UV inscribed long period gratings with femtosecond ablated axial fibre slots for polarization control

We present data on the development a new type of optical fibre polariser and the characterisation of its wavelength properties. The device is fashioned using a two step process. Firstly, a standard UV long period grating (LPG) with a period of 330μm is inscribed into hydrogenated SMF-28, followed by femtosecond laser ablation of a groove parallel to the fibre axis. The UV inscribed LPGs have inherently low birefringence. However, the removal of the cladding layer parallel to the location of the LPG within the fibre core (as a result the ablation) modifies the cladding modes that couple with the LPG. Furthermore, the groove breaks the fibre symmetry introducing a non-uniform stress profile across the fibre cross section leading to significant birefringence. We show that increasing the depth of the groove increases the birefringence, and this behaviour coupled with the ability to control the wavelength location of the LPGs attenuations peaks results in a polariser able to operate at almost any wavelength and birefringence. The maximum birefringence reported here as polarisation mode splitting was approximately 39±0.1nm with a polarisation loss of 10dB. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

Short and long hydroperiod Everglades periphyton mats: Community characterization and experimental hydroperiod manipulation

Hydroperiod, or the distribution, duration and timing of flooding affects both plant and animal distributions. The Florida Everglades is currently undergoing restoration that will result in altered hydroperiods. This study was conducted in Everglades National Park to document the variability in periphyton community structure and function between long and short hydroperiod Everglades marshes. Periphyton is an important primary producer and important food resource in the Everglades. Periphyton is also involved in marl soil formation and nutrient cycling. Although periphyton is an important component of the Everglades landscape, little is known about periphyton structural-functional variation between hydroperiods. ^ For this study diatoms, as well as fresh algae slides of diatoms, cyanobacteria and green algae were identified and enumerated. Short verse long hydroperiod soil and water column nutrients were compared. Short and long hydroperiod algal periphyton mat productivity rates were compared using BOD incubations. Experimental manipulations were performed to determine the effects of desiccation duration and rewetting on periphyton productivity, community structure, and nutrient flux. ^ Variation in periphyton community structure was significantly greater between hydroperiods than within hydroperiods. Short and long hydroperiod periphyton mats have the same algal species, it is the distribution and abundance that varies between hydroperiods. Long hydroperiod mats have greater diatom abundance while short hydroperiod mats have greater relative filamentous cyanobacterial abundance. ^ Long hydroperiod mats had greater net primary production (npp) than short hydroperiod mats. Short hydroperiod mats respond to rewetting more rapidly than do long hydroperiod mats. Dry short hydroperiod mats became net primary producers within 24 hours of rehydration. Increasing desiccation duration led to greater cyanobacterial abundance in long hydroperiod mats and decreased diatom abundance in both long and short hydroperiod mats. ^

Importance of storm events in controlling ecosystem structure and function in a Florida gulf coast estuary

From 8/95 to 2/01, we investigated the ecological effects of intra- and inter-annual variability in freshwater flow through Taylor Creek in southeastern Everglades National Park. Continuous monitoring and intensive sampling studies overlapped with an array of pulsed weather events that impacted physical, chemical, and biological attributes of this region. We quantified the effects of three events representing a range of characteristics (duration, amount of precipitation, storm intensity, wind direction) on the hydraulic connectivity, nutrient and sediment dynamics, and vegetation structure of the SE Everglades estuarine ecotone. These events included a strong winter storm in November 1996, Tropical Storm Harvey in September 1999, and Hurricane Irene in October 1999. Continuous hydrologic and daily water sample data were used to examine the effects of these events on the physical forcing and quality of water in Taylor Creek. A high resolution, flow-through sampling and mapping approach was used to characterize water quality in the adjacent bay. To understand the effects of these events on vegetation communities, we measured mangrove litter production and estimated seagrass cover in the bay at monthly intervals. We also quantified sediment deposition associated with Hurricane Irene's flood surge along the Buttonwood Ridge. These three events resulted in dramatic changes in surface water movement and chemistry in Taylor Creek and adjacent regions of Florida Bay as well as increased mangrove litterfall and flood surge scouring of seagrass beds. Up to 5 cm of bay-derived mud was deposited along the ridge adjacent to the creek in this single pulsed event. These short-term events can account for a substantial proportion of the annual flux of freshwater and materials between the mangrove zone and Florida Bay. Our findings shed light on the capacity of these storm events, especially when in succession, to have far reaching and long lasting effects on coastal ecosystems such as the estuarine ecotone of the SE Everglades.

