keyword
MENU ▼
Read by QxMD icon Read
search

Hypothesis

keyword
https://www.readbyqxmd.com/read/28938715/the-harm-done-to-reproducibility-by-the-culture-of-null-hypothesis-significance-testing
#1
Timothy L Lash
In the last few years, stakeholders in the scientific community have raised alarms about a perceived lack of reproducibility of scientific results. In reaction, guidelines for journals have been promulgated and grant applicants have been asked to address the rigor and reproducibility of their proposed projects. Neither solution addresses a primary culprit, which is the culture of null hypothesis significance testing that dominates statistical analysis and inference. In an innovative research enterprise, selection of results for further evaluation based on null hypothesis significance testing is doomed to yield a low proportion of reproducible results and a high proportion of effects that are initially overestimated...
September 15, 2017: American Journal of Epidemiology
https://www.readbyqxmd.com/read/28938714/lash-responds-to-is-reproducibility-thwarted-by-hypothesis-testing-and-the-need-for-cognitive-science-in-methodology
#2
Timothy L Lash
No abstract text is available yet for this article.
September 15, 2017: American Journal of Epidemiology
https://www.readbyqxmd.com/read/28938713/invited-commentary-can-issues-with-reproducibility-in-science-be-blamed-on-hypothesis-testing
#3
Clarice R Weinberg
In the accompanying article (Am J Epidemiol. 2017;186(6):646-647), Dr. Timothy Lash makes a forceful case that the problems with reproducibility in science stem from our "culture" of null hypothesis significance testing. He notes that when attention is selectively given to statistically significant findings, the estimated effects will be systematically biased away from the null. Here I revisit the recent history of genetic epidemiology and argue for retaining statistical testing as an important part of the tool kit...
September 15, 2017: American Journal of Epidemiology
https://www.readbyqxmd.com/read/28938712/invited-commentary-the-need-for-cognitive-science-in-methodology
#4
Sander Greenland
There is no complete solution for the problem of abuse of statistics, but methodological training needs to cover cognitive biases and other psychosocial factors affecting inferences. The present paper discusses 3 common cognitive distortions: 1) dichotomania, the compulsion to perceive quantities as dichotomous even when dichotomization is unnecessary and misleading, as in inferences based on whether a P value is "statistically significant"; 2) nullism, the tendency to privilege the hypothesis of no difference or no effect when there is no scientific basis for doing so, as when testing only the null hypothesis; and 3) statistical reification, treating hypothetical data distributions and statistical models as if they reflect known physical laws rather than speculative assumptions for thought experiments...
September 15, 2017: American Journal of Epidemiology
https://www.readbyqxmd.com/read/28938616/identification-of-potential-cancer-related-pseudogenes-in-lung-adenocarcinoma-based-on-cerna-hypothesis
#5
Yunzhen Wei, Zhiqiang Chang, Cheng Wu, Yinling Zhu, Kun Li, Yan Xu
Pseudogenes are initially regarded as non-functional genomic fossils resulted from inactivating gene mutations during evolution. Far from being silent, pseudogenes are proved to regulate the expression of protein-coding genes through function as microRNA sponge in vivo. The aim of our study was to propose an integrative systems biology approach to identify disease pseudogenes base on competitive endogenous RNA (ceRNA) hypothesis. Here, we applied our method to lung adenocarcinoma (LUAD) RNASeq data from TCGA and identified 33 candidate pseudogenes...
August 29, 2017: Oncotarget
https://www.readbyqxmd.com/read/28938596/vitamin-d3-induces-vitamin-d-receptor-and-hdac11-binding-to-relieve-the-promoter-of-the-tight-junction-proteins
#6
Feng-Hua Liu, Shan-Shan Li, Xiao-Xi Li, Shuai Wang, Mao-Gang Li, Li Guan, Tian-Gang Luan, Zhi-Gang Liu, Zhan-Ju Liu, Ping-Chang Yang
Intestinal epithelial barrier dysfunction and vitamin D (VitD)-deficiency play a critical role in a large number of diseases. The histone deacetylases (HDAC) are associated with a large number of immune diseases. This study tests a hypothesis that the interaction between VitD and HDAC is associated with the regulation of epithelial barrier functions. In this study, human intestinal epithelial cell line, T84 cells, was cultured into monolayers to be used as a model to test the epithelial barrier functions. We observed that in a VitD-deficient environment, the T84 monolayer barrier function was compromised...
