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Immediate Effects (immediate + effects)
Selected AbstractsImmediate effects of methylphenidate on cognitive attention skills of children with attention-deficit-hyperactivity disorderDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 6 2005Jane Hood MSc This study investigated the immediate effects of stimulant medication (methylphenidate) on cognitive attention processes in children with attention-deficit-hyperactivity disorder (ADHD). Thirteen males and two females (mean age 9y 5mo, SD 18.3mo) with a diagnosis of ADHD and who were to be prescribed methylphenidate were assessed twice on one day with the Test of Everyday Attention for Children, a neuropsychological battery designed to tap different aspects of cognitive attention. Between assessments, the children were administered methylphenidate (10mg). Each child had at least average intelligence (IQ 80 or over, as measured by the Wechsler Intelligence Scale for Children - III UK) and was on no other medication. A group of 16 children, who were matched for age, sex, and intelligence, also performed the cognitive tests twice on the same day to control for practice effects of testing. At the first assessment, children with ADHD demonstrated significant impairments in several aspects of cognitive attention in comparison with the control group, particularly sustained attention. After administration of methylphenidate for the children with ADHD, they showed significant improvements in their performance on measures of cognitive attention compared to controls. The immediate effects of methylphenidate and the significance of measuring cognitive aspects of attention as well as behavioural measures are discussed. [source] Immediate effects of prescribed burning, chopping and clearing on runoff, infiltration and erosion in a shrubland area in Galicia (NW Spain)LAND DEGRADATION AND DEVELOPMENT, Issue 5 2008C. Fernández Abstract The immediate effects of three different fuel management treatments on runoff, infiltration and erosion were evaluated in a mixed heathland in Galicia (NW Spain). The treatments compared were: prescribed burning, shrub chopping and shrub clearing. Rainfall simulations were conducted immediately before and after fuel reduction treatments. A rainfall rate of 67,mm,h,1 was applied for 30,min to each runoff plot. Application of treatments significantly affected runoff and infiltration, but the parameter most affected by treatment was soil erosion, especially after prescribed burning. However, sediment yields measured immediately after treatments were low in all the cases, varying from 32,kg,ha,1 after shrub clearing to 248,kg,ha,1 after prescribed burning. In the rainfall simulation plots subjected to prescribed burning, the maximum temperatures reached at mineral soil surface during burns significantly affected soil losses. The organic layer remaining after treatments and soil moisture contents appeared to be critical variables in controlling runoff and erosion during the first rainfall event following fuel reduction treatments. When the remaining organic layer was removed just after treatments and a new rainfall simulation was carried out, mean infiltration rate trended to decrease and cumulative runoff and sediment yield tended to increase. The above information could be useful for determining whether fuel management prescriptions are compatible with fire hazard reduction and soil conservation. Copyright © 2008 John Wiley & Sons, Ltd. [source] Immediate effects of methylphenidate on cognitive attention skills of children with attention-deficit-hyperactivity disorderDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 6 2005Jane Hood MSc This study investigated the immediate effects of stimulant medication (methylphenidate) on cognitive attention processes in children with attention-deficit-hyperactivity disorder (ADHD). Thirteen males and two females (mean age 9y 5mo, SD 18.3mo) with a diagnosis of ADHD and who were to be prescribed methylphenidate were assessed twice on one day with the Test of Everyday Attention for Children, a neuropsychological battery designed to tap different aspects of cognitive attention. Between assessments, the children were administered methylphenidate (10mg). Each child had at least average intelligence (IQ 80 or over, as measured by the Wechsler Intelligence Scale for Children - III UK) and was on no other medication. A group of 16 children, who were matched for age, sex, and intelligence, also performed the cognitive tests twice on the same day to control for practice effects of testing. At the first assessment, children with ADHD demonstrated significant impairments in several aspects of cognitive attention in comparison with the control group, particularly sustained attention. After administration of methylphenidate for the children with ADHD, they showed significant improvements in their performance on measures of cognitive attention compared to controls. The immediate effects of methylphenidate and the significance of measuring cognitive aspects of attention as well as behavioural measures are discussed. [source] Effects of Pair-Bond and Social Context on Male,Female Interactions in Captive Titi Monkeys (Callicebus moloch, Primates: Cebidae)ETHOLOGY, Issue 12 2000Eduardo Fernandez-Duque In monogamous