Ecosystem Structure and Function Still Altered Two Decades After Short-Term Fertilization of a Seagrass Meadow

An oligotrophic phosphorus (P) limited seagrass ecosystem in Florida Bay was experimentally fertilized in a unique way. Perches were installed to encourage seabirds to roost and deliver an external source of nutrients via defecation. Two treatments were examined: (1) a chronic 23-year fertilization and (2) an earlier 28-month fertilization that was discontinued when the chronic treatment was initiated. Because of the low mobility of P in carbonate sediments, we hypothesized long-term changes to ecosystem structure and function in both treatments. Structural changes in the chronic treatment included a shift in the dominant seagrass species from Thalassia testudinum to Halodule wrightii, large increases in epiphytic biomass and sediment chlorophyll-a, and a decline in species richness. Functional changes included increased benthic metabolism and quantum efficiency. Initial changes in the 28-month fertilization were similar, but after 23 years of nutrient depuration T. testudinum has reestablished itself as the dominant species. However, P remains elevated in the sediment and H. wrightii has maintained a presence. Functionally the discontinued treatment remains altered. Biomass exceeds that in the chronic treatment and indices of productivity, elevated relative to control, are not different from the chronic fertilization. Cessation of nutrient loading has resulted in a superficial return to the pre-disturbance character of the community, but due to the nature of P cycles functional changes persist.

A Conceptual Framework to Develop Long-Term Ecological Research and Management Objectives in the Wider Caribbean Region

The Caribbean Sea and its watersheds show signs of environmental degradation. These fragile coastal ecosystems are susceptible to environmental impacts, in part because of their oligotrophic conditions and their critical support of economic development. Tourism is one of the major sources of income in the Caribbean, making the region one of the most ecotourism dependent in the world. Yet there are few explicit, long-term, comprehensive studies describing the structure and function of Caribbean ecosystems. We propose a conceptual framework using the environmental signature hypothesis of tropical coastal settings to develop a series of research questions for the reef–sea-grass–wetland seascape. We applied this approach across 13 sites throughout the region, including ecosystems in a variety of coastal settings with different vulnerabilities to environmental impacts. This approach follows the strategy developed by the Long Term Ecological Research program of the National Science Foundation to establish ecological research questions best studied over decades and large spatial areas.

Children with special health care needs: Comparison of the effects of home care setting, prescribed pediatric extended care setting, and long-term care setting on child and family health outcomes and health care service use

Technological advances during the past 30 years have dramatically improved survival rates for children with life-threatening conditions (preterm births, congenital anomalies, disease, or injury) resulting in children with special health care needs (CSHCN), children who have or are at increased risk for a chronic physical, developmental, behavioral, or emotional condition and who require health and related services beyond that required by children generally. There are approximately 10.2 million of these children in the United States or one in five households with a child with special health care needs. Care for these children is limited to home care, medical day care (Prescribed Pediatric Extended Care; P-PEC) or a long term care (LTC) facility. There is very limited research examining health outcomes of CSHCN and their families. The purpose of this research was to compare the effects of home care settings, P-PEC settings, and LTC settings on child health and functioning, family health and function, and health care service use of families with CSHCN. Eighty four CSHCN ages 2 to 21 years having a medically fragile or complex medical condition that required continual monitoring were enrolled with their parents/guardians. Interviews were conducted monthly for five months using the PedsQL™ Generic Core Module for child health and functioning, PedsQL™ Family Impact Module for family health and functioning, and Access to Care from the NS-CSHCN survey for health care services. Descriptive statistics, chi square, and ANCOVA were conducted to determine differences across care settings. Children in the P-PEC settings had a highest health care quality of life (HRQL) overall including physical and psychosocial functioning. Parents/guardians with CSHCN in LTC had the highest HRQL including having time and energy for a social life and employment. Parents/guardians with CSHCN in home care settings had the poorest HRQL including physical and psychosocial functioning with cognitive difficulties, difficulties with worry, communication, and daily activities. They had the fewest hours of employment and the most hours providing direct care for their children. Overall health care service use was the same across the care settings.

