Tiny Codes for Guaranteeable Delay

Future 5G systems will need to support ultra-reliable low-latency communications scenarios. From a latency-reliability viewpoint, it is inefficient to rely on average utility-based system design. Therefore, we introduce the notion of guaranteeable delay which is the average delay plus three standard deviations of the mean. We investigate the trade-off between guaranteeable delay and throughput for point-to-point wireless erasure links with unreliable and delayed feedback, by bringing together signal flow techniques to the area of coding. We use tiny codes, i.e. sliding window by coding with just 2 packets, and design three variations of selective-repeat ARQ protocols, by building on the baseline scheme, i.e. uncoded ARQ, developed by Ausavapattanakun and Nosratinia: (i) Hybrid ARQ with soft combining at the receiver; (ii) cumulative feedback-based ARQ without rate adaptation; and (iii) Coded ARQ with rate adaptation based on the cumulative feedback. Contrasting the performance of these protocols with uncoded ARQ, we demonstrate that HARQ performs only slightly better, cumulative feedback-based ARQ does not provide significant throughput while it has better average delay, and Coded ARQ can provide gains up to about 40% in terms of throughput. Coded ARQ also provides delay guarantees, and is robust to various challenges such as imperfect and delayed feedback, burst erasures, and round-trip time fluctuations. This feature may be preferable for meeting the strict end-to-end latency and reliability requirements of future use cases of ultra-reliable low-latency communications in 5G, such as mission-critical communications and industrial control for critical control messaging.Comment: to appear in IEEE JSAC Special Issue on URLLC in Wireless Network

Lifetime measurement of excited low-spin states via the (p,p′γ(p,p^{\prime}\gamma) reaction

In this article a method for lifetime measurements in the sub-picosecond regime via the Doppler-shift attenuation method (DSAM) following the inelastic proton scattering reaction is presented. In a pioneering experiment we extracted the lifetimes of 30 excited low-spin states of $^{96}$Ru, taking advantage of the coincident detection of scattered protons and de-exciting $\gamma$-rays as well as the large number of particle and $\gamma$-ray detectors provided by the SONIC@HORUS setup at the University of Cologne. The large amount of new experimental data shows that this technique is suited for the measurement of lifetimes of excited low-spin states, especially for isotopes with a low isotopic abundance, where $(n,n^{\prime}\gamma$) or - in case of investigating dipole excitations - ($\gamma,\gamma^{\prime}$) experiments are not feasible due to the lack of sufficient isotopically enriched target material

Control of Chenopodium album L. utilizing two plant pathogenic fungi in combination with reduced doses of nicosulfuron

