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We consider the possibility of an extensive invasional meltdown occurring in central North America involving eleven Eurasian species. The scenario begins with the potential co-facilitation between the European earthworm Lumbricus terrestris and European buckthorn, Rhamnus cathartica. Once introduced, European buckthorn has served as the overwintering host for two important invasive crop pests, oat crown rust, Puccinea coronata and the soybean aphid, Aphis glycines. The spread of R. cathartica itself may have been aided by seed dispersal by the European starling, Sturnus vulgaris, and the presence of L. terrestris has likely facilitated the invasion of Bipalium adventitium, an Asian predatory flatworm that specializes on earthworms. Beyond this, the soybean aphid is consumed by a number of introduced species, including the lady beetle Harmonia axyridis, the ground beetle Agonum muelleri and the parasitoid Aphelinus certus. We hypothesize that the presence of soybean aphid increases regional abundances of these species. We discuss both the evidence for this multi-species invasional meltdown scenario and potential implications of meltdown dynamics for invasive species management. The particular management issues that we discuss are: (1) opportunities for managing multiple invasive species simultaneously by targeting facilitator species, and (2) implications of meltdown dynamics for biological control introductions against the soybean aphid.

Herbivores may significantly reduce plant populations by reducing seed set; however, we know little of their impact on seed movement. We show for the first time that the receptacle-feeding weevil Rhinocyllus conicus not only reduces seed production by the invasive thistle Carduus nutans but also inhibits release and subsequent wind dispersal of seeds. These effects generate large, though different, impacts on spatial spread and local abundance in two populations with differing demography, located in the United States and New Zealand. Furthermore, the mechanism is context dependent, with the largest effects through increased terminal velocity in the United States but through reduced seed production in New Zealand. Our results show that the benefit of biocontrol programs may have been underestimated; screenings of potential biocontrol agents should examine effects on pest dispersal and spread, as well as on abundance.

Most organisms disperse at some life-history stage, but different research traditions to study dispersal have evolved in botany, zoology, and epidemiology. In this paper, we synthesize concepts, principles, patterns, and processes in dispersal across organisms. We suggest a consistent conceptual framework for dispersal, which utilizes generalized gravity models. This framework will facilitate communication among research traditions, guide the development of dispersal models for theoretical and applied ecology, and enable common representation across taxonomic groups, encapsulating processes at the source and destination of movement, as well as during the intervening relocation process, while allowing each of these stages in the dispersal process to be addressed separately and in relevant detail. For different research traditions, certain parts of the dispersal process are less studied than others (e.g., seed release processes in plants and termination of dispersal in terrestrial and aquatic animals). The generalized gravity model can serve as a unifying framework for such processes, because it captures the general conceptual and formal components of any dispersal process, no matter what the relevant biological timescale involved. We illustrate the use of the framework with examples of passive (a plant), active (an animal), and vectored (a fungus) dispersal, and point out promising applications, including studies of dispersal mechanisms, total dispersal kernels, and spatial population dynamics.