Modeling, simulation, and characterization of space debris in low-Earth orbit

Every space launch increases the overall amount of space debris. Satellites have limited awareness of nearby objects that might pose a collision hazard. Astrometric, radiometric, and thermal models for the study of space debris in low-Earth orbit have been developed. This modeled approach proposes analysis methods that provide increased Local Area Awareness for satellites in low-Earth and geostationary orbit. Local Area Awareness is defined as the ability to detect, characterize, and extract useful information regarding resident space objects as they move through the space environment surrounding a spacecraft. The study of space debris is of critical importance to all space-faring nations. Characterization efforts are proposed using long-wave infrared sensors for space-based observations of debris objects in low-Earth orbit. Long-wave infrared sensors are commercially available and do not require solar illumination to be observed, as their received signal is temperature dependent. The characterization of debris objects through means of passive imaging techniques allows for further studies into the origination, specifications, and future trajectory of debris objects. Conclusions are made regarding the aforementioned thermal analysis as a function of debris orbit, geometry, orientation with respect to time, and material properties. Development of a thermal model permits the characterization of debris objects based upon their received long-wave infrared signals. Information regarding the material type, size, and tumble-rate of the observed debris objects are extracted. This investigation proposes the utilization of long-wave infrared radiometric models of typical debris to develop techniques for the detection and characterization of debris objects via signal analysis of unresolved imagery. Knowledge regarding the orbital type and semi-major axis of the observed debris object are extracted via astrometric analysis. This knowledge may aid in the constraint of the admissible region for the initial orbit determination process. The resultant orbital information is then fused with the radiometric characterization analysis enabling further characterization efforts of the observed debris object. This fused analysis, yielding orbital, material, and thermal properties, significantly increases a satellite's Local Area Awareness via an intimate understanding of the debris environment surrounding the spacecraft.

The rodent fauna of Long Pine Key, Everglades National Park: a comparison of habitat types

Rodents are often involved at several stages of trophic dynamics. Consequently they often play crucial roles in the structure and function of many complex ecological systems. This study sought to address the lack of baseline data concerning rodents in tropical areas, and south Florida in particular. Live trapping took place in the four major habitat types of the Long Pine Key area of Everglades National Park over the course of one year. I compared population structures and abundance of murid rodents in the four habitat types, and tested multiple weather variables for their effectiveness as predictors of rodent abundance. I found the Long Pine Key area to be depauperate in terms of species diversity. Each of the four species of rodent encountered favored a particular habitat type. The density of the understory vegetation and the avoidance of avian predators in particular appear to be the most important factors in the distribution and abundance of rodents in the Long Pine Key area of Everglades National Park.

When wolves cry: long distance calling by wild maned wolves

The maned wolf (Chrysocyon brachyurus Illiger 1815) is the biggest canid in South America and it is considered a “near threatened” species by IUCN. Because of its nocturnal, territorial and solitary habits, there are still many understudied aspects of their behavior in natural environments, including acoustic communication. In its vocal repertoire, the wolf presents a longdistance call named “roar-bark” which, according to literature, functions for spacing maintenance between individuals and/or communication between members of the reproductive pair inside the territory. In this context, this study aimed: 1) to compare four methods for detecting maned wolf’s roar-barks in recordings made in a natural environment, in order to elect the most efficient one for our project; 2) to understand the night emission pattern of these vocalizations, verifying possible weather and moon phases influences in roarbark’s emission rates; and 3) to test Passive Acoustic Monitoring as a tool to identify the presence of maned wolves in a natural environment. The study area was the Serra da Canastra National Park (Minas Gerais, Brazil), where autonomous recorders were used for sound acquisition, recording all night (from 06pm to 06am) during five days in December/2013 and every day from April to July/2014. Roar-barks’ detection methods were tested and compared regarding time needed to analyze files, number of false positives and number of correctly identified calls. The mixed method (XBAT + manual) was the most efficient one, finding 100% of vocalizations in almost half of the time the manual method did, being chosen for our data analysis. By studying roarbarks’ temporal variation we verified that the wolves vocalize more in the early hours of the evening, suggesting an important social function for those calls at the beginning of its period of most intense activity. Average wind speed negatively influenced vocalization rate, which may indicate lower sound reception of recorders or a change in behavioral patterns of wolves in high speed wind conditions. A better understanding of seasonal variation of maned wolves’ vocal activity is required, but our study already shows that it is possible to detect behavioral patterns of wild animals only by sound, validating PAM as a tool in this species’ conservation.

