Controllability and controller-observer design for a class of linear time-varying systems

“The final publication is available at Springer via http://dx.doi.org/10.1007/s10852-012-9212-6"In this paper a class of linear time-varying control systems is considered. The time variation consists of a scalar time-varying coefficient multiplying the state matrix of an otherwise time-invariant system. Under very weak assumptions of this coefficient, we show that the controllability can be assessed by an algebraic rank condition, Kalman canonical decomposition is possible, and we give a method for designing a linear state-feedback controller and Luenberger observer

A Condensation-Ordering Mechanism in Nanoparticle-Catalyzed Peptide Aggregation

Nanoparticles introduced in living cells are capable of strongly promoting the aggregation of peptides and proteins. We use here molecular dynamics simulations to characterise in detail the process by which nanoparticle surfaces catalyse the self- assembly of peptides into fibrillar structures. The simulation of a system of hundreds of peptides over the millisecond timescale enables us to show that the mechanism of aggregation involves a first phase in which small structurally disordered oligomers assemble onto the nanoparticle and a second phase in which they evolve into highly ordered beta-sheets as their size increases

Using a decline in serum hCG between days 0-4 to predict ectopic pregnancy treatment success after single-dose methotrexate:a retrospective cohort study

<p>Abstract</p> <p>Background</p> <p>The current measure of treatment efficacy of single-dose methotrexate for ectopic pregnancy, is a fall in serum hCG of ≥15% between days 4–7 of treatment, which has a positive predictive value of 93% for treatment success. Two small studies have proposed a fall in serum hCG between days 0–4 after treatment confers similar, earlier prognostic information, with positive predictive values of 100% and 88% for treatment success. We sought to validate this in a large, independent cohort because of the potentially significant clinical implications.</p> <p>Methods</p> <p>We conducted a retrospective study of women (n=206) treated with single-dose methotrexate for ectopic pregnancy (pre-treatment serum hCG levels ≤3000 IU/L) at Scottish hospitals between 2006–2011. Women were divided into two cohorts based on whether their serum hCG levels rose or fell between days 0–4 after methotrexate. Treatment outcomes of women in each cohort were compared, and the test performance characteristics calculated. This methodology was repeated for the current measure (≥15% fall in serum hCG between days 4–7 of treatment) and an alternate early measure (<20% fall in serum hCG between days 0–4 of treatment), and all three measures were compared for their ability to predict medical treatment success.</p> <p>Results</p> <p>In our cohort, the positive predictive value of the current clinical measure was 89% (95% CI 84-94%) (121/136). A falling serum hCG between days 0–4 predicted treatment success in 85% (95% CI 79-92%) of cases (94/110) and a <20% fall in serum hCG between days 0–4 predicted treatment success in 94% (95% CI 88-100%) of cases (59/63). There was no significant difference in the ability of these tests to predict medical treatment success.</p> <p>Conclusions</p> <p>We have verified that a decline in serum hCG between days 0–4 after methotrexate treatment for ectopic pregnancies, with pre-treatment serum hCG levels ≤3000 IU/L, provides an early indication of likelihood of treatment success, and performs just as well as the existing measure, which only provides prognostic information on day 7.</p

Association between carotid intima-media thickness and bone mineral density: A cross-sectional study in Vietnamese men and women aged 50 years and older

© 2019 Author(s). Objectives The association between osteoporosis and atherosclerosis remains controversial. We sought to define the relationship between carotid intima-media thickness and bone mineral density (BMD) in individuals of Vietnamese background. Design and setting Cross-sectional study in Ho Chi Minh City, Vietnam. Participants The study involved 1460 individuals (559 men) aged 50 years and older (average age 59 years) who were randomly recruited from the community. Outcome measures BMD at the femoral neck and lumbar spine was measured by dual-energy X-ray absorptiometry (Hologic, Waltham, Massachusetts, USA). Carotid intima-media thickness (cIMT) was measured using a Philips Ultrasonography (HD7XE). The presence of atherosclerotic plaque was ascertained for each individual. The association between cIMT and BMD was analysed by a multiple linear regression model. Results In unadjusted analysis, cIMT was positively associated with femoral neck BMD in men (p=0.005), but not in women (p=0.242). After adjusting for age, smoking, diabetes and hypertension, the association remained statistically significant in men (partial R 2 =0.005; p=0.015) but not in women (partial R 2 =0.008; p=0.369). When the analysis was limited to individuals aged 60 years and older, the association between cIMT and BMD was no longer statistically significant. There was no statistically significant association between cIMT and lumbar spine BMD in either men or women. Conclusions In Vietnamese individuals aged 50 years and older, there is a clinically non-significant but statistically significant association between carotid intima-media thickness and BMD in men, not in women