species, an abiding relationship between a specific adult male and a specific adult female is a defining feature of the social system. The interactions between these individuals are influenced by many factors, including not only the history of their relationship (for example, development of a mutual bond), but also the immediate effects of the prevailing social context (for example, presence and sex of extra-pair conspecifics). In this study we examined the effects of an existing bond and of social context on interactions between adult heterosexual pairs of the monogamous titi monkeys (Callicebus moloch). Twelve adult males and 12 adult females were tested with their cagemates and with an unfamiliar partner of the opposite sex in five social contexts: (1) mated male,female pair; (2) unfamiliar pair; (3) single female; (4) single male; and (5) empty stimulus cage. Results show that mated pairs were more affiliative than unfamiliar pairs and differentiated social contexts more sharply. Males were more responsive to context than females. Distance between mates was less and physical contact was more frequent in the presence of male,female pairs or a single male, than in the presence of a single female or an empty cage. These findings suggest that the presence and sex of strangers have a stronger influence on male,female interactions when the pair has an existing relationship. [source] PROGRAMS FOR PROMOTING PARENTING OF RESIDENTIAL PARENTS: Moving From Efficacy to EffectivenessFAMILY COURT REVIEW, Issue 1 2005Sharlene A. Wolchik This article reviews prevention programs that target primary residential parents as change agents for improving children's postdivorce adjustment. First, we review parental risk and protective factors for children from divorced families, including parenting quality, parental mental health problems, interparental conflict, and contact with the nonresidential parent. Following a discussion of brief informational interventions, we describe the findings of evaluations of three multisession, skill-building interventions for divorced parents. Impressive evidence is presented that parenting is a modifiable protective factor and that improving parenting leads to improvements in children's postdivorce adjustment. We then discuss, in greater detail, the New Beginnings Program, which we highlight because it has shown repeated, immediate effects on children's mental health outcomes as well as long-term effects on a wide array of other meaningful outcomes, such as diagnosis of mental disorder in the past year, externalizing problems, alcohol and drug use, and academic performance. Also, mediational analyses have shown that program-induced changes in parenting accounted for changes in mental health outcomes. The remainder of the article describes a research and action agenda that is needed to successfully implement the New Beginnings Program in domestic relations courts. [source] SPACES OF DIZZINESS AND DREAD: NAVIGATING ACROPHOBIAGEOGRAFISKA ANNALER SERIES B: HUMAN GEOGRAPHY, Issue 4 2007Gavin J. Andrews ABSTRACT As part of emerging disciplinary interests in well-being and emotions, geographers have recently begun to pay attention to common but often neglected psychological conditions that have the potential to impact considerably upon individuals and their daily lives. Specifically extending the scope of geographical inquiry on phobias, this paper considers acrophobia (known as being scared of heights). Through interviews with ten sufferers, the spatial character and intensity of the condition is articulated. The findings tell us that underpinning acrophobia is mathematical height: the vertical elevation from the lowest possible resting point of the body to the point at which the symptoms of acrophobia occur. This point is however - even for each individual - highly variable, context dependant and, in terms of explanatory potential, does not convey personal experiences. Instead, the idea of ,encounter spaces' provides far greater elaboration. Created by sufferers ,dysfunctional' spatial perceptions, these are the occupied spaces of mixed emotional and physical responses (such as fear and rapid breathing) and reactionary practices that are tactical yet somewhat involuntary in nature (such as gripping tighter or getting lower). Depending on the particular circumstances, sufferers might choose to, feel forced to, or might inadvertently enter encounter spaces. Their impacts also extend beyond immediate effects to sufferers' longer term lives and well-being. This might be negatively impacted, for example, through cumulative encounters, worrying about potential encounters or missing out on life events. At this level, reactionary practices - again which are tactical yet somewhat involuntary - are often employed in order to avoid height. Ultimately, the overall impact of acrophobia on an individual depends on a number of factors including the severity of their condition, the attitudes of the people they associate with, their job, lifestyle and the environments which they have to, or would like to, frequent. Consequently, while some sufferers cope with ease, others constantly navigate the altitude of their lives. [source] Caring for mom and neglecting yourself?HEALTH ECONOMICS, Issue 9 2009The health effects of caring for an elderly parent Abstract We