Restoration Capacity Research Articles

Accumulated-Downtime-Oriented Restoration Strategy With Service Differentiation in Survivable WDM Mesh Networks

Telecommunications service providers (SP) should place survivability expectations by guaranteeing maximal allowed system downtime for service-level agreement (SLA)-differentiated services. Furthermore, SPs should continuously focus on utilizing network resources effectively, by considering the bounded network capacity and the growth of future data traffic. In order to improve different service availabilities and achieve high resource efficiency, we present a novel restoration scheme by jointly considering accumulated downtime and SLA requirements of faulty connections. While most past related works have focused on providing statistical guarantees on availability when a connection is provisioned, our current approach recognizes that, after a connection has been in existence, it could be “ahead” (or “behind”) its performance guarantee based on what network outages it might have experienced, so the resources allocated to it may be revised judiciously. When a link failure occurs, two sets of faulty connections are examined: (a) connections whose primary or restoration path is disrupted by the failure and (b) connections that are in the “down” state due to some previous failures (which have not been repaired yet). An affected connection is switched to its pre-computed or an alternate restoration path if necessary, when its accumulated downtime plus the link repair time will exceed its SLA requirement. The scheme provides differentiated restoration to existing connections upon a link failure in order to satisfy the connections’ availability requirements. We also propose an upgraded version of the scheme that incorporates both excess capacity and resource preemption into the scheme. Given the network capacities and the current network state including routing information for all existing connections, a faulty connection is restored to its restoration path as long as there is enough excess capacity along the path. Otherwise, when protection switching of a high-SLA connection fails due to limited bandwidth on some link(s), it preempts restoration capacity on each link from a low-SLA connection if both disrupted connections share the same restoration capacity and the availability requirement of the low-SLA connection is not violated. Finally, we report simulation results for a large carrier-scale network to show computational performance of our proposed algorithm. The results demonstrate that the algorithm achieves a high availability satisfaction rate and good resource utilization, as well as greatly reduces protection-switching overhead.

Effect of cold fronts on the benthic macrofauna of exposed sandy beaches with contrasting morphodynamics

The aim of this study was to determine the short-term environmental changes caused by the simultaneous passage of a high energy event on two sandy beaches with different morphodynamic states and their influence on the richness, abundance and distribution of the benthic macrofauna. Two microtidal exposed sandy beaches with contrasting morphodynamics were simultaneously sampled before, during and after the passage of two cold fronts in Santa Catarina. The reflective beach showed a higher susceptibility to the increase in wave energy produced by the passage of cold fronts and was characterized by rapid and intense erosive processes in addition to a capacity for rapid restoration of the beach profile. As regards the dissipative beach, erosive processes operated more slowly and progressively, and it was characterized further by a reduced capacity for the recovery of its sub-aerial profile. Although the intensity of the environmental changes was distinct as between the morphodynamic extremes, changes in the composition, richness and abundance of macrobenthos induced by cold fronts were not evident for either of the beaches studied. On the other hand, alterations in the distribution pattern of the macrofauna were observed on the two beaches and were related to variations in sea level, position of the swash zone and moisture gradient, suggesting that short-term accommodations in the spatial structure of the macrobenthos occur in response to changes in environmental conditions in accordance with the temporal dynamics characteristic of each morphodynamic state.

Pattern of long‐term sensorimotor recovery following intrastriatal and ‐accumbens DA micrografts in a rat model of Parkinson's disease

