Optimal Cooperative Sensing using a Team of UAVs Gu, G.; Chandler, P.R.; Schumacher, C.J. ...
IEEE transactions on aerospace and electronic systems,
10/2006, Volume:
42, Issue:
4
Journal Article
Peer reviewed
The authors investigates the joint optimal estimation of both the position and velocity of a ground moving target (GMT) using pulse Doppler radars on-board unmanned aerial vehicles (UAVs). The ...problem of cooperative estimation using a UAV team and the optimization of the team's configuration to achieve optimal GMT position and velocity estimates are addressed. Based on the Cramer-Rao bound, the minimum achievable error variance of the GMT position and velocity estimates is derived. The expression of the minimum achievable estimation error variance for unbiased estimation provided by the Cramer-Rao bound is minimized yielding the optimal configuration of the UAV team. Our solution is complete in that it addresses various GMT tracking scenarios and an arbitrary number of UAVs. Optimal sensor geometries for typical applications are illustrated
Background: Many cases of acute adhesive small-bowel obstruction (SBO) can be successfully treated with intestinal tube decompression. There is considerable controversy, however, regarding whether a ...short nasogastric tube (NGT) or a long nasointestinal tube (LT) is the best method of intestinal tube decompression.
Patients and methods: A prospective, randomized trial was conducted to compare NGT and LT decompression with respect to the success of nonoperative treatment and morbidity of surgical intervention in 55 patients with acute adhesive SBO.
Results: Twenty-eight patients were managed with NGT and 27 with LT. There were 44 cases of partial SBO (23 NGT, 21 LT) and 11 cases of complete SBO (5 NGT, 6 LT). Twenty-one patients ultimately required operation, including 13 managed with NGT (46%) and 8 with LT (30%) (
P = 0.16). The mean period between admission and operation was 60 hours in the NGT group versus 65 hours in the LT group. At operation, 3 patients in the NGT group had ischemic bowel that required resection. Postoperative complications occurred in 23% of patients treated with NGT versus 38% of patients treated with LT (
P = 0.89). Postoperative ileus averaged 6.1 days for NGT patients versus 4.6 days for LT patients (
P = 0.44). There were no deaths.
Conclusions: Patients with adhesive SBO can safely be given a trial of tube decompression upon hospital admission. There was no advantage of one type of tube over the other in patients with adhesive SBO.
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IJS, IMTLJ, KILJ, KISLJ, NUK, SBCE, SBJE, UL, UM, UPCLJ, UPUK
An important subproblem in the area of cooperative control of multiple, autonomous, unmanned air vehicles is the determination of the minimum-time optimal paths for the agents to fly from one ...destination to the next. The tasks for the air vehicles are usually tightly coupled in time, and hence estimates of the times taken for each air vehicle to fly from one destination to the next is highly critical for correct assignment of tasks. In this article, we discuss the existence and uniqueness of minimum time solutions for the trajectory planning problem for a Micro Air Vehicle (MAV) under wind conditions. We show that there exists a minimum time solution for the trajectory planning problem with a minimum turn radius constraint for the air vehicle, and for a non-zero, time-varying wind vector field satisfying certain easily checked sufficient conditions. We also prove uniqueness for almost every combination of initial and final conditions in the case of a wind vector field that can vary with time but is constant in the spatial variable at each time instant.
