not well understood whether endurance athletes employ similar supplementation strategies in practice. The purpose of this study was to investigate caffeine supplementation protocols among endurance athletes. A survey conducted on Qualtrics returned responses regarding caffeine supplementation from 254 endurance athletes (f = 134, m =120; age = 39.4 ± 13.9 y; pro = 11, current collegiate athlete = 37, recreational = 206; running = 98, triathlon = 83, cycling = 54, other = 19; training days per week = 5.4 ± 1.3). Most participants reported habitual caffeine consumption (85.0%; 41.2% multiple times daily). However, only 24.0% used caffeine supplements. A greater proportion of men (31.7%) used caffeine supplements compared with women (17.2%; p = 0.007). Caffeine use was also more prevalent among professional (45.5%) and recreational athletes (25.1%) than in collegiate athletes (9.4%). Type of sport (p = 0.641), household income (p = 0.263), education (p = 0.570) or working with a coach (p = 0.612) did not have an impact on caffeine supplementation prevalence. Of those reporting specific timing of caffeine supplementation, 49.1% and 34.9% reported consuming caffeine within 30 min of training and races respectively; 38.6 and 36.5% used caffeine 30–60 min before training and races. Recreational athletes reported consuming smaller amounts of caffeine before training (1.6 ± 1.0 mg/kg) and races (2.0 ± 1.2 mg/kg) compared with collegiate (TRG: 2.1 ± 1.2 mg/kg; RACE: 3.6 ± 0.2 mg/kg) and professional (TRG: 2.4 ± 1.1 mg/kg; RACE: 3.5 ± 0.6 mg/kg) athletes. Overall, participants reported minor to moderate perceived effectiveness of caffeine supplementation (2.31 ± 0.9 on a four-point Likert-type scale) with greatest effectiveness during longer sessions (2.8 ± 1.1). It appears that recreational athletes use lower caffeine amounts than what has been established as ergogenic in laboratory protocols; further, they consume caffeine closer to exercise compared with typical research protocols. Thus, better education of recreational athletes and additional research into alternative supplementation strategies are warranted

Caffeine Supplementation Strategies Among Endurance Athletes

Caffeine is widely accepted as an ergogenic aid for endurance performance. Many laboratory studies use doses of 3-6 mg/kg of caffeine 60 min prior to exercise. It is unclear if endurance athletes employ similar supplementation schemes in practice. Further, there is a paucity of data regarding caffeine consumption in this population. PURPOSE: The purpose of this study was to investigate caffeine supplementation strategies and consumption among endurance athletes. METHODS: A survey conducted on Qualtrics returned responses regarding caffeine supplementation from 247 endurance athletes (f = 129, m =118; age = 40.4 ± 18.4 y; pro = 11, current/former collegiate athlete = 67, recreational = 169; running = 95, triathlon = 80, cycling = 54, other = 18; training days per week = 5.4 ± 1.3). Descriptive statistics were calculated using SPSS V26. Pearson chi-square tests of independence were performed to investigate potential associations between a variety of grouping variables and caffeine use. Further, supplementation schemes were analyzed. Finally, athletes’ perception of the effectiveness of caffeine were examined. RESULTS: The majority of participants reported habitual caffeine consumption (84.2%; 34.8% multiple times daily). Yet, only 23.5% reported using caffeine supplements. A greater percentage of men (30.5%) used caffeine supplements compared with women (17.1%; p = .013). Athlete status was significantly associated with caffeine consumption (p = .004). Caffeine use was more prevalent among professional (36.4%) and recreational athletes (28.4%) compared with current/former collegiate athletes (9.0%). There were no significant differences in caffeine supplementation when comparing across type of sport (p = .505), household income (p = .191), education (p = .453) or working with a coach (p = .560). While not statistically significant (p = .064), 53.4% of those using caffeine supplements reported placing among the top 3 in their age group in the past year, compared with only 39.7% of those not using caffeine supplements. Sixty-eight athletes (27.5%) reported that they specifically timed caffeine supplementation around training (60.3% only before, 14.7% only during, 25.0% before and during sessions). Seventy-seven (31.2%) athletes reported timing caffeine intake around races (55.8% before, 13.0% during, 31.2% both). Of those reporting specific timing of caffeine use, 47.3% and 33.9% reported consuming caffeine within 30 min of training sessions and races respectively; 40.0% and 35.5% used caffeine 30-60 min before training and races; 12.7% and 36.6% reported taking caffeine \u3e60 min before training and races. The most frequently reported interval of supplementation during training (64.0%) and races (45.2%) was every 60-90 minutes. Those reporting specific amounts of caffeine consumed before training (n = 27) and races (n = 14), used 1.8 ± 1.0 mg/kg and 2.4 ± 1.3 mg/kg respectively. On average, 53.6% and 39.1% of athletes reported that caffeine exerted no effects to only minor effects during various types of training and racing respectively. A greater percentage of athletes reported moderate and major effects during more intense training as well as longer training sessions and races (52.7 - 72.7%). CONCLUSION: Most athletes in the present study did not follow typical laboratory protocols that have elicited ergogenic effects of caffeine. Better education among athletes and coaches or research into more diverse supplementation schemes are needed

Kinetics of ballistic annihilation and branching

We consider a one-dimensional model consisting of an assembly of two-velocity particles moving freely between collisions. When two particles meet, they instantaneously annihilate each other and disappear from the system. Moreover each moving particle can spontaneously generate an offspring having the same velocity as its mother with probability 1-q. This model is solved analytically in mean-field approximation and studied by numerical simulations. It is found that for q=1/2 the system exhibits a dynamical phase transition. For q<1/2, the slow dynamics of the system is governed by the coarsening of clusters of particles having the same velocities, while for q>1/2 the system relaxes rapidly towards its stationary state characterized by a distribution of small cluster sizes.Comment: 10 pages, 11 figures, uses multicol, epic, eepic and eepicemu. Also avaiable at http://mykonos.unige.ch/~rey/pubt.htm