August 29, 2017: Oncotarget
https://www.readbyqxmd.com/read/28938523/hypothermia-induced-by-anesthesia-regulates-various-signals-expressions-in-the-hippocampus-of-animals
#7
Huimei Hao, Shanshan Wang
Though important for a variety of medical procedures, general anesthesia is not a problem free. Some anesthetics have been suggested to affect a number of signals, which are associated with memory consolidation and cognition. In the present study, we attempted to investigate the molecular mechanism of anesthesia-regulated processes. We found that under hypothermic condition, anesthetic of isoflurane enhances various signals expression in hippocampus, including Hspd1, Actb, Mgst1, THBS4, Syp, C1QC, Serpine, Plat, and Ngf, which were related to cellular stress, neural plasticity responses, and hippocampal injury...
September 18, 2017: Biomedicine & Pharmacotherapy, Biomédecine & Pharmacothérapie
https://www.readbyqxmd.com/read/28938478/roux-en-y-gastric-bypass-surgery-has-unique-effects-on-postprandial-fgf21-but-not-fgf19-secretion
#8
Lydia-Ann L S Harris, Gordon I Smith, Bettina Mittendorfer, J Christopher Eagon, Adewole L Okunade, Bruce W Patterson, Samuel Klein
Context: Fibroblast growth factors (FGF) 19 and FGF21 are secreted by the intestine and liver in response to macronutrient intake. Intestinal resection and reconstruction via bariatric surgery may alter their regulation. Objective: We tested the hypothesis that weight loss induced by Roux-en-Y gastric bypass (RYGB) surgery, but not matched weight loss induced by laparoscopic adjustable gastric banding (LAGB), increases postprandial plasma FGF19 and FGF21 concentrations...
August 17, 2017: Journal of Clinical Endocrinology and Metabolism
https://www.readbyqxmd.com/read/28938475/modeling-the-sex-differences-and-inter-individual-variability-in-the-activity-of-the-hypothalamic-pituitary-adrenal-axis
#9
Rohit T Rao, Ioannis P Androulakis
Significant sex differences exist in the activity of the hypothalamic-pituitary-adrenal (HPA) axis. These differences are thought to contribute to the disparity in the prevalence of various autoimmune and infectious diseases between males and females. We use a mathematical model of the HPA axis to evaluate the hypothesis that differential sensitivity and negative feedback of the HPA axis network are causal factors for the observed sex differences in its activity. In doing so, we implicitly account for the differential influence of gonadal hormones on the HPA axis...
August 31, 2017: Endocrinology
https://www.readbyqxmd.com/read/28938441/canonical-wnt-signaling-regulates-the-pituitary-organizer-and-pituitary-gland-formation
#10
Allison M Osmundsen, Jessica L Keisler, M Mark Taketo, Shannon W Davis
The pituitary organizer is a domain within the ventral diencephalon that expresses Bmp4, Fgf8, and Fgf10, which induces the formation of the pituitary precursor, Rathke's pouch, from the oral ectoderm. The WNT signaling pathway regulates this pituitary organizer such that loss of Wnt5a leads to an expansion of the pituitary organizer and an enlargement of Rathke's pouch. WNT signaling is classified into canonical signaling, which is mediated by β-CATENIN, and non-canonical signaling, which operates independently of β-CATENIN...