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FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Cytosolic DNA sensing activates the Stimulator of Interferon Genes (STING) adaptor to induce interferon type I (IFNαβ) production. Constitutive DNA sensing to induce sustained STING activation ...incites tolerance breakdown leading to autoimmunity. Here we show that systemic treatments with DNA nanoparticles (DNPs) induced potent immune regulatory responses via STING signaling that suppressed experimental autoimmune encephalitis (EAE) when administered to mice after immunization with myelin oligodendrocyte glycoprotein (MOG), at EAE onset, or at peak disease severity. DNP treatments attenuated infiltration of effector T cells into the central nervous system (CNS) and suppressed innate and adaptive immune responses to MOG immunization in spleen. Therapeutic responses were not observed in mice treated with cargo DNA or cationic polymers alone, indicating that DNP uptake and cargo DNA sensing by cells with regulatory functions was essential for therapeutic responses to manifest. Intact STING and IFNαβ receptor genes, but not IFNγ receptor genes, were essential for therapeutic responses to DNPs to manifest. Treatments with cyclic diguanylate monophosphate (c-diGMP) to activate STING also delayed EAE onset and reduced disease severity. Therapeutic responses to DNPs were critically dependent on indoleamine 2,3 dioxygenase (IDO) enzyme activity in hematopoietic cells. Thus DNPs and c-diGMP attenuate EAE by inducing dominant T cell regulatory responses via the STING-IFNαβ-IDO pathway that suppress CNS-specific autoimmunity. These findings reveal dichotomous roles for the STING-IFNαβ pathway in either stimulating or suppressing autoimmunity and identify STING activating reagents as a novel class of immune modulatory drugs.
Complexity in UAV cooperative control Chandler, P.R.; Pachter, M.; Swaroop, D. ...
Proceedings of the 2002 American Control Conference (IEEE Cat. No.CH37301),
2002, Volume:
3
Conference Proceeding
Open access
This paper addresses complexity and coupling issues in cooperative decision and control of distributed autonomous unmanned aerial vehicle (UAV) teams. In particular, the recent results obtained by ...the inhouse research team are presented. Hierarchical decomposition is implemented where team vehicles are allocated to sub-teams using the set partition theory. Results are presented for single assignment and multiple assignments using the network flow and auction algorithms. Simulation results are presented for wide area search munitions where complexity and coupling are incrementally addressed in the decision system, yielding a radically improved team performance.
Cytosolic DNA sensing via the STING adaptor incites autoimmunity by inducing type I IFN (IFNαβ). Here we show that DNA is also sensed via STING to suppress immunity by inducing indoleamine 2,3 ...dioxygenase (IDO). STING gene ablation abolished IFNαβ and IDO induction by dendritic cells (DCs) after DNA nanoparticle (DNP) treatment. Marginal zone macrophages, some DCs and myeloid cells ingested DNPs but CD11b
+
DCs were the only cells to express IFNβ, while CD11b
+
non-DCs were major IL-1β producers. STING ablation also abolished DNP-induced regulatory responses by DCs and regulatory T cells (Tregs), and hallmark regulatory responses to apoptotic cells were also abrogated. Moreover, systemic cyclic diguanylate monophosphate (c-diGMP) treatment to activate STING induced selective IFNβ expression by CD11b
+
DCs and suppressed Th1 responses to immunization. Thus, previously unrecognized functional diversity amongst physiologic innate immune cells regarding DNA sensing via STING is pivotal in driving immune responses to DNA.
Nanoparticles containing DNA complexed with the cationic polymer polyethylenimine (PEI)
2
are efficient vehicles to transduce DNA into cells and organisms. DNA/PEI nanoparticles (DNPs) also elicit ...rapid and systemic release of pro-inflammatory cytokines that promote anti-tumor immunity. Here we report that DNPs possess previously unrecognized immunomodulatory attributes due to rapid up-regulation of IDO enzyme activity in lymphoid tissues of mice. IDO induction in response to DNP treatment caused dendritic cells (DCs) and regulatory T cells (Tregs) to acquire potent regulatory phenotypes. As expected, DNP treatment stimulated rapid increase in serum levels of IFN type I (IFNαβ) and II (IFNγ), which are both potent IDO inducers. IDO-mediated Treg activation was dependent on IFN type I receptor signaling, while IFNγ receptor signaling was not essential for this response. Moreover, systemic IFNγ release was caused by TLR9-dependent activation of Natural Killer cells, while TLR9 signaling was not required for IFNαβ release. Accordingly, DNPs lacking immunostimulatory TLR9 ligands in DNA stimulated IFNαβ production, induced IDO and promoted regulatory outcomes, but did not stimulate potentially toxic, systemic release of IFNγ. DNP treatment to induce IDO and activate Tregs blocked antigen-specific T cell responses elicited
in vivo
following immunization, and suppressed joint pathology in a model of immune-mediated arthritis. Thus, DNPs lacking TLR9 ligands may be safe and effective reagents to protect healthy tissues from immune-mediated destruction in clinical hyper-immune syndromes.
