Distance Oracles for Time-Dependent Networks

We present the first approximate distance oracle for sparse directed networks with time-dependent arc-travel-times determined by continuous, piecewise linear, positive functions possessing the FIFO property. Our approach precomputes $(1+\epsilon)-$approximate distance summaries from selected landmark vertices to all other vertices in the network. Our oracle uses subquadratic space and time preprocessing, and provides two sublinear-time query algorithms that deliver constant and $(1+\sigma)-$approximate shortest-travel-times, respectively, for arbitrary origin-destination pairs in the network, for any constant $\sigma > \epsilon$. Our oracle is based only on the sparsity of the network, along with two quite natural assumptions about travel-time functions which allow the smooth transition towards asymmetric and time-dependent distance metrics.Comment: A preliminary version appeared as Technical Report ECOMPASS-TR-025 of EU funded research project eCOMPASS (http://www.ecompass-project.eu/). An extended abstract also appeared in the 41st International Colloquium on Automata, Languages, and Programming (ICALP 2014, track-A

Proizvodnja i kakvoća kokoši nesilica hranjenih obrocima s niskim fosforom na osnovi žitarica s dodatkom fitaze

The purpose of the present study was to evaluate the response of laying hens to the low-phosphorus diets based on different kinds of cereal grains and supplemented with microbial phytase. Laying performance, feed intake, egg shell quality as well as bone strength parameters and Ca, P, Mg and Zn contents in the bones were involved as experimental parameters. At the age of 17 weeks, 288 Lohmann Brown pullets were assigned to the six dietary treatments, each treatment consisting of 12 cages with 4 birds per one. Until the beginning of the laying period the pullets were fed a standard diet containing 145 g of crude protein and 11.3 MJ ME, 4 g non-phytate P and 10.6 g of Ca per kg feed. The experimental diets provided from the first day of laying were based on maize (diets I, II, III) or on a combination of maize, barley and wheat (diets IV, V, VI) and contained about 165 g CP and 11.2 MJ ME/kg. In diets I, III or IV and VI the level of non-phytate phosphorus was decreased to 1.41 g/kg while in control diets (III or V) the amount of non-phytate P was 3.0 g/kg. In low-P diets III and VI microbial 6-phytase was included at the level of 450 FTU/kg diet. The phosphorus level in diets did not affect the laying rate during the experimental period of 53 weeks. The higher P-level in feed enhanced egg shell strength only (P<0.01). Supplementation of low-P-diets with phytase did not affect the performance of hens, such as feed intake and egg quality, however it improved the egg shell strength as compared to low-P unsupplemented groups. Regarding strength and elasticity of the tibia, the P-level and phytase supplement were without visible effects. The best parameters that characterize the bone quality were obtained by addition of 3 g of non-phytate P level per kg of diets.Svrha ovog istraživanja bila je ocijeniti odgovor kokoši nesilica na obroke s niskim fosforom na bazi raznih vrsta žitarica s dodatkom mikrobijelne fitaze. Nesenje, unos hrane, kakvoća ljuske jaja kao i parametri čvrstoće kosti i sadržaj Ca, P, Mg i Zn u kostima bili su obuhvaćeni kao pokusni parametri. U dobi od 17 tjedana 288 pilenki Lohmann Brown izabrano je za šest hranidbenih tretmana, a svaki tretman sastojao se od 12 kaveza po 4 pilenke. Do početka nesenja pilenke su hranjene standardnim obrocima koji su sadržavali 145 g sirovih bje¬lančevina i 11.3 MJ ME, 4 g nefitinskog P i 10.6 g Ca po kilogramu hrane. Pokusni obroci su se prvog dana nesenja temeljili na kukuruzu (obro¬ci I, II, III) ili na kombinaciji kukuruza, ječma i pšenice (obroci IV, V, VI) i sadržavali su oko 165 g CP i 11.2 Mj ME/kg. U obrocima I, III ili IV i VI razina nefitinskog fosfora smanjena je na 1.41 g/kg dok je u kontrolnim obrocima (III ili V/) količina nefitinskog P bila 3.0 g/kg. U obrocima s niskim P (III i VI) uključena je mikrobijelna 6-fitaza na razini od 450 FTU/ kg obroka. Razina fosfora u obrocima nije djelovala na postotak nesivosti u pokusu od 54 tjedna. Više razine P u hrani povećale su samo čvrstoću ljuske jajeta. (P < 0,01). Dodavanje fitaze u obroke s niskim P nije dje¬lovalo na unos hrane i kakvoću jaja, međutim poboljšalo je čvrstoću ljuske jajeta u usporedbi sa skupinama s niskim P bez dodataka. Što se tiče čvrstoće i elastičnosti goljenice, razina P i dodavanje fitaze nije imalo vidljivih učinaka. Najbolji parametri koji karakteriziraju kakvoću kosti dobiveni su dodavanjem 3 g nefitinskog P na kg obroka