examine the physical and mental health effects of providing care to an elderly mother on the adult child caregiver. We address the endogeneity of the selection in and out of caregiving using an instrumental variable approach, using the death of the care recipient and sibling characteristics. We also carefully control for baseline health and work status of the adult child. We explore flexible specifications, such as Arellano,Bond estimation techniques. Continued caregiving over time increases depressive symptoms and decreases self-rated health for married women and married men. In addition, the increase in depressive symptoms is persistent for married women. While depressive symptoms for single men and women are not affected by continued caregiving, there is evidence of increased incidence of heart conditions for single men, and that these effects are persistent. Robustness checks indicate that these health changes can be directly attributable to caregiving behavior, and not due to a direct effect of the death of the mother. The initial onset of caregiving has modest immediate negative effects on depressive symptoms for married women and no immediate effects on physical health. Negative physical health effects emerge 2 years later, however, suggesting that there are delayed effects on health that would be missed with a short recall period. Initial caregiving does not affect health of married men. Published in 2009 by John Wiley & Sons, Ltd. [source] Value-based labels for fresh beef: an overview of French consumer behaviour in a BSE crises contextINTERNATIONAL JOURNAL OF CONSUMER STUDIES, Issue 5 2008Pierre Sans Abstract In the last decade, the French beef industry has been through two major health scares related to bovine spongiform encephalopathy. This paper describes and discusses changes in beef supply in France from the consumer's perspective. The authors review the initiatives implemented in each crisis and show that the immediate effects (slump in consumption), however spectacular, were not the most lasting effects. By contrast, responses from the industry and the authorities brought about a far-reaching change in practices by requiring new instruments to be used (traceability). Yet the information conveyed by this innovation cannot readily be appropriated by consumers who are not conversant with the characteristics of beef production systems. [source] Water Deficit Reduced Fertility of Young Microspores Resulting in a Decline of Viable Mature Pollen and Grain Set in RiceJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 1 2009G. N. Nguyen Abstract Pollen formation in rice (Oryza sativa L.) is highly vulnerable to environmental stresses such as heat, chilling and drought. In rice plants exposed to drought during male reproductive development, the most obvious damage often observed is a decline in the number of engorged pollen and grain set. This has been well characterized in rice under chilling and to a lesser extent under drought stress. Moreover, detailed literature on the immediate effects of drought on developing young microspores in rice is still limited. Here, we report findings from experiments on rice plants exposed to water deficit for three consecutive days during early stages of anther development. When the osmotic potential of the growing medium was equal to or less than ,0.5 MPa, as induced by polyethylene glycol, the leaf water potential was significantly lowered and grain set was reduced. A strong correlation between grain set and viable young microspores (P < 0.001, r2 = 0.8223) indicates that water deficit immediately reduced fertility of rice plants at the time of exposure. This result suggests a new underlying mechanism of water deficit-induced pollen abortion in rice. [source] Long-term effects of computer training of phonological awareness in kindergartenJOURNAL OF COMPUTER ASSISTED LEARNING, Issue 1 2005Eliane Segers Abstract The present study examined the long-term effects of a computer intervention for the development of phonological awareness in Dutch kindergartners. Native Dutch and immigrant children worked with the software 15 min/week during one school year. Following a pretest , interim test , post-test , retention test design, the effects on rhyming, phonemic segmentation, auditory blending, and grapheme knowledge were assessed. The intervention showed significant immediate effects on rhyming and grapheme knowledge. The time spent on the computer games also correlated with the learning gains for the experimental group. In the first grade, retention effects were demonstrated after 4 months of formal reading education. [source] Interregional Disparities in Productivity and the Choice of Fiscal RegimeJOURNAL OF PUBLIC ECONOMIC THEORY, Issue 3 2009KIMIKO TERAI Two districts with divergent productivity levels engage in policy-making on the provision of local public goods that enhance future income and hence create a dynamic linkage across periods. The policy choices of district representatives are derived under alternative fiscal systems, and the relative merits of the systems are evaluated. It is predicted that a decentralized system is more likely to be selected in a more equal society. On the other hand, when a great deal of benefit spills over from a local public good, or when policy makers are expected to care