The functional restorative capacity of fetal dopaminergic (DA) transplants is governed by a number of critical parameters including graft location, survival of DA neurons, and transplantation technique. In addition, there is an ongoing controversy whether "too much" or "too little" survival of DA neurons is responsible for the incomplete functional recovery observed in some transplanted Parkinson's disease (PD) patients. Here we investigated two implantation sites, the nucleus accumbens (NAc) and the caudate-putamen unit (CPU), and two different graft distributions within the CPU, i.e., two 0.75 microL deposits (CPU-2) versus six 0.25 microL deposits (CPU-6) in a rat model of PD. Grafts were derived from E14 rat ventral mesencephalon and the long-term functional outcome was evaluated with a wide range of complex-sensorimotor behavioral tests. The data show that forelimb stepping, balancing behavior, and skilled forelimb reaching behavior was more restored in CPU-6-grafted animals as compared to CPU-2 animals, although the number surviving dopaminergic neurons and dopamine release were similar in the two groups. Furthermore, a correlation analysis revealed a number of inverse relationships between the rate of DA neuron survival and sensorimotor performances, e.g., for skilled forelimb use. DA grafts placed into the NAc induced a partial recovery in drug-induced rotation tests but failed to restore any of the other sensorimotor behaviors tested. Taken together, these data have important implications both for a better understanding of the complex functional graft-host interactions as well as for the further optimization of clinical neural transplantation strategies in neurodegenerative diseases.

Survival and early functional integration of dopaminergic progenitor cells following transplantation in a rat model of Parkinson's disease

Dopaminergic (DA) grafts in rat models of Parkinson's disease (PD) have previously been derived from embryonic day (E) 14 grafts. Because there is an increasing interest in the restorative capacity of DA stem and progenitor cells, in the present study we examined the survival and early and late functional behavioral effects of DA progenitor cells derived from E12, E13, E14, and E15 grafts transplanted into rats with unilateral 6-hydroxydopamin lesions. DA transplant-induced functional recovery was already observed in postural balancing reactions after 10 days and in stepping behavior after 13 days, that is, in spontaneous complex behaviors, and later, after 16 days, in the amphetamine-induced rotation test. Three distinct patterns of functional recovery could be observed at 6-9 weeks posttransplantation. First, behavioral improvements in drug-induced rotational asymmetry, stepping, and skilled forelimb behavior were directly related to DA neuron survival and TH-positive fiber reinnervation. Second, recovery in postural balancing reactions was closely related to a specific developmental time window of donor age, for example, only seen in E13 and E14 grafts. Finally, no functional graft effects were seen in the table lift test. Interestingly, DA neuron graft survival, TH-positive fiber outgrowth, and graft volume were significantly influenced by the developmental time window in which the DA progenitor cells were dissected from the ventral mesencephalon, that is, from E12, E13, E14, or E15 rat embryos. These data highlight the complexity of graft-host interactions and provide novel insights into the dynamics of DA progenitor graft-mediated functional recovery in animal models of Parkinson's disease.

Another New “Super Muscle Stem Cell” Leaves Unaddressed the Real Problems of Cell Therapy for Duchenne Muscular Dystrophy

The history of preclinical efforts toward developing cell transplantation therapy to treat Duchenne muscular dystrophy (DMD) has been marked by a series of promising studies in mice, with sometimes surprising results, that generated large expectations that in some cases remain valid and in others have been refuted or slowly forgotten. Therefore, after many years working in the field of cell transplantation in neuromuscular diseases, we respond a priori to any announcement of a proposed “super-cell” for clinical cell regeneration therapy with a healthy dose of skepticism. This skepticism has been reinforced in many cases after a critical reading of the articles in question and has often been further validated by the inability of others to reproduce the reported results. Indeed, with few exceptions, the results published by different teams describing this or that new cell with greater proliferative or restorative capacities have not been reproduced by independent groups.

Bandwidth Guaranteed Routing With Fast Restoration Against Link and Node Failures

An important feature of MPLS networks is local restoration where detour paths are set-up a priori. The detour is such that failed links or nodes can be bypassed locally from the first node that is upstream from the failures. This local bypass activation from the first detection point for failures permits much faster recovery than end-to-end path based mechanisms that require failure information to propagate to the network edges. However, local restoration of bandwidth guaranteed connections can be expensive in the additional network capacity needed. Hence, it is important to minimize and share restoration capacity. The problem of routing with local restoration requirements has been studied previously in a dynamic on-line setting. However, there are no satisfactory algorithms for the problem of pre-provisioning fast restorable connections when the aggregate traffic demands are known (as would be the case when a set of routers are to be interconnected over an optical network or for pre-provisioned ATM over MPLS overlays). The contribution of this paper is a fast combinatorial approximation algorithm for maximizing throughput when the routed traffic is required to be locally restorable. To the best of our knowledge, this is the first combinatorial algorithm for the problem with a performance guarantee. Our algorithm is a fully polynomial time approximation scheme (FPTAS), i.e., for any given epsiv > 0, it guarantees (1+epsiv)-factor closeness to the optimal solution, and runs in time polynomial in the network size and [ 1/( epsiv)]. We compare the throughput of locally restorable routing with that of unprotected routing and 1+1-dedicated path protection on actual US/European ISP topologies taken from the Rocketfuel project .