August 16, 2017: Endocrinology
https://www.readbyqxmd.com/read/28938440/sex-differences-in-the-hormonal-and-metabolic-response-to-dietary-protein-dilution
#11
Karlton R Larson, Kimberly A Russo, Yanbin Fang, Niloufar Mohajerani, Michael L Goodson, Karen K Ryan
Consumption of a low-protein, high-carbohydrate diet induces a striking increase in circulating fibroblast growth factor-21 (FGF21), which is associated with improved cardiometabolic health and increased longevity. Increased lifespan during this dietary protein 'dilution' has been explained by resource-mediated trade-offs between reproduction and survival, such that fecundity is optimized at a greater relative intake of proteins:carbohydrates. The magnitude of this trade-off is thought to be sex-dependent. Here, we tested the hypothesis that metabolic responses to dietary protein dilution are likewise dependent on sex...
August 9, 2017: Endocrinology
https://www.readbyqxmd.com/read/28938425/linking-stress-and-infertility-a-novel-role-for-ghrelin
#12
Luba Sominsky, Deborah M Hodgson, Eileen A McLaughlin, Roger Smith, Hannah M Wall, Sarah J Spencer
Infertility affects a remarkable one in four couples in developing countries. Psychological stress is a ubiquitous facet of life, and while stress affects us all at some point, prolonged or unmanageable stress may become harmful for some individuals, negatively impacting on their health, including fertility. For instance, women who struggle to conceive are twice as likely to suffer from emotional distress than fertile women. Assisted reproductive technology treatments place an additional physical, emotional and financial burden of stress, particularly on women, who are often exposed to invasive techniques associated with treatment...
July 27, 2017: Endocrine Reviews
https://www.readbyqxmd.com/read/28938276/anesthesia-with-dexmedetomidine-and-low-dose-isoflurane-increases-solute-transport-via-the-glymphatic-pathway-in-rat-brain-when-compared-with-high-dose-isoflurane
#13
Helene Benveniste, Hedok Lee, Fengfei Ding, Qian Sun, Ehab Al-Bizri, Rany Makaryus, Stephen Probst, Maiken Nedergaard, Elliot A Stein, Hanbing Lu
BACKGROUND: The glymphatic pathway transports cerebrospinal fluid through the brain, thereby facilitating waste removal. A unique aspect of this pathway is that its function depends on the state of consciousness of the brain and is associated with norepinephrine activity. A current view is that all anesthetics will increase glymphatic transport by inducing unconsciousness. This view implies that the effect of anesthetics on glymphatic transport should be independent of their mechanism of action, as long as they induce unconsciousness...
September 22, 2017: Anesthesiology
https://www.readbyqxmd.com/read/28938177/the-osmotin-of-calotropis-procera-latex-is-not-expressed-in-laticifer-free-cultivated-callus-and-under-salt-stress
#14
Isabel C C Souza, Márcio V Ramos, José H Costa, Cleverson D T Freitas, Raquel S B Oliveira, Frederico B Moreno, Renato A Moreira, Cristina P S Carvalho
The latex of Calotropis procera has previously been reported to contain osmotin. This protein (CpOsm) inhibited phytopathogens and this was mechanistically characterized. Here, the time-course profile of CpOsm transcripts was examined in the salt-stressed cultivated callus of C. procera in order to better understand its role in the physiology of the plant. Stressed callus (80 mM NaCl) showed an unbalanced content of organic compounds (proline and total soluble sugar) and inorganic ions (Na(+), Cl(-), and K(+))...
September 14, 2017: Plant Physiology and Biochemistry: PPB
https://www.readbyqxmd.com/read/28938009/altering-neuronal-excitability-to-preserve-network-connectivity-in-a-computational-model-of-alzheimer-s-disease
#15
Willem de Haan, Elisabeth C W van Straaten, Alida A Gouw, Cornelis J Stam
Neuronal hyperactivity and hyperexcitability of the cerebral cortex and hippocampal region is an increasingly observed phenomenon in preclinical Alzheimer's disease (AD). In later stages, oscillatory slowing and loss of functional connectivity are ubiquitous. Recent evidence suggests that neuronal dynamics have a prominent role in AD pathophysiology, making it a potentially interesting therapeutic target. However, although neuronal activity can be manipulated by various (non-)pharmacological means, intervening in a highly integrated system that depends on complex dynamics can produce counterintuitive and adverse effects...