A novel hybrid swarm optimized multilayer neural network for spatial prediction of flash floods in tropical areas using sentinel-1 SAR imagery and geospatial data

© 2018 by the authors. Licensee MDPI, Basel, Switzerland. Flash floods are widely recognized as one of the most devastating natural hazards in the world, therefore prediction of flash flood-prone areas is crucial for public safety and emergency management. This research proposes a new methodology for spatial prediction of flash floods based on Sentinel-1 SAR imagery and a new hybrid machine learning technique. The SAR imagery is used to detect flash flood inundation areas, whereas the new machine learning technique, which is a hybrid of the firefly algorithm (FA), Levenberg–Marquardt (LM) backpropagation, and an artificial neural network (named as FA-LM-ANN), was used to construct the prediction model. The Bac Ha Bao Yen (BHBY) area in the northwestern region of Vietnam was used as a case study. Accordingly, a Geographical Information System (GIS) database was constructed using 12 input variables (elevation, slope, aspect, curvature, topographic wetness index, stream power index, toposhade, stream density, rainfall, normalized difference vegetation index, soil type, and lithology) and subsequently the output of flood inundation areas was mapped. Using the database and FA-LM-ANN, the flash flood model was trained and verified. The model performance was validated via various performance metrics including the classification accuracy rate, the area under the curve, precision, and recall. Then, the flash flood model that produced the highest performance was compared with benchmarks, indicating that the combination of FA and LM backpropagation is proven to be very effective and the proposed FA-LM-ANN is a new and useful tool for predicting flash flood susceptibility

Evaluation of a Modified Single-Stage Continuous Curvilinear Capsulorhexis Technique Using 18-Gauge Needle Decompression in Intumescent Cataracts

Trung Kien Hoang,1,2 Huynh Phuc Nguyen,1,3 Van Nam Phan2 1Department of Ophthalmology, Saigon Vinh Eye Hospital, Vinh City, Vietnam; 2Department of Ophthalmology, Hue University of Medicine and Pharmacy, Hue City, Vietnam; 3Department of Ophthalmology, University of Medicine and Pharmacy at Ho Chi Minh City, Ho Chi Minh City, VietnamCorrespondence: Huynh Phuc Nguyen, Department of Ophthalmology, Saigon Vinh Eye Hospital, Vinh City, Vietnam, Email [email protected]: To evaluate the safety and efficacy of a modified anterior capsulorhexis technique using an 18-gauge needle puncture at the peripheral one-third of the anterior capsule to control intralenticular pressure and achieve single-stage continuous curvilinear capsulorhexis (CCC) in intumescent cataract surgery.Methods: This prospective, cross-sectional descriptive study included patients with intumescent cataracts indicated for surgery at Saigon Vinh Eye Hospital from August 2024 to March 2025. Before CCC, all patients underwent an 18-gauge needle puncture at the peripheral one-third of the anterior capsule near the main incision.Results: A total of 99 eyes from 99 patients were included in the study. The mean axial length was 23.12 ± 0.55 mm, anterior chamber depth 2.62 ± 0.43 mm, and lens thickness 4.91 ± 0.72 mm. In 65 patients (65.7%), the milky liquefied cortex escaped into the anterior chamber after the needle puncture. Single-stage CCC was successfully performed in 98 of 99 cases (98.9%) with a mean capsulorhexis diameter of 5.5 ± 0.3 mm. All surgeries were performed using standard phacoemulsification and in-the-bag IOL implantation (100%). Three months post-operatively, all patients had well-centered IOLs with a best-corrected visual acuity (BCVA) ≥ 4/10.Conclusion: An 18-gauge needle puncture at the peripheral one-third of the anterior capsule offers effective decompression, improves safety, and facilitates CCC in patients with intumescent cataracts. This technique is simple, feasible, and highly applicable in clinical practice.Keywords: intumescent cataract, capsulorhexis, 18-gauge needle, Argentinian flag sig

Measurement of the top quark mass using the matrix element technique in dilepton final states

We present a measurement of the top quark mass in pp¯ collisions at a center-of-mass energy of 1.96 TeV at the Fermilab Tevatron collider. The data were collected by the D0 experiment corresponding to an integrated luminosity of 9.7  fb−1. The matrix element technique is applied to tt¯ events in the final state containing leptons (electrons or muons) with high transverse momenta and at least two jets. The calibration of the jet energy scale determined in the lepton+jets final state of tt¯ decays is applied to jet energies. This correction provides a substantial reduction in systematic uncertainties. We obtain a top quark mass of mt=173.93±1.84  GeV