solely about the immediate effects of their decisions on their districts, a centralized system is more likely to be selected. [source] Death and International Travel,The Canadian Experience: 1996 to 2004JOURNAL OF TRAVEL MEDICINE, Issue 2 2007Douglas W. MacPherson MD, FRCPC, MSc(CTM) Background Death during international travel concerns several levels of the travel industry. In addition to the immediate effects for the traveler, their family and friends, the nature of travel-related mortality has important implications for pretravel health advisors and providers of medical care services. Methods The Consular Affairs Bureau, Foreign Affairs Canada provides information and assistance to Canadian civilians abroad. Beginning in 1995, the Consular Management and Operations System tracked Canadian deaths abroad notifications. The annual data for 1996 to 2004 was extracted for sex, age, and cause of death by location for all reports received. Results There were 2,410 reported deaths in Canadians abroad; reported sex was 32% female and 68% male, average age of 61.7 and 60.4 years, respectively. Recorded causes of death: natural (1,762), accidental (450), suicide (92), and murder (106). Country of death reflected the pattern of Canadian international travel for recreation, business, and ancestral linkages. Average age of natural death (66 years) distinguished it from all other causes of death: accidental (45), suicide (41), and murder (43). Conclusion Natural causes and suicide deaths may be anticipated or planned to occur abroad. The risk of death may be mitigated through personal knowledge and medical assessment and prevention strategies. Deaths due to vaccine-preventable diseases, exotic and infectious diseases were rare in this population. Consular services may be able to provide various types of support. Local laws and customs, as well as international regulations in health and quarantine govern other responsibilities such as funeral services and repatriation of the deceased to Canada. [source] Effect of Transcutaneous Electrical Nerve Stimulation on Primary DysmenorrheaNEUROMODULATION, Issue 4 2009Shwu-Fen Wang PT ABSTRACT Objectives.,Dysmenorrhea is a disturbing problem among women of childbearing age. The purpose of this study is to investigate the effect of high-frequency transcutaneous electrical nerve stimulation (TENS) on primary dysmenorrhea and to compare the placebo effect by sham TENS in a randomized controlled study. Materials and Methods.,Twenty-two women participated in the two-month experiment by using TENS or sham TENS in a random order for their dysmenorrhea. Outcome measures included self-reported pain intensity, symptom and function questionnaire related to dysmenorrhea, quality of life, satisfaction after TENS application, and other pain management agents adapted by the participants. Two-way repeated measures analysis of variance (two-way ANOVA) was conducted to compare pain intensity between pre-post values and groups (TENS vs. placebo). One-way repeated measures analysis of variance (one-way ANOVA) was conducted to compare scores from questionnaire of symptoms and quality of life at baseline, and after placebo or TENS stimulation. Results.,Pain intensity in TENS is significantly decreased than in the placebo group (p= 0.018). The decrease of pain intensity after TENS and placebo TENS were both significant, with p < 0.00005 and p < 0.00005 respectively. Furthermore, TENS significantly changed the degree of autonomic symptoms (p= 0.048); but not after placebo TENS. Conclusion.,This result supports that women in our country who suffer from primary dysmenorrhea could benefit by using TENS, which is consistent with the previous studies. In addition to pain-relieving effects, relief of the autonomic symptoms associated with dysmenorrhea also indicated that the mechanism of TENS might be different from the placebo effect of the sham TENS stimulation. These findings indicate the immediate effects of TENS in women with primary dysmenorrheal. [source] Atrial Activation Occurring Immediately after Successful Cardioversion of Atrial FibrillationPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 1 2008ARTURO MARTÍN PEÑATO MOLINA M.D. Background and Objective: Electrical defibrillation is very effective in interrupting atrial fibrillation (AF). However, its mechanism is not completely understood. We report our observations in patients subjected to external electriocardioversion (ECV) of atrial fibrillation and contrast them with recent theories about defibrillation mechanism. Methods: In 13 consecutive patients transthoracic electrical cardioversion for AF was performed during an electrophysiological study (11 monophasic -200,360 J- and 9 biphasic shocks -50,150 J-). About 10,16 electrograms were obtained with multipolar catheters recording right atrium, coronary sinus, and right pulmonary artery. AF was defined by interelectrogram intervals and changing sequences among recordings, indicating complete lack of organization. We evaluated the presence of propagated activations immediately (<300 ms) after successful shocks (,1 discrete electrogram in all recordings). In unsuccessful shocks we evaluated changes in electrogram morphology (discrete/fragmented) and interelectrogram intervals before and after defibrillation. Results: About 16/20 shocks terminated AF. In 6/16 one or two cycles of atrial activation were recorded just after the shock and before AF ended. In 10/16 AF was interrupted immediately after the shock. 