Functional Patterns of HIV-1-Specific CD4 T-Cell Responses in Children Are Influenced by the Extent of Virus Suppression and Exposure

Correa R, Harari A, Vallelian F, et al. AIDS. 2007;21(1):23–30 PURPOSE OF THE STUDY. HIV-specific CD4+ T cells seem to play a critical role in antiretroviral immunity and particularly in maintaining cytotoxic T-cell responses. The objective of this study was to evaluate the function of HIV-specific T cells in antiviral treated, HIV-infected children. STUDY POPULATION. The researchers evaluated 23 HIV-infected children who were treated with antiretroviral therapy for a mean of 7 years. METHODS. Flow-cytometric analysis was used to measure the ability of HIV-specific T cells to secrete interleukin 2 (IL-2) and interferon γ (IFN-γ) after stimulation of patient cells with p55 gag protein. RESULTS. Three patterns of intracellular cytokine generation were identified: in 10 subjects, antigen-specific cytokine production was characterized by IL-2 production, 8 subjects’ CD4+ T cells expressed IL-2 and IFN-γ, and 5 subjects’ T cells expressed IFN-γ alone. These 3 groups were then analyzed for factors that might explain the different patterns. The patterns correlated with viral load at the time of functional analysis and over the previous 2 years. The group with dominant IFN-γ responses had high viremia levels, a pattern similar to that observed in patients with uncontrolled viral replication. Patients with combined IL-2 and IFN-γ production had relatively lower viral loads but had experienced viral “blips” over the 2 years before analysis. This pattern was similar to adults who were long-term nonprogressors or those whose conditions continued to progress despite antiretroviral therapy. The subjects with a dominant IL-2 response had very low levels of viremia and had not experienced viral “blips” over the previous 2 years. This pattern was similar to that generally observed in individuals who have cleared the infecting agent. It is important to note that this pattern has not been observed in HIV-infected adults. CONCLUSIONS. Children with HIV have a higher frequency of HIV-specific CD4+ T cells compared with adults, and their recovery of an IL-2–secreting T-cell pattern indicates a greater capacity for immune restoration in children than adults. REVIEWER COMMENTS. This elegant study provides a biological rationale for the clinical observation that young children started on antiretroviral therapy have the capacity for remarkable reconstitution of immune functions relative to those reported in adults and older children who have been infected for prolonged periods before antiretroviral therapy. Perhaps it is unfair to compare these results with findings in adults that included patients who were infected for many years before their initiation of therapy. A more appropriate comparative adult group would be those treated within 6 months of their diagnosis. Most importantly, this study demonstrates that children are “different” and that treatment early in infection allows excellent immune reconstitution if viral replication is completely controlled.

Changes in plant species diversity along a chronosequence of vegetation restoration in the humid evergreen broad‐leaved forest in the Rainy Zone of West China