Realized Matrix-Exponential Stochastic Volatility with Asymmetry, Long Memory and Spillovers

The paper develops a novel realized matrix-exponential stochastic volatility model of multivariate returns and realized covariances that incorporates asymmetry and long memory (hereafter the RMESV-ALM model). The matrix exponential transformation guarantees the positivedefiniteness of the dynamic covariance matrix. The contribution of the paper ties in with Robert Basmann’s seminal work in terms of the estimation of highly non-linear model specifications (“Causality tests and observationally equivalent representations of econometric models”, Journal of Econometrics, 1988, 39(1-2), 69–104), especially for developing tests for leverage and spillover effects in the covariance dynamics. Efficient importance sampling is used to maximize the likelihood function of RMESV-ALM, and the finite sample properties of the quasi-maximum likelihood estimator of the parameters are analysed. Using high frequency data for three US financial assets, the new model is estimated and evaluated. The forecasting performance of the new model is compared with a novel dynamic realized matrix-exponential conditional covariance model. The volatility and co-volatility spillovers are examined via the news impact curves and the impulse response functions from returns to volatility and co-volatility.

Towards the design of monolithic decoupled XYZ compliant parallel mechanisms for multi-function applications

This paper deals with the monolithic decoupled XYZ compliant parallel mechanisms (CPMs) for multi-function applications, which can be fabricated monolithically without assembly and has the capability of kinetostatic decoupling. At first, the conceptual design of monolithic decoupled XYZ CPMs is presented using identical spatial compliant multi-beam modules based on a decoupled 3-PPPR parallel kinematic mechanism. Three types of applications: motion/positioning stages, force/acceleration sensors and energy harvesting devices are described in principle. The kinetostatic and dynamic modelling is then conducted to capture the displacements of any stage under loads acting at any stage and the natural frequency with the comparisons with FEA results. Finally, performance characteristics analysis for motion stage applications is detailed investigated to show how the change of the geometrical parameter can affect the performance characteristics, which provides initial optimal estimations. Results show that the smaller thickness of beams and larger dimension of cubic stages can improve the performance characteristics excluding natural frequency under allowable conditions. In order to improve the natural frequency characteristic, a stiffness-enhanced monolithic decoupled configuration that is achieved through employing more beams in the spatial modules or reducing the mass of each cubic stage mass can be adopted. In addition, an isotropic variation with different motion range along each axis and same payload in each leg is proposed. The redundant design for monolithic fabrication is introduced in this paper, which can overcome the drawback of monolithic fabrication that the failed compliant beam is difficult to replace, and extend the CPM’s life.