4/20 shocks did not interrupt the arrhythmia. After these shocks, transient organization of recorded activity with longer interelectrogram cycle length and disappearance of fragmented activity were transiently observed. Conclusion: Our clinical findings in atrial defibrillation in vivo reproduce experimental data that show myocardial activations early after successful direct current shocks. These observations suggest that successful defibrillation depends not only on the immediate effects of the shock, but also on transient effects on electrophysiological properties of the myocardium, capable of interrupting persistent or reinitiated activations. [source] Liposomes in investigative dermatologyPHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 5 2001Daniel B. Yarosh Liposomes are microscopic spheres, usually composed of amphiphilic phospholipids. They may be useful without skin penetration if they simply protect or sequester compounds that would otherwise be unstable in the formulation. Liposomes that remain on the skin surface are useful as light-absorbers, agents to deliver color or sunscreens, or as depots for timed-release. Liposomes that penetrate the stratum corneum have the potential to interact with living tissue. Topically applied liposomes can either mix with the stratum corneum lipid matrix or penetrate the stratum corneum by exploiting the lipid-water interface of the intercellular matrix. There are at least four major routes of entry into the skin: pores, hair follicles, columnular spaces and the lipid:water matrix between squames. A major force driving liposome penetration is the water gradient, and flexible liposomes are best able to exploit these delivery opportunities. Some liposomes release their contents extracellularly. Topical application of photosensitizers may be enhanced by encapsulation in liposomes. Higher and longer-lasting drug concentrations may be produced in localized areas of skin, particularly at disease sites where the stratum corneum and the skin barrier function are disrupted. The liposome membrane should be designed to capture lipophilic drugs in the membrane or hydrophilic drugs in the interior. Other types of liposomes can be engineered to be taken up by cells. Once inside cells, the lysosomal sac and clatherin-coated pit are the dead-end destinations for liposomes unless an escape path has been engineered into the liposome. A novel method has been developed to allow delivery into cells of the skin, by escape from the lysosomal sac. These liposomes have been used to topical deliver active DNA repair enzymes from liposomes into epidermal cells and to enhance DNA repair of UV-irradiated skin. From these studies a tremendous amount has been learned about the relationship of DNA damage and skin cancer. Both mutations and immunosuppression appear to be essential to skin cancer and both are induced by DNA damage. DNA damage produces immediate effects by inducing the expression of cytokines, which means that DNA damage can induce signaling in neighboring, undamaged cells. The repair of only a fraction of the DNA damage has a disproportionate effect on the biological responses, clearly demonstrating that not all DNA damage is equivalent. This technology demonstrates that biologically active proteins can be delivered into the cells of skin, and opens up a new field of correcting or enhancing skin cell metabolism to improve human health. [source] A pilot study of the immediate effects of mirror feedback on sitting postural control in normal healthy adultsPHYSIOTHERAPY RESEARCH INTERNATIONAL, Issue 4 2008Martin Watson Background and Purpose.,The remediation of postural control problems is a common feature of many physiotherapy interventions. Provision of augmented visual feedback through use of mirror-reflected body image is one means by which therapists can purportedly facilitate patients' postural correction abilities. Despite the historic place of this treatment modality within the physiotherapist's armamentarium, the strategy has however received very limited investigation. The aim of this study was to evaluate the extent to which availability of reflected body image influences the normal subjects' postural control abilities when in a sitting position.,Method.,A pilot investigation was undertaken, utilizing a sample of convenience comprising 18 healthy female subjects (mean age 20.8 years). All subjects underwent testing of their sitting postural control abilities in two separate conditions: with and without mirror feedback. A full length therapy mirror, as typically found in many rehabilitation departments, was used where appropriate to provide the reflected body image. Testing was carried out three times for each condition (six tests in total), obtaining average performance across three tests for each condition. Test order for each subject for the six tests was varied using a Latin square procedure to control for learning effect. Measurement of the subjects' postural control abilities was achieved by Balance Performance Monitor using a seat plate monitor and evaluating body sway path (mm). Postural control was challenged during testing by asking