Control Over a Network: Using Actuation Buffers to Reduce Transmission Frequency

We consider a discrete time linear feedback control system with additive noise where the control signals are sent across a network from the controller to the actuators. Due to network considerations it is desired to reduce the transmission frequency of the control signals. We show that by including a finite sequence of predicted control signals in each communication packet the frequency of transmission can be reduced by transmitting only when the previously sent sequence has run out, although as a consequence the closed loop error will increase. We introduce a communication protocol, which we call Input Difference Transmission Scheme (IDTS), that transmits control packets when the difference between newly computed control values and the predicted control sequence previously transmitted is larger than a certain threshold. This threshold is a design parameter and we show how the closed loop behavior varies with this threshold. Simulation results are provided to augment the theory

Stabilizing dynamic controllers for hybrid systems : a hybrid control lyapunov function approach

This paper proposes a dynamic controller structure and a systematic design procedure for stabilizing discrete-time hybrid systems. The proposed approach is based on the concept of control Lyapunov functions (CLFs), which, when available, can be used to design a stabilizing state-feedback control law. In general, the construction of a CLF for hybrid dynamical systems involving both continuous and discrete states is extremely complicated, especially in the presence of non-trivial discrete dynamics. Therefore, we introduce the novel concept of a hybrid control Lyapunov function, which allows the compositional design of a discrete and a continuous part of the CLF, and we formally prove that the existence of a hybrid CLF guarantees the existence of a classical CLF. A constructive procedure is provided to synthesize a hybrid CLF, by expanding the dynamics of the hybrid system with a specific controller dynamics. We show that this synthesis procedure leads to a dynamic controller that can be implemented by a receding horizon control strategy, and that the associated optimization problem is numerically tractable for a fairly general class of hybrid systems, useful in real world applications. Compared to classical hybrid receding horizon control algorithms, the proposed approach typically requires a shorter prediction horizon to guarantee asymptotic stability of the closed-loop system, which yields a reduction of the computational burden, as illustrated through two examples

Sensory Properties and Consumer Liking of Buffalo Stracchino Cheese

The present study aims to characterize buffalo Stracchino cheese (BS) from a sensory point of view and verify how much consumers like it compared with the standard Stracchino cheese obtained from cow milk (CS). Nine panelists specifically trained to evaluate Stracchino cheese were used to conduct a quantitative descriptive sensory analysis, whereas 80 untrained consumers balanced for gender participated in the hedonic consumer test. Stracchino appearance was affected by milk type with higher intensities perceived for BS in terms of whiteness (P<0.0001) and shininess (P<0.001). As to taste and texture, BS showed higher sourness and oiliness intensities than CS, respectively (P<0.0001). Milk type did not affect the overall liking or the liking in terms of taste/flavor, texture, and appearance, but consumers rated both products at scores well above the neutral point. In addition, the liking expressed in blind conditions (i.e., without information on the milk type) was significantly lower as compared with the liking elicited by the expectations (i.e., based only on the information on the milk type) (P<0.05 and P<0.10, for CS and BS, respectively). We conclude that the good eating quality of buffalo Stracchino cheese as assessed by the consumer panel and the lack of differences between CS and BS in terms of a consumer may anticipate a possible good positioning of this novel product in the market of fresh cheese

Threonine 67 is a key component in the coupling of the NSS amino acid transporter KAAT1

The crystallizations of the prokaryotic LeuT and of the eukaryotic DAT and SERT transporters represent important steps forward in the comprehension of the molecular physiology of Neurotransmitter: Sodium Symporters, although the molecular determinants of the coupling mechanism and of ion selectivity still remain to be fully elucidated. The insect NSS homologue KAAT1 exhibits unusual physiological features, such as the ability to use K+ as the driver ion, weak chloride dependence, and the ability of the driver ion to influence the substrate selectivity; these characteristics can help to define the molecular determinants of NSS function. Two non-conserved residues are present in the putative sodium binding sites of KAAT1: Ala 66, corresponding to Gly 20 in the Na2 site of LeuT, and Ser 68, corresponding to Ala 22 in the Nal site. Thr 67 appears also to be significant since it is not conserved among NSS members, is present as threonine only in KAAT1 and in the paralogue CAATCH1 and, according to LeuT structure, is close to the amino acid binding site. Mutants of these residues were functionally characterized in Xenopus oocytes. The T67Y mutant exhibited uptake activity comparable to that of the wild type, but fully chloride-independent and with enhanced stereoselectivity. Interestingly, although dependent on the presence of sodium, the mutant showed reduced transport-associated currents, indicating uncoupling of the driver ion and amino acid fluxes. Thr 67 therefore appears to be a key component in the coupling mechanism, participating in a network that influences the cotransport of Na+ and the amino acid

Effect of sucrose replacement and resistant starch addition on textural properties of gluten-free doughs and biscuits