AbstractPlant species diversity has been recognized as one of the vital attributes for assessing vegetation restoration. Changes in the diversity may be related to different stages of succession. In this study, 54 sites of humid, evergreen, broad‐leaved forest were selected in the Rainy Zone of West China. A chronosequence of the sites was used to study the successive patterns of the diversity in the forest that had undergone natural regeneration for 5 to 350 years and to test the hypothesis that the diversity is maximized in mid‐succession. Data were collected simultaneously at different stages of succession, and four α‐diversity indices (species richness, Margalef index, Shannon‐Wiener index, Pielou Evenness index) and two β‐diversity indices (Whittaker index, Sørensen's index) were calculated for each stratum in each plot. A total of 394 vascular plant species were recorded. From the β‐diversity indices, the forest succession may be divided into the early‐successional stage (before 50 years), mid‐successional stage (from 50 to 300 years), and late‐successional stage (after 300 years). In this community, the species diversity and richness were found to be the greatest at the mid‐successional stage, followed by the late‐ and early‐successional stages. The results of regression analysis indicated that the richness and Margalef index peaked around the 175th and 165th year, respectively. Shannon‐Wiener index values also appeared to follow an approximately humped pattern of succession and were maximal around the 100th year. However, the species evenness did not show any significant relationship with successional age. Our results demonstrate (1) forest restoration is a long‐term process and the formation of climax forest requires at least 300 years and (2) the forest has a strong capacity for restoration. Our results also suggestLindera limprichitiiandMachilus pingiias ideal tree species for afforestation because of their wide niche.

Joint homeostasis, restoration, and remodeling in osteoarthritis

Osteoarthritis is the major cause of joint failure. The outcome of the disease process is determined by complex interactions between cells and molecules steering homeostasis, destruction, restoration, and remodeling. The articular cartilage has a limited restoration and repair capacity. Genetic studies in humans and the development of mouse models have identified the role of signaling pathways that are important for skeletal development in the postnatal biology and pathology of articular cartilage. These include bone morphogenetic protein, transforming growth factor beta, fibroblast growth factor, wingless-type signaling, and their respective antagonists such as noggin and frizzled related protein. The synovium is prone to inflammation and emerging evidence suggests that innate and adaptive immune responses are important. Bone and cartilage form a biomechanical unit; stiffer bones might impair cartilage homeostasis. The biology of frizzled related protein provides a basis for the hypothesized inverse relationship between osteoarthritis and osteoporosis.

Tissue engineering of osteochondral constructs in vitro using bioreactors

Articular cartilage is a relatively simple tissue, but has a limited capacity of restoration. Tissue engineering is a promising field that seeks to accomplish the in vitro generation of complex, functional, 3-dimensional tissues. Various cell types and scaffolds have been tested for these purposes. The results of tissue engineered cartilage and bone are as yet inferior to native tissue. Strain and perfusion have been shown to stimulate cell proliferation and differentiation of various cell phenotypes. The perfect protocol to produce articular cartilage has not been defined yet. Bioreactors could provide the environment to engineer osteochondral constructs in vitro and to provide a stress protocol. The bioreactor has to provide an economically viable approach to automated manufacture of functional grafts under clinical aspects. Composite engineered tissues, like an engineered joint, represent a future goal. Cross-disciplinary approaches are necessary in order to succeed in engineering osteochondral grafts that provide adequate primary biomechanical stability and incorporate rapidly in vivo with histological appearance close to healthy osteochondral tissue. This review surveys current clinical and experimental concepts and discusses challenges and future expectations in this advancing field of regenerative medicine focusing human osteochondral constructs in bioreactors.

Premier bilan des opérations de restauration et de gestion conservatoires des landes du Moulinel à Saint—Josse (Pas-de-Calais)

The heathlands of Moulinel (Saint-Josse, Pas-de-Calais, France) are of great interest for flora and vegetation in north of France. Following the abandonment of traditional use they were threatened by shrubs at the beginning of the 80's. The Conservatoire des sites naturels du Nord et du Pas-de-Calais (CSN), with the help of the Centre régional de phytosociologie/Conservatoire botanique national de Bailleul (CRP/CBNBL), took several measures to enhance heathland and its flora on the basis of vegetation history and soil seed bank studies. First results show that soil seed bank study for evaluating vegetation capacity of restoration is usefull. Rapidity of development and restoration for some plant populations and some vegetations is pointed out. Quality of the results obtained is also due to the diversity of techniques and tools used for restoration

Regeneration of the adult thymus is preceded by the expansion of K5+K8+ epithelial cell progenitors and by increased expression of Trp63, cMyc and Tcf3 transcription factors in the thymic stroma