Scheduling Algorithms for Procrastinators

This paper presents scheduling algorithms for procrastinators, where the speed that a procrastinator executes a job increases as the due date approaches. We give optimal off-line scheduling policies for linearly increasing speed functions. We then explain the computational/numerical issues involved in implementing this policy. We next explore the online setting, showing that there exist adversaries that force any online scheduling policy to miss due dates. This impossibility result motivates the problem of minimizing the maximum interval stretch of any job; the interval stretch of a job is the job's flow time divided by the job's due date minus release time. We show that several common scheduling strategies, including the "hit-the-highest-nail" strategy beloved by procrastinators, have arbitrarily large maximum interval stretch. Then we give the "thrashing" scheduling policy and show that it is a \Theta(1) approximation algorithm for the maximum interval stretch.Comment: 12 pages, 3 figure

Etiologic predictive value of a rapid immunoassay for detection of group A streptococcus antigen from throat swabs in patients presenting with a sore throat

Context: A sore throat is a common symptom mainly caused by virus but also by a variety of bacteria such as group A betahaemolytic streptococci (GAS) often resulting in unnecessary antibiotic prescribing. Combinations of symptoms and scores are not specific enough to accurately sort out aetiology. Rapid diagnostic antigen tests (RADT) have demonstrated high sensitivity and specificity in detecting presence of GAS. Objective: Establish the probability that finding of GAS in a RADT shows a true link between symptoms and GAS while considering carriers of GAS ill from a virus. Design: Cross-sectional study comparing two groups. Setting: Emergency department (ED) also managing primary health care cases in a remote rural town with 22,000 residents. Patients/Participants: 101 consecutive children aged 3-15 years attending for a sore throat as the main complaint and 147 consecutive children of the same age attending the same ED for other reasons than an infection. Main And Secondary Outcome Measures: Positive and negative Etiologic Predictive Value (EPV). Results: Positive EPV was 98% (88-100%). Negative EPV was 98% (97-99%). The positive EPV depends on setting and findings in this study and may not be transferable to other settings. It was mathematically shown that negative EPV found in this study is valid in all other reasonable settings and hence can be transferred to any other setting. Conclusions: The evaluated RADT (Alere Test Pack+Plus With OBC Strep A) is always useful to rule out GAS infection in patients with an uncomplicated sore throat. It is often, depending on setting, useful to rule in a GAS infection in these patients

Computing Shortest Paths for Any Number of Hops

In this paper, we introduce and investigate a “new” path optimization problem that we denote the all hops optimal path (AHOP) problem. The problem involves identifying, for all hop counts, the optimal, i.e., minimum weight, path(s) between a given source and destination(s). The AHOP problem arises naturally in the context of quality-of-service (QoS) routing in networks, where routes (paths) need to be computed that provide services guarantees, e.g., delay or bandwidth, at the minimum possible “cost” (amount of resources required) to the network. Because service guarantees are typically provided through some form of resource allocation on the path (links) computed for a new request, the hop count, which captures the number of links over which resources are allocated, is a commonly used cost measure. As a result, a standard approach for determining the cheapest path available that meets a desired level of service guarantees is to compute a minimum hop shortest (optimal) path. Furthermore, for efficiency purposes, it is desirable to precompute such optimal minimum hop paths for all possible service requests. Providing this information gives rise to solving the AHOP problem. The paper’s contributions are to investigate the computational complexity of solving the AHOP problem for two of the most prevalent cost functions (path weights) in networks, namely, additive and bottleneck weights. In particular, we establish that a solution based on the Bellman–Ford algorithm is optimal for additive weights, but show that this does not hold for bottleneck weights for which a lower complexity solution exists

Epidemiology, prehospital care and outcomes of patients arriving by ambulance with dyspnoea: An observational study

Background: This study aimed to determine epidemiology and outcome for patients presenting to emergency departments (ED) with shortness of breath who were transported by ambulance. Methods: This was a planned sub-study of a prospective, interrupted time series cohort study conducted at three time points in 2014 and which included consecutive adult patients presenting to the ED with dyspnoea as a main symptom. For this sub-study, additional inclusion criteria were presentation to an ED in Australia or New Zealand and transport by ambulance. The primary outcomes of interest are the epidemiology and outcome of these patients. Analysis was by descriptive statistics and comparisons of proportions. Results: One thousand seven patients met inclusion criteria. Median age was 74 years (IQR 61-68) and 46.1 % were male. There was a high rate of co-morbidity and chronic medication use. The most common ED diagnoses were lower respiratory tract infection (including pneumonia, 22.7 %), cardiac failure (20.5%) and exacerbation of chronic obstructive pulmonary disease (19.7 %). ED disposition was hospital admission (including ICU) for 76.4 %, ICU admission for 5.6 % and death in ED in 0.9 %. Overall in-hospital mortality among admitted patients was 6.5 %. Discussion: Patients transported by ambulance with shortness of breath make up a significant proportion of ambulance caseload and have high comorbidity and high hospital admission rate. In this study, >60 % were accounted for by patients with heart failure, lower respiratory tract infection or COPD, but there were a wide range of diagnoses. This has implications for service planning, models of care and paramedic training. Conclusion: This study shows that patients transported to hospital by ambulance with shortness of breath are a complex and seriously ill group with a broad range of diagnoses. Understanding the characteristics of these patients, the range of diagnoses and their outcome can help inform training and planning of services