84 research outputs found
MEMS-based thermal management of high heat flux devices edifice: Embedded droplet impingement for integrated cooling of electronics
Increases in microprocessor power dissipation coupled with reductions in feature sizes due to
manufacturing process improvements have resulted in continuously increasing heat fluxes. The ever
increasing chip-level heat flux has necessitated the development of thermal management devices
based on spray and evaporative cooling. This lecture presents a comprehensive review of liquid and
evaporative cooling research applied to thermal management of electronics. It also outlines the
challenges to practical implementation and future research needs.
This presentation also describes the development of EDIFICE: Embedded Droplet Impingement
For Integrated Cooling of Electronics. The EDIFICE project seeks to develop an integrated droplet
impingement cooling device for removing chip heat fluxes over 100 W/cm2, employing latent heat of
vaporization of dielectric fluids. Micro-manufacturing and MEMS (Micro Electro-Mechanical
Systems) will be discussed as enabling technologies for innovative cooling schemes recently
proposed. Micro-spray nozzles are fabricated to produce 50-100 micron droplets coupled with
surface texturing on the backside of the chip to promote droplet spreading and evaporation. A novel
feature to enable adaptive on-demand cooling is MEMS sensing (on-chip temperature, remote IR
temperature and ultrasonic dielectric film thickness) and MEMS actuation. EDIFICE is integrated
within the electronics package and fabricated using advanced micro-manufacturing technologies
(e.g., Deep Reactive Ion Etching (DRIE) and CMOS CMU-MEMS). The development of EDIFICE
involves modeling, CFD simulations, and physical experimentation on test beds. This lecture will
then examine jet impingement cooling of EDIFICE with a dielectric coolant and the influence of fluid
properties, micro spray characteristics, and surface evaporation. The development of micro nozzles,
micro-structured surface texturing, and system integration of the evaporator will also be discussed
Modeling and simulation of a rollerball microfluidic device
The fluid delivery process through a rollerball device is investigated by means of physical modeling and numerical simulations. The microfluidic device is intended to deliver liquid above a substrate interacting with the surrounding air. While the fluid is delivered, air entrainment occurs through the capillary gap, creating a two-phase liquid-gas mixture whose composition and properties affect significantly the quality of the continuous fluid deposition. For the numerical solution of the 2D two-phase flow governing equations, the finite volumebased finite element method is used with 2nd order time-space schemes for the fully coupled system of equations. The quality of the liquid micro-volume delivery proves to be largely affected by both the speed of the roller and fluid properties. It
is found that only under very low speed and some fluid properties, it is possible to guarantee a gas free liquid deposition. Envisioning the potential use of this convenient and
popular device in the deployment of microfluid layers or substances at very small quantities with controlled quality, it is apparent the need for handling and channeling out the air entrainment without perturbing the liquid qualit
Hypomelanosis of Ito with a trisomy 2 mosaicism: a case report
Introduction: Hypomelanosis of Ito is a rare neurocutaneous disorder, characterized by streaks and swirls of hypopigmentation following the lines of Blaschko that may be associated to systemic abnormalities involving the central nervous system and musculoskeletal system. Despite the preponderance of reported sporadic hypomelanosis of Ito, few reports of familial hypomelanosis of Ito have been described. Case presentation: A 6-month-old Caucasian girl presented with unilateral areas of hypomelanosis distributed on the left half of her body and her father presented with similar mosaic hypopigmented lesions on his upper chest. Whereas both blood karyotypes obtained from peripheral lymphocyte cultures were normal, a 16% trisomy 2 mosaicism was found in cultured skinfibroblasts derived from a hypopigmented skin area of her father. Conclusions: Familial cases of hypomelanosis of Ito are very rare and can occur in patients without systemic involvement. Hypomelanosis of Ito constitutes a non-specific diagnostic definition including different clinical entities with a wide phenotypic variability, either sporadic or familial. Unfortunately, a large number of cases remain misdiagnosed due to both diagnostic challenges and controversial issues on cutaneous biopsies in the pediatric population
KiDS-1000 Cosmology:Multi-probe weak gravitational lensing and spectroscopic galaxy clustering constraints
We present a joint cosmological analysis of weak gravitational lensing
observations from the Kilo-Degree Survey (KiDS-1000), with redshift-space
galaxy clustering observations from the Baryon Oscillation Spectroscopic Survey
(BOSS), and galaxy-galaxy lensing observations from the overlap between
KiDS-1000, BOSS and the spectroscopic 2-degree Field Lensing Survey (2dFLenS).