Studies of HIV-1-infected individuals on anti-retroviral therapies and of patients receiving lymphoablating treatments indicate that the thymus retains restorative capacity even in adults. The contributions of the thymic epithelial cells (TECs) to the regeneration of the thymus and the identity of epithelial cell progenitors were evaluated in murine models of transient thymic atrophy followed by a complete regeneration. Using microarray approach, we analyzed the pattern of gene expression in TECs sorted from mice that were depleted of thymocytes by steroid treatment or by irradiation. The initial analysis identified significant increases in the mRNA for cMyc, Trp63 and Tcf3 transcription factors known to be expressed in early epithelial cell progenitors in tissues other than the thymus. Immunohistochemistry showed that in involuted thymuses, the cMyc and Trp63 proteins were expressed in a subset of cortical thymic epithelial cells (cTECs) that were keratin 5 positive (K5(+)), typifying cTEC precursors. Importantly, confocal microscopy established that epithelial cells with the phenotype of putative TEC progenitors (i.e. K5(+)K8(+)) expressed the Trp63 protein and confirmed that K5(+)K8(+) TEC progenitors expanded significantly during atrophy and prior to the thymic regeneration. Thus, our data demonstrated for the first time that critical steps in the recovery of the adult thymus include expansion of TEC progenitors and elevated expression of Trp63, cMyc and Tcf3 transcription factors in the thymic stroma. These results suggest that TEC progenitors could be reactivated in the adult thymus and, therefore, reactivation of TEC progenitors could provide a new approach for thymic reconstitution.

Oxidative Stress of Neural, Hematopoietic, and Stem Cells: Protection by Natural Compounds

During natural aging, adult stem cells are known to have a reduced restorative capacity and are more vulnerable to oxidative stress resulting in a reduced ability of the body to heal itself. We report here that the proprietary natural product formulation, NT020, previously found to promote proliferation of human hematopoietic stem cells, reduced oxidative stress-induced apoptosis of murine neurons and microglial cells in vitro. Furthermore, when taken orally for 2 weeks, cultured bone marrow stem cells from these mice exhibited a dose-related reduction of oxidative stress-induced apoptosis. This preclinical study demonstrates that NT020 can act to promote healing via an interaction with stem cell populations and forms the basis of conducting a clinical trial to determine if NT020 exhibits similar health promoting effects in humans when used as a dietary supplement.

Fertilization ensures rapid formation of ground vegetation on cut-away peatlands

Mechanical harvesting of peatlands completely changes the original bog ecosystem and without afteruse causes long-lasting disturbance in the environment due to the limited restoration capacity of the habitat. We studied the effects of fertilization on the establishment of vegetation on a cut-away peatland in Finland. Six treatments of different quantities and mixtures of wood ash, peat ash, biotite, or forest P–K fertilizer were replicated in three plots. Although all the fertilizers accelerated the revegetation of a cut-away peatland significantly, ash-based fertilizers had the greatest and most immediate impact on the formation of vegetation. Ash fertilizers especially increased the coverage of small fire-loving moss species such as Ceratodon purpureus (Hedw.) Brid., Funaria hygrometrica Hedw., and Leptobryum pyriforme (Hedw.) Wils. in the early stages of the succession. Furthermore, the succeeding coverage of vascular plants improves nutritional conditions through the rapid accumulation and decomposition of plant-derived litter. The rapid formation of ground vegetation on bare peat surface after ash fertilizer application indicated that wood and peat ash are suitable for mined peatlands. This being the case, peat and wood ash should be regarded more as a recyclable constituent rather than as waste in afforestation of cut-away peatlands.

