Papers by Michael David Hidalgo Valdez
Transportation Journal, 2005
Page 1. H. DAVID BESS HENRY S. MARCUS MICHAEL E. VALDEZ Notes and Comments: Government Transporta... more Page 1. H. DAVID BESS HENRY S. MARCUS MICHAEL E. VALDEZ Notes and Comments: Government Transportation Statistics: Use with Caution: A Research Note This note relates an experience-based lesson: Empirical ...
Proceedings of the 38th Annual Hawaii International Conference on System Sciences
When introducing a new technology that changes the core processes of an organization, such as an ... more When introducing a new technology that changes the core processes of an organization, such as an e-health initiative, it is important that the structural design and culture of the organization is aligned with the predominant national culture in which the organization is embedded. When a harmonious alignment is achieved, speedy and effective organizational learning can occur. This, in turn, promotes effective utilization of the new technology. The cultural dimension of uncertainty avoidance provides guidance on the type of organizational culture and structure to establish. Our research in five countries supports the believe that in national cultures in which high uncertainty avoidance is predominant, such as France, a highly mechanistic organization is favored; in cultures in which a low uncertainty avoidance dominates, such as the USA, a more organic organizational form should increase the probability of success in promoting effective organizational learning and thereby successfully implementing an ehealth strategic intent.
Journal of Investigative Medicine High Impact Case Reports, 2021
The cases of human infections caused by Serratia fonticola are relatively rare. The few cases tha... more The cases of human infections caused by Serratia fonticola are relatively rare. The few cases that have been reported primarily describe skin and soft tissue, urinary, and biliary tract infections. We describe a case of a 59-year-old man with infected bilateral lower extremity wounds who developed endocarditis due to S fonticola confirmed with transesophageal echocardiogram. The patient was treated with 6 weeks of antibiotic therapy and had an uneventful recovery. After a thorough review of the literature using PubMed and Google Scholar, we concluded that this is the first reported case of endocarditis caused by S fonticola.
Journal of Transportation Management, 2005
Blanket" rate structures apply uniform rates to a geographical region in spite of differences in ... more Blanket" rate structures apply uniform rates to a geographical region in spite of differences in the costs of carrying the goods. They are generally utilized by carriers to achieve some strategic objective, whether rate simplification, to be more competitive, or to meet some political objectives. While blanket rates are common in land transportation, the Hawai'i waterborne trade offers a unique example of this pricing mechanism. Further, given new and potential competitive factors in this trade, this is a unique case study for those interested in transportation pricing and the economic impacts of changes in the competitive struct ure in an isolated market.
Human Systems Management, 2011
Entrepreneurship is viewed as an important driver of economic development. Scholars have differen... more Entrepreneurship is viewed as an important driver of economic development. Scholars have differentiated two dimensions of entrepreneurship: (1) opportunistic entrepreneurship driven primarily by the recognition of opportunity arising from an innovative idea and, (2) necessity entrepreneurship driven primarily by the belief that one's own business offers the likelihood of the highest utility. Both opportunistic and necessity entrepreneurship contribute to economic development. However, cultural norms of comfort with uncertainty may impact these two dimensions of entrepreneurship differentially. Therefore, in order to maximize economic development through entrepreneurial activities, differential national policy and managerial approaches may be advised across diverse nation states.
Journal of Investigative Medicine High Impact Case Reports, 2019
Opportunistic infections (OIs) are a significant cause of morbidity and mortality in immunosuppre... more Opportunistic infections (OIs) are a significant cause of morbidity and mortality in immunosuppressed patients and may be due to bacteria, virus, protozoa, or fungi. Toxoplasmosis is a common cause of central nervous system infection in human immunodeficiency virus (HIV) patients. Coccidioidomycosis is a relatively common fungal infection that may lead to disseminated disease and fungemia in immune-compromised hosts living in endemic regions. This single-patient case report documents the presentation, diagnosis, management, and outcome of concomitant central nervous system toxoplasmosis and diffuse miliary pneumonia with fungemia due to disseminated seronegative Coccidioides immitis in a 33-year-old male patient recently diagnosed with chronic advanced HIV. Impaired cellular immune function, such as defects in the IL-12/IFN-γ pathway or T-helper IL-17-mediated response, is associated with increased severity of coccidioidomycosis. Fungemia and acute respiratory distress syndrome are ...
