Impact Angle Control Guidance to Intercept Moving Targets by Virtual Target Technique

To solve the problem regarding the impact angle of the missile, this paper proposes a novel guidance law, which can control the missile to hit the target at the desired angle. The key of the guidance law is selecting a moving point on the collision line as the virtual target, and the tactical requirements can be fulfilled by the missile directly pursuing the virtual target. The Lyapunov stable theory is used to prove the convergence of the proposed guidance law. The guidance command is generated by a PID controller to make the missile towards the virtual target. The proposed guidance law makes the lateral acceleration of the missile converge to zero, which leads the angle of attack to zero, and it theoretically guarantees the flight path angle equals the attitude angle. Numerical simulations demonstrate this impact angle control guidance law is very accurate and robust. Regardless of whether the initial heading error is large or small, the missile which employs the proposed guidance law can always hit the target from the preset direction and the guidance process is smooth.

Enhancing Robots Navigation in Internet of Things Indoor Systems

In this study, an effective local minima detection and definition algorithm is introduced for a mobile robot navigating through unknown static environments. Furthermore, five approaches are presented and compared with the popular approach wall-following to pull the robot out of the local minima enclosure namely; Random Virtual Target, Reflected Virtual Target, Global Path Backtracking, Half Path Backtracking, and Local Path Backtracking. The proposed approaches mainly depend on changing the target location temporarily to avoid the original target’s attraction force effect on the robot. Moreover, to avoid getting trapped in the same location, a virtual obstacle is placed to cover the local minima enclosure. To include the most common shapes of deadlock situations, the proposed approaches were evaluated in four different environments; V-shaped, double U-shaped, C-shaped, and cluttered environments. The results reveal that the robot, using any of the proposed approaches, requires fewer steps to reach the destination, ranging from 59 to 73 m on average, as opposed to the wall-following strategy, which requires an average of 732 m. On average, the robot with a constant speed and reflected virtual target approach takes 103 s, whereas the identical robot with a wall-following approach takes 907 s to complete the tasks. Using a fuzzy-speed robot, the duration for the wall-following approach is greatly reduced to 507 s, while the reflected virtual target may only need up to 20% of that time. More results and detailed comparisons are embedded in the subsequent sections.

VIRTUAL TARGET CONSTRUCTION FOR STRUCTURE-BASED SCREENING IN THE DISCOVERY OF HISTAMINE H2 RECEPTOR LIGANDS

Objective: This study aimed to develop validated targets to be employed in structure-based virtual screening (SBVS) to discover ligands for the human histamine H2 receptor (hHRH2). Methods: The virtual targets construction was initiated by homology modeling with the reference compound ranitidine as the ligand followed by 100 ns molecular dynamics (MD) simulations. During MD simulations, the snapshot with the lowest value of the free energy of binding was selected for further validation by re-docking simulations. All simulations were performed in YASARA-Structure. Results: The research presented here resulted in one validated target for the SBVS. Additionally, by employing a clustering module in MD simulations analysis in YASARA-Structure, more than ten different virtual targets are also available for further uses. Conclusion: The virtual targets resulted in this research offer possibilities to construct valid SBVS protocols to identify ligands for the hHRH2.

Construction of a hippocampal cognitive map depends upon spatial context

The hippocampus encodes both spatial and non-spatial features of an environment thought to be critical to guide navigational trajectories and associative learning, respectively. These seemingly dichotomous roles have been reconciled in a proposed cognitive map - a representation of environment structure abstracted away from specific behavioral demands. However, the extent to which a cognitive map is independent of behavioral demands remains unclear because direct comparisons across environments with common structure but different spatial/behavioral context is lacking. Here we compare behaviors in mice trained to navigate to a hidden target in a physical arena and manipulate a joystick to a virtual target to collect a delayed reward. Comparison of behaviors with an artificial agent revealed a common algorithmic basis for learned foraging trajectories in both contexts. Imaging CA1 neural activity revealed a similar map-like encoding of active foraging; however, detailed analysis of ensemble activity, optogenetic inactivation, and modeling revealed a context-specific functional dissociation. In a navigational context, CA1 was critical for retrospective evaluation of spatial trajectories, but dispensable for initiation. In a non-navigational context, CA1 activity was critical for initiation and planning foraging trajectories. This work highlights how construction of a cognitive map to facilitate idiosyncratic behavioral demands7 is critical for foraging in diverse spatial contexts.

Identifying Biomolecular Targets of the Anticancer Vitamin-E-δ-Tocotrienol Using a Computational Approach: Virtual Target Screening

In recent years, evidence has mounted that a particular form of vitamin E (its δ-tocotrienol variant) may have cellular functions beyond that of an antioxidant, a role commonly ascribed to the tocotrienol class of compounds. In particular, numerous studies of δ-tocotrienol’s effect on cancer cells have identified it as a potent anticancer and antitumor agent. However, this important revelation of potential therapeutic use poses a series of new challenges, with arguably the most important being the elucidation of the precise mechanism of action responsible for the anticancer activity of δ-tocotrienol. As an initial step to address this question, we have used a computational tool, Virtual Target Screening (a molecular docking-based tool that identifies potential binding partners for small molecules), to identify potential biomolecular targets of δ-tocotrienol. Then, to gain a consensus as to the type of biomolecular entity that could be a target for δ-tocotrienol, we utilized PharmMapper and PASS (a ligand-based chemoinformatic approach), and ProBiS (a tool that analyses binding site similarities across known proteins). The results of our multipronged computational consensus-seeking approach showed that such a strategy can identify potential cellular targets of small molecules. This is evidenced by our identification of estrogen receptor-beta, a protein that has been previously shown to bind δ-tocotrienol, which elicited a cellular response. This study supports the use of such a computational approach as an initial step in target identification to avoid time-consuming, costly large-scale experimental screening, greatly reducing the experimental work to just one or a few candidate proteins.

A novel fluorescent lung-marking technique using the photodynamic diagnosis endoscope system and vitamin B2

OBJECTIVES For small pulmonary nodules that are unidentifiable by palpation or in endoscopic surgeries wherein palpation is not feasible, visualizing their location is necessary when performing pulmonary sublobar resection procedures, such as wedge resection or segmentectomy. We invented a new transbronchial lung-marking technique using the photodynamic diagnosis endoscope system and vitamin B2 and examined its feasibility and safety via porcine studies. METHODS We established the marking procedure in pigs and examined the marking clarity and size, fluorescence intensity and duration and possible complications. In another study, sublobar resection for virtual target lesions was performed in pigs based on the fluorescent markings. The procedure duration, marking visibility, surgical margin from the lesions and technique-related complications were assessed. RESULTS All 36 markings in 6 pigs were identifiable and were widely distributed over the right lung. The median diameter and fluorescence intensity at 60 min after marking were 6.0 (5.5–6.7) mm and 137.5 (122–168), respectively. All 18 markings for the 6 virtual target lesions (3 markings for each target) were clearly identified, and all target lesions were found in the resected specimens. The median duration per marking was 244 (194–255) seconds. The shortest median surgical margin from a target lesion was 11.5 (9.3–13.5) mm. No procedure-related complications were observed. CONCLUSIONS This novel transbronchial fluorescent lung-marking technique was useful and safe in sublobar resections for small non-palpable pulmonary lesions.