Sensitivity minimization by stable controllers for a class of unstable time-delay systems

In this paper sensitivity minimization problem is considered for a class of unstable time delay systems. Our goal is to find a stable controller stabilizing the feedback system and giving rise to smallest H∞ norm for the sensitivity function. This problem has been solved by Ganesh and Pearson (1986) for finite dimensional plants using Nevanlinna-Pick interpolation. We extend their technique to include possibly unstable time delay systems. Moreover, we illustrate suboptimal solutions, and their robust implementation. © 2006 IEEE

Remarks on H ∞ controller design for SISO plants with time delays

The skew Toeplitz approach is one of the well developed methods to design H ∞ controllers for infinite dimensional systems. In order to be able to use this method the plant needs to be factorized in some special manner. This paper investigates the largest class of SISO time delay systems for which the special factorizations required by the skew Toeplitz approach can be done. Reliable implementation of the optimal controller is also discussed. It is shown that the finite impulse response (FIR) block structure appears in these controllers not only for plants with I/O delays, but also for general time-delay plants

On the mixed sensitivity minimization for systems with infinitely many unstable modes

In this note we consider a class of linear time invariant systems with infinitely many unstable modes. By using the parameterization of all stabilizing controllers and a data transformation, we show that ℋ ∞ controllers for such systems can be computed using the techniques developed earlier for infinite dimensional plants with finitely many unstable modes. © 2004 Elsevier B.V. All rights reserved

Geni potencijalne virulencije i profili antibiotske rezistencije bakterije campylobacter jejuni izolirane iz mačaka