the subjects to maintain a standardized complex sitting position.,Results.,Group mean sway path with mirror feedback was lower than without: means 165.72,mm (standard deviation [SD] = 40.52,mm) versus 244.74,mm (SD = 68.48,mm). This suggested improved postural control ability when the subjects were able to view their reflected body image during testing. A related t test (t = 4.873, n = 18) showed differences between the two conditions to be statistically significant (p < 0.001), 95% confidence interval = 44.80,mm,113.23,mm.,Conclusion.,This relatively unsophisticated evaluation of mirror feedback nonetheless suggested a potential intervention effect. The precise mechanism(s) by which this strategy might effect changes in postural control ability, as well as the likely carryover of the effect and its replication in individuals with movement control problems, are all issues requiring further investigation. Nonetheless, these results provide provisional support for the notion that mirror feedback is a potentially useful strategy in the training of postural control. Copyright © 2008 John Wiley & Sons, Ltd. [source] How Big Was the Effect of Budget Consolidation on the Australian Economy in the 1990s?THE AUSTRALIAN ECONOMIC REVIEW, Issue 1 2006Lei Lei Song This article evaluates the effects of budget consolidation on the Australian economy in the 1990s. As the economy recovered from the 1991,92 recession, the need to improve the fiscal balance to lift national saving became the dominant influence on fiscal policy. The article argues that spending cuts by the Australian federal government announced in 1996 had immediate effects on financial markets, with reduced long-term interest rates of about 50 basis points in 1996,97. Using a modified version of the Treasury macroeconometric model of the Australian economy (TRYM), the article simulates the net macroeconomic effects of the expenditure cuts, fiscal consolidation and lower long-term interest rates. The article finds that the program of budget consolidation had a sizeable short- and medium-term impact on the economy, raising Gross Domestic Product by up to three-quarters of a percentage point and reducing unemployment by 0.3 percentage points over the next two to three years. [source] Characteristics of a group of Hubei Golden Snub-nosed Monkeys (Rhinopithecus roxellana hubeiensis) before and after major snow stormsAMERICAN JOURNAL OF PRIMATOLOGY, Issue 6 2009Yiming Li Abstract Natural disasters can negatively affect primate population demography and social group structure. A clear understanding of these effects has important implications for wildlife conservation. The worst snow storms in nearly five decades hit portions of southern and central China between January 10 and February 6, 2008, presenting a unique opportunity to observe their immediate effects on a previously studied group of Hubei Golden Snub-nosed Monkeys (Rhinopithecus roxellana hubeiensis) in temperate forests in Shennongjia Nature Reserve, Hubei Province, China. We recorded social and demographic characteristics of the group before and after the snow storms. The average group size decreased from 270 individuals before the storms to 197 individuals after the storms, a reduction of 27.2%. Adult females (30.1%), juveniles (38.1%) and infants (55.4%) suffered higher mortality than did adult males (15.7%). Despite age and sex-based differences in mortality, the ratios of adult males to adult females, adults to immatures and adult females to immatures remained similar before and after the storms. However, higher mortality among females, juveniles and infants may reduce the group's long-term potential for growth. Am. J. Primatol. 71:523,526, 2009. © 2009 Wiley-Liss, Inc. [source] The Effects of Unanticipated Macroeconomic News on Debt MarketsTHE JOURNAL OF FINANCIAL RESEARCH, Issue 3 2003Rohan Christie-David Abstract We examine the effects of unanticipated macroeconomic news on two interest rate futures using intraday data. The surprises are identified on the basis of their potential effects on debt markets (positive or negative) and by their size (large, medium, or small). The results show distinct ex-post return patterns associated with different categories of news surprises. For example, large surprises have the strongest immediate effects whereas negative surprises have the longest persisting effects. Tests that examine the separate effects of each announcement suggest that debt responses vary with the size and potential effect of the news surprise in each announcement. [source] Visible and invisible effects of hurricanes on forest ecosystems: an international reviewAUSTRAL ECOLOGY, Issue 4 2008A. E. LUGO Abstract Hurricanes have visible and invisible effects on forests. The visible effects are dramatic, noticeable over the short-term and relatively well documented in the literature. Invisible effects are less understood as they require well-focused research both in the short- and long-term time scales. This review of the literature on hurricane effects focuses on the Neotropics and the temperate zone of North America. The material is organized according to a heuristic model that distinguishes between immediate effects (0 to 3 years), immediate responses (0 to 20 years), trajectories of responses (0 to 100 years) and long-term legacies (>100 