Although biological control agents provide satisfactory weed control in solely few cases, they should be considered as a part of integrated weed management (IWM) strategy in most cases. Using herbicides in reduced doses became an important strategy within the concept of IWM. Therefore, a combination of biological control agents and reduced herbicide doses could be considered as a good strategy for controlling some important weeds. Studies were carried out in 2008-09 to investigate the efficacy of a combination of Motivell (nicosulfuron) in reduced doses and two plant pathogenic fungi (Ascochyta caulina and Stagonospora vitensis) for the control of Chenopodium album. First, ED50 dose of Motivell for C. album was determined by four doseresponse experiments conducted in pots. In the second step of the study nicosulfuron tolerance of fungi was determined in three experiments in petri dishes. At the last step six different pot experiments were carried out on C. album to evaluate the efficacy of reduced herbicide rates and fungi spores alone or in combination. The studies showed that the dose corresponding ED50 was about 12.5 % of the recommended dose. Doses up to 50 % of the recommended did not affect fungi growth under laboratory conditions, so that a combination was possible. Fungi treatments alone provided no effect in most cases. In 3 of 6 experiments, herbicide at 12.5 %-dose in combination with fungi treatments provided higher effects than 12.5 %-dose alone. Application of 25 % nicosulfuron dose alone was highly effective so that there is no need for a combination with biological control agents. It can be concluded that the combination of biological control agents with reduced herbicide doses could be an effective alternative in suppressing C. album under optimal climatic conditions. Keywords: Ascochyta caulina, biological control, Chenopodium album, Motivell, nicosulfuron, Stagonospora vitensisBekämpfung von Chenopodium album L. mit Hilfe von zwei pflanzen-pathogenen Pilzen in der Kombination mit reduzierten Aufwandmengen von NicosulfuronDie biologische Unkrautbekämpfung könnte ein wichtiges Verfahren sein, aber ihr Erfolg war bei den bisherigen Versuchen durch einige Faktoren begrenzt. Obwohl biologische Methoden in einigen Fällen eine ausreichende Unkrautbekämpfung bewirkten, sollten sie eher als ein Teil der Integrierten Unkrautbekämpfung (IWM) betrachtet werden. Die Anwendung reduzierter Herbizidaufwandmengen ist ein fester Bestandteil des IWM, so dass deren kombinierte Anwendung mit spezifischen Pflanzenpathogenen als künftige Bekämpfungsstrategie gegenüber wichtigen Unkrautarten zu untersuchen ist. Mit diesem Ziel wurden 2008-2009 Untersuchungen zur Wirkung von reduzierten Motivell-Aufwandmengen in Kombination mit zwei Pflanzenpathogenen (Ascochyta caulina und Stagonospora vitensis) auf Chenopodium album durchgeführt. Zuerst wurde die ED50 von Motivell unter Anwendung von vier Aufwandmengen in Topfversuchen ermittelt. Im zweiten Schritt wurde die Toleranzgrenze der untersuchten Pilze gegenüber Nicosulfuron in drei Untersuchungen auf Nährboden in der Petrischale festgestellt. In insgesamt sechs Topfversuchen wurde dann die alleinige und kombinierte Anwendung von Motivell und Suspensionen der Pilzsporen gegenüber C. album geprüft. Als ED50 wurden 12,5 % der zugelassenen Aufwandmenge von Motivell festgestellt. Da erst Motivell-Aufwandmengen über 50 % das Pilzwachstum beeinflussten, waren Kombinationen bis zu 25 % der Herbizidkonzentration ohne Einfluss auf die Pilze. Die 12,5 %ige Aufwandmenge plus Pilzsporen zeigte in drei von sechs Versuchen eine bessere Wirkung als das Herbizid allein. Die alleinige Anwendung von Motivell 25 % hatte jedoch eine stärkere Wirkung als die 12,5 %ige plus Pilz, womit durch diese Ergebnisse der Sinn einer Kombination in Frage gestellt werden kann. Daraus schlussfolgernd sollte man trotzdem für die Zukunft die Möglichkeit einer Kombination reduzierten Herbizidaufwands mit geeigneten Pflanzenpathogenen nicht ausschließen und die Untersuchungen fortführen. Stichwörter: Ascochyta caulina, biologische Kontrolle, Chenopodium album, Motivell, Nicosulfuron, Stagonospora vitensi

ARQ with Cumulative Feedback to Compensate for Burst Errors

We propose a cumulative feedback-based ARQ (CF ARQ) protocol for a sliding window of size 2 over packet erasure channels with unreliable feedback. We exploit a matrix signal-flow graph approach to analyze probability-generating functions of transmission and delay times. Contrasting its performance with that of the uncoded baseline scheme for ARQ, developed by Ausavapattanakun and Nosratinia, we demonstrate that CF ARQ can provide significantly less average delay under bursty feedback, and gains up to about 20% in terms of throughput. We also outline the benefits of CF ARQ under burst errors and asymmetric channel conditions. The protocol is more predictable across statistics, hence is more stable. This can help design robust systems when feedback is unreliable. This feature may be preferable for meeting the strict end-to-end latency and reliability requirements of future use cases of ultra-reliable low-latency communications in 5G, such as mission-critical communications and industrial control for critical control messaging.Comment: GLOBECOM'18. arXiv admin note: substantial text overlap with arXiv:1806.0577

Doubly Robust Estimation of Local Average Treatment Effects Using Inverse Probability Weighted Regression Adjustment

We revisit the problem of estimating the local average treatment effect (LATE) and the local average treatment effect on the treated (LATT) when control variables are available, either to render the instrumental variable (IV) suitably exogenous or to improve precision. Unlike previous approaches, our doubly robust (DR) estimation procedures use quasi-likelihood methods weighted by the inverse of the IV propensity score - so-called inverse probability weighted regression adjustment (IPWRA) estimators. By properly choosing models for the propensity score and outcome models, fitted values are ensured to be in the logical range determined by the response variable, producing DR estimators of LATE and LATT with appealing small sample properties. Inference is relatively straightforward both analytically and using the nonparametric bootstrap. Our DR LATE and DR LATT estimators work well in simulations. We also propose a DR version of the Hausman test that compares different estimates of the average treatment effect on the treated (ATT) under one-sided noncompliance