Daily contact with cats is an important risk factor for human campylobacteriosis. The main goal of this study was to investigate the virulence genes and antibiotic resistances of C. jejuni isolated from the stools of cats brought to Erciyes University, Faculty of Veterinary Medicine, Training and Research Hospital Clinics. In the study, feces taken from different breeds and ages (1 month to 9 years) of 200 (116 female, 84 male) cats were examined between May 2017 and April 2018. Campylobacter spp. isolates were identified at genus and species level using genus specific multiplex PCR (mPCR), and the existence of iam, cadF, cdtA, flaA, ceuE, cdtC, cdtB and virB11 genes were found by PCR. The antimicrobial resistance and multidrug resitance (MDR) of the isolates were determined by disc diffusion test. By means of Enterobacterial Repetitive Intergenic Consensus Polymerase Chain Reaction (ERIC-PCR), the genetic relativeness of the isolates were revealed. In this study, 41 (20.5%) of 200 stool samples were shown to be positive for Campylobacter spp. in the isolation of Campylobacter spp. from stool samples. In the positive samples, 14 of 22 (63.6%) were from diarhoeic cats and 27 of 178 (15.1%) were non-diarhoeic cats. Also, in total 71 Campylobacter spp. suspicious isolates were recovered from the 41 positive samples obtained. Phenotypic tests and PCR revealed that 65 isolates (20 from diarrhoeic and 45 from non-diarhoeic cat isolates) were identified as C. jejuni. The differences in isolation rate in relation to sex or age were not statistically significant (P>0.05). In terms of virulence genes, all C. jejuni isolates harbored at least five virulence genes. All isolates were positive for the cadF, cdtC and ceuE genes, respectively. C. jejuni isolates contained iam, cadF, cdtA, flaA, ceuE, cdtC, cdtB and virB11, at the rate of 19 (29.2%), 65 (100%), 64 (98.4), 54 (83%), 65 (100%), 65 (100%), 64 (98.4%) and 22 (33.8%) respectively. Moreover, cdtA and cdtB toxin genes were found in most of the isolates analysed. All C. jejuni isolates were susceptible to amoxicillin clavulanic acid. The highest resistances of the isolates were found as follows; 64 (98.4%), 63 (96.9%), 62 (95.3%) for ciprofloxacin (CIP), trimethoprim sulfamethoxazole (SXT), nalidixic acid (NA) antibiotics, respectively. Multiple resistance of isolates was detected in the present study. Sixty-one (93.8%) out of 65 isolates were resistant to three or more antibiotics, and the highest resistance levels to three and seven antimicrobials were observed in 23.1% and 15.3% of the isolates respectively. In the study, C. jejuni isolates were resistant to most antibiotics currently used, and had extraordinary virulence traits in cats which may constitute a non-negligible risk for public health.Svakodnevni kontakt s mačkama znatan je čimbenik rizika za kampilobakteriozu u ljudi. Glavni je cilj ovoga rada bio istražiti gene virulencije i antibiotsku rezistenciju bakterije C. jejuni izolirane iz izmeta mačaka dovedenih na Erciyes University, Faculty of Veterinary Medicine, Training and Research Hospital Clinics. Izmet je uzet od 200 mačaka (116 ženki i 84 mužjaka) različitih pasmina i dobi (1 mjesec do 9 godina), od svibnja 2017. do travnja 2018. Izolati Campylobacter spp. identificirani su na razini roda i vrste primjenom genski specifičnog multipleks PCR-a (mPCR) kojim je ustanovljena prisutnost gena iam, cadF, cdtA, flaA, ceuE, cdtC, cdtB i virB11. Antimikrobna rezistencija i otpornost na širok spektar lijekova (MDR) izolata određeni su disk-difuzijskim testom. Primjenom Enterobacterial Repetitive Intergenic Consensus Polymerase Chain Reaction (ERIC-PCR) otkriveni su genski srodnici izolata. U ovom je istraživanju 41 (20,5 %) od 200 uzoraka izmeta bio pozitivan na Campylobacter spp. Među pozitivnim uzorcima njih 14 od 22 (63,6 %) potjecalo je od mačaka koje su imale proljev, a 27 od 178 (15,1 %) uzoraka bilo je od mačaka koje nisu imale proljev. Fenotipski testovi i PCR pokazali su da je 65 izolata (20 od njih potjecalo je od mačaka koje su imale proljev i 45 od mačaka koje nisu imale proljev) identificirano kao C. jejuni. Razlike u broju izolata s obzirom na spol i dob nisu bile statistički znakovite (P > 0,05). Svi izolati C. jejuni imali su barem pet gena virulencije i bili pozitivni na gene cadF, cdtC i ceuE. Gen iam sadržavalo je 19 izolata C. jejuni (29,2 %), gen cadF 65 izolata (100 %), gen cdtA 64 izolata (98,4 %), gen flaA 54 izolata (83 %), gen ceu E 65 izolata (100 %), gen cdtC 65 izolata (100 %), gen cdtB 64 izolata (98,4 %) i gen virB11 22 izolata (33,8 %). Geni toksina cdtA i cdtB pronađeni su u većini analiziranih izolata. Svi su izolati C. jejuni bili osjetljivi na amoksicilin-klavulansku kiselinu. Najveća rezistencija bila je: 64 izolata (98, 4 %) na ciprofloksacin (CIP), 63 izolata (96,9 %) na trimetoprim- sulfametoksazol (SXT) i 62 izolata (95,3 %) na nalidiksičnu kiselinu (NA). U ovom je istraživanju ustanovljena višestruka rezistencija izolata. 61 od 65 izolata (93,8 %) bilo je otporno na tri ili više antibiotika, a najveća je otpornost utvrđena na tri antimikrobna lijeka u 23,1 % izolata i na sedam antimikrobnih lijekova u 15,3 % izolata. Istraživanjem je ustanovljena otpornost izolata C. jejuni na većinu antibiotika koji se trenutačno primjenjuju te iznimna svojstva virulencije u mačaka, koja mogu imati određeni rizik za javno zdravstvo

The role of female volunteers in disaster response organisations: A qualitative research