SPIE Proceedings, 1993
Experiments were conducted with a neutral-buoyancy robot to test whether vehicle station keeping ... more Experiments were conducted with a neutral-buoyancy robot to test whether vehicle station keeping and end effector disturbance compensation significantly affect human teleoperation performance. The vehicle used for experiments, called the Submersible for Telerobotic Astronautical Research, or STAR, is a free-flying underwater telerobot equipped with a three degree of freedom arm, a stereo pan/tilt camera platform, and a vision-based navigation system. Using visual feedback from a fixed onboard camera, test subjects performed a Fitts-type tapping task with the arm while the vision navigator and control system held the vehicle steady relative to a visual reference target. In the absence of other factors, tight station keeping was clearly desirable as test subjects performed the task significantly better with a steady vehicle. However, tight station keeping makes more demands on the propulsion system, increasing fuel requirements substantially. An alternative is to have the robotic arm compensate for vehicle motion, reducing end effector position sensitivity to vehicle motion. With the arm in effect bearing a portion of the station keeping burden, subjects performed essentially as well whether vehicle station keeping was tight or loose. Since end effector disturbance compensation requires little if any extra arm motion, it provides the benefits of tight station-keeping without the associated cost in fuel. The implications for space-based operations are twofold. First, the use of arm motion compensation may significantly reduce the mass of fuel that must be launched into orbit to resupply the propulsion system. Second, free-flying telerobots do not need to be designed for high-authority thruster control.
Systematic and Applied Microbiology, 2012
Several closely related strains of the thermophilic bacterium Dictyoglomus have been isolated fro... more Several closely related strains of the thermophilic bacterium Dictyoglomus have been isolated from various hot springs on the Philippine archipelago. These strains as well as Dictyoglomus thermophilum H-6-12 were analyzed in view of the structure-functional relationships of the cell envelopes. All envelopes of Dictyoglomus strains show several peculiar features that are apparently either unique for the genus or common for other phylogenetically related Thermotogales. The filamentous cells develop pili at the cell poles, guided by large columnar protein assemblies that traverse the periplasm. Filamentous protein complexes span the periplasmic space at the longitudinal sides of the cell. By the end of the exponential growth phase, Dictyoglomus strains form multicellular aggregates ("rotund bodies") inside a compartment surrounded by a single, continuous outer envelope. The formation of these rotund bodies which are also found in some other deeply branching thermophilic phyla (Thermotoga, Thermus) was studied in detail. The transition between unicellular and multicellular lifestyle can be explained by the partial detachment of a protoplast from the outer envelope during cell division. When the outer envelope is partially detached from the protoplast, mechanical forces generated by protoplast elongation may drive cell rearrangement of daughter cells inside the compartment. During the following rounds of cell division, the overall shape of the compartment changes from spindle-like to globular geometry. Analysis of subcellular fractions of Dictyoglomus cells shows that glucan hydrolases are associated with the compartment. This feature is discussed in view of the multicellular life style of Dictyoglomus.
Proceedings of the National Academy of Sciences, 2014
Significance A subset of our body’s tissues is continuously renewed through cell division. Tissue... more Significance A subset of our body’s tissues is continuously renewed through cell division. Tissue-specific stem cells support this tissue turnover, and understanding the mechanisms that control the behavior of these stem cells is important to understanding the health of the tissue. In this work, we identify a novel regulator of the intestinal stem cells. We find that, when the transcription factor YY1 is inactivated, intestinal stem cells can no longer renew themselves. We show that YY1 controls mitochondrial gene expression, and loss of YY1 results in loss of mitochondrial structural integrity. This work, therefore, provides a link between a mitochondrial regulator and stem cell function and broadens our appreciation of metabolic regulation in tissue-specific stem cells.
Nephrology Dialysis Transplantation, 2009
Background. Autosomal dominant polycystic kidney disease (ADPKD) shows an increase in both urine ... more Background. Autosomal dominant polycystic kidney disease (ADPKD) shows an increase in both urine monocyte chemoattractant protein-1 (MCP-1) and carotid intimamedia thickness (CIMT) before changes in serum creatinine concentration. Although microalbuminuria is an index of disease progression, data on whether renal alterations and vascular remodelling are already present at normal or minimally increased levels of urine albumin excretion in early stages of the disease are lacking. Methods. Forty-eight ADPKD patients (24.8 ± 0.8 years) with normal renal function (MDRD 108.1 ± 3.1 ml/min) and 21 age-matched controls were studied in a crosssectional study. The urine albumin/creatinine ratio (UACR) above the upper range of controls (6.8 mg/g) was taken as the predictor of renal alterations and vascular remodelling. Urine MCP-1, MCP-1 fractional excretion (FE MCP-1), endothelial-dependent vascular relaxation (EDVR), aortic pulse-wave velocity (Ao-PWV) and CIMT were chosen as biological markers. Results. No differences between ADPKD with UACR ≤6.8 mg/g and controls were observed in urine MCP-1 (77.7 ± 13.9 versus 57.8 ± 6.3 ng/g), FE MCP-1 (91 ± 19 versus 74 ± 8%) and CIMT (0.47 ± 0.06 versus 0.44 ± 0.07 mm), respectively. Conversely, ADPKD with UACR >6.8 mg/g showed values that were different from the two other groups. In addition, patients with UACR >6.8 and <20 mg/g showed greater values for urine MCP-1, FE MCP-1 and CIMT (131.8 ± 21.7 ng/g, 159 ± 31% and 0.55 ± 0.05 mm, respectively), as compared with patients with UACR ≤6.8 mg/g. The same pattern was found in a subset of normotensive ADPKD patients. No differences were found in EDVR and Ao-PWV. Conclusion. In young ADPKD patients, normal levels of UACR suggest that renal interstitium is comparable to that in healthy subjects and indicate an absence of subtle atherosclerotic changes in the carotid arteries. Likewise, early renal and vascular changes may be present at UACR below the levels defined as microalbuminuria.