Following CD80/86 (B7) and TLR9 ligation, small subsets of splenic dendritic cells expressing CD19 (CD19+ DC) acquire potent T cell regulatory functions due to induced expression of the intracellular ...enzyme indoleamine 2,3-dioxygenase (IDO), which catabolizes tryptophan. In CD19+ DC, IFN typeI (IFN-) is the obligate inducer of IDO. We now report that IFN- production needed to stimulate high-level expression of IDO following B7 ligation is itself dependent on basal levels of IDO activity. Genetic and pharmacologic ablation of IDO completely abrogated IFN- production by CD19+ DC after B7 ligation. In contrast, IDO ablation did not block IFN- production by CD19+ DC after TLR9 ligation. IDO-mediated control of IFN- production depended on tryptophan depletion as adding excess tryptophan also blocked IFN- expression after B7 ligation. Consistent with this, DC from mice deficient in general control of non-derepressible-2 (GCN2)-kinase, a component of the cellular stress response to amino acid withdrawal, did not produce IFN- following B7 ligation, but produced IFN- after TLR9 ligation. Thus, B7 and TLR9 ligands stimulate IFN- expression in CD19+ DC via distinct signaling pathways. In the case of B7 ligation, IDO activates cell-autonomous signals essential for IFN- production, most likely by activating the GCN2-kinase-dependent stress response. See accompanying commentary: http://dx.doi.org/10.1002/eji.20073737184 .
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
CpG oligodeoxynucleotides (CpG-ODNs) stimulate innate and adaptive immunity by binding to TLR9 molecules. Paradoxically, expression of the immunoregulatory enzyme indoleamine 2,3-dioxygenase (IDO) is ...induced following i.v. CpG-ODN administration to mice. CpG-ODNs induced selective IDO expression by a minor population of splenic CD19 super(+) dendritic cells (DCs) that did not express the plasmacytoid DC marker 120G8. Following CpG-ODN treatment, CD19 super(+) DCs acquired potent IDO-dependent T cell suppressive functions. Signaling through IFN type I receptors was essential for IDO up-regulation, and CpG-ODNs induced selective activation of STAT-1 in CD19 super(+) DCs. Thus, CpG-ODNs delivered systemically at relatively high doses elicited potent T cell regulatory responses by acting on a discrete, minor population of splenic DCs. The ability of CpG-ODNs to induce both stimulatory and regulatory responses offers novel opportunities for using them as immunomodulatory reagents but may complicate therapeutic use of CpG-ODNs to stimulate antitumor immunity in cancer patients.
Task allocation for wide area search munitions Schumacher, C.; Chandler, P.R.; Rasmussen, S.R.
Proceedings of the 2002 American Control Conference (IEEE Cat. No.CH37301),
2002, Volume:
3
Conference Proceeding
Open access
Addresses the problem of task allocation for wide area search munitions. The munitions are required to search for, classify, attack, and perform battle damage assessment on potential targets. It is ...assumed that target field information is communicated between all elements of the swarm. A network flow optimization model is used to develop a linear program for optimal resource allocation. Periodically re-solving this optimization problem results in coordinated action by the search munitions. The network optimization model can be initialized such that multiple vehicles can be assigned to service a single target. Memory of previous task assignments is included in the task benefit calculations to reduce churning due to frequent reassignments. Simulation results are presented for a swarm of eight vehicles searching an area containing three potential targets. All targets are quickly classified, attacked, and verified as destroyed.
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