Removal of Microplastics from Laundry Wastewater Using Coagulation and Membrane Combination: A Laboratory-Scale Study

Microplastic (MP) pollution has recently emerged as a critical global environmental issue. Laundry wastewater is a significant contributor to MP pollution, containing high concentrations of MPs. Although coagulation has recently been widely applied to remove MPs from such wastewater, its efficiency remains poor, and the removal mechanisms are not yet fully elucidated. In this study, the occurrence and characteristics of MPs in raw domestic laundry wastewater were investigated. The coagulation process was combined with ultrafiltration (UF) membrane filtration to enhance MP removal. The results showed that the concentrations of MPs in laundry wastewater ranged from 9000 to 11,000 particles/L, with fibrous particles constituting the majority (42.6%) and polyester accounting for 68.2% of detected MPs. Using aluminium chloride and ferric chloride as coagulants, maximum removal efficiencies of 91.7 and 98.3% were achieved, respectively. Mechanistic analysis revealed that charge neutralization played a dominant role during coagulation. Fourier transform infrared spectroscopy further demonstrated the formation of new functional groups, substituted benzene rings, and the presence of Fe-O and Al-O bonds, indicating the interaction between MPs and coagulants. Furthermore, the UF membrane was used to remove fibrous MPs and MPs with low densities. These MPs had not been removed with pre-coagulation. The removal efficiency of these MPs reached 96 ± 2%, reducing their concentration to only 60 particles/L in the UF permeate. These findings highlight the synergistic potential of coagulation and UF membrane filtration for effective MP removal and provide a valuable reference for advancing wastewater treatment technologies targeting MP pollution.</jats:p

Space Telescope and Optical Reverberation Mapping Project. V. Optical Spectroscopic Campaign and Emission-line Analysis for NGC 5548

We present the results of an optical spectroscopic monitoring program targeting NGC 5548 as part of a larger multiwavelength reverberation mapping campaign. The campaign spanned 6 months and achieved an almost daily cadence with observations from five ground-based telescopes. The Hβ and He ii λ4686 broad emission-line light curves lag that of the 5100 +-optical continuum by 4.17+0.36-0.36 and 0.79+0.35-0.34 days, respectively. The Hβ lag relative to the 1158 ultraviolet continuum light curve measured by the Hubble Space Telescope is ∼50% longer than that measured against the optical continuum, and the lag difference is consistent with the observed lag between the optical and ultraviolet continua. This suggests that the characteristic radius of the broad-line region is ∼50% larger than the value inferred from optical data alone. We also measured velocity-resolved emission-line lags for Hβ and found a complex velocity-lag structure with shorter lags in the line wings, indicative of a broad-line region dominated by Keplerian motion. The responses of both the Hβ and He ii emission lines to the driving continuum changed significantly halfway through the campaign, a phenomenon also observed for C iv, Lyα, He ii(+O iii]), and Si iv(+O iv]) during the same monitoring period. Finally, given the optical luminosity of NGC 5548 during our campaign, the measured Hβ lag is a factor of five shorter than the expected value implied by the R BLR-L AGN relation based on the past behavior of NGC 5548

A facile technique to prepare MgO-biochar nanocomposites for cationic and anionic nutrient removal

The removal of NH4+ and PO43− from water using adsorbents produced from rice husk and corn cob byproducts was examined. The synthesis of MgO-biochar nanocomposites was conducted by magnesium activation under nitrogen atmosphere at 400 °C and 500 °C. The characterization of different materials was performed using various modern instruments such as XPS, SEM, EDS, XRD, FT-IR, BET…The comparison between modified and unmodified biochars for removing NH4+ and PO43− from water and the impact of different parameters on adsorption capacity of obtained materials were also performed. The results showed that the activation of biochar by magnesium led to changes in surface areas, pore volume, surface charge, and chemical properties of biochars and to increases in NH4+ and PO43− adsorption capacity. The adsorption of NH4+ and PO43− onto biochar-based nanocomposites followed both chemisorption and physisorption, were spontaneous, and endothermic. The NH4+ maximum uptake calculated according to Langmuir model were 21.32 mg/g for RMgN500 and 16.31 mg/g for CMgN500 while the PO43− maximum uptake were 117.77 mg/g and 52.24 mg/g for of RMgN500 and CMgN500, respectively. The desorption and recyclability of the RMgN500 and CMgN500 were very effective by using 0.5 M NaOH solution for PO43− and diluted HCl solutions for NH4+. This approach of synthesizing MgO nanoparticles impregnated in biochar matrix provided new opportunities in developing low-cost and highly efficient adsorbent to removal and recovery of NH4+ and PO43− from water