Abadie's Kappa and Weighting Estimators of the Local Average Treatment Effect

In this paper we study the finite sample and asymptotic properties of various weighting estimators of the local average treatment effect (LATE), several of which are based on Abadie (2003)'s kappa theorem. Our framework presumes a binary endogenous explanatory variable ("treatment") and a binary instrumental variable, which may only be valid after conditioning on additional covariates. We argue that one of the Abadie estimators, which we show is weight normalized, is likely to dominate the others in many contexts. A notable exception is in settings with one-sided noncompliance, where certain unnormalized estimators have the advantage of being based on a denominator that is bounded away from zero. We use a simulation study and three empirical applications to illustrate our findings. In applications to causal effects of college education using the college proximity instrument (Card, 1995) and causal effects of childbearing using the sibling sex composition instrument (Angrist and Evans, 1998), the unnormalized estimates are clearly unreasonable, with "incorrect" signs, magnitudes, or both. Overall, our results suggest that (i) the relative performance of different kappa weighting estimators varies with features of the data-generating process; and that (ii) the normalized version of Tan (2006)'s estimator may be an attractive alternative in many contexts. Applied researchers with access to a binary instrumental variable should also consider covariate balancing or doubly robust estimators of the LATE

Covariate Balancing and the Equivalence of Weighting and Doubly Robust Estimators of Average Treatment Effects

We show that when the propensity score is estimated using a suitable covariate balancing procedure, the commonly used inverse probability weighting (IPW) estimator, augmented inverse probability weighting (AIPW) with linear conditional mean, and inverse probability weighted regression adjustment (IPWRA) with linear conditional mean are all numerically the same for estimating the average treatment effect (ATE) or the average treatment effect on the treated (ATT). Further, suitably chosen covariate balancing weights are automatically normalized, which means that normalized and unnormalized versions of IPW and AIPW are identical. For estimating the ATE, the weights that achieve the algebraic equivalence of IPW, AIPW, and IPWRA are based on propensity scores estimated using the inverse probability tilting (IPT) method of Graham, Pinto and Egel (2012). For the ATT, the weights are obtained using the covariate balancing propensity score (CBPS) method developed in Imai and Ratkovic (2014). These equivalences also make covariate balancing methods attractive when the treatment is confounded and one is interested in the local average treatment effect

Distinct Types of Fibrocyte Can Differentiate from Mononuclear Cells in the Presence and Absence of Serum

Background: Ageing, immunity and stresstolerance are inherent characteristics of all organisms. In animals, these traits are regulated, at least in part, by forkhead transcription factors in response to upstream signals from the Insulin/Insulin–like growth factor signalling (IIS) pathway. In the nematode Caenorhabditis elegans, these phenotypes are molecularly linked such that activation of the forkhead transcription factor DAF-16 both extends lifespan and simultaneously increases immunity and stress resistance. It is known that lifespan varies significantly among the Caenorhabditis species but, although DAF-16 signalling is highly conserved, it is unclear whether this phenotypic linkage occurs in other species. Here we investigate this phenotypic covariance by comparing longevity, stress resistance and immunity in four Caenorhabditis species. Methodology/Principal Findings: We show using phenotypic analysis of DAF-16 influenced phenotypes that among four closely related Caenorhabditis nematodes, the gonochoristic species (Caenorhabditis remanei and Caenorhabditis brenneri) have diverged significantly with a longer lifespan, improved stress resistance and higher immunity than the hermaphroditic species (C. elegans and Caenorhabditis briggsae). Interestingly, we also observe significant differences in expression levels between the daf-16 homologues in these species using Real-Time PCR, which positively correlate with the observed phenotypes. Finally, we provide additional evidence in support of a role for DAF-16 in regulating phenotypic coupling by using a combination of wildtype isolates, constitutively active daf-16 mutants and bioinformatic analysis. Conclusions: The gonochoristic species display a significantly longer lifespan (p<0.0001) and more robust immune and stress response (p<0.0001, thermal stress; p<0.01, heavy metal stress; p<0.0001, pathogenic stress) than the hermaphroditic species. Our data suggests that divergence in DAF-16 mediated phenotypes may underlie many of the differences observed between these four species of Caenorhabditis nematodes. These findings are further supported by the correlative higher daf-16 expression levels among the gonochoristic species and significantly higher lifespan, immunity and stress tolerance in the constitutively active daf-16 hermaphroditic mutants