years). It is suggested that the ecological role of hurricanes involves six principal effects: 1. they change the ecological space available to organisms; 2. they set organisms in motion; 3. they increase the heterogeneity of the landscape and the variability in ecosystem processes; 4. they rejuvenate the landscape and its ecosystems and redirect succession; 5. they shape forest structure, influence their species composition and diversity and regulate their function; and 6. they induce evolutionary change through natural selection and ecological creativity through self-organization. A new approach to hurricane research will study hurricanes at the same scale at which they operate (i.e., across latitudes and longitudes and over disturbed and undisturbed landscapes). This research will require networks of observation platforms located along expected hurricane paths to facilitate forest structure and functioning observations across gradients of hurricane frequency and intensity. This research will also require use of remote sensing and automated wireless technology, hardened to survive hurricane-strength winds and floods to assure real time measurements of the characteristics of hurricanes and ecosystem responses. No progress will be forthcoming in the understanding of hurricane effects if we do not learn to quantify objectively the energy dissipation of hurricanes on the full grid of affected forests as the hurricane passes over a landscape. [source] Thyroid hormones and their effects: a new perspectiveBIOLOGICAL REVIEWS, Issue 4 2000A. J. HULBERT ABSTRACT The thyroid hormones are very hydrophobic and those that exhibit biological activity are 3,,5,,3,5-Ltetraiodothyronine (T4), 3,,5,3-L-triiodothyronine (T3), 3,,5,,3-L-triiodothyronine (rT3) and 3,5,-Ldiiodothyronine (3,5-T2). At physiological pH, dissociation of the phenolic -OH group of these iodothyronines is an important determinant of their physical chemistry that impacts on their biological effects. When non-ionized these iodothyronines are strongly amphipathic. It is proposed that iodothyronines are normal constituents of biological membranes in vertebrates. In plasma of adult vertebrates, unbound T4 and T3 are regulated in the picomolar range whilst protein-bound T4 and T3 are maintained in the nanomolar range. The function of thyroid-hormone-binding plasma proteins is to ensure an even distribution throughout the body. Various iodothyronines are produced by three types of membrane-bound cellular deiodinase enzyme systems in vertebrates. The distribution of deiodinases varies between tissues and each has a distinct developmental profile. Thyroid hormones have many effects in vertebrates. It is proposed that there are several modes of action of these hormones.(1) The nuclear receptor mode is especially important in the thyroid hormone axis that controls plasma and cellular levels of these hormones.(2) These hormones are strongly associated with membranes in tissues and normally rigidify these membranes.(3) They also affect the acyl composition of membrane bilayers and it is suggested that this is due to the cells responding to thyroid-hormone-induced membrane rigidification. Both their immediate effects on the physical state of membranes and the consequent changes in membrane composition result in several other thyroid hormone effects. Effects on metabolism may be due primarily to membrane acyl changes. There are other actions of thyroid hormones involving membrane receptors and influences on cellular interactions with the extracellular matrix. The effects of thyroid hormones are reviewed and appear to be combinations of these various modes of action. During development, vertebrates show a surge in T4 and other thyroid hormones, as well as distinctive profiles in the appearance of the deiodinase enzymes and nuclear receptors. Evidence from the use of analogues supports multiple modes of action. Re-examination of data from the early 1960s supports a membrane action. Findings from receptor ,knockout' mice supports an important role for receptors in the development of the thyroid axis. These iodothyronines may be better thought of as ,vitamone' -like molecules than traditional hormonal messengers. [source] China's Economic Prospects and Sino,US Economic RelationsCHINA AND WORLD ECONOMY, Issue 2 2006Pingfan Hong F00; P21 Abstract A better comprehension of the mixed sentiment in the rest of world towards the rapid rise of the Chinese economy will depend on the understanding of some key features of the Chinese economy, such as those associated with its size, structure and institution. To further sustain its high growth, China is facing more challenges than it has encountered in the past 2 decades, including a gamut of material constraints. Although polices and technological progress might alleviate many of these constraints, the ultimate solution will still lie in continued institutional reform. China's recent move towards a more flexible exchange rate regime is in line with its broad reform and in accordance with the progress of its development. However, such a move will have limited immediate effects on the prodigious US trade deficit, which itself is a problem rooted in the flawed international reserve system, far beyond a Sino-US trade issue. Edited by Xiaoming Feng [source] | ||||||||||||||||||||||