How herbivores locate and select their host plants is of fundamental importance in a variety of basic and applied ecological fields, including spatial population dynamics, invasive species management and biological control. This thesis addresses these questions for Rhinocyllus conicus, a flower head weevil that is a specialist herbivore of thistles, in particular the musk thistle, Carduus nutans. Rhinocyllus conicus has been widely used as a biological control agent for C. nutans, but success has been very variable, and a better understanding of the ecological determinants of host location, choice and impact will be invaluable. In order to assess the ecological determinants of patch finding and patch choice by R. conicus, C. nutans patches of varying size and density were artificially created. With an individually mark - mass release - resight (IMMRR) technique, the dispersal abilities, host location, and between patch movement patterns of R. conicus were studied. Rhinocyllus conicus was able to find host plant patches from a distance of up to a kilometer, though it located taller and closer patches at the highest rate. Weevils were more likely to leave small patches, and more likely to disperse to large patches. There was no significant effect of patch size and plant density on the number of weevils resighted per plant. Plant level characteristics, such as flower head diameter, plant height and total number of heads on a plant, were found to be important determinants of R. conicus oviposition response; no patch level characteristics were significant predictors of attack. In a related study, the effect of management practices, such as availability of plant resources, mowing, and abundance of the biocontrol agent R. conicus and their interaction on the oviposition response were also investigated. While an abundance of the biocontrol agent led to an increase in the number of eggs per flower head, this positive effect was eliminated by mowing. Fertilizer addition did not have an effect on R. conicus attack rates. As before, oviposition rates were found to increase significantly with flower head diameter, and there was a small positive effect of plant height. However, while larger C. nutans flower heads provide more sites for oviposition, there is also more seed production in these heads, and the reduction in seed production by R. conicus is not sufficient for complete control of its host. In an effort to determine some of the sensory mechanisms underlying the weevils' behavior, olfactometer studies were conducted. The behavioral response of R. conicus to C. nutans olfactory cues in the presence or absence of feeding weevil conspecifics, and also to two key life stages, bolting plants and rosettes, were investigated. Rhinocyllus conicus showed a preference for bolting C. nutans both in the presence and absence of weevil conspecifics. Colonization and establishment of the insect herbivore relative to the patch dynamics of its host strongly determine the success or failure of biological control efforts. The thesis concludes with a model that explores the thistle-herbivore dynamics in a metapopulation context. This framework will allow the empirical results to be extrapolated to larger spatial and temporal scales. The results of the baseline model show that the proportion of the landscape occupied by C. nutans decreases in the presence of R. conicus, though it predicts a lower proportion of attacked patches of C. nutans than actually occurs in central Pennsylvania. This model does not yet take into account the detailed results of the empirical work in this thesis; however it is a useful starting point for exploring these issues at larger scales. In conclusion this thesis shows for the first time that R. conicus moves further than previously known, locates its host based on characteristics of the host patch, but oviposits in response to plant characteristics. The weevil has a moderate negative impact on seed production, but, critically, it may miss isolated plants, which has significant implications for its efficacy as a biocontrol agent as the thistle spreads.

Metal sektöründe yüksek adetli seri üretim yapan firmalar arasında artan rekabet, firmaların daha kaliteli üretimi daha az maliyette ve daha kısa zamanda yapmalarını zorunlu kılmıştır. Bu amaçla sektör içinde yaygın olarak kullanılan üniversal CNC makinelere alternatif olarak yüksek hızlarda çalışabilen, yalnızca yüksek adette işlenecek olan ve biçimsel olarak birbirine benzeyen sınırlı sayıdaki malzemeye özel olarak üretilen CNC transfer makinelerine olan talebi arttırmıştır. Ayrıca, bu makinelerin yüksek hızlarda çalışmaları, robotik otomasyon ile besleme sistemlerini kullanma ihtiyacını ortaya çıkarmıştır. Bir vardiya zamanında binlerce malzemenin işlendiği düşünüldüğünde ham malzemelerin robot alanına getirilmesinin sağlanması da oldukça önemli bir iştir. Bu işin otomatikleştirilmesi amacıyla uzun süre malzeme temini sağlayan malzeme besleme ünitesi sistemleri yine bu uygulama tipinde sıklıkla kullanılmaktadır. Bu çalışma kapsamında üç tip musluk malzemesinin tüm talaş kaldırma işlemlerini gerekli işleme toleransları içinde kalarak 8s ile 11s aralığında çevrim sürelerinde tamamlayabilen CNC transfer makinesinin tasarımı ve üretimi gerçekleştirilmiştir. Ayrıca makineye adapte edilen kameralı robotik otomasyon uygulaması ve malzeme besleme ünitesi ile sistemin insansız şekilde çalışması sağlanmıştır. Çalışmanın birinci bölümünde endüstride kullanılmakta olan CNC makineler, malzeme besleme üniteleri sistemleri ve endüstriyel robotlar hakkında genel bilgiler verilmiştir. İkinci bölümde üretimi gerçekleştirilecek sistemin tasarım süreçleri ve otomasyonun çalışma algoritması konularına değinilmiştir. Üçüncü bölümde üretimin gerçekleştirilmesi ve sistemin devreye alınması işlemleri anlatılmıştır. Dördüncü bölümde ise sonuçlar verilmiş, son değerlendirmeler yapılmıştır.