HPA Axis Activation by Ethanol Dependence in Adult and Adolescent Rats

Alcoholism is a disorder marked by cycles of heavy drinking and chronic relapse, and adolescents are an age cohort particularly susceptible to consuming large amounts of alcohol, placing them at high risk for developing an alcohol use disorder. Adolescent humans and rats voluntarily consume more alcohol than their adult counterparts, suggesting that younger consumers of alcohol may be less sensitive to its aversive effects, which are regulated by the function of the hypothalamic-pituitary-adrenal (HPA) stress axis. While HPA axis dysfunction resulting from ethanol exposure has been extensively studied in adult animals, what happens in the adolescent brain remains largely unclear. In this study, chronic injections of ethanol was used to model alcohol dependence in adult and adolescent rats, and post-withdrawal anxiety behaviors were measured using light-dark box testing. Furthermore, corticosterone (CORT) release during treatment and after withdrawal was measured by collecting fecal and plasma samples from adults and adolescents. It was found that adults, but not adolescents, exhibit significant anxiety-like behavior following chronic ethanol withdrawal. Additionally, while the process of chronic ethanol treatment elicits an increase in day-by-day CORT release in both adults and adolescents, significantly sustained levels of CORT were not observed during withdrawal for either age group. Moreover, it was found that adults experience a longer-lasting CORT increase during chronic treatment, suggesting a larger and more robust period of dysfunction in the HPA axis for older consumers of alcohol. These results highlight CORT and glucocorticoids in general as a potential therapeutic target for treatment for alcoholism, especially that which has an onset during adolescence.

Metabolism Regulates the Fate and Function of T Lymphocytes

Proper balancing of the activities of metabolic pathways to meet the challenge of providing necessary products for biosynthetic and energy demands of the cell is a key requirement for maintaining cell viability and allowing for cell proliferation. Cell metabolism has been found to play a crucial role in numerous cell settings, including in the cells of the immune system, where a successful immune response requires rapid proliferation and successful clearance of dangerous pathogens followed by resolution of the immune response. Additionally, it is now well known that cell metabolism is markedly altered from normal cells in the setting of cancer, where tumor cells rapidly and persistently proliferate. In both settings, alterations to the metabolic profile of the cells play important roles in promoting cell proliferation and survival.

It has long been known that many types of tumor cells and actively proliferating immune cells adopt a metabolic phenotype of aerobic glycolysis, whereby the cell, even under normoxic conditions, imports large amounts of glucose and fluxes it through the glycolytic pathway and produces lactate. However, the metabolic programs utilized by various immune cell subsets have only recently begun to be explored in detail, and the metabolic features and pathways influencing cell metabolism in tumor cells in vivo have not been studied in detail. The work presented here examines the role of metabolism in regulating the function of an important subset of the immune system, the regulatory T cell (Treg) and the role and regulation of metabolism in the context of malignant T cell acute lymphoblastic leukemia (T-ALL). We show that Treg cells, in order to properly function to suppress auto-inflammatory disease, adopt a metabolic program that is characterized by oxidative metabolism and active suppression of anabolic signaling and metabolic pathways. We found that the transcription factor FoxP3, which is highly expressed in Treg cells, drives this phenotype. Perturbing the metabolic phenotype of Treg cells by enforcing increased glycolysis or driving proliferation and anabolic signaling through inflammatory signaling pathways results in a reduction in suppressive function of Tregs.

In our studies focused on the metabolism of T-ALL, we observed that while T-ALL cells use and require aerobic glycolysis, the glycolytic metabolism of T-ALL is restrained compared to that of an antigen activated T cell. The metabolism of T-ALL is instead balanced, with mitochondrial metabolism also being increased. We observed that the pro-anabolic growth mTORC1 signaling pathway was limited in primary T-ALL cells as a result of AMPK pathway activity. AMPK pathway signaling was elevated as a result of oncogene induced metabolic stress. AMPK played a key role in the regulation of T-ALL cell metabolism, as genetic deletion of AMPK in an in vivo murine model of T-ALL resulted in increased glycolysis and anabolic metabolism, yet paradoxically increased cell death and increased mouse survival time. AMPK acts to promote mitochondrial oxidative metabolism in T-ALL through the regulation of Complex I activity, and loss of AMPK reduced mitochondrial oxidative metabolism and resulted in increased metabolic stress. Confirming a role for mitochondrial metabolism in T-ALL, we observed that the direct pharmacological inhibition of Complex I also resulted in a rapid loss of T-ALL cell viability in vitro and in vivo. Taken together, this work establishes an important role for AMPK to both balance the metabolic pathways utilized by T-ALL to allow for cell proliferation and to also promote tumor cell viability by controlling metabolic stress.

