Prickle1 is required for EMT and migration of zebrafish cranial neural crest

The neural crest—a key innovation of the vertebrates—gives rise to diverse cell types including melanocytes, neurons and glia of the peripheral nervous system, and chondrocytes of the jaw and skull. Proper development of the cephalic region is dependent on the tightly-regulated specification and migration of cranial neural crest cells (NCCs). The core PCP proteins Frizzled and Disheveled have previously been implicated in NCC migration. Here we investigate the functions of the core PCP proteins Prickle1a and Prickle1b in zebrafish cranial NCC development. Using analysis of pk1a and pk1b mutant embryos, we uncover similar roles for both genes in facilitating cranial NCC migration. Disruption of either gene causes pre-migratory NCCs to cluster together at the dorsal aspect of the neural tube, where they adopt aberrant polarity and movement. Critically, in investigating Pk1-deficient cells that fail to migrate ventrolaterally, we have also uncovered roles for pk1a and pk1b in the epithelial-to-mesenchymal transition (EMT) of pre-migratory NCCs that precedes their collective migration to the periphery. Normally, during EMT, pre-migratory NCCs transition from a neuroepithelial to a bleb-based and subsequently, mesenchymal morphology capable of directed migration. When either Pk1a or Pk1b is disrupted, NCCs continue to perform blebbing behaviors characteristic of pre-migratory cells over extended time periods, indicating a block in a key transition during EMT. Although some Pk1-deficient NCCs transition successfully to mesenchymal, migratory morphologies, they fail to separate from neighboring NCCs. Additionally, Pk1b-deficient NCCs show elevated levels of E-Cadherin and reduced levels of N-Cadherin, suggesting that Prickle1 molecules regulate Cadherin levels to ensure the completion of EMT and the commencement of cranial NCC migration. We conclude that Pk1 plays crucial roles in cranial NCCs both during EMT and migration. These roles are dependent on the regulation of E-Cad and N-Cad

Offshore wind energy in the U.S. Mid-Atlantic Region and the EPA clean power plan proposed rule

ABSTRACT Offshore Wind Energy in the U.S. Mid-Atlantic Region and the EPA Clean Power Plan Proposed Rule Kamil E. Armaiz Nolla Carbon dioxide (CO2) levels in the atmosphere have been experiencing a rapid rise since the start of the Industrial Era. Human activities have been recognized by the scientific community as the main contributors to CO2 emissions by way of the combustion of fossil fuels such as coal, oil, and natural gas. Scientific consensus about human-induced climate change has been recognized since 1992 by the work of the United Nations Framework Convention on Climate. Since then, global efforts to mitigate climate change have been underway. On June 2, 2014 the U.S. Environmental Protection Agency published a proposal to reduce the emissions of carbon dioxide produced by existing power plants. The plan is based on state-specific emission rate targets for the power sector in order to achieve a national carbon emission reduction of 30 percent by 2030 from 2005 levels. The plan proposes measures known as the Best System of Emission Reduction, or BSER, to achieve the required targets. One of these measures is to use renewable energy technology that is already part of the renewable portfolio standards that have been established by each state. This work looks at the role of offshore wind (OSW) energy as a significant contributor to CO2 reductions. The U.S. Mid-Atlantic Region, specifically the states of Delaware, Maryland, New Jersey, and Virginia, holds an abundance of strong and steady offshore winds already identified by the Bureau of Ocean Energy Management in Wind Energy Areas. The Clean Power Plan does not include OSW energy as part of the BSER due to the current absence of operational OSW facilities in the United States, preventing the calculation of a benchmark development rate target. However, this dissertation makes a compelling case for the integration of OSW energy as a significant player in the EPA Clean Power Plan Proposed Rule through scenarios that consider different levels of OSW deployment for the Mid-Atlantic Region within the Plan’s methodology calculations