K-Ras is the most frequently mutated oncoprotein in human cancers, and G12D is its most prevalent mutation. To understand how G12D mutation impacts K-Ras function, we need to understand how it alters the regulation of its dynamics. Here, we present local changes in K-Ras structure, conformation and dynamics upon G12D mutation, from long-timescale Molecular Dynamics simulations of active (GTP-bound) and inactive (GDP-bound) forms of wild-type and mutant K-Ras, with an integrated investigation of atomistic-level changes, local conformational shifts and correlated residue motions. Our results reveal that the local changes in K-Ras are specific to bound nucleotide (GTP or GDP), and we provide a structural basis for this. Specifically, we show that G12D mutation causes a shift in the population of local conformational states of K-Ras, especially in Switch-II (SII) and α3-helix regions, in favor of a conformation that is associated with a catalytically impaired state through structural changes; it also causes SII motions to anti-correlate with other regions. This detailed picture of G12D mutation effects on the local dynamic characteristics of both active and inactive protein helps enhance our understanding of local K-Ras dynamics, and can inform studies on the development of direct inhibitors towards the treatment of K-Ras G12D -driven cancers.

Background: Ischaemia-reperfusion (IR) injury, which can be encountered during surgical procedures involving the abdominal aorta, is a complex process that affects distant organs, such as the heart, liver, kidney, and lungs, as well as the lower extremities. In this study, we aimed to contribute to the limited literature by investigating the protective effect of dexmedetomidine, which was administered through different routes, on kidney tissue in rats with spinal cord IR injury. Methods: A total of 30 rats were randomly divided into five groups: control (C group), IR (IR group), IR-intraperitoneal dexmedetomidine (IRIPD group), IR-intrathecal dexmedetomidine (IRITD group), and IR-intravenous dexmedetomidine (IRIVD group). The spinal cord IR model was established. Dexmedetomidine was administered at doses of 100 [micro]g/kg intraperitoneally, 3 [micro]g/kg intrathecally, and 9 [micro]g/kg intravenously. Histopathologic parameters in kidney tissue samples taken at the end of the reperfusion period and biochemical parameters in serum were evaluated. Results: When examined histopathologically, tubular dilatation was found to be significantly reduced in the IRIVD, IRITD, and IRIPD groups compared with the IR group (p = 0.012, all). Vascular vacuolization and hypertrophy were significantly decreased in the IRIVD, IRITD, and IRIPD groups compared with the IR group (p = 0.006, all). Tubular cell degeneration and necrosis were significantly reduced in the IRIVD, IRITD, and IRIPD groups compared with the IR group (p = 0.008, p = 0.08, and p = 0.030, respectively). Lymphocyte infiltration was significantly decreased in the IRIVD and IRITD groups compared with the IR group (p = 0.006 and p = 0.06, respectively). Conclusion: It was observed that dexmedetomidine administered by different routes improved the damage caused by IR in kidney histopathology. We think that the renoprotective effects of dexmedetomidine administered intravenously and intrathecally before IR in rats are greater. Keywords: dexmedetomidine, ischaemia-reperfusion, intrathecal, intravenous, rat