BACKGROUND: Despite a high demand for people to participate in disaster volunteering, the extent of contribution received from female volunteers in disaster response organisations constitutes an important debate. In the Elazığ earthquake on 24 January 2020, the role of female volunteers in rescuing a female victim from the wreckage once again demonstrated the importance of considering female volunteers when creating response capacities for disaster risks. OBJECTIVE: This qualitative study aims to evaluate the roles of female volunteers who play an active role in disaster response organisations in a society with gender equality issues. METHODS: This qualitative study included 15 National Medical Rescue Team (UMKE) female volunteers who took an active role in the Elazig earthquake and was performed between 15.07.2020 and 16.04.2021. Data were collected using an in-depth interview method. The data were analyzed using content analysis and the comments were given descriptively. RESULTS: Based on the qualitative analysis, the following concepts were explored among the participants: Volunteering, volunteering in disasters, the effects of volunteering on social life, being a woman in disasters, volunteering female in disasters, the 'motherhood myth', gender inequality. Women are key actors in tackling disaster damage and increasing available social resilience to disasters. In addition, women can use special attributes such as motherhood, which is socio-culturally defined and taught as an advantage, for the common good of society. Moreover, special elements, such as the image of the 'superwoman' in relation to the responsibilities imposed on women in disaster response organisations, which distort gender equality against women, appear as possible factors of harm for women. CONCLUSION: This study shows that female volunteers can play a life-saving role in chaotic situations such as disasters, contribute to the empowerment of women, increase sensitivity to gender and, in connection with this, the development of democracy in societies where gender inequality is high. On the other hand, special situations such as the image of 'superwoman', which aims for excellence in both private and public spheres in the responsibilities imposed on women, can destroy gender equality against women and increase women's fragility

Remarks on strong stabilization and stable H∞ controller design

A state space based design method is given to find strongly stabilizing controllers for multiple-input-multiple-output plants (MIMO). A sufficient condition is derived for the existence of suboptimal stable H∞ controller in terms of linear matrix inequalities (LMIs) and the controller order is twice that of the plant. A new parameterization of strongly stabilizing controllers is determined using linear fractional transformations (LFTs). © 2005 IEEE

Effect of the COVID-19 pandemic on violence against pre-hospital emergency health workers

BACKGROUND: Violence against pre-hospital emergency health workers is a growing problem worldwide and negatively impacts the effectiveness of emergency services. The social distancing, isolation and quarantine measures that have been employed to reduce the spread of COVID-19 have also had economic and psychosocial effects. Therefore, it is important to explore how the negative repercussions of the COVID-19 pandemic have influenced these violent incidents that interfere with the work of emergency medical services (EMS). OBJECTIVE: This study aims to evaluate how violence against EMS workers has been impacted by the effects of the COVID-19 pandemic. METHODS: This study takes an interpretive social science approach, using the qualitative method of in-depth semi-structured interviewing. Audio of the interviews was recorded with the interviewee's consent. Sound recordings were transcribed and their content was categorised into themes. Categorised texts were then evaluated using descriptive analysis. RESULTS: Participants reported that, during the COVID-19 pandemic, they encountered more violence than usual on EMS assignments to non-emergency situations, though a sense of gratitude towards health workers at the beginning of the pandemic and positives attitudes towards health workers also contributed to reduced violence towards them. The data indicate that workplace violence among EMS employees has increased as the problems caused by the pandemic have intensified, suggesting that additional measures need to be taken to protect them. CONCLUSION: In parallel with an increase in social violence during the COVID-19 pandemic, violence against EMS workers also increased in prevalence. A multidimensional approach should now be taken to determine how violence against EMS employees will be affected by risks such as the intergenerational transmission of social violence, a psychosocial repercussion of the COVID-19 pandemic, especially considering the increasing workplace violence among EMS employees

Stabilization of some fractional neutral delay systems which possibly possess an infinite number of unstable poles

International audienceWe consider fractional delay systems of neutral type and prove that many systems with infinitely many unstable poles cannot be stabilized by the class of rational fractional controllers of commensurate order. For a class of fractional neutral delay systems with an infinite number of poles asymptotic to the imaginary axis from the right or left hand side, we are able to derive a parametrization of all stabilizing controllers from fractional PI controllers obtained from previous work