Overall, this work demonstrates the importance of the proper coupling of metabolic pathway activity with the function needs of particular types of immune cells. We show that Treg cells, which mainly act to keep immune responses well regulated, adopt a metabolic program where glycolytic metabolism is actively repressed, while oxidative metabolism is promoted. In the setting of malignant T-ALL cells, metabolic activity is surprisingly balanced, with both glycolysis and mitochondrial oxidative metabolism being utilized. In both cases, altering the metabolic balance towards glycolytic metabolism results in negative outcomes for the cell, with decreased Treg functionality and increased metabolic stress in T-ALL. In both cases, this work has generated a new understanding of how metabolism couples to immune cell function, and may allow for selective targeting of immune cell subsets by the specific targeting of metabolic pathways.

Study of insulin-like growth factor signaling in mitochondrial function

Insulin-like Growth Factor-1 (IGF-1) signalling promotes cell growth and is associated with cancer progression, including metastasis, epithelial-mesenchymal transition (EMT), and resistance to therapy. Mitochondria play an essential role in cancer cell metabolism and accumulating evidence demonstrates that dysfunctional mitochondria associated with release of mitochondrial reactive oxygen species (ROS) can influence cancer cell phenotype and invasive potential. We previously isolated a mitochondrial UTP carrier (PNC1/SLC25A33) whose expression is regulated by IGF-1, and which is essential for mitochondrial maintenance. PNC1 suppression in cancer cells results in mitochondrial dysfunction and acquisition of a profound ROS-dependent invasive (EMT) phenotype. Moreover, over-expression of PNC1 in cancer cells that exhibit an EMT phenotype is sufficient to suppress mitochondrial ROS production and reverse the invasive phenotype. This led us to investigate the IGF-1-mitochondrial signalling axis in cancer cells. We found that IGF-1 signalling supports increased mitochondrial mass and Oxphos potential through a PI3K dependant pathway. Acute inhibition of IGF-1R activity with a tyrosine kinase inhibitor results in dysfunctional mitochondria and cell death. We also observed an adaptive response to IGF-1R inhibition upon prolonged exposure to the kinase inhibitor, where increased expression of the EGF receptor can compensate for loss of mitochondrial mass through activation of PI3K/mTOR signalling. However, these cells exhibit impaired mitochondrial biogenesis and mitophagy. We conclude that the IGF-1 is required for mitochondrial maintenance and biogenesis in cancer cells, and that pharmacological inhibition of this pathway may induce mitochondrial dysfunction and may render the cells more sensitive to glycolysis-targeted drugs.

MicroRNA expression and function in neonatal hypoxic ischaemic encephalopathy

Hypoxic ischaemic encephalopathy (HIE) is a devastating neonatal condition which affects 2-3 per 1000 infants annually. The current gold standard of treatment - induced hypothermia, has the ability to reduce neonatal mortality and improve neonatal morbidity. However, to be effective it needs to be initiated within the therapeutic window which exists following initial insult until approximately 6 hours after birth. Current methods of assessment which are relied upon to identify infants with HIE are subjective and unreliable. To overcome this issue, an early and reliable biomarker of HIE severity must be identified. MicroRNA (miRNA) are a class of small non-coding RNA molecules which have potential as biomarkers of disease state and potential therapeutic targets. These tiny molecules can modulate gene expression by inhibiting translation of messenger RNA (mRNA) and as a result, can regulate protein synthesis. These miRNA are understood to be released into the circulation during cellular stress, where they are highly stable and relatively easy to quantify. Therefore, these miRNAs may be ideal candidates for biomarkers of HIE severity and may aid in directing the clinical management of these infants. By using both transcriptomic and proteomic approaches to analyse the expression of miRNAs and their potential targets in the umbilical cord blood, I have confirmed that infants with perinatal asphyxia and HIE have a significantly different UCB miRNA signature compared to UCB samples from healthy controls. Finally, I have identified and investigated 2 individual miRNAs; both of which show some potential as classifiers of HIE severity and predictors of long term outcome, particularly when coupled with their downstream targets. While this work will need to be validated and expanded in a new and larger cohort of infants, it suggests the potential of miRNA as biomarkers of neonatal pathological conditions such as HIE.