September 22, 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28938005/recombinant-vaccines-of-a-cd4-t-cell-epitope-promote-efficient-control-of-paracoccidioides-brasiliensis-burden-by-restraining-primary-organ-infection
#16
Rodrigo Assunção Holanda, Julián Esteban Muñoz, Lucas Santos Dias, Leandro Buffoni Roque Silva, Julliana Ribeiro Alves Santos, Sthefany Pagliari, Érica Leandro Marciano Vieira, Tatiane Alves Paixão, Carlos Pelleschi Taborda, Daniel Assis Santos, Oscar Bruña-Romero
Paracoccidioidomycosis (PCM) is an infectious disease endemic to South America, caused by the thermally dimorphic fungi Paracoccidioides. Currently, there is no effective human vaccine that can be used in prophylactic or therapeutic regimes. We tested the hypothesis that the immunogenicity of the immunodominant CD4+ T-cell epitope (P10) of Paracoccidioides brasiliensis gp43 antigen might be significantly enhanced by using a hepatitis B virus-derived particle (VLP) as an antigen carrier. This chimera was administered to mice as a (His)6-purified protein (rPbT) or a replication-deficient human type 5 adenoviral vector (rAdPbT) in an immunoprophylaxis assay...
September 22, 2017: PLoS Neglected Tropical Diseases
https://www.readbyqxmd.com/read/28938002/regional-endothermy-as-a-trigger-for-gigantism-in-some-extinct-macropredatory-sharks
#17
Humberto G Ferrón
Otodontids include some of the largest macropredatory sharks that ever lived, the most extreme case being Otodus (Megaselachus) megalodon. The reasons underlying their gigantism, distribution patterns and extinction have been classically linked with climatic factors and the evolution, radiation and migrations of cetaceans during the Paleogene. However, most of these previous proposals are based on the idea of otodontids as ectothermic sharks regardless of the ecological, energetic and body size constraints that this implies...
2017: PloS One
https://www.readbyqxmd.com/read/28937989/limited-synapse-overproduction-can-speed-development-but-sometimes-with-long-term-energy-and-discrimination-penalties
#18
Harang Ju, Costa M Colbert, William B Levy
Neural circuit development requires that synapses be formed between appropriate neurons. In addition, for a hierarchical network, successful development involves a sequencing of developmental events. It has been suggested that one mechanism that helps speed up development of proper connections is an early overproduction of synapses. Using a computational model of synapse development, such as adaptive synaptogenesis, it is possible to study such overproduction and its role in speeding up development; it is also possible to study other outcomes of synapse overproduction that are seemingly new to the literature...
September 22, 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28937820/sex-allocation-patterns-across-cooperatively-breeding-birds-do-not-support-predictions-of-the-repayment-hypothesis
#19
Nyil Khwaja, Ben J Hatchwell, Robert P Freckleton, Jonathan P Green
The repayment hypothesis predicts that reproductive females in cooperative breeding systems overproduce the helping sex. Thanks to well-documented examples of this predicted sex ratio bias, repayment has been considered an important driver of variation in sex allocation patterns. Here we test this hypothesis using data on population brood sex ratios and facultative sex allocation from 28 cooperatively breeding bird species. We find that biased sex ratios of helpers do not correlate with production biases in brood sex ratios, contrary to predictions...
October 2017: American Naturalist
https://www.readbyqxmd.com/read/28937816/resemblance-to-the-enemy-s-eyes-underlies-the-intimidating-effect-of-eyespots
#20
Karin Kjernsmo, Sami Merilaita
Eyespots of some prey are known to deter predators, but the reason for this response has not yet been established, and thus the taxonomically widespread occurrence of this color pattern has remained an evolutionary conundrum. Two alternative hypotheses propose that (1) the eyelike appearance of the pattern falsely indicates the presence of the predator's own enemy or (2) predators are hardwired to be cautious toward conspicuous prey. Earlier research has pertained mainly to eyespots in butterflies. Here we tested the hypothesis that eyespots resemble eyes by utilizing the lateral position of eyes in fishes...
October 2017: American Naturalist
keyword
keyword
8322
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"