There is a need to develop low-sugar healthy products. The aim of this research was to evaluate the effect of maltitol and inulin as sucrose replacement alongside resistant starch (RS) and green banana flour (GBF) on the texture and physical properties of gluten-free doughs and biscuits formulated with buckwheat, sorghum and lentil flours. These properties are important to predict the dough workability, how easy the biscuits could be mass-produced and determine consumers’ acceptability. Results showed that partial and complete substitution of sucrose could be achieved and appropriate concentration of resistant starch or green banana flour contributed to better dough and biscuit texture. RS content showed the biggest influence on dough stickiness and biscuit hardness and could be used to correct the negative effect of sucrose replacement and to maximise both the dough processability and biscuit acceptability

Autoantibodies against the glial glutamate transporter GLT1/EAAT2 in Type 1 diabetes mellitus-Clues to novel immunological and non-immunological therapies

: Islet cell surface autoantibodies were previously found in subjects with type 1 diabetes mellitus (T1DM), but their target antigens and pathogenic mechanisms remain elusive. The glutamate transporter solute carrier family 1, member 2 (GLT1/EAAT2) is expressed on the membrane of pancreatic β-cells and physiologically controls extracellular glutamate concentrations thus preventing glutamate-induced β-cell death. We hypothesized that GLT1 could be an immunological target in T1DM and that autoantibodies against GLT1 could be pathogenic. Immunoprecipitation and ELISA experiments showed that sera from T1DM subjects recognized GLT1 expressed in brain, pancreatic islets, and GLT1-transfected COS7-cell extracts. We validated these findings in two cohorts of T1DM patients by quantitative immunofluorescence assays. Analysis of the combined data sets indicated the presence of autoantibodies against GLT1 in 32 of the 87 (37%) T1DM subjects and in none of healthy controls (n = 64) (p < 0.0001). Exposure of pancreatic βTC3 cells and human islets to purified IgGs from anti-GLT1 positive sera supplemented with complement resulted in plasma membrane ruffling, cell lysis and death. The cytotoxic effect was prevented when sera were depleted from IgGs. Furthermore, in the absence of complement, 6 out of 16 (37%) anti-GLT1 positive sera markedly reduced GLT1 transport activity in βTC3 cells by inducing GLT1 internalization, also resulting in β-cell death. In conclusion, we provide evidence that GLT1 is a novel T1DM autoantigen and that anti-GLT1 autoantibodies cause β-cell death through complement-dependent and independent mechanisms. GLT1 seems an attractive novel therapeutic target for the prevention of β-cell death in individuals with diabetes and prediabetes

PCSK9 deficiency reduces insulin secretion and promotes glucose intolerance: the role of the low-density lipoprotein receptor

Aims PCSK9 loss of function genetic variants are associated with lower low-density lipoprotein cholesterol but also with higher plasma glucose levels and increased risk of Type 2 diabetes mellitus. Here, we investigated the molecular mechanisms underlying this association. Methods and results Pcsk9 KO, WT, Pcsk9/Ldlr double KO (DKO), Ldlr KO, albumin AlbCre+/Pcsk9LoxP/LoxP (liver-selective Pcsk9 knock-out mice), and AlbCre-/Pcsk9LoxP/LoxP mice were used. GTT, ITT, insulin and C-peptide plasma levels, pancreas morphology, and cholesterol accumulation in pancreatic islets were studied in the different animal models. Glucose clearance was significantly impaired in Pcsk9 KO mice fed with a standard or a high-fat diet for 20\u2009weeks compared with WT animals; insulin sensitivity, however, was not affected. A detailed analysis of pancreas morphology of Pcsk9 KO mice vs. controls revealed larger islets with increased accumulation of cholesteryl esters, paralleled by increased insulin intracellular levels and decreased plasma insulin, and C-peptide levels. This phenotype was completely reverted in Pcsk9/Ldlr DKO mice implying the low-density lipoprotein receptor (LDLR) as the proprotein convertase subtilisin/kexin Type 9 (PCSK9) target responsible for the phenotype observed. Further studies in albumin AlbCre+/Pcsk9LoxP/LoxP mice, which lack detectable circulating PCSK9, also showed a complete recovery of the phenotype, thus indicating that circulating, liver-derived PCSK9, the principal target of monoclonal antibodies, does not impact beta-cell function and insulin secretion. Conclusion PCSK9 critically controls LDLR expression in pancreas perhaps contributing to the maintenance of a proper physiological balance to limit cholesterol overload in beta cells. This effect is independent of circulating PCSK9 and is probably related to locally produced PCSK9

All-optical header processing in a 42.6Gb/s optoelectronic firewall

A novel architecture to enable future network security systems to provide effective protection in the context of continued traffic growth and the need to minimise energy consumption is proposed. It makes use of an all-optical pre-filtering stage operating at the line rate under software control to distribute incoming packets to specialised electronic processors. An experimental system that integrates software controls and electronic interfaces with an all-optical pattern recognition system has demonstrated the key functions required by the new architecture. As an example, the ability to sort packets arriving in a 42.6Gb/s data stream according to their service type was shown experimentally

Geometric Mechanics Based Nonlinear Model Predictive Spacecraft Attitude Control with Reaction Wheels

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143101/1/1.G001923.pd