Journal of Bacteriology, 2007
The cellular localization and processing of the endo-xylanases (1,4-β- d -xylan-xylanohydrolase; ... more The cellular localization and processing of the endo-xylanases (1,4-β- d -xylan-xylanohydrolase; EC 3.2.1.8) of the hyperthermophile Thermotoga maritima were investigated, in particular with respect to the unusual outer membrane (“toga”) of this gram-negative bacterium. XynB (40 kDa) was detected in the periplasmic fraction of T. maritima cells and in the culture supernatant. XynA (120 kDa) was partially released to the surrounding medium, but most XynA remained cell associated. Immunogold labeling of thin sections revealed that cell-bound XynA was localized mainly in the outer membranes of T. maritima cells. Amino-terminal sequencing of purified membrane-bound XynA revealed processing of the signal peptide after the eighth residue, thereby leaving the hydrophobic core of the signal peptide attached to the enzyme. This mode of processing is reminiscent of type IV prepilin signal peptide cleavage. Removal of the entire XynA signal peptide was necessary for release from the cell becau...
Journal of Asia Business Studies, 2009
... Bhawuk, Dharm PS, Vijayan Munusamy, and David Bechthold (2004), Cul-ture and Economic Succes... more ... Bhawuk, Dharm PS, Vijayan Munusamy, and David Bechthold (2004), Cul-ture and Economic Success, paper presented at the XVIIth International ... House, Robert J., Paul J. Hanges, Mansour J. Javidan, Peter W. Dorfman, and Vipin Gupta (Eds.), (2004), Culture, Leadership ...
Journal of Organizational Psychology vol, 2011
This study empirically examines the relationship between entrepreneurial success and individual e... more This study empirically examines the relationship between entrepreneurial success and individual entrepreneurs' traditional genealogical-status as well as the status of immediate family members. Results indicated that an individual entrepreneurs' traditional genealogical-status is negatively related to success. Furthermore, a strong positive relationship was evidenced by the status of entrepreneurs' families. In other words, the higher the status of an individual, the less entrepreneurial success achieved. However, if the entrepreneurs' family members were of a higher status, the greater the entrepreneurial success of the entrepreneur. These findings are specifically relevant to developing countries, indigenous populations, and societies with strong traditional obligations.
Entrepreneurship Theory and Practice, 2013
This multicountry study empirically explores the institutional determinants of macro–level entrep... more This multicountry study empirically explores the institutional determinants of macro–level entrepreneurship. Findings suggest that a society's normative, cultural–cognitive, and regulative institutions are related to entrepreneurial activity. Normative and cultural–cognitive institutions’ descriptive power in explaining entrepreneurial activity is higher than regulative institutions’ or per capita gross domestic product. This suggests that differences in values, beliefs, and abilities may play a greater role than purely economic considerations of opportunity and transaction costs. Specific attention is given to opportunity– and necessity–motivated entrepreneurship due to their relationship to economic development.
Clinical Cardiology, 1992
For nearly 30 years clinicians have assumed that diuretic therapy, per se, even in the absence of... more For nearly 30 years clinicians have assumed that diuretic therapy, per se, even in the absence of clinical hypokalemia, can cause false-positive exercise ST-segment responses. The precept has stubbornly persisted in the literature and in the day-today interpretation of exercise tests in clinical settings. The assumption probably originated with very early studies of patients on diuretics, in which other causes of false-positive tests were not excluded. This study was undertaken to show that diuretic therapy alone is not sufficient to cause ST depression. lbenty healthy male volunteers, aged 18 to 35, with normal history and physical examinations, echocardiograms, electrocardiograms, serum electrolytes, renal function tests and exercise tests, took 50 mg of hydrochlorothiazide daily for four weeks. Exercise tests, serum electrolytes, and renal function tests were repeated at Weeks 2 and 4. The administration of the diuretic resulted in a statistically significant reduction in serum potassium (from 4.37f0.37 to 3.96f0.28, and 3.94 f0.31 mEqA at 2 and 4 weeks, respectively). There were no abnormal ST-segment shifts on any of the exercise tests. It is concluded that exercise-induced ST-segment shifts in otherwise healthy young male normokalemic subjects who are taking diuretics should not be ascribed to a false-positive response to diuretics.
Academy of Management Review, 2009
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Papers by Michael David Hidalgo Valdez