This combination of large-scale structure probes breaks the degeneracies
between cosmological parameters for individual observables, resulting in a
constraint on the structure growth parameter , that has the same overall precision as that
reported by the full-sky cosmic microwave background observations from Planck.
The recovered amplitude is low, however, by % relative to
Planck. This result builds from a series of KiDS-1000 analyses where we
validate our methodology with variable depth mock galaxy surveys, our lensing
calibration with image simulations and null-tests, and our
optical-to-near-infrared redshift calibration with multi-band mock catalogues
and a spectroscopic-photometric clustering analysis. The systematic
uncertainties identified by these analyses are folded through as nuisance
parameters in our cosmological analysis. Inspecting the offset between the
marginalised posterior distributions, we find that the -difference with
Planck is driven by a tension in the matter fluctuation amplitude parameter,
. We quantify the level of agreement between the CMB and our
large-scale structure constraints using a series of different metrics, finding
differences with a significance ranging between , when
considering the offset in , and , when considering the
full multi-dimensional parameter space.Comment: 25 pages, 11 figures, 5 tables, A&A accepted, including a new
appendix on Intrinsic Alignments. The KiDS-1000 data products are available
for download at http://kids.strw.leidenuniv.nl/DR4/lensing.php. This data
release includes open source software, the shear-photo-z catalogue, the
cosmic shear and 3x2pt data vectors and covariances, and posteriors in the
form of Multinest chain
Strong detection of the CMB lensingxgalaxy weak lensingcross-correlation from ACT-DR4,PlanckLegacy and KiDS-1000
We measure the cross-correlation between galaxy weak lensing data from the
Kilo Degree Survey (KiDS-1000, DR4) and cosmic microwave background (CMB)
lensing data from the Atacama Cosmology Telescope (ACT, DR4) and the Planck
Legacy survey. We use two samples of source galaxies, selected with photometric
redshifts, and , which produce a
combined detection significance of the CMB lensing/weak galaxy lensing
cross-spectrum of . With the lower redshift galaxy sample, for which
the cross-correlation is detected at a significance of , we present
joint cosmological constraints on the matter density parameter, , and the matter fluctuation amplitude parameter, , marginalising
over three nuisance parameters that model our uncertainty in the redshift and
shear calibration, and the intrinsic alignment of galaxies. We find our
measurement to be consistent with the best-fitting flat CDM
cosmological models from both Planck and KiDS-1000. We demonstrate the capacity
of CMB-weak lensing cross-correlations to set constraints on either the
redshift or shear calibration, by analysing a previously unused high-redshift
KiDS galaxy sample , with the cross-correlation detected at
a significance of . This analysis provides an independent assessment
for the accuracy of redshift measurements in a regime that is challenging to
calibrate directly owing to known incompleteness in spectroscopic surveys.Comment: 13 pages, 9 figures, 1 tables, submitted to A&
Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)
In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field
Shape deposition manufacturing with microcasting
Abstract: "This paper provides a brief overview of an emerging application for solid freeform fabrication known as Shape Deposition Manufacturing (SDM) with Microcasting. The SDM microcasting process has been used to manufacture complex geometric shapes from CAD models. This novel manufacturing process is briefly described, and a sample artifact is shown. Our current research is described, involving the thermal behavior of the process, the bonding of deposited layers, and droplet fluid dynamics. We have gained significant understanding of the relationship between process parameters and the final quality of artifacts created by microcasting, and continue to investigate the effect of process parameters to develop a systematic representation of the parameter design space; current efforts are directed towards improving the numerical simulations to more accurately predict and control the microcasting process.
- …