Counting elements of the congruence subgroup

We obtain asymptotic formulas for the number of matrices in the congruence subgroup $$\Gamma_0(Q) = \left\{ A\in\mathrm{SL}_2(\mathbb Z):~c \equiv 0 \pmod Q\right\},$$ which are of naive height at most $X$. Our result is uniform in a very broad range of values $Q$ and $X$

Modelling foraging movements of diving predators : A theoretical study exploring the effect of heterogeneous landscapes on foraging efficiency

Peer reviewedPublisher PD

Intraproblem retention during learning-set acquisition in bluejays (Cyanocitta eristata)

Recent experiments have shown that bluejays and rhesus monkeys experienced in object-discrimination learning set (ODLS) exhibit a rapid decline in performance when a retention interval is inserted between successive trials of individual ODLS problems (Bessemer & Stollnitz, 1971; Kamil, Lougee, & Shulman, 1973). This intraproblem retention loss (IRL), or forgetting, has been interpreted as reflecting the importance of relatively transient memory traces for events of previous trials of the ODLS problem as determinants of choice behavior on the current trial of the same problem. According to this model, these memory traces function as discriminative stimuli in a conditional discrimination which controls choice behavior in the sophisticated subject. For example, if the subject remembers having responded to Object x, and having been rewarded on the previous trial(s), then he approaches Object x on the next trial; however, if he remembers nonreward, then he avoids Object x. This model is obviously similar to the win-stay, lose-shift hypothesis proposed by Levine (1959), but would seem to have two advantages. First, it specifies the stimuli, specific memory traces of previous trial events, necessary for hypothesis behavior to occur. Second, it explains the finding of rapid IRL if we assume that these memory traces are transient, losing strength during retention intervals

Counting embeddings of free groups into SL2(Z)\mathrm{SL}_2(\mathbb{Z}) and its subgroups

We show that if one selects uniformly independently and identically distributed matrices $A_1, \ldots, A_s \in \mathrm{SL}_2(\mathbb{Z})$ from a ball of large radius $X$ then with probability at least $1 - X^{-1 + o(1)}$ the matrices $A_1, \ldots, A_s$ are free generators for a free subgroup of $\mathrm{SL}_2(\mathbb{Z})$. Furthermore, to show the flexibility of our method we do similar counting for matrices from the congruence subgroup $\Gamma_0(Q)$ uniformly with respect to the positive integer $Q\le X$. This improves and generalises a result of E. Fuchs and I. Rivin (2017) which claims that the probability is $1 + o(1)$. We also disprove one of the statements in their work that has been used to deduce their claim

Inpatient charges among HIV/AIDS patients in Rhode Island from 2000–2004

<p>Abstract</p> <p>Background</p> <p>Inpatient HIV/AIDS charges decreased from 1996–2000. This decrease was mainly attributable to treatment of HIV/AIDS patients with Highly Active Antiretroviral Therapy (HAART). This study aims to evaluate the trend in inpatient charges from 2000–2004.</p> <p>Methods</p> <p>Rhode Island Hospital Discharge Data (HDD) from 2000 to 2004 was used. International Classification of Disease (ICD-9) diagnosis code 042–044 was used to identify HIV/AIDS admissions. The final study population included 1927 HIV/AIDS discharges. We used a multivariable linear regression model to examine the factors associated with inflation adjusted inpatient charges.</p> <p>Results</p> <p>We found a significant increase in inpatient charges from 2000–2004 after adjusting for length of stay (LOS), gender, age, race and point of entry for hospitalization. In addition to calendar year, LOS, gender and race were also associated with inpatient charges.</p> <p>Conclusion</p> <p>HIV/AIDS inpatient charges increased after adjusting for inflation despite earlier studies that showed a decline. Our results have implications for uninsured, as well as insured HIV/AIDS patients who do not have a medical plan that covers their charges sufficiently. Future research should investigate what factors are contributing to rising inpatient charges among HIV/AIDS patients.</p