Evaluation of the implementation of a goal-oriented peatland rehabilitation plan

Ecological restoration is a problem-driven scientific discipline. Thus an evaluation of the restoration strategies is needed periodically to improve the concepts. In Northern Germany, the Environmental Ministry adopted a peatland action plan in 2002 with the goal to (I) rehabilitate the water quality improvement potential of degraded peatlands and (II) to create suitable habitat conditions for endangered wetland species. The plan is implemented in a series of stages. The goals are clearly stated in the plan. For state-wide site selection, a GIS-based peatland information system was developed. For each peatland, information about land use, hydrology, conservation status, species occurrence and soil is stored in the database. Peatland sites with a high risk for nitrogen leaching are identified by calculating a land use intensity index. A flow path-oriented decision support system was developed to calculate the effect of land use and water management changes on nitrogen outflow and nitrogen transformation. The model result – absolute reduction of nitrogen outflow – is transformed into a cost-effectiveness value, which is used by water authorities to rank funding proposals. The DSS is developed as user-friendly, web-based software; its handling requires basic knowledge of landscape hydrology. However, local authorities do not use both tools intensively. For them, the most important factor for site selection is the possibility of land acquisition. To improve goal-oriented site selection and planning, local authorities need more training and a better hydrological understanding. To improve the effectiveness of ecological restoration projects, training and capacity building are as important as tool development and research.

Functional patterns of HIV-1-specific CD4 T-cell responses in children are influenced by the extent of virus suppression and exposure

Virus-specific CD4 T cells play a critical role in antiviral immunity. HIV-1-specific CD4 T cells in chronically infected adults are mostly composed of IFN-gamma-secreting cells, whereas a selective defect in IL-2-secreting CD4 T cells has been demonstrated. HIV-1-specific IL-2-secreting CD4 T cells are key components of effective immunity. To determine the function of HIV-1-specific CD4 T cells in HIV-1 vertically infected children after antiretroviral treatment (ART). Twenty-three vertically HIV-infected children treated with ART for an extended period (mean 7 years) were retrospectively studied. The function of HIV-1-specific CD4 T cells was determined by their ability to secrete IL-2 and IFN-gamma after stimulation with HIV-1 p55 gag protein using polychromatic flow cytometry. : Substantial differences in the patterns of CD4 T-cell responses were associated with different conditions of response to ART. Interestingly, children with suppression of viraemia below 50 HIV-1-RNA copies/ml of plasma for at least 2 years showed dominant IL-2 CD4 T-cell responses; children with viraemia below 50 copies but experiencing transient blips of viraemia showed polyfunctional (IL-2 plus IFN-gamma) CD4 T-cell responses; children with uncontrolled high viraemia levels had dominant IFN-gamma CD4 T-cell responses. Furthermore, the total frequency of HIV-1-specific CD4 T cells including IL-2 and IFN-gamma-secreting cells was significantly higher compared with HIV-infected adults with chronic infection. The higher frequency of HIV-1-specific CD4 T cells in children compared with adults and the recovery of IL-2-secreting CD4 T cells after successful ART-mediated suppression of virus replication indicate a greater capacity of immune restoration in children than adults.

Influence of bond quality on failure load of leucite- and lithia disilicate–based ceramics

The long-term survival of bonded ceramic restorations for posterior teeth is a clinical concern. The durability of the bond between the ceramic and dentin during clinical service is a factor in the load-bearing capacity of the restoration. This study aimed to evaluate the effect of interfacial bonding quality on the interface failure initiation loads of 2 all-ceramic systems. One leucite-reinforced ceramic, IPS Empress (E1), and 1 lithia disilicate glass-ceramic, IPS Empress 2 (E2), were used to form disks 8.5 mm in diameter, with an approximate 1.35-mm total thickness (n=45). The ceramic specimens were fabricated in a manner that simulated their clinical application. The E1 specimens were fabricated using the staining technique, and the E2 specimens were made using a layering technique. Completed disks of each ceramic system were divided into 3 subgroups (n=15) that were subsequently cemented using 1 of 3 bonding conditions (Control, Cer, Sub). The control group followed ideal bonding protocol, whereas groups Cer and Sub had bonds that were compromised between the cement and the ceramic (Cer) or the substrate and the cement (Sub). All luted specimens were loaded at the center with a 10-mm-diameter ball indenter at a crosshead speed of 0.01 mm/min in a universal testing machine. Intermittent loads were applied in increasing increments of 50 N until a fracture could be observed in the ceramic substrate by transillumination with x2.6 optical magnification. The maximum load applied prior to crack observation was recorded as the failure initiation load. Survival analytical methods were used to determine differences between groups. The characteristic fracture initiation loads ranged from 223.5 to 760.6 N. Group E2 had the greatest mean observed load to failure (715.6 N), which was significantly greater than group E1 (P<.001). For both the E1 and E2 ceramic systems, the control groups had significantly greater mean fracture initiation loads than either of the interface-inhibited Cer and Sub groups. Poor bond quality at either the ceramic-cement or dentin-cement interface can significantly reduce the fracture initiation load-bearing capacity of ceramic disks bonded to compliant dentin-like substrates. For the E2 ceramic material, disruption of the ceramic-cement interface had a more detrimental effect on the load-bearing capacity of the simulated restoration than the disruption of the cement-dentin interface.