Introduction: Stenotrophomonas maltophilia is the only opportunistic human pathogen in the genus Stenotrophomonas. These bacteria can be isolated from healthcare settings, possibly resulting in bacterial colonization of medical devices, which cause nosocomial infections. S. maltophilia bacteremia results in high mortality and morbidity. This study aimed to determine the outcomes of S. maltophilia bacteremia and its associated mortality risk factors. Methodology: This was a retrospective study conducted at the University of Medical Sciences, Bakirkoy Dr. Sadi Konuk Training and Research Hospital (Istanbul, Turkey) from December 2015 to December 2022. Medical records, demographic information, clinical conditions, laboratory data, antimicrobial susceptibility, and clinical outcomes were retrospectively analyzed for the period between December 2015 and December 2022. Results: Data from 87 patients (median age 61 years) with bacteremia were included in this study. The most common underlying conditions were diabetes mellitus (DM; 32.2%), hypertension (29.9%), and malignancies (19.5%). The most common sources of bacteremia were central venous catheters (CVCs; 44%), primary blood infection (32%), respiratory tract infection (20.7%), and wound site/abscess infection (2.3%). Seventy-eight percent of the patients were admitted to the intensive care unit (ICU) when bacteremia was detected. The 28-day mortality rate was 55%. The mortality rate was significantly higher in the ICU (p < 0.001). Elevated values of procalcitonin and C-reactive protein, and the presence of CVC were significant risk factors for mortality in those with S. maltophilia bacteremia. Conclusions: S. maltophilia bacteremia should be carefully monitored in patients with CVCs. Timely removal of CVCs can result in decreased mortality.

Spinal cord ischemia-reperfusion injury (IRI) is a serious condition that can develop after spinal and thoracoabdominal surgeries or spinal cord traumas. The aim of this study was to investigate the effects of different administration routes of ozone on testicular tissue in rats with spinal cord ischemia and reperfusion injury. Rats were divided into five groups (n:5): control (C), ischemia-reperfusion (IR), IR-rectal ozone (IR+RO), IR-intratechal ozone (IR+ITO), and IR-intraperitoneal (i.p) ozone (IR+IPO). Ozone-oxygen mixture was administered 30 minutes before midline laparotomy: 1 mg/kg (50 µg/mL) by rectal insufflation to the IR+RO group, 20 µL (20 µg/mL) intratechally to the IR+ITO group, and 0.7 µg/kg (50 µg/mL) intraperitoneally to the IR+IPO group. The spinal cord IR model was established. The testicular tissue was collected for histopathological and biochemical analyses. The Malondialdehyde (MDA) levels and Paraoxonase-1 (PON1) activities were significantly lower in the IR+RO, IR+ITO, and IR+IPO groups than in the IR group. Catalase (CAT) was significantly higher in the IR+ITO and IR+IPO groups than in the IR group. While the Cosentino score was significantly higher in the IR group than in the C group (p<0.001), it was significantly lower in the IR+RO, IR+ITO and IR+IPO groups than in the IR group (p<0.001, all). Ozone can regulate the negative effects of IRI by regulating cellular oxidative stress mechanisms. This effect can be achieved most effectively on testis tissue in the spinal cord IRI model through intrathecal and intraperitoneal administration.

K-Ras is the most frequently mutated oncogene in human cancers, but there are still no drugs that directly target it in the clinic. Recent studies utilizing dynamics information show promising results for selectively targeting mutant K-Ras. However, despite extensive characterization, the mechanisms by which K-Ras residue fluctuations transfer allosteric regulatory information remain unknown. Understanding the direction of information flow can provide new mechanistic insights for K-Ras targeting. Here, we present a novel approach – conditional time-delayed correlations (CTC) – using the motions of all residue pairs of a protein to predict directionality in the allosteric regulation of the protein fluctuations. Analyzing nucleotide-dependent intrinsic K-Ras motions with the new approach yields predictions that agree with the literature, showing that GTP-binding stabilizes K-Ras motions and leads to residue correlations with relatively long characteristic decay times. Furthermore, our study is the first to identify driver-follower relationships in correlated motions of K-Ras residue pairs, revealing the direction of information flow during allosteric modulation of its nucleotide-dependent intrinsic activity: active K-Ras Switch-II region motions drive Switch-I region motions, while α-helix-3L7 motions control both. Our results provide novel insights for strategies that directly target mutant K-Ras.