Short and intermediate economic impacts of a terrorist-initiated loss of electric power: Case study of New Jersey

The economic impacts of potential terrorist attacks on the New Jersey electric power system are examined using a regional econometric model. The magnitude and duration of the effects vary by type of business and income measure. We assume damage is done during in the summer 2005 quarter, a peak period for energy use. The state economy recovers within a year, if we assume that economic activity is restored in the next time period. However, if the attacks prompt an absolute of loss of activity due to firm relocation, closing, and geographical changes in expansion plans, then the economy does not fully recover by the year 2010. Hence, the electrical power system's resiliency to damage is the key to the extent and duration of any economic consequences of a terrorist attack, at least in New Jersey. The policy implication is that the costs and benefits of making the electric power system more resilient to plausible attacks should be weighed and that the restorative capacity of the system should be strengthened.

Fiber-reinforced composite substructure: Load-bearing capacity of an onlay restoration

Objective. To determine the static load-bearing capacity of composite resin onlay restorations made of particulate filler composite (PFC) with two different types of fiber-reinforced composite (FRC) substructures. Material and Methods. Specimens were prepared to simulate an onlay restoration, composed of a 2 to 3 mm FRC layer as the substructure (short random and continuous bidirectional fiber orientation) and a 1 mm surface layer of PFC. Control specimens were prepared from plain PFC. The specimens were incrementally polymerized with a hand-light curing unit for 40 s and then post-cured in a light-curing oven for 15 min. The specimens were cemented on dentin substrate of extracted human molars using a standard adhesive resin cementation technique. The specimens (n=8/group) were water stored either for 24 h at room temperature or for 4 weeks at 37°C before they were statically loaded until fracture using a universal testing machine. Failure modes were visually examined. Results. ANOVA revealed that all specimens with FRC substructures had higher values of static load-bearing capacity than those obtained with plain PFC (p<0.001). The load-bearing capacity of all the specimens decreased after water storage (p<0.001). Conclusions. Restorations made from a combination of FRC and PFC showed better load-bearing capacity than those obtained with PFC alone.

Growth regulators restore germination of Orobanche seeds that are conditioned under water stress and suboptimal temperature

Broomrapes (Orobanche spp.) are serious root parasitic weeds that cause great damage to crop production in many parts of the world. The study focussed on the influence of plant growth regulators on germination of Orobanche seeds conditioned under suboptimal temperature (at 13°C) and under water stress (at –1 and –2 MPa). Three widely distributed species of broomrapes (O. aegyptiaca, O. ramosa, and O. minor) were used in the experiments. Exogenous GA3 (10 mg/L), brassinolide (1 mg/L), and fluridone (10 mg/L) significantly increased the broomrape seed response to the germination stimulant GR24 (10–6 m) even when seeds were first conditioned at a suboptimal temperature and under water stress. The highest germination was obtained when the combined treatments with fluridone and brassinolide, or with GA3 and brassinolide were applied together with the germination stimulant. This indicates that there were additive effects among various plant growth regulators in the regulation of germination response in Orobanche seeds. With the prolongation of conditioning periods under low temperature stress, the restoration capacities of seed germination by a single growth regulator decreased, but the combined treatments of growth regulators retained their positive effects in restoring seed germination.